II Thoracic Limb

76

I. Vessels & Nerves, left neck & shoulder area, lateral view

B. Cephalic v.*

w

v

NERVES & VESSELS of the THORACIC LIMB - 1

t a

b

A. Ext. jugular v.

1. Axillobrachial v. (I, III): in the carnivore, it is a branch of the cephalic v. in the arm, passing proximally between the deltoideus and triceps brachii mm., then under the deltoideus m. and behind the humerus to dump into the axillary v. (found later) in the armpit (axilla).

2. Omobrachial v. (I, III): a branch of the axillobrachial v. that crosses over the brachio-cephalicus m. to empty into the external jugular v. in the carnivore.

a. Omotransversarius m. (I)b. Trapezius m. (I)c. Latissimus dorsi m. (I) d. Deep pectoral m. (I)e. Long head - triceps brachii m. (I) f. Lateral head - triceps brachii m. (I)g. Deltoid m. (I)h. Extensor carpi radialis m. (II)i. Medial & lateral branches of the superficialbrachiala.(II) j. Medial & lateral branches of the superficialradialn.(I, II) k.Superficialcervicala.andv.(I)m. Cranial vena cava (III)n. Brachiocephalic v. (III)o. Subclavian v. (III)p. Axillary v. (III)

Left side: place your dog in right lateral recumbency. Carefully remove the skin from the neck, left limb, and thorax very carefully, saving all vessels and nerves! Do not have to worry about the cutaneous trunci m., unlike on the right side. - Incise transversely from both ends of your midline inci-sion to the dorsal midline. The cranial incision should pass over the caudal side of the mandible and 1/100" behind the ear.

- Circumscribe an incision 2" (5 cm) distal to the carpus (not the elbow, as was done on the right limb).

- Connect your midline incision with an incision across the axilla and medial side of the limb to the circumscribed incision.

After all the skin incisions are done, separate the skin from

Skinning the left thoracic limb

the body and arm, roughly as done for the right side: - Separate the skin so your assistant can pull on the two skin flaps, stretching the subcutaneous (SQ) tissue.

- Take long, sweeping passes through the SQ reflecting the skin as two long planes to the thoracic limb.

- Extreme care is needed to NOT remove the cephalic v. from the cranial aspect of the forearm and elbow (do not pull off the veins with the skin).. Dissect the skin off the limb to meet the two skin flaps past the limb forming one continuous line of dissection.

. Continue reflecting the single line to the dorsal midline with sweeping passes of the scalpel.

Dissect the large superficial vein in the neck:A. External jugular v. (I, III): the large cutaneous vessel in the neck that is the main venous return from the head. It is formed by the joining of the maxillary and linguofacial vv. near the mandible.

Locate and carefully bluntly dissect the vessels (see box opposite).

B. Cephalic v.: arises on the palmar side of the paw, travels proximally, wrapping around the medial side of the ante-brachium to reach the cranial forearm. It is joined there by the accessory cephalic v. The cephalic v. then continues up the cranial forearm and elbow. It passes over the triceps brachii m. in the arm, then under the brachiocephalicus m. to empty into the external jugular v. close to the thoracic inlet.

C. Accessory cephalic v. (II, III): arising from the dorsum of

2* 1*

z

d

c

f

e

g

q. Subscapular v. (III) r. Brachial v. (III)s. Median v. (III)t. Proximal lateral cutaneous branches (I)u. Intercostobrachial n. (I) v. Sternocephalicus m. (I)w. Brachiocephalicus m. (I)x. Maxillary v. (I) y. Linguofacial v. (I)z. Accessory n. (I)

u

k

y

x

* Definedinthelegendortext j

D*

II Thoracic Limb

77

In the illustration, notice that the cephalic v. is associated with the brachioradialis m., the medial and lateral branches of the superficial brachial a., and the lateral and medial branches of the superficial radial n. (Do not dissect these).

D. Mediancubitalv.:crossesthecranial(flexor)aspectofthe elbow, connecting the cephalic v. with the deep vein on the medial side of the arm (brachial v.),whichyouwillfindlater.E. Brachioradialis m. (II): passes with the cephalic v.

SUPERFICIAL VEINS - 2

B. Cephalic v.*

C. Accessory cephalic v.*

E. Brachioradialis m.

D. Median cubital v.*

i

j

Dissecting vessels and nerves: use a probe and for-ceps /scissors (open and close them in the fascia) to break down the enclosing tissue while the vessels and nerves stretch. Do NOT use a scalpel! Once free and exposed from the fascia, continue freeing the vessel /nerve along its path.

A. Ext. jugular v.*

B. Cephalic v.*

D. Median cubital v.*

1*

2*

m

n

o

pq

r

s

II. Vessels & Nerves, forearm, cranial view

III. Veins of the neck & shoulder, cranial view (modifiedfromEvans'Miller's Anatomy of the Dog)

h

CLINICAL: • Cephalic v.: easiest for venipunc-ture in the dog and thus is often saved for emergencies, using the

external jugular v. instead.• Jugular v. (I, III): just beneath the skin, it is the 2nd most common site for venipuncture after cephalic in the dog. It is not bound in a jugular groove by the brachiocephalicus and sternocephalicus mm. as in the large animals (horse and cow), so it is harder to puncture, as it moves freely.

• Brachioradialis m. (II): not the cephalic v., note when performing a venipuncture, p62.

the paw, it joins the cephalic v. proximal to the carpus. If you can't locate these two veins, look for them attached to the reflected skin of the forearm and arm.

• Veins over the shoulder (axillobrachial, omobrachial): ligate during surgery if

they are in the way.

B*

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78

CERVICAL & BRACHIAL PLEXUSES - 1Start to learn about the nervous system before dissecting the nerves of the thoracic limb.

NERVOUS SYSTEM: the control center allowing the body to react to the environment. It stores, integrates, and initi-ates all appropriate responses to information it receives. It is organized into a communication network.

Structurally the nervous system is divided into the central andperipheralsystems.Thisisanartificialdivisionbe-cause many of the nerves of the body are partly in both divisions.

• Central nervous system (CNS): the control center consist-ing of the brain and spinal cord.

• Peripheral nervous system (PNS): all nerve processes connecting to the CNS, consisting of cranial and spinal nerves and ganglia.

Functionally thenervoussystemisclassifiedbytheactivi-ties that are directed into a somatic and autonomic nervous systems.

• Somatic nervous system (soma, body): carries sensory information from the skin and deeper structures of the body such as skeletal muscle, tendons, joint capsules, bones, etc. to the CNS, and conscious voluntary motor impulses from the CNS to the skeletal muscles along cranial and spinal nn. It functions to keep the body in balance with its external environment by allowing the animal to move and interact with its surroundings. We will deal with this system (somatic) now.

• Autonomic nervous system (ANS): carries involuntary impulses (sensory and motor) to and from smooth muscle, cardiac muscle, and glands of the body via cranial and spinal nn. to and from the CNS (spinal cord and brain). It regulatesthebalance(homeostasis)ofthebody'sinternalenvironment, and, when needed, deals with emergency situations. We will start to learn more about this system in the next chapter: "Thorax."

• Sensory (afferent)and motor(efferent):thetwoimpulsesof the nervous system, both somatic and autonomic.

Read the following and study the illustration, and any avail-able models before dissecting the nerves and vessels of the neck and forelimb.

A. Spinal nerve: formed by the joining of the ventral (mo-tor) and dorsal (sensory) roots that arise from the spinal cord. A spinal nerve leaves the spinal canal through the intervertebral foramen to immediately branch into dorsal and ventral branches that supply the periphery with motor andsensoryfibers(axons).B. Dorsal (sensory) root (I, III): carries only sensory infor-mation from the periphery to the spinal cord. C. Dorsal root ganglion (I, III): a collection of cell bodies of sensory nn. that passes over the dorsal root.

D. Ventral root (I, III): carries only motor nervefibers/axons from the spinal cord to the periphery. These are also called lower motor neurons (LMN).

E. Dorsal branch (I, II): roughly innervate the structures dorsally to the transverse processes (motor: epaxial muscles of the trunk and sensory: skin over the back). The dorsal branches like the ventral ones form plexuses by joining

A. Spinal n.

D. Ventr. root

E. Dors. br.

F. Ventr. br.

Motor n. (LMN,

Sensory n.

Sensory nerve cell

I. Cervical spinal nerve, cranial view, schematic

lower motor neuron)

each other. F. Ventral branch (I, II): roughly supplies structures ventral to the transverse processes (motor: hypaxial mm., trunk mm., almost all of the muscles of the limbs; and sensory: the skin). As the spinal nerves and the dorsal branches, theycarrybothsensoryandmotorfibers/axons.

Locate on an articulated skeleton and in the illustrations: G. Intervertebral foramina (I, II): the openings where spinal nerves exit the vertebral column to branch into dorsal and ventral branches.

Note in the illustrations:H. Cervical spinal nn. (II): 8 pairs of nerves. Most leave the vertebral column through the intervertebral foramina (see "Back" chapter for more).

I. Phrenic n. (II): formed by ventral branches of cervical nerves 5-7 (± 4) and passes through the thorax to the diaphragm.

J. Brachial plexus (II): the network formed from the ventral branches of the last few cervical and first one or two tho-racic spinal nn. It gives rise to the named nerves supplying the thoracic limb and adjacent areas.

B. Dors. (sensory) root

C. Dors. root ganglion

G

REFLEX ARC (III): the simplest impulse pathway, it is an involuntaryresponsetoasensorystimulus.Mostreflexarcs involve a sensory neuron, an interneuron, and a motor neuron. This makes them multisynaptic (the patellar tap reflexlacksaninterneuron[monosynaptic]).Specializedreceptors at the end of sensory neurons receive a stimulus (e.g., pin prick), resulting in an impulse (nerve action poten-tial/NAP)intothespinalcordtosynapseonaninterneuronwhich synapses on a motor neuron. The motor neuron stimulates a receptor organ (muscle or gland) to complete thereflex(e.g.,withdrawalfromthestimulus).

F. Stimulus (III): a change in the environment (e.g., pin prick/noxiousstimulus).

G. Receptor (III): of a sensory neuron (e.g., pain detector in

II Thoracic Limb

79

C1, C2....T1: Cervical spinal n. 1, 2.... Thoracic spinal n. 1

1. ^ Great auricular n. (II): the large cuta-neous branch of the ventral branch of second cervical n. (C2) that passes craniodorsally to the ear. It is sensory to the skin of the neck, ear, and back of the head.

2. Transverse colli n. (II): the other large cutaneous branch of the ventral branch of second cervical n. C2 that crosses ventrally over the cranial part of the neck.

3. Occipital n. (II): the dorsal branch of the second cervical n. (C2)

4. ̂ Ventral branches of the cervical nn. (II): join to form the cervical plexus and the last couplejoinwiththefirstfewthoracicventralbranches to form the brachial plexus.

5. Cervical plexus (II): the joining of many ventral branches of the cervical nn., supplying structures in the neck.

6. ^Intercostobrachial nn. (II): branches of the second and third intercostal nn. (ventral branches of T2-3) that pass in the wall of the thorax and wrap around the caudal arm to reach the skin of the caudolateral part of the brachium to which they supply cutaneous sensory innervation.

7. Cervical loop (ansa cervicalis) (II): com-munication between the ventral branch of the 1st cervical n. and the small descending branch of the hypoglossal n.

a. Suprascapular n. (C6-7) (II)b. Subscapular nn. (C6-8) (II)c. Musculocutaneous n. (C7-8) (II)d. Axillary n. (C8) (II)e. Radial n. (C7-T1) (II)f. Median n.(C8-T1/T2) (II)g. Ulnar n. (C8-T1) (II)

IX. Glossopharyngeal n. (II): cranial n. 9# X. Vagus n. (II): cranial n. 10XI. Accessory n. (II): cranial n. 11XII. Hypoglossal n. (II): cranial n. 12

II. Cervical nn. & brachial plexus, lateral view, schematic

C2C1

C3 C4C5 C6 C7 C8 T1

T2

I. Phrenic n.

a b

d c

e f g

G. Intervertebral foramina

1*

2*

3*

4*

A. Spinal n.

E. Dors. br.

J. Brachial plexus

5*

6*

X

IX

XII

XI. Accessory n.

7*

H. Cervical spinal nn.

*Definedinthelegend

a digit of paw) that responds to change (stimulus-flame)bygeneratinganim-pulse (NAP).

H. Sensory (afferent) neuron (III): carries a sensory impulses to the CNS.

I. Interneuron or association neuron (III): located in the spinal cord, connects a sensory neuron with a motor neuron. It can also connect with other neurons and send information up to the brain (so whenthereflexisover,itcanbeperceivedand commented on, “ouch!”).

J. Motor (efferent) neuron or lower motor neuron (I. III): carries an impulse to an effectororgan.

K. Effector (target) organ (III): the muscle or gland innervated by a motor neuron which reacts to the stimulus (e.g., pulling away from the pin).

