Shoulder and Pectoral regions

Dr.Elraiah Mohamed

Makie 0122858517

Msc

Anatomy department

Faculty Of Medicine2nd Year Semster4

By the end of this session the student should be able to :

Describe the muscles of the pectoral & shoulder regions , their action and innervations

study the common clinical correlations

Topographical Anatomy of the pectoral and shoulder regions

Shoulder: proximal segment of the limb that overlaps

parts of the trunk

Arm (L. brachium): first segment of the free upper

limb and the longest segment of the limb.

Forearm (L. antebrachium): second longest segment

of the limb.

Hand (L. manus): part of the upper limb distal to the

forearm that is formed around the carpus,

metacarpus, and phalanges.

An injury to the upper limb, particularly the

hand, are far out of proportion to the extent of

the injury,

A sound understanding of the structure and

function of the upper limb is of the highest

importance.

Knowledge of its structure without an

understanding of its functions is almost useless

clinically because the aim of treating an injured

limb is to preserve or restore its functions.

G-H joint A-C joint S-C joint S-T joint Subacromial space

-Trapezius.-Latissimus dorsi.

- Levator scapulæ. - Rhomboideus major.- Rhomboideus minor.

Superficial layer

Deep layer

•Muscles Connecting the Upper Limp to the Vertebral Column

The superficial axioappendicular muscles are

trapezius

latissimus dorsi

The deep posterior thoracoappendicularmuscles are

levator scapulae and rhomboids.

These muscles provide direct attachment of the appendicular skeleton to the axial skeleton.

Muscles connecting scapula to humerus◦ Teres Major◦ Rotator Cuff Supraspinatus Infraspinatus Teres Minor Subscapularis

◦ Deltoid

Subscapularis

Supraspinatus

Infraspinatus

Teres Minor

◦ Function mainly to reinforce the capsule of the shoulder

◦ Act to stabilize head of humerusin glenoid cavity and prevent dislocation

◦ Secondarily act as synergists and fixators

Supraspinatus assists deltoid in abduction

Subscapularis, infraspinatus & teres minor depress humeral head

Injury or disease may damage the musculotendinous rotator cuff, producing instability of the glenohumeral joint.

Trauma may tear or rupture one or more of the tendons of the SITS muscles; that of the supraspinatus is most commonly involved.

Degenerative tendonitis of the rotator cuff is common, especially in older people.

Origin :from occipital bone, ligamentum nuchae, spine of seventh cervical vertebra, spines of all thoracic vertebrae

Insertion: Upper fibers into lateral third of clavicle; middle and lower fibers into acromion and spine of scapula

Innervations :Spinal part of accessory nerve (motor) and C3 and 4 (sensory) XI cranial nerve (spinal part)

Action :Upper fibers elevate the scapula; middle fibers pull scapula medially; lower fibers pull medial border of scapula downward

Origin : Transverse processes of first four cervical

vertebrae

Insertion: Medial border of scapula

Innervations : C3 and 4 and dorsal scapular nerve C3, 4, 5

Action : Raises medial border of scapula

Origin :from Ligamentum nuchae and spines

of seventh cervical and first thoracic vertebrae

Insertion: Medial border of scapula

Innervations : Dorsal scapular nerve C4, 5

Action : Raises medial border of scapula

upward and medially

Origin : Second to fifth thoracic spines

Insertion: Medial border of scapula

Innervations : Dorsal scapular nerve C4, 5

Action : Raises medial border of scapula

upward and medially

Origin : Lateral third of clavicle, acromion,

spine of scapula

Insertion: Middle of lateral surface of shaft of

humerus

Innervations : Axillary nerve C5, 6

Action : Abducts arm; anterior fibers flex and

medially rotate arm; posterior fibers extend

and laterally rotate arm

Origin : Supraspinous fossa of scapula

Insertion: Greater tuberosity of humerus;

capsule of shoulder joint

Innervations : Suprascapular nerve C4, 5, 6

Action : Abducts arm and stabilizes shoulder

joint

Origin : Infraspinous fossa of scapula

Insertion: Greater tuberosity of humerus;

