Axilla Region

Lateral Wall

Humerus

Posterior Wall

Latissimus dorsi, Supscapularis, Teres major

Latissimus dorsi Orign

Spinous processes T7-T12

Thoracolumbar fascia

Ililac crest

Inferior 3 or 4 ribs

Latissimus dorsi Insertion

Intertubercular groove of humerus

Latissimus dorsi Innervation

Thoracodorsal nerve (C6-C8 ventral rami)

Latissimus dorsi Action

Extend, adduct, medial rotate shoulder joint, elevates body towards arm during climbing

Subscapularis Origin

Subscapular fossa

Subscapularis Insertion

Lesser tubercle of humerus

Subscapularis Innervation

Upper and lower subscapular nerves (C5-C7 ventral rami)

Subscapularis Action

Adduction, medial rotation, stabilize humeral head

Teres major Origin

Inferior part of lateral border of scapula

Posterior surface of inferior angle of scapula

Teres major Insertion

Medial lip of intertubercular groove of humerus

Teres major Innervation

Lower subscapular nerve (C5-C6 ventral rami)

Teres major Action

Adducts and medially rotates shoulder

Medial wall

Serratus anterior

Serratus anterior Origin

External surface of lateral parts of 1st-8th ribs

Serratus anterior Insertion

Anterior surface of entire medial border of scapula

Serratus anterior Innervation

Long thoracic nerve (C5-C7 ventral rami)

Serratus anterior Action

Protracts scapula and holds it against thoracic wall, rotates scapula

Anterior Wall

Pectoralis major and Pectoralis minor

Pectoralis major Origin

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 Insertion

Lateral lip of intertubercular sulcus (groove) of humerus

Pectoralis major Innervation

Lateral pectoral nerve (C5-C7 ventral rami)

Medial pectoral nerve (C8-T1 ventral rami)

Clavicular head (C5-C6 ventral rami)

Sternocostal head (C7-T1 ventral rami)

Pectoralis major Action

Adducts and medially rotates shoulder joint, draws scapula anteriorly and inferiorly 

Clavicular head flexes shoulder joint (alone)

Sternocostal head and extends it from the flexed position (alone)

Pectoralis minor Origin

3rd–5th ribs near their costal cartilages

Pectoralis minor Insertion

Medial border and superior surface of coracoid process of scapula

Pectoralis minor Innervation

Medial pectoral nerve (C8-T1 ventral rami)

Pectoralis minor Action

Stabilizes scapula by drawing inferiorly and anteriorly against thoracic wall