K. Effector organ(muscle or gland)

H. Sensory neuron I. Interneuron

J. Motor neuron

G. Receptor

F. Stimulus

III. Reflex arch, schematic

A. Nerve (spinal n.)

B

D

C

CERVICAL & BRACHIAL PLEXUSES - 2

F. Ventr. br.

#Arabic numerals are used because the authors think they help with learning especially for those with learning disorders, so sorry..

II Thoracic Limb

80

As you dissect the vessels, nerves, and lymph nodes of the thoracic limb; dissect the extrinsic muscles of the thoracic limb.

Locate and isolate the brachiocephalicus m. (A) com-pletely separate the it from the body and the omotransver-sarius m. Do this completely or you will not be able to find the following structures.

Transect the brachiocephalicus m. (cervical and mastoid parts) where it crosses over the cephalic v. Reflect the muscle and note the large nerve entering its deep sur-face.

• VentralbranchofC6spinaln./cleidobrachialis n.: enters the brachiocephalicus m.

Cut this nerve to complete the reflection of the parts of the brachiocephalic m. (This means all the way to the ear and dorsal neck! Just do it!)

Dissect the parts of the trapezius m. (B) and cut them 1/2" (1 cm) from their attachments to the spine of the scapula and reflect them as you did for the right limb.

Identify and dissect the omotransversarius m. (D) that arises from the acromion and travels cranially up the neck deep to the brachiocephalic m. If you haven't completely reflected the brachiocephalic m., do it now, separating it from the omotransversarius m.

Bluntly dissect the fascia along the dorsal border of the omotransversarius m. where it was under the brachio-cephalic m. to locate:

1. Accessory n. (cranialn.11[XI],spinal accessory n.) (II, III):acranialn.(comingoffthebraininthecranium)thatexits from the skull and travels on the dorsal side of the omotransversarius m. to innervate, among others, the trapezius m.

Transect the omotransversarius m. 1/2" (one cm) from the acromion of the scapula and reflect it.

2. Superficial cervical (prescapular) lymph nodes (I, II): the usually two (one-four) large glandular structures cranial to the shoulder under the omotransversarius m. They drain thesuperficialandlateralneckregion,lateralsurfaceofthethoraciclimb,andcaudalhead(ear).Theirefferentspass to the venous angle inside the thoracic inlet (external jugular, tracheal duct, or tracheal trunks).

3. Superficialcervicala.(II):locatednearandsupplyingthesuperficialcervicallnn.andthecaudalneck.Followitbackuntil it disappears into the thorax (you will dissect its origin from the subclavian a. in the Thorax chapter).

Reflect any of the cutaneous trunci m. left on the body to the axilla (armpit) and transect it 1/2" (one cm) from the caudal border of the arm. Discard the detached piece.

Dissect and transect the superficial and deep (F) pectoral mm. 1/4" (.5 cm) from their attachments to the humerus (don't leave too much with the limb).

4. Accessory axillary lymph node (I): may or may not be present on the dorsal border of the deep pectoral m. in the caudalaxilla(armpit).Ifpresent,itsefferentductsdrains

NECK - 1the thoracic wall, shoulder and arm, and cranial mammary glandstotheaxillarylymphnode(FigI[5]).

Transect the latissimus dorsi m. (C) 2" from its brachial attachment.

Abduct the limb and move the part of the deep pectoral m. medially to observe:

• Vessels and nerves of the axilla: fascia-obscured, they cross the axilla.

Abduct the limb and identify the serratus ventralis m. Cut through the rhomboideus and serratus ventralis (G) mm. close to the scapula as you abduct and twist the limb. Cut all attachments until the limb is connected to the trunk by only the brachial plexus and axillary vessels.

Bluntly separate the vessels and nerves crossing the axilla and locate:

5. Axillary lymph node(s) (I): the glandular structure (usually just one) associated with the vessels and nerves of the axilla. It drains the deep thoracic limb, thoracic wall, and cranial mammaryglands. Itsefferentductspasstothevenousangle inside the thoracic inlet (external jugular, tracheal duct, or tracheal trunks). It, with the accessory axillary node if present, make up the axillary lymphocenter.

4. ± Accessory axillary ln.

5. Axillary ln.

2. Supf. cervical lnn.

I. Lymph centers of the shoulder region, lateral view, schematic

Venous angle

b*

c

c*

a*

b* Thoracic duct

%Roman numeral(s) in parentheses after a structure indicate in which illustration(s) they are labeled. Absence indicates they are in all illustrations.

II Thoracic Limb

81

NECK - 2

II. Superficial neck & thoracic limb, brachiocephalic & omotransversarius mm. cut, lateral view

a. ^Sternal lymph node (I): also drains the cranial mammary glands

b. Afferentlymphvessels/ducts (I): enter a lymph node

c. Efferentducts (I): pass from a lymph noded. Cephalic v. (II) e. Jugular v. (II)f. Radial n. (C7-T1) deep branch (II) fi. Superficial branch of radial n. g. Lateral thoracic n. (II, III) h. ^Great auricular n. (II)i. Transverse colli n. (II)j. Ventral branch of the cervical n. (II)

k. Cranial lateral cutaneous brachial n. (II) from axillary n.

m. Omobrachialis v. (II) n. Intercostobrachial n. (II)o. Median cubital v. (II) p. Thoracodorsal vessels & n. (II)q. Cutaneous vessels and nerves (II)r. Supraspinatus m. (II)s. Splenius m. (II) t. Sternocephalicus m. (II)u. Deltoid m. (II) v. Lateral head of triceps brachii m. (II)

Review these extrinsic muscles as you find the nerves of the area p50-3.

Extrinsic mm. of the limb A. Brachiocephalicus m. (II)B. Trapezius m (II)C. Latissimus dorsi m. (II)D. Omotransversarius m. (II)E. Rhomboid m. (II)F. Deep pectoral m. (II)G. Serratus ventralis m. (II)

2. Supf. cervical lnn.

3. Supf. cervical a.

m1. Accessory n.

A

D

B

n

A

e

d

m

g

C

G

E

F

h

i

kf

fi

j

o

p

G

q

q

r

q

t

u

v

q

s

* Definedinthelegend

II Thoracic Limb

82

S SM

A

Overview page, not dissection page: Use the schematics on these two pages to orient yourself as you dissect out the nerves of the thoracic limb and refer back to them constantly. Learn the names that are written in the legends (A-M). Those that are numbered are best used for reference, for anatomy trivia quizzes, or if your instructor demands.

Be able to trace the paths of the nerves in relationship to an articulated skeletal limb.

Dissection continues after the following page.

A. Suprascapular n.

B. Subscapular n.

Ci. Med. cutaneous antebrachial n.

D. Axillary n.

E. Radial n.

Ei. Deep br. Eii. Supf. br.

G. Median n.

F. Ulnar n.

Fi. Dorsal br.

M. Lat. thoracic n.

I, K, L. Digital nn.

C. Musculocutaneous n.

A. Suprascapular n. (C6-7)(I)B. Subscapular n. (C6-8)(I)C. Musculocutaneous n. (C7-8)(I, II)Ci. Median cutaneous antebrachial n.

(I, II)D. Axillary n. (C8)(I)E. Radial n. (C7-T1)(I, II)Ei. Deep branch of the radial n. (mo-

tor) (I, II)Eii. Superficial branch (radial n.) (I, II)

F. Ulnar n. (C8-T1)Fi. Dorsal branch of the ulnar n.

G Median n. (C8-T1/T2)(I)I. Digital nn., dorsal and palmar (II,

III) - K. Axial digital nn. (II, III)- L. Abaxial digital nn. (II, III)

M. Lateral thoracic n. (C8-T1) (I)

Brachial plexusCranial plexusSuprascapular n. Subscapular n.

SS MAR MU (Memory Aid: the order of the main nerves in the brachial plexus

to help in lesion localization if there are problems

Middle part of plexus Musculocutaneous n. Axillary n. Radial n.

Caudal part of plexus Median n. Ulna n.

R

M U

I. Nerves of the thoracic limb, medial view, schematic

1*2*

4*

5*

6*

9*

C6C7C8T1T2

8*

10*

3*

13*

12*

11*a

15*

19*

E. Radial n.

7*

NERVES - THORACIC LIMB - 1

a

a

*Definedinthelegend

1. ^Proximal muscular branch of the muscu-locutaneous n. (I): supplies the coracobrachialis and biceps brachii mm.

2. Communicating branch (I): between the musculocutaneous and median nn. near the elbow in carnivores.

3. Distal muscular branch of the musculocutane-ous n. (I)

4. Cranial lateral cutaneous brachial n. (I): a sensory branch of the axillary n. to the lateral arm

5. Cranial cutaneous antebrachial n. (I): the continuation of the cranial lateral cutaneous brachial n. (axillary n.), sensory to the cranial antebrachium

6. ^Cranial pectoral nn. (C6-8) (I): motor to the superficialpectoralm.

7. ^Long thoracic n. (C7&/orC8)(I):runsoverand innervates the serratus ventralis m.

8. ^Thoracodorsal n. (C8) (I): motor to the latis-simus dorsi m.

9. ^Caudal pectoral nn. (C6-8) (I): motor to the deep pectoral m.

14*

II Thoracic Limb

83

Caudal part of plexus Median n. Ulna n.

I. Nerves of the thoracic limb, medial view, schematic

C. Musculocutaneous n.

Fi. Dors. br. of ulnar n.

Ci. Medial cutaneous antebrachial n.

E. Radial n.

E'. Deep branch

E''. Superficial branch

F. Ulnar n.

15*

G. Median n.

II. Nerves of the left forepaw, cranial view, schematic

12*

F

E

III. Nerves of the left forepaw, caudal view, schematic

13*

I

II

III IV

V

a

I

II

IIIIV

V

16*

18*

I. Dorsal digital nn.

K. Axial digital nn. K. Axial digital nn.L. Abaxial digital nn.

L. Abaxial digital nn.

17*

16. Palmar branch of the ulnar n. (III)

• Palmar digital nn. in the metacarpus: di-videdintosuperficialanddeepsetsarisingfromthemedian and ulnar nn. The dorsal digital nn. (14) only havesuperficialnn.

- 17. Palmar common digital nn.:superficialbranches in the metacarpus that bifurcate in the digits (ex. 19i).Superficialbranchesthatdon'tbifurcatehavethe same digital name in the metacarpus (ex. 19ii).

- 18. Palmar metacarpal nn.: deep branches of the ulnar n. (palmar branch) located next to the metacarpal bones

19. Proper or not: proper may be added to the name of a dorsal or palmar digital nn. (in the digital area) that arises from a bifurcation of a common digital nn., and

isnotproperifitdoesn'tarisefromabifurcation.- 19i. Properpalmar/dorsal(axial)digitaln. V (IV):

- 19ii. Abaxial palmar/dorsal digital n.V (IV): both palmar and dorsal carry only ulnar n.fibers.

20. Dorsal branches and plexuses of the spinal nerves C6-T2 (I) roughly innervate the structures dorsal to the transverse processes of the vertebrae

a. ^Muscular branches: include all visible branches of each nerve that pass to muscles

11*

NERVES - THORACIC LIMB - 2

a

10. Lateral caudal cutaneous brachial n. (I): from radial n., sensory to the skin over the lateral arm

11. Lateral cutaneous antebrachial n. (I): of the radial n., sensory to craniolateral forearm

12. Medial branch ofthesuperficialradialn.(I,II):traveling with the cephalic v., sensory to dorsum of the paw

13. Lateral branch of the superficial radial n. (I,II): travels with the cephalic v., sensory to dorsum of the paw

14. Dorsal common digital nn.: located in the metacarpus, there are no dorsal metacarpal nn.

15. ̂ Caudal cutaneous antebrachial n. (I): from ulnar n., sensory to the caudal forearm.

19ii*

19i*

19ii*

19i*

14*

*Definedinlightlegend (LPI: low priority item)^ More important (LPI)

Axis

II Thoracic Limb

84

BRACHIAL PLEXUS - 1

1. Supraspinatus m. 2. Subscapularis m. 3. Coracobrachialis m.4. Biceps brachii m.5. Teres major m.6-7. Triceps brachii m. 6. Long head 7. Medial head

8. Tensor fascia antebrachii m.9. Pronator teres m. 10. Latissimus dorsi m. 11. Superficial pectoral m. 12. Deep pectoral m. 13. Cutaneous trunci m. (maybe with skin)14. Serratus ventralis m.

Dissect these muscles as you find the nerves of the area p50-60.