capsule of shoulder joint

Innervations : Suprascapular nerve (C4), 5, 6

Action : Laterally rotates arm and stabilizes

shoulder joint

Origin : Lower third of lateral border of scapula

Insertion: Medial lip of bicipital groove of

humerus

Innervations : Lower subscapular nerve C6, 7

Action : Medially rotates and adducts arm and

stabilizes shoulder joint

Origin : Upper two thirds of lateral border of

scapula

Insertion: Greater tuberosity of humerus; capsule of

shoulder joint

Innervations : Axillary nerve (C4), C5, 6

Action : Laterally rotates arm and stabilizes

shoulder joint

Origin : Subscapular fossa

Insertion: Lesser tuberosity of humerus

Innervations : Upper and lower subscapular

nerves C5, 6, 7

Action : Medially rotates arm and stabilizes

shoulder joint

Origin : Iliac crest, lumbar fascia, spines of lower six

thoracic vertebrae, lower three or four ribs, and

inferior angle of scapula

Insertion: Floor of bicipital groove of humerus

Innervations : Thoracodorsal nerve C6, 7, 8,

Action : Extends, adducts, and medially rotates the

arm

Blood supply of scapulohumeral Muscles

nerves supply of scapulohumeral Muscles

nerves supply of scapulohumeral Muscles

The deltoid atrophies when the axillary nerve (C5 and C6) is severely damaged. the axillary nerve is usually injured during:

fracture of surgical neck of the humerus dislocation of the. glenohumeral joint compression from the incorrect use of crutches. Result of deltoid atrophy : rounded contour of the shoulder disappears. This gives the shoulder a flattened appearance and

produces a slight hollow inferior to the acromion. a loss of sensation may occur over the lateral side of the

proximal part of the arm

The deltoid is a common site for the intramuscular injection of drugs.

The axillary nerve runs transversely under cover of the deltoid at the level of the surgical neck of the humerus.

Awareness of its location avoids injury to it during surgical approaches to the shoulder.

Four anterior axioappendicular (thoracoappendicular or

pectoral) muscles move the pectoral girdle:

pectoralis major

pectoralis minor

subclavius

serratus anterior.

Anterior Axioappendicular Muscles

Pectoralis major.

Pectoralis minor.

Subclavius.

Serratus anterior.

Main Action Innervation Distal

Attachment

(Insertion)

Proximal

Attachment

(Origin)

Muscle

Adducts and

medially rotates

humerus; draws

scapula anteriorly

and inferiorly

Acting alone,

clavicular head

flexes humerus

and sternocostal

head extends it

from the flexed

position

Lateral and

medial

pectoral

nerves;

clavicular

head (C5, C6),

sternocostal

head (C7, C8,

T1)

Lateral lip of

intertubercular

groove of

humerus

Clavicular head:

anterior surface of

medial half of

clavicle

Sternocostal head:

anterior surface of

sternum, superior

six costal cartilages,

aponeurosis of

external oblique

muscle

Pectoralis

major

Stabilizes scapula

by drawing it

inferiorly and

anteriorly against

thoracic wall

Medial pectoral

nerve (C8, T1)

Medial border

and superior

surface of

coracoid

process of

scapula

3rd to 5th ribs near

their costal

cartilages

Pectoralis

minor

Muscles of the Pectoral region:

Main Action Innervation Distal

Attachment

Proximal

Attachment

Muscle

Anchors and

depresses

clavicle

Nerve to sub-

clavius (C5,

C6)

Inferior

surface of

middle third

of clavicle

Junction of

1st rib and

its costal

cartilage

Subclavius

Protracts

scapula and

holds it against

thoracic wall;

rotates scapula

Long

thoracic

nerve (C5,

C6, C7)

Anterior

surface of

medial

border of

scapula

External

surfaces of

lateral parts

of 1st to 8th

ribs

Serratus

anterior

Muscles of the Pectoral region:

Subclavius Muscle

winged scapula

- winged scapula Due to injury to the longthoracic nerve which leads to Paralysis ofthe Serratus Anterior , giving the scapulathe appearance of a wing.- the medial border of the scapula moveslaterally and posteriorly away from thethoracic wall,

long thoracic nerve

Nerve supply of the Serratus Anterior

Suprclavicular & intercostal Nerves

Clavipectoral fascia

clavipectoral fascia

Thanks