BIO 206 (2) Muscles of the Body and Upper Limb

8/10/2019 BIO 206 (2) Muscles of the Body and Upper Limb

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BIO 206 Muscles of the Body

Christopher J. Kauhn M.S.


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Muscle Criteria

Each individual muscle canonly be properly described

according to its 4 unique

criteria.

These criteria include:

Origin

Insertion

Action

Innervation


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Muscle Criteria

The Originis the non-movable point of

attachment for a muscle

when considering that

muscles action.

Even though the point of

origin may be movable,

the action of a particular

muscle does not elicit

movement at its ownorigin.

Biceps Brachii originates

on the coracoid process

and the supraglenoidtubercle of the scapula.


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Muscle Criteria

The Insertionis themovable point of

attachment for a muscle.

Both the origin and

insertion points are

formed as the muscle

tendon fuses with the

periosteum (outer fibrous

tissue) of bones at specific

locations.

Biceps Brachii

inserts onto theradial tuberosity of

the radius.


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Muscle Criteria

The Actionof a muscle isthe movement that muscle

produces upon receiving

its nervous innervation

(muscle contraction).

The action of a muscle

dictates that the muscles

insertion (moveable point

of attachment) always

moves toward the musclesorigin (non-movable point

of attachment).


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Muscle Criteria

The Innervationof amuscle refers to the nerve

supply to that particular

muscle which leads to its

contraction.


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Movements at

Synovial Joints

ANGULAR MOVEMENTS:Flexion: bending of a jointso that the angle becomesmore acute.

Extension: straightening

of a flexed joint so that theangle becomes moreobtuse.

Abduction: movement infrontal plane away fromthe median plane.

Adduction: movement infrontal plane toward themedian plane.

Circumductionis acombination of the above4 movements. Abduction Adduction


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Movements at

Synovial Joints

Rotation Movements:

Medialrotation: anterior

aspect of the limb rotates

medially

Lateralrotation: anterior

aspect of the limb rotates

laterally

Pronation: medial rotation

of forearm

Supination: lateral rotation

of forearm

Medial Rotation Lateral Rotation

Pronation Supination


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Movements at

Synovial Joints

Factors that limit movementat synovial joints include:

The shape of thearticulating surfaces.

Ligaments and thecapsule at the joint.

Muscles that act on thejoint.

Muscles are namedaccording to the following

criteria: Location

The muscles action

The shape of the muscle

The number of heads oforigin


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Muscles of Facial Expression


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Orbicularis Oculi

Orbicularis Oculi is acircular muscle

surrounding the orbit of

the eye.

The Orbital Part ofOrbicularis Oculi courses

around the periphery of

the eye orbit.

The Palpebral Part of

Orbicularis Oculi comprises

the musculature of the

eyelids and is responsible

for blinking actions.


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Zygomaticus Major

and Minor

Zygomaticus Major andZygomaticusMinor

Both muscles are involved

with elevation of the

corners of the mouth uponsmiling.

Orbicularis Oris is a

circular muscle

surrounding the mouth

that is involved with

contracting the lips.


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Procerus & Risorius

Procerusmuscles areinvolved with furrowing

the brow and are located

medial to the orbicularis

oculi.

Risoriusmuscles are

located lateral to the

orbicularis oris muscles

and serve to expand thecorners of the mouth.


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Zygomaticus Major

and Minor

Buccinator muscles arelocated laterally and deep

along the sides of the

cheeks.

The buccinator muscleskeep the bolus of food

close to the bicuspid and

molar teeth while chewing.


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Muscles of Mastication

The following muscles are involved inelevation, depression, protrusion,

retrusion of the mandible uponchewing.


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Masseter

MasseterOrigin: zygomatic bone

Insertion: external ramus

and angle of the mandible

Action: elevation of the

mandible

Innervation: Mandibular

branch of the Trigeminal n


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Muscles of the Anterior Neck


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Platysma

The Platysma is asuperficial neck muscle

which originates along the

clavipectoral fascia and

inserts at the inferior

border of the body of themandible. The action of

the platysma muscle is to

elevate the skin of the

neck.


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Sternocleidomastoid

Origin: Manubrium of thesternum and clavicle

Insertion: Mastoid process

of the temporal bone

Action: Flexion of the head

(if both sides areinnervated simultaneously)

or rotation of the head

toward the opposite side

(if only one side is

innervated).Innervation: CN XI,

Accessory nerve


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Suprahyoid and

Infrahyoid Muscles

The SuprahyoidandInfrahyoid muscle groups

are located superior and

inferior to the hyoid bone

respectively.