Plan for Identifying Nerves (Memorize yesterday!)Suprascapular n. (B) between the supraspinatus & subscapularis mm.Subscapular n. (C): into the subscapularis m. Musculocutaneous n. (D): beside & into the coracobrachialis & biceps brachii mm.Axillary n. (I): between the subscapularis & teres major mm.Radial n. (J): medially: dives into the triceps m. - laterally: under the lateral head (triceps) -Superficialbranches: onthesidesofthecephalicv. - Deep branch: into the extensor mm. of the forearm.Median & ulnar nn.: together in the brachium.Ulnar n. (K): runs to the ulna (olecranon) in arm. -caudal:undertheextensor&flexorcarpiulnarismm.

in forearm. Median n. (L): down the medial arm & forearm. Digital nn. (p102): sides of the digitsThoracodorsaln.(E): intothelatissimusdorsim.Long thoracic n. (G): over the serratus ventralis m. Lateral thoracic n.(F): passes to the cutaneous trunci m.(don'tlocate,butknow).

*Definedinthelegend

2

B. Suprascapular n.

I. Axillary n.

D. Musculocutaneous n.*

L. Median n. K. Ulnar n.

J. Radial n.

C. Subscapular n.

H. Phrenic n. 4

k

j

Ji. Superficial radial n. (med. br.)

5

h

A. Brachial plexus

E.Thoracodorsaln.

F. Lat. thoracic n.

g

9

m

3

7

6

i

1

11

14

12

f*

G. Long thoracic n.

C6

C7C8

T1

T2

12

10

11

8

a*

b*

c*d*

e

Di. Med. cutaneous antebrachial n.

I. Nerves of the brachial plexus, left axilla, ventral view

II Thoracic Limb

85

BRACHIAL PLEXUS - 2

@ Textbook of Veterinary Anatomy, Dyce- Sack-Wensing# Underlined structures: often hard to find, so don't, instead note them in

the illustration; and, if bold, know why (they may not be tagged on the lab test, but will be part of the lecture test).

Poke a blunt probe between the vessels and nerves and repeatedly move it back and forth in the direction of these structures. Repeat this over and over, and over, and over ... until individual vessels and nerves appear. Use a thumb forceps to pick away fat and fascia as it clumps up. Then pick a single structure, strip it, and dissect it to its termination to name it.

Dissect and identify the medial muscles of the shoulder and the arm as a review (see box opposite), and to help name the arteries and nerves entering them, while dissecting the vessels and nerves. Bluntly dissect and identify the network of nerves that come together and then separate into individual nerves in the axilla.

A. Brachial plexus (C6,7,8,&T1±C5&/orT2):thenetworkformed from the ventral branches of the last few cervical andfirstoneortwothoracicspinalnn.(C6-T2±C5)Theventral branches emerge ventral to the scalenus m. to reach the axilla, where they further divide and communicate with eachothertoformthebrachialplexus.Fromthebrachialplexus, peripheral named nerves extend to innervate the thoracic limb, adjacent muscles and skin, and, via the phrenic n., the diaphragm.

"Get a plan": to identify the nerves, memorize the "Plan of Forelimb Nerves" NOW. As you locate a nerve, find where it travels, usually either into a specific muscle or between two muscles. From this information and the "Plan", name the nerve. Do this during lab quizzes with confidence!

"Several branches...bare mention of their names and desti-nation is all that is required" (as other anatomists include: long thoracic, thoracolumbar, cranial and caudal pectoral, and subscapular - these are not bolded in this text).

B. Suprascapular n. (C6-7)@: dives between the supraspina-tus and the subscapularis mm. and crosses the scapular notch to innervate the infraspinatus and supraspinatus mm.

Optional: Remove a wedge of the supraspinatus m. over the suprascapular n. to follow its course across the neck of the scapula to reach the infraspinatus m.

C. Subscapular n. (C6-7): one or two branches that dive into the subscapularis m. (2)

D. Musculocutaneous n. (C6-8): runs along the medial side of the coracobrachialis m. and the biceps brachii which it innervates, along with the brachialis m.

See the musculocutaneous n. branches dive into the biceps brachii proximally and distally to identify it. Di. Medial cutaneous antebrachial n. (I): cutaneous branch of the musculocutaneous n. to the skin of the medial side of the forearm to the level of the carpus (do not dissect).

E.Thoracodorsal n. (C8): passes to the latissimus dorsi m. (10) with the thoracodorsal vessels.

F. Lateral thoracic n.# (C8-T2):clinicallysignificant,itextendscaudally with the lateral thoracic a. and v. to supply the cutaneous trunci m. (13), do not dissect.

G. Longthoracicn.:thelarge,flat,palewhitestructurelyingon and supplying the serratus ventralis m.

H. Phrenic n.: formed by ventral branches of the fourth or fifthtoseventh cervical nn, it passes through the thorax to the diaphragm (dissect later).

I. Axillary n. (C7-8): crosses the axilla and dives, with the subscapular vessels, between and into the subscapularis and teres major mm. It passes behind the humerus to reach the lateral side of the arm to innervate the deltoideus, teres major,andteresminormm.Itgivesoffthecraniolateralcutaneous brachial n.

J-L: see following pages or chart opposite.

a. ^Proximal muscular branch of the musculocutaneous n.: supplies the coracobrachialis and biceps brachii mm.

b. Distal muscular branch of the musculocutaneous n. c. Communicating branch: the connection between the musculocutane-

ous and median nn. just proximal to the elbow.d. ^Caudal cutaneous antebrachial n.: from ulnar., p88e. ^Cranial pectoral nn. (C6-8): supply the superficial pectoral m.f. ^Caudal pectoral nn. (C8-T2): innervate the deep pectoral m.g. Sternocephalicus m. (I)h. Axillary a. and v. (I)i. External jugular v. (I)j. Extensor carpi radialis m.k. Brachiocephalicus m. (I)m. Flexor carpi ulnaris m.

arises, not from the brachial plexus, but from intercostal nn.[T2-3]).Therefore,feelingonthecaudolaterallimbsometimes gives owners a false sense of hope. - Incomplete avulsion: you may be able to determine which part of the plexus is avulsed by loss of muscular function using SS MAR MU and by loss of sensation

todifferentareasofthelimb,butitis doubtful if this will change your treatment.

• Suprascapular n. damage ("Sweeney"): most common in horses, it causes paralysis of the

CLINICAL:• Brachial plexus avulsion: results in a flaccid limb. The limb will be insensitive to pain, except on the cau-dolateral arm, which is innervated by the intercostobrachial n. (which

infraspinatus and supraspinatus mm., resulting in lateral instability of the shoulder joint ("joint slip"). With time, the muscle atrophy corrects the instability, but results in a prominent scapular spine.

• Panniculus/cutaneous trunci response: mediated by lateral thoracic n. (motor) and the lumbar and thoracic spinal nn. (sensory) helps to localize T3-L4 spinal cord damage (see p90).

II Thoracic Limb

86

THORACIC LIMB NERVES - 1

NERVE MOTOR: muscles SENSORY: skin area

Suprascapular n. (B) .............. M: supraspinatus & infraspinatus mm. None Subscapular n. (C)..................... M: subscapularis m. NonePectoral nn. (a, b)...................... M: pectoral m. NoneLong thoracic n. (G)................ M: serratus ventralis m. None Thoracodorsal n. (E)............... M: latissimus dorsi m. None Lateral thoracic n. (F).......... M: cutaneous trunci m. & deep pectoral m. None Musculocutaneous n. (D)....... M: flexors of the elbow (coracobrachialis, biceps brachii, & brachialis mm.) - Medial cutaneous .............................................................................................. S: medial forearm (overlapped by others) antebrachial n. (Di) (clinical: horse for nerve blocks)Axillary n. (I)......................... M: flexors of the shoulder (teres major, teres minor & deltoideus mm.) Cranial lateral cutaneous brachial n. (g)............................................................... .................. S: lateral side of the arm Cranial cutaneous antebrachial n. (h)........................................................................................ S: shares the cranial surface of the forearm w/ other nn. (radial & musculocutaneous) Radial n. (J)....................... M: extensors of the elbow, carpus & digits (triceps brachii, anconeus, tensor fasciae antebrachii mm.) - Deep br. (Ji) M: extensors of the carpus & digits (extensor carpi radialis, common digital extensor, lat. digital extensor, lat.

ulnar, oblique carpal extensor, & supinator mm.) - Superficial branch (Jii) ....................................................................................... S: lateral forearm & dorsal manus/paw . Medial br. (i) S: dorsal paw . Lateral br. (j) S: dorsal paw .. Lateral cutaneous antebrachial n. (k) S: lateral forearmUlnar n. (K) ............................ M: some flexors of forearm & muscles of manus (flexor carpi ulnaris, interosseous mm.) - Caudal cutaneous antebrachial n. (f).....................................................................S: caudolateral forearm - Dorsal branch (p 89).......................................................................................S: dorsolateral metacarpus & 5th digitMedian n. (L)....................... M: most of flexors of forearm ................................S: w/ ulnar n. to ca. forearm & palmar pawIntercostobrachial n. (M) S: lateral side of the arm (Not from the brachial plexus, but from intercostal nn. T2-3)

a. ^Cranial pectoral n. (I)b. ^Caudal pectoral n. (I)c. ^Proximal muscular branch of the

musculocutaneous n. (I) d. Distal muscular branch of the muscu-

locutaneous n. (I) e. Communicating/anastomotic

branch (I): connects musculocutaneous and median nn. just proximal to the elbow.

f. ^Caudal cutaneous antebrachial n.: a branch of the ulnar n. arising proximal to the elbow and traveling caudally with the col-lateral ulnar a. over the medial surface of the olecranon. It supplies sensory innervation to the caudal forearm. (It may have been removed with the skin).

g. Cranial lateral cutaneous brachial n. (II): a sensory branch of the axillary n. appear-ing just caudal to the deltoideus m., it supplies sensation to the lateral side of the arm and caudal scapular region.

h. Cranial cutaneous antebrachial n. (II): the continuation of the cranial lateral cutaneous brachial n. (axillary n.).

i. Medial branch ofthesuperficialradialn. (I): travels with the cephalic v.

j. Lateral branchofthesuperficialradialn.(II): travels with the cephalic v.

k. Lateral cutaneous antebrachial n. (II): from radial, it is sensory to the skin covering the extensor mm. in the forearm (craniolateral surface).

I. Nerves & vessels of the shoulder, medial view

A. Brachial plexus

C. Subscapular n.

D. Musculocutaneous n.

I. Axillary n.J. Radial n.

K. Ulnar n.

L. Median n.

E.Thoracodorsaln.B. Suprascapular n.

C6C7

C8T1

T2

c

de*

f*

Jii, i* 14

5

6

7

8

9

16

14

15

17

11

12ii

12ii

13

F. Lateral thoracic n.

G. Long thoracic n. a

Di. Med. cutaneous antebrachial n.

22

b

II Thoracic Limb

87

I. Nerves & vessels of the shoulder, medial view

THORACIC LIMB NERVES - 2

A-I: see preceding pages or chart opposite. Move to the lateral side of the left shoulder to dissect the axillary n. and the deltoid m. (see box).

Dissect and transect the two parts of the deltoideus m. very close to the acromion of the scapula (1/1000") and reflect the parts to observe the axillary n.:

Relocate the axillary n. in the axilla (medially). Pull on it and see it move where it enters the deltoid m. on the lateral side of the limb.

J. Radial n. (C7-T2):thelarge,clinicallysignificantnervecross-ing the axilla to dive between and into the long and medial heads of the triceps brachii m.. It innervates the extensors of

the limb (arm and antebrachium). Move to the lateral side of the left shoulder to dissect the radial n. and the brachialis m.

Bluntly dissect the distal side of the lateral head of the triceps brachii m. to locate:

The radial n. passing with the collateral radial a. on the brachialis m., which is in the brachial groove, to reach the lateralsideofthearm.Itbecomessuperfi-cial under the distal border of the lateral head triceps brachii m.

Transect the lateral head of the triceps and reflect its parts. Note the radial n. on the brachial m. that divides near the elbow, into: J'.Deepbranch(ramusprofundus)(II):motortoex-tensors of the forearm.

J''. Superficial branches (II): sensory to the dorsal paw travelling on either side of the cephalic v.

Flip the limb over to see the medial side. Locate:K, L. Ulnar and median nn. (C8-T2)(I): arise together from the brachial plexus and, as a nerve bundle, travel with the brachial vessels in the arm, caudal to the musculocutaneous n. It bifurcates proximal to the elbow into the median and ulnar nn., both which innervate the flexors of the forearm.

K. Ulnar n. (C8-T2)(I): separates from the median n. in the distal brachium and passes toward the ulna (olecranon process).

L. Median n. (C8-T2)(I): continues down the medial side of the arm and forearm with the brachial and median vessels respectively. It crosses over the me-dial collateral ligament to reach the forearm, where it dives under the pronator teres m. (we will continue to dissect it later).

