Muscle | Proximal attachment | Distal attachment | Innervation* | Main action |
Pectoralis major | Clavicular head: anterior surface of medial half of clavicle Sternocostal head: anterior surface of sternum, superior six costal cartilages, aponeurosis of external oblique muscle | Lateral lip of intertubercular sulcus of humerus | Lateral and medial pectoral nerves; clavicular head (C5, C6), sternocostal head (C7, C8, T1) | 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 |
Pectoralis minor | 3rd - 5th ribs near their costal cartilages | Medial border and superior surface of coracoid process of scapula | Medial pectoral nerve (C8, T1) | Stabilizes scapula by drawing it inferiorly and anteriorly against thoracic wall |
Subclavius | Junction of 1st rib and its costal cartilage | Inferior surface of middle third of clavicle | Nerve to subclavius (C5, C6) | Anchors and depresses clavicle |
Serratus anterior | External surfaces of lateral parts of 1st - 8th ribs | Anterior surface of medial border of scapula | Long thoracic nerve (C5, C6, C7) | Protracts scapula and holds it against thoracic wall; rotates scapula |
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