Their primary actions

involve either depression

or elevation of the hyoid

bone anterior to the neck.


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Muscles of Respiration

The following muscles are involved in

movements of the thoracic wall uponinspiration and expiration.


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Diaphragm

The Diaphragm receives itsinnervation from thePhrenic Nerve (derivedfrom cervical spinal nervesC3, C4 and C5).

The Diaphragmis the

primary muscle involvedwith respiration and, uponcontraction, will result inthe elevation of the ribcage (increasing thenegative hydrostaticpressure between theparietal and visceralpleura) thus forcing air intothe lungs.


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Muscles of

Respiration

The External IntercostalMuscles originate from the

lower margins of the first

eleven ribs.

The muscle fibers course

inferiorly and anteriorly toinsert along the upper

margins of the infrajacent

ribs below.

External Intercostal

Muscles function in

elevating the rib cage and

are important for

Inspiration. (E.I.I.)


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Muscles of

Respiration

The Internal andInnermost IntercostalMuscles originate alongthe upper margins of thefirst eleven ribs and costalcartilages.

The muscle fibers coursesuperiorly and medially toinsert at the lower marginof the suprajacent ribs andcostal cartilages.

Internal and InnermostIntercostal Musclesfunction in depression ofthe rib cage and areimportant for Expiration.(I.I.E)


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Muscles of the Trunk


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External Oblique

Origin: Lower 8 ribs (Theorigin of external obliqueinterdigitates with thelatissimus dorsi andserratus anteriormuscles.)

Insertion: Iliac crest andRectus sheath (via anaponeurosis)

Action: Rotation andlateral flexion of thetrunk, Forced expiration

Innervation: Thoraco-abdominal nerves (T7-T11) and the Subcostalnerves (T12)

The aponeurosis of theexternal oblique forms the

INGUINAL LIGAMENT.


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Internal Oblique

Origin: Iliac crest

Insertion: Costalmargin, Rectus sheathvia an aponeurosis,Pubic crest


Innervation: Thoraco-Abdominal nerves (T7-T11) and Subcostal

nerves (T12)The muscle fibers of theinternal oblique courseanteriorly and superiorly inthe upper half andtransversely in the lower

half.


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Transversus

Abdominis

Origin: Iliac crest, Lower6 costal cartilages andfascia of the back

Insertion: Rectussheath via anaponeurosis


Innervation: Thoraco-abdominal nerves (T7-

T11) and subcostalnerves (T12)

The muscle fibers oftransversus abdominiscourse transversely as itsname indicates.


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Rectus Abdominis

Origin: Xiphoid Processand Costal Cartilages ofribs 5-7

Insertion: Pubic crestand symphysis

Action: Flexion of the

trunk Innervation: Thoraco-

Abdominal nerves (T7-T11) and Subcostalnerves (T12)

The muscle fibers of rectusabdominis course verticallyand the muscle is enclosedby the RECTUS SHEATH.


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Rectus Sheath

The RectusSheath is thefibrous connective tissue

that envelopes the rectus

abdominis muscle.

It is formed by theAponeurosis (flattened

tendon)of the external

oblique, internal oblique

and transversus

abdominus muscles.

Midsagittally, the rectus

sheath flattens to form the

Linea Alba.


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Inguinal Ligament

The InguinalLigamentisan aponeurosis of the

external oblique muscle.

The inguinal ligament

attaches from the anteriorsuperior iliac spine to the

pubic tubercle.

Nerves and vasculature

course from the pelvicregion toward the anterior

thigh by passing deep to

the inguinal ligament.


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Erector Spinae

ILIOCOSTALISis the most lateral of theerector spinae muscles,extending from the ilium tothe ribs.

LONGISSIMUS

is the longest of the groupextending from the sacrumto the base of the skull.

SPINALISis approximately 1 cm wideand is the most medial of

the group, coursing alongeither side of the spinousprocesses.

The Erector Spinae musclegroup act in coordination to

keep the spine erect.


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Quadratus

Lumborum

Quadratus Lumborum is apostural muscle and hip

stabilizer located along the

posterior abdominal

region.