M. Intercostobrachial nn.: lateral cutaneous branches of the second and third intercostal nn. (not from the brachial plexus) that supply the lateral skin of the arm/brachium over the long head of the tricepsbrachii m.

1. Cephalic v. 2. Axillobrachial v. (II)3. Omobrachial v. (II)4. Median cubital v. (I)5. Supraspinatus m. 6. Subscapularis m. (I)7. Teres major m. (I)8. Coracobrachialis m. (I)9. Biceps brachii m.10. Brachialis m. (II)11. Tensor fascia antebrachii m. (I)12. Triceps brachii m. - 12i. Long head

- 12ii. Medial head (I) - 12iii. Lateral head (II)

13. Latissimus dorsi m. 14. Brachiocephalic m.15. Pronator teres m. (I) 16. SDF m. (I) 17. Flexor carpi ulnaris m. (I) 18. Trapezius m. (II) 19. Omotransversarius m. (II)20. Infraspinatus m. (II) 21. Teres minor m. (II) 22. Superficial pectoral m.23. Extensor carpi ulnaris m. (II)

II. Nerves & vessels of the shoulder, lateral view

J. Radial n.Fi

Fii

Accessory n.

1 12iii

Deltoid m.

k*

g*

J", h*

Jii, j*

2 3

57

10

12iii

12i

13

14

23

18

19

20

2122

23

22

I. Axillary n.

M. Intercosto- brachial nn.

K, f*

• Intercostobrachial n. and complete brachial plexus avulsion: sensation on the lateral arm is due to this nerve and not nerves of the brachial plexus, sosensationtoarmdoesn'tindicatereturn to function.

CLINICAL: • Radial n. paralysis (more on p90): supplies all the extensors of the thoracic limb. - "High paralysis" results in

an inability to stand on the limb, along with "knuckling over" (see below).

- "Low paralysis" doesn'tprevent standing, but causes "knuckling over." see p90)

II Thoracic Limb

88

A. Median n.

15

B. Ulnar n.

1*

Incise the skin longitudinally down the caudal aspect of the manus medial to the carpal pad and through the middle of the metacarpal pad.

Cut around the base of the dew claw. Reflect the skin distally to the metacarpal pad, removing the carpal pad with the skin. Leave the skin and digital pad on the dew claw. Leave the skin attached (or save the skin if removed) so you can wrap it around the limb each day.

Di. Med. cutaneous antebrachial n.

10

14

18

Cii. Supf. radial br. (med.)

13

16

9

NERVES - FOREARM - 1

17

11

1. ^Caudal cutaneous antebrachial n.: a branch of the ulnar n. arising proximal to the elbow and traveling caudally with the collateral ulnar a. over the medial surface of the olecranon. It sup-plies sensory innervation to the caudal forearm. (It may have been removed with the skin).

2. ^Palmar branch of the ulnar n. (II): extends distally on the palmar side of the paw, supplying, along with the median n., most of the muscles of the forepaw and sensation (from a communicating branch to the median n.) to the palmar aspect of the forepaw.

3, 4. Medial (II) and lateral branches of the superficialbranch of the radial n.: terminal branches arising in the proximal forearm that pass with the medial and lateral branches of the super-ficialbrachialaa.oneithersideofthecephalicv.tothecarpus.Theysupply sensory innervation to the cranial surface of the antebrachium and the dorsum of the forepaw.

5. Lateral cutaneous antebrachial n. (II): a branch of the larger lateralbranchofthesuperficialbranchoftheradialn.totheskinofthe lateral side of the forearm.

6. Cranial lateral cutaneous brachial n. (II): a sensory branch of the axillary n. appearing just caudal to the deltoid m.

7. Cranial cutaneous antebrachial n. (II): the continuation of

12

D. Musculocutaneous n.

h

i. SDF

a. Extensor carpi radialis m.f. Pronator

teres m.

g

the cranial lateral cutaneous brachial n. (axillary n.). It is sensory to the proximocraniolateral side of the antebrachiumoverlappingthesuperficialbranchesof the radial n. and the musculocutaneous n.

8. Intercostobrachial n. (II) 9. Cephalic v. (I) 10. Brachial a. (I)11. Median cubital v. (I) 12.Superficialbrachiala. (I) 13. Cranial superficial antebrachial a.,

medial branch (I)14. Median a. (I)

15. Accessory cephalic v. (I) 16. Collateral ulnar a. (I)17. Biceps brachii m.18. Flexor retinaculum (I)19. Deltoid m. (II) 20-21. Triceps brachii m. 20. Long head (II)21. Lateral head (cut) (II)

22. Brachialis m. (II) 23. Tensor fascial antebrachii (I)24. Anconeus m.

h

I. Nerves & vessels of the forearm, medial view

3*

23

Review (dissect and identify) the extensor and flexors mm. of the forearm as you dissect the nerves (p63-71):

a. Extensor carpi radialis m.b. Common digital extensor m. (II)c. Lateral digital extensor m. (II) d. Extensor carpi ulnaris (lateral ulnar) m. (I)e. Oblique carpal extensor (abductor pollicis longus) m. (II)f. Pronator teres m. (cut) (I)g. Flexor carpi ulnaris m.h. Flexor carpi radialis m. (cut) (I)i. SDF (superficial digital flexor) m. (I)j. DDF (deep digital flexor) m. (not shown)k. Supinator m. (not shown)

Relocate the median n. in the arm:A. Median n. (I): separates from the ulnar n. proxi-mal to the elbow to pass deep to the pronator teres m.. It gives, with the ulnar n., motor branches to the flexor mm. of the forearm.

Transect the pronator teres m. and separate the flexor carpi radialis and deep digital flexor mm. to follow the median nerve distally.

The median n. continues with the median a. and v. into the forearm, then passes through the carpal canal to the manus. Here it supplies sensory innervation to the palmar surface of the paw, along with the ulnar n. Do not dissect the digital branches of the median n.

II Thoracic Limb

89

a. Extensor carpi radialis m.

Bi. Dors. br. of the ulnar n.

C. Radial n.Ci. Deep br.

Cii. Supf. brs.

B. Ulnar n.

NERVES - FOREARM - 2

II. Nerves of the forearm, lateral view

19

20

8

6

21

22

13

17

7*3*

4*

5*

1

24

e

b. Common digital extensor m.

c

d. Extensor carpi ulnaris m.

g. Flexor carpi ulnaris m.

2*

B. Ulnar n.: along with the median n., innervates the flexors of the forearm and, by itself, the interosseous mm. of the manus. It separates from the median n. in the distal arm and goes toward the ulna. Passing under the ulnar head of theflexorcarpiulnarism.,itinnervatestwoflexormuscles(flexorcarpiulnarism.andpartofthedeepdigitalflexorm.).Itcontinuesdeeptotheflexorcarpiulnarism.andsuperficialtotheDDFm.tothecarpus,whereitbifurcatesinto dorsal and palmar branches.(Don'tdissect,butnotethem in the illustrations).Bi. Dorsal branch of the ulnar n.(don'tdissect)(II):travelsforward (cranially) and distally to supply sensation to the lateral (abaxial) side of the metacarpus and 5th digit.

Now note the nerve passing distal to the lateral head of the triceps brachii m.

C. Radial n. (II): after entering the triceps brachii m. on the medial side It travels distally on the brachialis m. with the collateral radial a. to reach the lateral side. It becomes superficialunderthedistalborderofthelateral head of the triceps brachii m. Near the elbow, it divides into deep and superficial branches.

Trace the radial n. proximally and verify with a probe, that it is a continuation of the radial n. on the medial side of the arm. Follow it distally until it divides into a superficial (Cii) and a:- Ci. Deep branch of the radial n. (II): passes under the cranial edge of the extensor carpi radialis m. to innervate the extensors of the carpus and digits.

Dissect the extensor carpi radialis and common and lat-eral digital extensors mm. and cut through the extensor retinaculum to the metacarpal region.

Follow the deep branch into the extensor mm.Dissect around the cephalic v. to follow: - Cii. Superficial branch of the radial n.: bifurcates into lateral and medial branches that pass distally on either side of the cephalic v. These branches supply sensation to the lateral forearm and the dorsal aspect of the paw.

Relocate:D. Musculocutaneous n. (I): runs along the biceps brachii m. in the arm separated from the median and ulnar nn. - Di. Medial cutaneous antebrachial n. (I): (note in the il-lustration, not on your cadaver) arises from the musculo-cutaneous n. and supplies the skin on the medial side of the forearm. It is usually removed with the skin during dissection.

E. Digital nn. (II):(don'tdissect)many,inthemanustheyare divided into dorsal or palmar; and in the digit, further divided into axial or abaxial and have the Roman numeral of the digit they supply (e.g., abaxial dorsal digital n. III).

CLINICAL: • Medial cutaneous antebrachial and dorsal branchoftheulnarnn.:oflittleclinicalsignifi-cance in the dog, they may be involved in nerve blocks to diagnose lameness in horses.

E. Digital nn.

*Definedinthelegend

a

II Thoracic Limb

90

CUTANEOUS INNERVATION - CLINICAL 1

Cutaneous innervation:onlymemorizeradialandulnarnn.,astheresthavelittleclinicalsignificance.1. Axillary n. (cranial cutaneous brachial n.): lateral side of the arm. 2. Axillary n. (cranial cutaneous antebrachial n.): cranial surface of the forearm.3. Musculocutaneous n. (medial cutaneous antebrachial n.): medial surface of the forearm.4. Ulnar n. (caudal cutaneous antebrachial n.): caudal surface of the forearm.5. Radial n.(superficialbranches):lateralforearmand dorsal paw.6. Ulnar n. (dorsal branch): lateral paw (digit 5). 7. Ulnar & median nn.: caudal forearm & palmar paw.

8. Intercostobrachial nn.: lateral skin of the arm.

Read this page, there is no dissection involved.Cutaneous areas of innervation (CA): the areas of skin innervatedbyanerve.Thecutaneousareasofdifferentnerves overlap (overlap zones - OZ). • Dermatome or autonomous zone* (AZ): the area of the skin innervated by only one nerve. Absence of feeling fromanautonomouszoneindicateswhatspecificnervehas been damaged.

• Radial n. (superficial branch): innervates the dorsal paw and is the most clinically important dermatome, helping diagnose its damage. Besides the radial n., the other sensory areas are interesting, but probably not used in clinics.

• Ulnar n. (dorsal branch): sensory to the lateral digit, (which is often asked on national boards).

• Intercostobrachial nn.: lateral cutaneous branches of the second and third intercostal nn. (not from the brachial plexus) that supply the lateral skin of the arm over the long head of the triceps brachii m.

to stand on the limb, along with "knuckling over" (see below).

CLINICAL:• Clinical significance of the thoracic limb nerves: only a few situations (i.e., radial n. paralysis, complete brachial plexus avulsion, and possibly supraspinatus n. damage) are significant to the general small animal veterinarypractitioner.Damagetoanyoftheotherspecificnervesshows very subtle signs, if any, due to compensation. What is more important than cutaneous zones is know-ing where the nerves pass in order to avoid them during surgery.Morenervesbecomeclinicallysignificantinthehorse when doing nerve blocks to localize a lameness.

• Radial n.: supplies all the extensors of the thoracic limb. - Path of the radial n.: passes into the triceps mm. then curves around the humerus in the brachial groove to the lateral side to become su-perficialwhereitisvulnerableto

trauma from the side or damage to a humeral fractured.

- "High" paralysis: paralyses the tri-ceps brachii m., preventing extension of the elbow resulting in an inability

- "Low" paralysis (damage below triceps innervation) would permit standing on the limb, but eliminates the ability to extend the distal limb, resulting in "knuckling over" and dragging the limb on its dorsum. Animalslearntocompensatebyflippingtheir limb forward to extend the digits and plant the limb when moving.

• Panniculus/cutaneous trunci response: used to localize thoracic spinal cord damage. It is mediated by the lateral thoracic n. that passes from the bra-chial plexus and ex-tends caudally with the lateral thoracic a. and v. to supply the cutaneous trunci m.

(sensation and motor loss)• Intercostobrachial n.: sensation toarm,sodoesn'tindicatereturnto function after brachial plexus avulsion (see p85).

• Suprascapular n. damage ("Sweeney"): causes paralysis

of the infraspinatus and supraspinatus mm. (see p85).

• Dorsal branch of the ulnar n. and medial cutaneous an-tebrachial n.: may be blocked to help diagnose lameness in the horse (see p89).

Sensationfromthelateraltrunk(flyorpinch)passesupover the thoracic and lumbar spinal ventral branches which pass caudoventrally to the spinal cord, up the cord to the cell bodies of the lateral thoracic n. Motor fiberspasstothecutaneoustruncim.- Absence of the panniculus response cau-dally which then appears cranial to a point localizes the lesion to the spinal cord.

• Brachial plexus avulsion = flaccid limb. In incomplete avulsion use SS MAR MU

II Thoracic Limb

91

Cutaneous sensation of the forelimb• Arm- Lateral surface: Intercostobrachial nn. (8), axillary n. (cranial cutaneous brachial n.)(1)•Forearm:- Cranial surface: axillary n. (cranial cutaneous antebrachial n.)(2)- Medial surface: musculocutaneous n. (medial cutaneous antebrachial n.) (3)- Caudal surface: ulnar n. (caudal cutaneous antebrachial n.) (4)- Lateral surface proximally: radial n. (lateral cutaneous antebrachial n.) (5)- Lateral surface distally: radial n. (superficialbranch)(5)

• Manus:- Dorsal paw: radial n. (superficialbranch)(5)- Lateral paw (digit 5): ulnar n. (dorsal branch) (6)- Palmar paw - ulnar & median nn. (7)

5. Radial n.

8. Intercostobrachial nn.

7

6. Ulnar n.

53

2

1

4

CUTANEOUS INNERVATION - CLINICAL 2

Cutaneous innervation of the thoracic limb, lateral view

II Thoracic Limb

92

I. Arteries of left arm, medial view

ARTERIES - THORACIC LIMB - 1

B. Axillary a.*

C. Subscapular a.*

D. Brachial a.*

Axillary ln.

Accessory axillary ln.

2*

1*

6*4*

3*

5

8*

9*

10*

13*12i

12*

11*

A. Subclavian a.

Median a.

a

b

c

ef

fi

g

h

i

d

j

k

nm

A. SUBCLAVIAN A. (see text opposite page)1. Superficialcervicala.: supplies the muscles of thescapulaandtheshoulder,superficialcervicallymphnode,andsuperficialmm.ofthebaseoftheneck

- 2. Suprascapular a.: passes between supraspina-tus and subscapular mm. with the suprascapular n. to supply the scapula and the supraspinatus m.

B. AXILLARY A. see text opposite page.3. ̂ Externalthoracica.: the branch of the axillary a. supplyingthesuperficialpectoralm.,itisaccompaniedby the cranial pectoral nn.

4. Lateral thoracic a.: runs caudolaterally with the lateral thoracic n. over the thoracic wall on the dorsal border of the deep pectoral m. to supply the axillary lymph node, deep pectoral, latissimus dorsi, cutaneous trunci mm., and the thoracic mammary glands.

C. SUBSCAPULAR A. (see text opposite page)

5. ^Thoracodorsal a.: arises from the start of the subscapular a. and extends caudally with its satellite v. and n. to the latissimus dorsi m.

6. ̂ Caudalcircumflexhumerala.: arises from the subscapular a. and travels behind the caudal side of the humerus to anastomose with the cranial circumflexhumerala. It is themainsupply to thetriceps brachii m.

7. Collateral radial a. (II)%: accompanies the radial n. on the brachial m. which it supplies

8.^ Cranialcircumflexhumerala.: can arise from either the axillary or subscapular a. It travels in front of the humerus and anastomoses with the caudal circumflexhumerala.

D. BRACHIAL A.: (see text opposite page)9. ̂ Deep brachial a.: passes with the radial n. into

the triceps brachii m. which they both supply

10.^ Bicipital a.: passes into the distal end of the biceps brachii m. which it supplies

11.^ Collateral ulnar a.: travels with the ulnar n. (caudal cutaneous antebrachial n.) toward the elbow which it supplies.

12. ^Superficialbrachiala.: branch of the bra-chial a., it passes from the brachium to the cranial surfaceoftheantebrachiumwhereitgivesoffame-dialbranch,thencontinuesasthecranialsuperficialantebrachial a.

- 12i.Cranialsuperficialantebrachiala.- 12ii. Medial branch: other branch of 12

13. ̂ Transverse cubital a.: transverses the elbow cranially under the biceps brachii m. to supply the elbow.

14. Recurrent ulnar a.: supplies the forearm flexors.

a. Subscapularis m. (I)%

b. Supraspinatus m. (I)c. Teres major m. (I)d. Biceps brachii m.e. Tensor fascia antebrachii m. (I)f. Triceps brachii m., long head (I) - fi. Medial head (I)g. Latissimus dorsi m. (I) h. Pectoral mm. (I) i. Brachiocephalicus m. j. Extensor carpi radialis m. k. Pronator teres (cut) (I)m. Superficial digital flexor m. (I) n. Flexor carpi ulnaris m. (I)

E. Common interosseous a.*

12ii

Cephalic v.

*Definedintextorlegend^ More important (LPI)

II Thoracic Limb

93

Transect the teres major m. and reflect it to see:C. Subscapular a.: the large branch of the axillary a. passing caudodorsally along the border of the scapula, between the subscapularis and teres major mm. It becomes subcutane-ous at the caudal angle of the scapula.

D. Brachial a.: the continuation of the axillary a. on the me-dial aspect of the arm/brachiumroughlypasttheoriginof the subscapular a.# It continues as the median a. in the forearmaftergivingoffthecommoninterosseousa.Thebrachial a. travels on the medial side of the arm with the musculocutaneous n., median n., and brachial v. between the biceps brachii and the triceps brachii mm.

Transect the pronator teres m. and reflect its parts (if it hasn't already been done for the median n.), to follow the brachial a. past the elbow.

Pull the brachial a. medially and bluntly locate its last branch diving deep between the two bones of the forearm (ulna and radius):

E. Common interosseous a.: the last branch of the brachial a. (NAV), it dives through the interosseous space between the ra-dius and ulna. and branches into cranial and caudal interosseous branches

# The conjoined tendon of the teres major and latissimus dorsi mm. is the actual demarcation between the axillary and brachial aa.

ARTERIES - THORACIC LIMB - 2

We will now start learning the circulatory system by dissecting out the arteries of the thoracic limb. They come from the heart in the thorax by way of the subclavian aa.

Arterial patterns are variable. The main branches usually follow the text books, but lesser branches will vary con-siderably from dog to dog. Even though origins may vary, the area supplied is consistent. Veins vary even more than arteries, nerves less, and lymphatics the most.

Therefore, identify a vessel nerve by the structure it supplies, not where it arises.

Dissect the following vessels of the arm and antebrachium to their terminations.

Locate the artery crossing the axilla (axillary a.) and follow it back to the first rib to its parent artery:

A. Subclavian a.: arises in the chest on the left side directly from the aorta and on the right from the brachiocephalic trunk (which arises from the aorta). It passes cranially out of the thorax through the thoracic inlet, then around the 1st rib to become the axillary a.

Relocate the large artery crossing the axilla:B. AXILLARY A.: the continuation of the subclavian a. af-terthefirstrib,itcrossestheaxilla(armpit)tosupplythestructures of the shoulder and continues as the brachial a. in the arm.#

D. Brachial a.

Median a.

C. Subscapular a.*

E. Common interosseous a.*

B. Axillary a.*

Ca. interosseous a.

1*

2*

3*

4*

5*

6*

7*

8*

9*

10*

13*

11*

12*

14*

A. Subclavian a.*

12i

12ii

II. Arteries of left arm, medial view, schematic

II Thoracic Limb

94

Relocate: A. Common interosseous a. (I, IV): the last branch of the brachial a.

Cut longitudinally the proximal end of the pronator quadratus m. and, with the end of a scalpel handle, scrape the muscle off the ulna and radius to locate:

B Caudal interosseous a. (IV): the continuation of the com-mon interosseous a. passing distally in the space between the caudal ulna and radius.

C. Median a. (I, IV): the direct continuation of the brachial a. in the forearm after the common interosseous a. It continues to the manus as the main arterial supply of the manus.

Do not dissect the following:D-G. Digital aa. (III, IV): on the dorsal and palmar sides of the digits and metacarpus. They can be further divided into dorsal and palmar branches which can also be divided in the digits into axial and abaxial aa.-D, E. Palmar and dorsal digital aa. (III, IV): are further divided into superficial (common digital aa.) and deep sets(metacarpal aa.) in the metacarpus. They join at the digits and then branch into medial and lateral branches that pass on the axial and abaxial sides of the digits. The palmar digital aa.arisefromthesuperficialanddeeppalmararches.

- F, G. Axial and abaxial digital aa. (palmar or dorsal). (III, IV): further division of the digital arteries once they reach the digits depending on which side of the digit they pass on.

Relocate and trace: H. Cephalic v. (I, II): arises on the palmar aspect of the paw and passes proximally, wrapping around the medial side of the forearm to be joined by the accessory cephalic v. It then continues up the cranial side of the forearm.

I. Accessory cephalic v. (I): arising on the dorsum of the paw, it passes proximally to empty into the cephalic v.

J. Median cubital v. (I): connects the cephalic and brachial vv.

I. Arteries of left forearm, medial view

ARTERIES - THORACIC LIMB - 1

II. Arteries of left forearm, lateral view

Brachial a.

H. Cephalic v.*

A. Common interosseous a.*

C. Median a.*

I. Accessory cephalic v.*

H. Cephalic v.*

Radial n.

i

16*

4*

5i*

5ii*

Deep br.

m

j

k

aa

b

bii

n

e

f

h

g

h

d

d

c

f

j

7*

5*

c

Median n.

Median n.

Ulnar n.

Ulnar n.

Supf. br. J. Median cubital v.*

3*

CLINICAL:• Cephalic v.: the most common site of venipuncture. Realize that the super-ficialbranchesoftheradialn.andthe

• Caudal interosseous a.:can'tbeoccludedwithatour-niquet in the mid-forearm as it is protected

between the radius and ulna. It is also prone to injury if the forearm is fractured.

branchesofthesuperficialbrachiala.travelwithit.

II Thoracic Limb

95

*Definedinthetextorlegend

A. COMMON INTEROSSEOUS A. (I, III) see text

1. Ulnar a. (IV): arises from the common interosseous a. and travels distally with the ulnar n.

B. Caudal interosseous a. (IV) see text2. ^Cranial interosseous a. (III, IV): continues

through the interosseous space between the radius andulnaafterthecaudalinterosseousa.isgivenoff.Once on the cranial side of the ulna and radius, it extends distally.

C. MEDIAN A. (I, IV) see text^3. ^Deep antebrachial a. (I, IV): runs caudally fromthemediana. tosupply theflexorsideof theforelimb.

4. ^Radial a. (I, III, IV): runs cranial to the median a. on the radius.

5.^ Superficial brachial a. (I, III): branch of brachial a. see p 92

- 5i. ^Cranial superficial antebrachial a. (III): : along with the medial branch (12ii) courses withthecephalicv.andbranchesofthesuperficialradial n. to supply the dorsum of the paw via dorsal common digital aa.

- ^5ii. Medial branch (III)6. ^Transverse cubital a. (III) see p 927. ̂ Collateral ulnar a. (I, IV) travels with the ulnar

n. (caudal cutaneous antebrachial n.) toward the elbow which it supplies.

8. Recurrent ulnar a. (IV): see p929. Dorsal carpal rete (III): network on dorsal

carpusARTERIES - FOREPAW/metapodium (meta-

carpus and digits): divided into palmar and dorsal branches,whichcanbefurtherdividedintosuperficialand deep.

D, Palmar digital aa: dividedintosuperficialanddeepsetsarisingfromthesuperficialanddeeppalmararches (15)

- 10. ^Palmar common digital aa. (IV): the mainsupplytothedigits,superficialbranchesthatbifurcateinthedigits.Superficialbranchesthatdon'tbifurcate have their digital name in the metacarpus also (ex. 14ii).

- 11. ̂ Palmar metacarpal aa. (IV) deep branches located next to the metacarpal bones

• Dorsal branches: also divided - 12. ^Dorsal common digital aa. (III): su-perficialbranches

- 13. ̂ Dorsal metacarpal aa. (III): deep branches near the metacarpal bones

14. Proper or not: proper may be added to a digital aa. in the digital area that arises from a bifurcation ofacommondigitalaa.,andisnotifitdoesn'tarisefrom a bifurcation.- 14i. Properpalmar/dorsal(axial)digital

a. V (III, IV):

ARTERIES - THORACIC LIMB - 2

III & IV. Left forearm & manus, III.Cranial/dorsalview, IV.Caudal/palmarview, schematic

- 14ii. Abaxialpalmar/dorsaldigitala.V(III, IV)

15. Superficialanddeeppalmar arches (IV)

a. Biceps brachii m. (I, II)b. Triceps brachii m., long head (I, II) - bii. Lateral head (II) c. Extensor carpi radialis m. (I, II)d. Pronator teres (cut) (I)e. Superficial digital flexor m. (I) f. Flexor carpi ulnaris m. (I)g. Extensor carpi ulnaris m. (ulnaris lat-

eralis) m. (II)h. Flexor carpi radialis m. (I)i. Caudal cutaneous antebrachial n. (ulnar n.) (II)j.Medialbranch(superficialbranch,radial

n. (I)k. Lateral branch (of superficial branch,radial n.) (II)

m. Lateral cutaneous antebrachial n. (II)n. Dorsal branch of ulnar n. (II)

Med. side

Lat. side

D. Brachial a.

6*

C

A. Common interosseous a.*

B. Ca. interosseous a.

C. Median a.*

5*

12*

13*

11*

10*

7*

Brachial a.