Origin: iliac crest andilio-lumbar ligament

Insertion: 12thrib and

transverse processes of

lumbar vertebrae


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Muscles of the Superficial Back


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Trapezius

Origin: Skull, cervical andthoracic vertebrae

Insertion: Clavicle,

acromion, spine of scapula


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Latissimus Dorsi

Origin: Thoracic andlumbar vertebrae, sacrum,

iliac crest

Insertion: Intertubercular

groove of the humerus


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Latissimus Dorsi

Origin: Thoracic andlumbar vertebrae, sacrum,

iliac crest

Insertion: Intertubercular

groove of the humerus

Action: Adduction,

extension, medial rotation

or the arm

Innervation: Thoracodorsal

nerve


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Levator Scapula

Origin: Cervical vertebraeC1 to C4

Insertion: medial border of

the scapula above the level

of the scapular spine


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Levator Scapula

Origin: Cervical vertebraeC1 to C4


the scapula above the level


Action: elevation of the

scapula

Innervation: Cervical spinal

nerves C3 & C4, accessory

nerve


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Rhomboid Minor

Origin: Cervical vertebraeC7 and Thoracic vertebrae

T1


the scapula at the level ofthe scapular spine


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Rhomboid Minor

Origin: Cervical vertebraeC7 and Thoracic Vertebrae

T1

Insertion: Medial border of

the scapula at the level ofthe scapular spine

Action: Adduction of the

scapula

Innervation: Dorsal

scapular nerve


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Rhomboid Major

Origin: Thoracic VertebraeT2 through T5


the scapula below the level



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Rhomboid Major

Origin: Thoracic VertebraeT2 through T5


the scapula below the level


Action: Adduction of the

scapula

Innervation: Dorsal

scapular nerve


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Muscles of the Chest


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Pectoralis Major

Origin:Clavicular part- medial half

of the clavicle

Sternocostal part- sternum

and first 6 costal cartilages

Insertion: Crest of greater

tubercle of the humerus


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Pectoralis Minor

Origin: Ribs 2-5

Insertion:Coracoid process

of the scapula


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Pectoralis Minor

Origin: Ribs 2-5

Insertion: Coracoid process

of the scapula

Action: depression of the

scapula

Innervation: medial

pectoral nerve


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Serratus Anterior

Origin: Ribs 1-8


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Serratus Anterior

Origin: Ribs 1-8


scapula


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Serratus Anterior

Origin: Ribs 1-8


scapula

Action: Upward rotation of

the scapula (so that the

inferior angle of the

scapula rotates laterally)

Innervation: Long thoracic

nerve


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Serratus Anterior

Action: Upward rotation ofthe scapula (so that the

inferior angle of the

scapula rotates laterally)

When the arm is abductedto 90 degrees, the long

thoracic nerve innervates

serratus anterior which

rotates the acromion out

of the way of the greatertubercle; allowing greater

than 90 degrees of

abduction.


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Muscles of the Shoulder


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Deltoid

Origin: spine of thescapula, acromion, clavicle


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Deltoid


Insertion: deltoid

tuberosity of the humerus


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Deltoid


Insertion: deltoid

tuberosity of the humerus

Action: flexion, extension,

abduction medial and

lateral rotation of the arm

at the shoulder joint

Innervation: Axillary nerve


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Supraspinatus

Origin: supraspinous fossa

Insertion: greater tubercle

of humerus

*Rotator Cuff Muscle


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Supraspinatus

Origin: supraspinous fossa


of humerus

Action: abduction of the

arm at the shoulder joint

Innervation: suprascapular

nerve



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Infraspinatus

Origin: infraspinous fossa


of humerus



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Infraspinatus

Origin: infraspinous fossa


of humerus

Action: lateral rotation of

the arm at the shoulder

joint

Innervation: suprascapular

nerve



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Teres Minor

Origin: lateral border ofthe infraspinous fossa


of humerus



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Teres Minor

Origin: lateral border ofthe infraspinous fossa


of humerus

Action: lateral rotation of

the arm at the shoulder

joint

Innervation: axillary nerve



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Subscapularis

Origin: subscapular fossa

Insertion: lesser tubercle

of humerus



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Subscapularis

Origin: subscapular fossa

Insertion: lesser tubercle

of humerus

Action: medial rotation ofthe arm at the shoulder

joint

Innervation: upper and

lower subscapular nerves



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Teres Major

Origin: inferior angle of theinfraspinous fossa


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Teres Major


Insertion: crest of the

lesser tubercle of humerus


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Teres Major


Insertion: crest of the

lesser tubercle of humerus

Action: adduction and

medial rotation of the arm

at the shoulder joint

Innervation: lower

subscapular nerve

BIO 206 (2) Muscles of the Body and Upper Limb

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