1*

2*

3*

4*

2* Med. side

4*

5i* 5ii*

8*

E. Abaxial dors. digital aa. D. Axial dors. digital aa.

E. Abaxial palm. digital aa.

D. Axial palm. digital aa.

9*

15

14i*

14ii*

14i*

14ii*

Digital aa.

Light legend (LPI, lower priority items)^ More important (LPI)

Axis

II Thoracic Limb

96

THORACIC LIMB PALPATION - 1Palpate the regions of the thoracic limb and the bone(s) in each:

• Shoulder: area around the scapula and humeral joint.• Brachium or arm: area containing the humerus.• Elbow/cubital region: area where humerus, radius, and ulna articulate.

• Antebrachium: area containing the ulna and radius.• Manus: area containing the carpal, metacarpal, digital, and sesamoid bones.

Palpate on the live animal the following structures:A. Spine of the scapula:pressandrunyourfingertipsata right angle over the scapula.

N. Metacarpal bones: palpate distal to the carpus. O. Digits and phalanges: palpate at the end of the limb. P. Digital joints (metacarpophalangeal joints, proximal and distal interdigital joints):locatebyflexingandextendingthe digits

Q. Claws: check for length, imagine clipping. R-S-T. Pads of the dog/cat:- R. Carpal pad: located palmar to the carpus. - S. Metacarpal: locate this heart-shaped padonthepalmar/plantar surface at the level of the metacarpophalangeal joints.

- T. Digital pads: locate these pads on the distal end of each digit.

U. Dew claw or paradigit: medial side of the limb. Muscles: stand or lean over the animal and palpate the re-gions of the limb on both side of the animal at the same time. Compare the sides for any lesions or abnormalities.

1. Superficial cervical lymph nodes: retract the limb and runyourfingersfromtheshoulderupthenecktofeelthelarge lumps at the level of the acromion.

2. Axillary lymph node: not palpable unless enlarged, it is located on the medial side of the shoulder.

3. Accessory axillary lymph node: occasionally is present caudal to the shoulder on the chest wall at the level of the olecranon.

4. Tendon of the biceps brachii m.:first,locatethegreater tubercleofthehumerusthenpushyourfingersmediallyto feel the tendon in the bicipital groove. It is covered by a continuation of the joint capsule (synovial sheath) which willfillwithpalpablefluidifthetendon,sheathorshoulderjoint capsule are injured.

Palpate vessels and nerves:5. Pulse of the brachial a.: palpated on the medial side of the arm between the biceps brachii and the medial head of the triceps brachii mm.

6. Ulnar n.: press from cranial to caudal just caudal to the medial epicondyle to feel the nerve "pop" under your finger.

7. Radial n.: palpate just past the distal border of the lateral head of the triceps brachii m. on the brachialis m. from proximal to distal to feel the pop of the

byflexionandextension.- Antebrachiocarpal joint: palpate the dorsal surface as youflexthecarpusandnoteitopensmorethanthedistaltwo carpal joints.

- Carpal joints: the distal two communicate.M. Accessory carpal bone: locate on the lateral and palmar

B. Acromion: once the spine of the scapula is found, palpate down to theendofthescapulatofindtheacromion.

C. Point of the shoulder/greater tubercle: feel the most cranial aspect of the upper thoracic limb distal to the acromion.

D. Shoulder joint: locate its level between the acromion and the pointoftheshoulderbyflexingand extending it.

F. Elbow joint: locate it distal to the shoulderbyflexingandextendingthe elbow.

G, H. Lateral and medial epicon-dyles: feel the lateral and medial most points of the distal humerus just proximal to the elbow joint byrunningyourindexfingerandthumb up and down this area of the limb. Note the medial epicondyle projects further caudally thus preventing medial luxation of the elbow.

I. Point of the elbow/olecranon (process): locate the large process proximocaudal to the elbow joint. It is at the level of the 5th ICS (intercostal space) in the standing dog.

J. Styloidprocessoftheradius:maximallyflextheantebra-

superficialbranchoftheradialn.Test of the nervous system• Proprioception placing: an easy check is to stand the animal on the dorsum of the paw. Normal animals will quickly replace the paw in the correctposition.Failuredoesn'tlocal-izethelesiontoaspecificareabutdoeslocalize it to the nervous system.

• Extensor carpi radialis reflex: a stretch (myotatic) reflex that tests the radialn., it roots, and spinal cord segments C7-T2. Place the animal in lateral recumbency, support the elbowwiththeelbowandcarpusflexed,andtaptheexten-sor muscle just distal to the elbow. Normally the carpus willextend.Thisisthemostreliablemyotaticreflexoftheforelimb,butstilllessreliablethanthepatellarreflexofthe

chiocarpal joint and palpate the point on the distal end of the radius on the medial side of thelimb(ifnotflexed,theradialcarpalbonewill be felt instead).

K. Styloid process of the ulna: palpate the distal end of the ulna on the lateral side of the limb.

L. Carpus/carpal joints: locate distal to the elbow

side of the carpus under the carpalpad.Flexandextendthecarpus while palpating this area. This is a lateral/palmar landmark for radiographs of the limb.

II Thoracic Limb

97

THORACIC LIMB PALPATION - 2

I. Palpable structures of the thoracic limb, lateral view

hindlimb.Otherlessreliablereflexesarethetriceps,bicepsanddigitalflexor.

• Withdrawal reflex: pinch the digit of each limbtocheckthisreflex(veryreliable).

cephalicv.andimagineinsertinganeedle(firstthroughskin and then treading the vein).

Optional:• Tricepsreflex:tapthetendonofthetricepsbrachiitendonneartheole-

cranon to check the radial n. (not reliable)

• Joint blocks: injection to anaesthetize the joint to localize where lameness is, this is more commonly done in horses. - Shoulder block: place needle through the deltoid m. between the acromion

and greater tubercle cranial to the tendon of the infraspinatus m. -Elbowjointblock:inserttheneedlebetweenthelateralepicondyleand

the olecranon through the anconeus m. - Antebrachiocarpaljointblock:flexthecarpusandinsertaneedleinto

the proximal depression (antebrachiocarpal joint) on either side of the extensor carpal radialis tendon. This only blocks the proximal carpal joint.-Middlecarpaljointblock:flexthecarpusandinsertaneedleintothe

depression distal to the antebrachiocarpal joint on either side of the extensor carpal radialis tendon. This blocks both the distal 2 of the three carpal joints.

across the medial and cranial surface of the elbow. -Compressthelimbwhilemovingyourfin-ger or thumb slightly lateral to straighten the cephalic v. in the forearm.

- Hold the back of the elbow with your

Radial n.

Ulnar n.

• Bicepsreflex:tapthe insertion of biceps brachii and brachialis mm. on the cranial side of the elbow to elicit flexionoftheelbowtocheckthemusculocutaneousn. (not reliable).

P. Digital joints

A. Spine of the scapula

C. Point of the shoulder

B. Acromion

D. Shoulder joint

4. Tendon of biceps brachii m.

F. Elbow joint

H. Lat. epicondyle

G. Med. epicondyle

I. Point of elbow

J. Styloid process of radius

K. Styloid process of ulna

L. Carpus/carpal joints

M. Accessory carpal bone

N. Metacarpal bones

O. Digits & phalanges

Metacarpophalangeal joint

Prox. interdigital joint

Dist. interdigital joint

R. Carpal pad

S. Metacarpal pad

5. Pulse - brachial a.

6. Ulnar n.

7. Radial n.

T. Digital pad

W. Cephalic v.

Q. Claw

U. Dew claw

2

1. Supf. cervical lnn.

3

thumborfingertopreventjerkingofthelimb.- Veterinarian: palpate distally to locate the fluid-filled

11 Radial n. - autonomous zone: pinch the dorsum of the paw.

12 Ulnar n. - autonomous zone: pinch the lateral digit (V) of the paw.

• RAISE THE CEPHALIC VEIN for veni-puncture: an assistant and a veterinarian.-Assistant:placeyourindexfingerorthumb

II Thoracic Limb

98

VIEWS OF THE THORACIC LIMB: the most common:- Lat (mediolateral) view of limb bones and joints: out-lines/silhouettesthecranial and caudal surfaces of the bones. Place the affected limbon the cassette, so it isusually shot from medial to lateral.

- Craniocaudal (caudocranial) or dorsopalmar views (pal-marodorsal) (anterior-posterior [AP%]) view: outlines/silhouettes the medial and lateral structures of the limb.

• Long bones of the limbs: always include the proximal and distal joints in the radiograph.

• Joints of the limbs: center the joint on the cassette.• Comparisonfilms:taketheoppositelimbifthereisaques-tion as to what you are seeing, and compare the two.

Evaluating radiographs of the limbs:recognizedifferentanatomical variations for the bones (German Shepherd humeruscomparedtoachondrodystrophicdog[Dachs-hund]).Followthecortexandseeifitthinsorthickensorif there are breaks in it.

Put up radiographs of the bones and joints of the thoracic limb on a viewing screen. Use individual and articulated bones while viewing radiographs, identify the following.

1. Scapula(I,II):accessoryossificationcenterofthecaudalaspect of the scapula.- 2. Glenoid cavity (I, IV): outline, note not a straight line. - 3. Spine (I, II): check for fractures on the CrCa view. - 4. Acromion (I, II): distal end of spine. - 5. Supraglenoid tubercle (I, II): anossification center,origin of biceps brachii m.

6. Clavicle: seen in cats, it is absent (usually) or rudimentary

in the dog, if present it may be seen in radiographs.7. Humerus (II, III, IV, V): craniocaudal and lateral views.- 8. Head of the humerus (II, III, IV, I): smooth and round, withnoflattening,directedcaudally.

- 9. Greater tubercle (III, IV, V): laterocranial structure.- 10. Lesser tubercle (IV, V): medial structure. - 11. Humeral condyle (III, IV, VI): whole distal end of humerus, there is only 1. . 12. Medial epicondyle (IV, VI, VII) silhouetted in both the craniocaudal and lateral projections.

. 13. Lateral epicondyle (VI): silhouetted only in the cran-iocaudal projection.

SHOULDER JOINT/scapulohumeral or humeral joint: standard views: lateral and caudocranial views. Remember tolookatallthefilm,noticingneck,cervicalvertebrae,air-filledtrachea,ribs,andlungfields(air-filled).

14. Joint space (IV, V, VI): should be of equal width all around the humeral head.

ELBOW JOINT: a flexed lateral view (VII) is added to standard craniocaudal and lateral. 15. Radius (IV, VI, VII): cranial in lateral view. 16. Olecranon (III, IV, VI): the point of the elbow.-17. Trochlear notch (VI)): cups the humerus-18. Anconeal process(VII):ossificationcenterununitedifnot joined by 6 months, best seen in flexed lateral view.

-19. Medial coronoid process (VII) large distal end of notch: clinicallysignificancehardtoseeinradiographs.

20. Supinator sesamoid bone: seen occasionally in the dog on the lateral side of the elbow joint.

I. Scapula, Craniocaudal view (taken CaCr)

a

7

Radiographs: Dr. Small-wood, NCS University

RA

DIO

LOG

Y - T

LIM

B BO

NES

- 1

3. Spine

1. Scapula

4. Acromion

5. Supraglenoid tubercle

2. Glenoid cavity

II. Shoulder, lat view, Not atruescapularviewasdoesn'tinclude all of the bone5

Lat. surface

Med. surface

Ca. edge

8

7 Review bones: p33-5

II Thoracic Limb

99

RADIOLOGY - THORACIC LIMB BONES - 2

13. Lat. epicondyle

IV. Humerus, Elbow, lat view

1. Supraglenoid tubercle

12. Med. epicondyle

VI. Elbow, CrCa view

VII. Elbow,Flexed lateral view

14. Joint space 15. Radius

17. Trochlear notch

16

a. Supraspinous fossa (II)b. Deltoid tuberosity (IV)c. Brachial groove (IV)d. Lateral coronoid processe. Olecranon process

19

e

V. Shoulder, craniocaudal view

14

11

15

15

c

b

12

9. Greater tubercle

19. Med. coronoid process

d

e

18. Anconeal process

16III. Humerus, craniocaudal view

18

8. Head

2 Glenoid cavity

4

12

14

Med. surface

11. Condyle

2

16

10. Lesser tubercle

7. Humerus

VII

III IVV

VI

8

II Thoracic Limb

100

2. Styloid process (radius)

4. Olecranon5. Trochlear notch 6. Anconeal process

8. Styloid process (ulna)

RADIOLOGY - THORACIC LIMB BONES - 3

1. Radius (I, II): curves cranially in lateral view.2. Styloid process of radius (II): on medial side.3. Ulna (I, II): caudal in a lateral view.8. Styloid process of the ulna (I): lateral side.

9. Interosseous space (II)10. CARPUS: proximal and distal rows.10. Cr, Radial carpal bone (III, IV, V, VI): medial side10. Cu, Ulnar carpal bone (III, IV, V): lateral side

10. Ca, Accessory carpal bone (III, IV, V, VI): landmark for the palmar and lateral sides of the carpus.

10. C1-4, Carpal bones (IV): numbered medial to lateral 11. Sesamoid bone of the oblique carpal extensor (IV): medial side of the carpus, not a chip fracture

12. Antebrachiocarpal joint (III)13. Middle carpal joint (III)14. Carpometacarpal joint (III)15. Intercarpal joints (VII): plane joints

1. Radius

9.

3. Ulna

32. Digital pad

12. Antebrachiocarpal joint

Ca

Cr

Cu

20. Prox. sesamoids

22. P1

25. Ungual process

23. P2

24. P3

III. Manus, lateral view

I. Forearm, craniocaudal view

II. Antebrachium, lateral view

14. Car joint

27. Horny claw

a. Lateral coronoid process (II)

a

Dors. surface

Palm. surface

Edgeof ulna

Interosseous space

21. Dors. sesamoid

7. Med. coronoid process

pometacarpal rpal

17

13. Middle carpal joint

21.

Ca

Review bones: p36-9

II Thoracic Limb

101

20. Prox. sesamoids

16. Intermetacarpal joints (V)17. Carpal pad (III):outlined/silhouettedinLat18. Mc 1-5, Metacarpal bones I-V (III, IV, V)DIGITS: 1-5 or I-V. 19. Dew claw or paradigit (IV)20. Proximal sesamoid bones (III, IV)21. Dorsal sesamoid bones (III): lateral view 22. Proximal phalanx/P1 (III, IV)23. Middle phalanx/ P2 (III, IV)

10. C2

RADIOLOGY - THORACIC LIMB BONES - 4

24. Distal phalanx/P3 (III, IV)25. Ungual process (III, IV)26. Ungual crest (IV): only tangential side ("hook") is seen 27. Horny claw (III)28. Metacarpophalangeal joint (VIII)29. Proximal interphalangeal joint (VIII)30. Distal interphalangeal joint (VIII)31. Metacarpal pad (IV)32. Digital pad (III)

Pinky naming obliques: • Clue: accessory carpal is located palmar and lateral•DecidethefilmisNOTaDPorlateral,thus,anoblique

- Lateral (LM): the accessory carpal on palmar side- DP (dorsal palmar view): the accessory is overlapped • Eyeball and pinky: check if the accessory carpal is slightly

highlighted or overlapped-Flexyourlittlefinger(representingtheaccessorycarpal,asit

is on the lateral and palmar side)-Pointyouroppositeindexfinger(representstheprimarybeam)

at either the medial or lateral side of the dorsal surface of your hand.Lookdownthefingertomatchtheamountofthepinkyseenwiththeaccessorycarpalonthefilm,eitherhighlightedoroverlapped. Name the oblique by the entrance and exit points of the beam always starting with dorsal. . Dorsomedial-palmarolateral oblique (DMPLO), or. Dorsolateral-palmaromedial oblique (DLPMO).

Ca

Cr

Cu

C3

10. C1C4

18. Mc 5

Mc 4

17. Mc1

Mc 2

18. Mc 3

II

IIIIV

V

22. P123. P2

24. P3

31. Metacarpal pad

IV. Left manus, DP view

VI. Carpus, DMPLO, dorso-medial/palmarolateraloblique view, slight

V. Carpus, DLPMO, dorso-lateral/palmaromedialoblique view

Radiographs:Dr.EdSmallwood,NCSU

19. Dew claw

11. Oblique carpal extensor sesamoid

20. Prox. palmar sesamoid bones

crest

25. Ungual process

10. Accessory carpal

Dorsolat. surface

Radiograph: Dr. Mariona Makara

Cu

18. Mc 2

Cr

Palmaromed. surface

Palmarolat. surface

Lat. surface

Med. surface

26. Ungual

16

16

II Thoracic Limb

102

Joint mouse

RADIOGRAPHS - THORACIC LIMBDist. Physis - ulna

Dist. physis - radius

Fractures

Dist. epiphysis Mc 5

Prox. epiphysis P1, digit 4

Prox. Physis P1, digit 1

I. Manus, young, dorsal view

CLINICAL:• Osteochondrosis (OC): seen in young, rapidly growing, large breeds. The shoulder is the #1 location. Radiographically, carti-lage is invisible, so check the subchondral bone for indications of cartilage damage (flatteningorcrateringofthecaudalaspect

YOUNG DOG - RADIOGRAPHS: are confusing especially of the manus or pes.

• Growth plate (physis): appears as a dark line easily confusedwithajoint.Inthemanus,firstlocatethedistalphalanx of a digit and the associated metacarpal bone, then locate the middle and proximal phalanges and their growth plates and epiphyses. At first use growth plate instead of physis during tests to avoid confusion with epiphysis.- Proximal and distal: don't forget to include when identifying. In the metacarpals, and proximal, and middle phalanges there is usually only the proximal is visible as the distal has closed.

• Epiphyses (sin. = epiphysis): distal ends of forming long bones. Include proximal and distal when identifying, give number of metacarpal bone or the phalanx, and for pha-langes the number of the digit for full credit on tests.

Crater & subchondral sclerosis

Anconeal process

of the humeral head with subchondral bone sclerosis (thickening/"whitening");seenbestinaLat radiograph.

• Osteochondrosis dissecans:OCwith adissectedflapofcartilagewhichcancalcifyand/orbreakoffandfloat

around in the synovium, it is called a “joint mouse”.

• Ununited anconeal process: failure of the anconeal process to unite with the ulnabyfiveto 6 months of age. A straight or ragged radiolucent line is seen. There may be degenerative changes in the el-bow (DJD). The best view is the flexed

lateral elbow, which pulls the anconeal process out of the olecranon fossa of the humerus.

Dist. humeral physis

Prox. radial physis

Dist. radial physis

Dist. ulnar physis

Accessory carpal bone

Dist. physis of Mc5

Distal epiphysis - humerus

Prox. epiphysis- radius

Diaphysis - humerus

Metacarpophalan-geal joint

II. DP view, manus, puppy

I. Lat view, forearm, puppy

Dist. radial epiphysis

Distal epiphysis - ulna

Metaphysis

II Thoracic Limb

103

REGIONS:Shoulder: Scapula (clavicle absent or greatly

reduced)

Brachium: humerusCubital region: elbowAntebrachium: ulna & radiusManus: carpal, metacarpal, digital & sesamoid bones

BONESScapula- Spine: long lateral projection

- Acromion: distal end of the spine

- Supraspinous fossa: above the spine

- Infraspinous fossa: below the spine

- Subscapular fossa: medial (costal)- Supraglenoid tubercle: above cr. glenoid

cavity

- Glenoid cavity: + head of humerus = shoulder

- Scapular cartilage: thin bandClavicle:absent/rudimentaryindog.Presentincat.Humerus:- Head: rounded articular process

- Intertubercular groove: between tubercles

- Greater tubercle: point of shoulder- Lesser tubercle: medial side

- Intertubercular (bicipital) groove: between greater & lesser tubercles

- Deltoid tuberosity: lat., dist. to greater tubercle

- Humeral condyle: whole distal humerus

-- Medial epicondyle: large medial projection

-- Lateral epicondyle: most lateral condyle

-- Olecranon fossa (excavation for anconeal p.)

Radius- Styloid process: distal point on medial side

Ulna- Olecranon: point of elbow- Trochlear notch: indention of olecranon

- Anconeal process: prox. end of trochlear notch

- Medial coronoid process: large dist. trochlear notch

- Styloid process of ulna: distal - lateral

Interosseous space: between ulna & radiusManus/Paw: carpal, metacarpal phalangeal

& sesamoid bonesCarpus- Radial carpal bone: med. side of prox. row

- Ulnar carpal bone: lateral side of prox. row

- Cleidobrachialis: clavicular intersection to arm

- Cleidocephalicus: intersection to head or neck

-- Mastoid part: to mastoid process (skull)

-- Cervical part:todorsalfibrousrapheofneck- Clavicular tendon: remnant of clavicle

Omotransversarius m.: wing C1 to acromion

Trapezius m.:fromspinetodors.fibrousraphe- Cervical part (trapezius cervicis): over neck- Thoracic part (trapezius thoracis): above thorax

Rhomboideus m.: inside of scapula, dorsally - Capital part: to skull- Cervical part: over neck- Thoracic part: over thorax

Latissimus dorsi m.: inside arm, over thorax Aponeurosis of: tendon of insertion

Pectoral mm.- Superficial pectoral: cranially

-- Descending part-- Transverse part

- Deep pectoral: located cranially & caudally

Serratus ventralis: suspends body

- Cervical part: from cervical transverse processes

- Thoracic part: from cranial ribs

Subscapularis m. INTRINSIC MUSCLESSupraspinatus m.:fillssupraspinatusfossaDeltoideus m.: lateral to deltoid tuberosity

- Scapular part: from spine of scapula

- Acromial part: from acromion

Infraspinatus m.:fillsinfraspinatusfossa - Bursa of: between tendon & greater tubercle

Teres minor m.: below infraspinatus m.

Subscapularis m.: fills subscapular fossa, deep toscapula

Teres major m.: below scapula, medial to humerus

Coracobrachialis m.: from coracoid process to medial humerus

Triceps brachii m.: caudal mass of arm

- Long head: crosses elbow & shoulder

- Lateral head- Medial head- Accessory head: surrounded

Anconeus m.: lateral, over elbow joint

Tensor fasciae antebrachii m.: thin m. over medial side of triceps

Biceps brachii m.: medial- Tendon of origin: in intertubercular groove

THORACIC LIMB STRUCTURES - ID

WirehairedPointerGriffon

- Accessory carpal bone: palmar & lateral

- Carpal bones 1-4: distal row

- Sesamoid of oblique carpal extensor (abductor pollicis longus)

Metacarpal bones 1-5 (Mc 1-5)- Sagittal ridge

DIGITS = Phalanges + sesamoid bones

- P1. Proximal phalanx

- P2. Middle phalanx

- P3. Distal phalanx- Palmar sesamoid bones: 2 for each main

digit, 1 for dewclaw

- Dorsal sesamoid bones: 4

• Umbilicus or belly button: remnant • Vortices (sing. = vortex) (cowlicks): umbilicus.

• Thorax or chest: cr. trunk • Mammae: 10 average

- D. Thoracic mammae: cr. & ca. -E.Abdominalmammae: cr. & ca. -F.Inguinalmammae: 1 pair - G. Papillae, nipple, or teat

REGIONS:• Withers: highest back

• Scapular region: over scapula

• Shoulder: between scapula & humerus

• Point of the shoulder: most cr. - greater tubercle

• Axillary region:armpit/axilla

• Brachium, arm, brachial region: between shoulder & elbow

• Elbow, cubital region• Point of the elbow/olecranon region: at 5th ICS

• Antebrachium or forearm: between elbow & carpus

• Paw, forepaw or manus: contains carpus, metacarpus, & digits

- Carpus/carpal region: between antebrachium &metacarpus

- Metacarpus/metacarpalregion:betweencarpus&metacarpophalangeal joint

- Digits/phalangealregion: ends of limb

DISSECTION - CADAVER• Skin or common integument: 2 layers:

epidermis & dermis

Superficial fascia: envelops body

Deep fascia: envelops body & compartmentalizes mm.

- Septa: extensions between muscles to bones

. Fascial planes: potential continuous spaces

. Retinacula (sin. = retinaculum): localized thickenings of deep fascia, hold down tendons

Cutaneous mm.- Cutaneous trunci m.: lateral thorax

- Platysma m.: over neck & face

- Preputial m.: cran. to prepuce near midline (male)

MUSCLESEXTRINSIC MUSCLESBrachiocephalicus: from arm to head & neck Labrador Retriever

II Thoracic Limb

104

- Transverse humeral lig.: holds biceps tendon in bicipital groove

Brachialis m.: lateral, passes in brachial groove

FOREARM MUSCLESBrachioradialis m. Extensor mm. of carpus & digits: radial n.

- Extensor carpi radialis m.: medial

- Common digital extensor m.: to PI

- Lateral digital extensor m. - Extensor carpi ulnaris (lateral ulnar) m.: to accessory carpal

-Obliquedigitalextensorm./abductorpollicis longus m.

- Extensor retinaculum: deep carpal fascia

Flexor mm.: median & ulnar n.

- Flexor carpi ulnaris m.: accessory carpal-- Ulnar head-- Humeral head

- Superficial digital flexor m. (SDF): to digits

--Manicaflexoria:sleeveforDDF- Flexor carpi radialis m.: medial & cranial

- Deep digital flexor m. (DDF): to P3

. Humeral head

. Radial head

. Ulnar head- Supinator: lateral under extensor carpi radialis

- Pronator teres m.: medial

- Pronator quadratus m.:deeptoDDFCarpal canal:accessory,carpals,flexorretinaculumFlexor retinaculum: deep fascia

MUSCLESOFTHEMANUS- Interosseous m.: suspensory lig. in horse

JOINTSShoulder joint: scapulohumeral joint

- Supraglenoid tubercle: origin of biceps

- "Tendon sheath" around tendon of biceps brachii m.

- Shoulder joint capsule- Articular head of humerus - Glenoid cavity of the scapula

Elbow/cubital joint: hinge joint

- Lateral & medial collateral ligg.- Anconeal process: into fossa on extension

- Medial coronoid process- Sesamoid bone of supinator m. - Anconeus m.: opened to enter elbow

- Joint capsuleCarpus: compound joint - acts as a hinge joint

- Antebrachiocarpal joint: proximal, most movement

- Middle carpal joint: half as much movement

- Carpometacarpal joint: little movement

- Intercarpal joints: plane joints

- Collateral ligg.: medial & lateral, short

- Intercarpal ligg.: many

- Joint capsule: forms the deep sheath

- Extensor & flexor retinacula:modifieddeep carpal fascia

- Carpal canal: carpal bones, accessory carpal bone & flexorretinaculum

-Palmarcarpalfibrocartilage/lig.: thick connective tissue, dorsal wall of carpal canal

- Interosseous spaces: between Mc bones

Digital joints- Metacarpophalangeal joints: Mc & P1

- Proximal sesamoid bones: palm. side McP

- Medial & lateral collateral ligaments: each side of all joints

- Proximal interdigital joint: P1 & P2

- Distal interdigital joints: P2 & P3

- Palmar annular ligament- Proximal & distal annular ligg. - Dorsal elastic lig.: P2 to dorsal P3

- Distal sesamoidean ligg.: anchor sesamoids

LYMPH NODESSuperficial cervical lymph node: in front

of shoulder under omotransversarius m.

Axillary lymph node: in armpit (axilla)

Accessory axillary lymph node: inconstant

SUPERFICIAL VEINSCephalic v.: from palmar paw, up arm, over shoulder to

external jugular v.

Accessory cephalic v.: from dorsal paw to join the cephalic v.

Median cubital v.: from cephalic over elbow to brachial v.

External jugular v.:superficialinneck-Superficialcervicalv.: drains into jugular v.

ARTERIESSubclavian a.: inside chest, axillary around 1st rib

-Superficialcervicala.:toneck,nearsuperficialcervical lnn.

Axillary a.: continuation of subscapular in armpit

Subscapular a. & v.: branch of axillary ventral to scapula

-Caudal circumflexhumerala.: around caudal humerus

-- Collateral radial a.: with radial n. in brachial groove

Brachial a. & v.: vessels in arm

Common interosseous a.: last br. of brachial a.

- Caudal interosseous a.: caudal ulna & radius

Median a.: continuation of brachial a. after common interosseous

Axial & abaxial digital aa.: on sides of digits

NERVESSpinal nn.: formed by dorsal & ventral roots.

- Dorsal branch: above transverse processes.

- Ventral branch: below transverse processes.

C6 nerve to brachiocephalicus m.Accessory n.: cranial n. 11 to trapezius m., etc.

BRACHIAL PLEXUS: ventr. brs. of C6-T1-2

Musculocutaneous n.: to biceps brachii m.

- Medial cutaneous antebrachial n.: sensory to medial forearm.

Ulnar n.: toward ulna.

- Dorsal branch of the ulnar n.: abaxial side of 5th digit

Median n.: passes down medial side of forearm.

Radial n.: into triceps, brachial groove. - Deep branch: to extensors of forearm.

- Superficial branch: skin dorsum of paw.

Suprascapular n.: between supraspinatus & sub-scapular mm.

Subscapular n.: into subscapular m.

Axillary n.: between teres major & subscapularis mm, deep to deltoideus m.

Thoracodorsal n.: to latissimus dorsi m.

Long thoracic n.: over serratus ventralis m.

Lateral thoracic n.: to cutaneous trunci m.

Cranial & caudal pectoral nn.:tosuperficial& deep pectoral mm.

Phrenic n.: from C5, 6, 7 into thorax

Intercostobrachial nn.: cutaneous brs. of intercostal n. T1&2 to caudolateral arm

Axial & abaxial digital nn.: on sides of digits.

THORACIC LIMB STRUCTURES - ID

Golden Retriever

Boston Terrier

Chesapeake Bay Retriever

II Thoracic Limb

Giant Schnauzer

II Thoracic Limb

105

THORACIC LIMB STRUCTURES - ID

PALPATION - LIVE DOG • REGIONS:Shoulder: Scapula (clavicle absent or greatly

reduced)

Brachium: humerusCubital region: elbowAntebrachium: ulna and radiusManus: carpal, metacarpal, digital & sesamoid bones

BONES• Spine of scapula: lateral structure

• Acromion: distal end of spine

• Greater tubercle: point of shoulder: most cranial point

• Shoulder joint• Elbow joint/cubital joint • Medial & lateral epicondyles: distal

• Point of the elbow/ olecranon: 5th ICS

• Styloid process:distalmedialprocess(flex)• Styloid process of the ulna: distal lateral

process

• CARPUS: carpal bones & compound joint formed, or region between forearm & metacarpus

- Accessory carpal bone: landmark = palm. & lat.

• Metacarpal bones 1-5: # med. to lat. • Digits & phalanges• Digital joints (metacarpophalangeal joints, proximal & distal interdigital joints):flex&extendthedigits.

• Claw• Footpads of the dog- Carpal pad: locate palmar to the carpus.

- Metacarpal pad: heart-shaped pad on the palmar surface at the level of the metacarpophalangeal joints.

- Digital pads: on the distal end of each digit.

• Dew claw: medial side of limb

• Superficial cervical lymph nodes: retractlimb,fingersfromshoulderupneck

• Axillary lymph node: not palpable unless enlarged

• Tendon of the biceps brachii m.: between greater & lesser tubercle in groove

• Extensor carpi radialis reflex (C7-T2): tap proximal muscle

• Withdrawal reflex: pinch the digit of each limb

THORACIC LIMB STRUCTURES - IDRadius: curves cr.

Styloid process: distal on the med. side

Interosseous space: between ulna & radius

ANTEBRACHIOCARPAL JOINTCARPUS: carpal bones & compound joint formed, or region

between forearm & metacarpus

Radial carpal bone: med.

Ulnar carpal bone: lat.

Accessory carpal bone: landmark = palmar & lat.

MIDDLE CARPAL JOINT Carpal bones 1-4: distal row

Sesamoid bone of oblique carpal ex-tensor (abductor pollicis longus): med.

CARPOMETACARPALJOINTMetacarpal bones 1-5: # med. to lat. Metacarpal 1: part of dew claw

DIGITS: subdivision of manus & pes

Dew claw or paradigit: 1st digit (P1 & P3), 1 palmar sesamoid bone & 1st metacarpal bone

Palmar sesamoid bones: metacarpophalangeal joint, 2 - main digit, 1 - dewclaw

Dorsal sesamoid bones: seen in lateral view

METACARPOPHALANGEAL JOINTSPhalangesP1, Proximal phalanx

PROXIMAL INTERDIGITAL JOINTP2, Middle phalanx: shorter

tocheckthisreflex

• Pulse of the brachial a.: medial arm between biceps brachii & medial triceps brachii mm.

• Ulnar n.: medial, press caudal to the medial epi-condyle from cr. to ca. = nerve pops

• Radial n.: distal border of the lateral triceps b.• Radial n. autonomous zone: pinch the

dorsum of the paw. • Ulnar n. autonomous zone: pinch the

lateral digit (V) of the paw. • Raise cephalic vein for venipuncture: fingerorthumbacrosselbow

RADIOGRAPHSBONES Clavicle: rudimentary in dog, may see

Scapula:flatSpine:lateral-fractureinthecr/caviewAcromion: distal end of spine

Supraspinous fossa: above the spine

Accessory ossification center of thecaudal aspect of the scapula: not OCD

Supraglenoid tubercle: above glenoid cavity

Glenoid cavity: forms shoulder with humerus

SHOULDER (HUMERAL) JOINTHumerus: the arm or brachial bone

Head: caudally directed rounded

Greater tubercle: point of shoulder cr. & lat.

Lesser tubercle: med.Intertubercular groove: between tubercles

Deltoid tuberosity: lat. small

Brachial groove: curves, lat.

Humeral condyle: distal end

Medial epicondyle:seencr/ca,&latviews Lateral epicondyle: lat.

ELBOW (CUBITAL) JOINTUlna:ca.inlat.view,distalendlat.incr/ca.viewOlecranon: the point of the elbowTrochlear notch: cups condyle - humerus

Anconeal process: prox. end trochlear notch, best inflexedlat.

Medial coronoid process: large distal end of trochlear notch

Styloid process: dist. end - lat.

Boxer pup

Cavalier King Charles Spaniel

Boerboel

II Thoracic Limb

106

AmericanEnglishCoonhound

DISTAL INTERDIGITAL JOINTSP3, Distal phalanxUngual process: for horny claw

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LPIs (Low priority items)BONES• Scapula- Neck: constricted part - Coracoid process: medial - supraglenoid tubercle- Serrated surface: dorsal costal surface for serratus

ventralis m.• Humerus- Neck of humerus- Brachial (musculospiral, spiral) groove: ca. to lat. - Lateral supracondylar crest: prox. from lat. epicondyle- Articular surface of the condyle: divided

. Trochlea: groove for trochlear notch

. Capitulum: for radial head - Supratrochlear foramen: ± in dog

• Radius - Head - Neck- Grooves: 3, Cr. distal extremity

• Ulna- Olecranon tuberosity: end of olecranon - Lateral coronoid process

• Metacarpals- Base: proximal extremity-Head/trochlea: distal extremity

. Condyles (medial & lateral)• Phalanges

- Base: proximal extremity of P1 & P2- Axial groove of P1: for Mc sagittal ridge - Head: distal trochlea of P1 & P2MUSCLES•Dorsalfibrousraphe: connective tissue where mm. from

both sides meet on dorsal midline• Thoracolumbar fascia•Extensorbranchofinterosseousm.• Branch of interosseous m.: to prox. sesamoid boneJOINTS• Glenohumeral ligaments (medial & lateral): thicken-

ings of joint capsule •Elbow- Tricipital (olecranon) bursa: over olecranon

• Carpus-Intercarpal joints: plane joints between individual

carpal bones- Intercarpal, antebrachiocarpal, & carpometa-

carpal ligaments: connect antebrachial, carpal, & metacarpal bones

• Digital joints

THORACIC LIMB STRUCTURES - ID

Brittany Spaniel

- Distal sesamoidean lig.: anchors sesamoidsNERVES• Great auricular n.: C2 to ear• Cervical plexus: joining of ventral brs. of cervical nn.• Intercostobrachial nn.: brs. of 2nd & 3rd intercostal nn.

(thoracic) to caudolateral brachium - sensory• Brachial plexus- Cranial pectoral nn. (C6-8): motor - supf. pectoral m. - Caudal pectoral nn. (C6-8): motor to the deep pectoral m. - Caudolateral cutaneous brachial n.: of radial n.,

sensory to lateral arm - Medial & lateral branches of superficialbranches

of radial n.: travel on sides of cephalic v. . Dorsal digital nn.:continuationofsuperficialradialnn.

pass on dorsal abaxial & axial sides of digits- Caudal cutaneous antebrachial n.: ulnar n. - sensory

to caudal forearm- Palmar branch of the ulnar n.: gives rise to palmar

metacarpal nn. - Axial & abaxial palmar digital nn.

• Dorsal branches & plexuses of spinal nn. C6-T2ARTERIES• Suprascapular a.: between supraspinatus & subscapular mm.,w/supraspinatusn.•Externalthoracic:tosuperficialpectoralm.• Lateral thoracic: to deep pectoral m. • Thoracodorsal a.: to latissimus dorsi m. •Caudalcircumflexhumerala.: around ca. humerus• Collateral radial a.: with radial n. in brachial groove•Cranialcircumflexa.: cr. to humerus• Deep brachial a.: to triceps brachii m.• Bicipital a.: to distal biceps brachii m.• Collateral ulnar a.: with ulnar n. toward ulna• Transverse cubital: transverses elbow deep to biceps

brachii m.•Superficialbrachiala.: with cephalic v. in forearm

- Medial & lateral branches

St Bernard

EnglishToySpaniel