Lab 1 - Module 1: Pectoral Region - Page 5 of 5
Pectoral Muscles
| Begin with the Bones of the Pectoral Girdle. |
| Add the Subclavius muscle, which has no real significant function in bipeds. |
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Origin - junction of the first rib and its costal cartilage. Insertion - inferior surface of clavicle in the “groove for sublavius”. Innervation - nerve to subclavius. Action - no real action of significance. Blood supply - clavicular branch of thoracoacromial trunk. |
| Add the Pectoralis Minor Muscle, which is surrounded by clavipectoral fascia. |
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Origin - Ribs 3, 4, 5 Insertion - coracoid process Innervation - medial pectoral nerve Action - stabilizes the scapula by drawing it inferior and anterior. Blood supply - pectoral branch of thoracoacromial trunk, lateral thoracic artery. |
| Add the Pectoralis Major muscle. |
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Origin - Clavicular Head – anterior surface of medial half of clavicle. Sternal Head – anterior surface of the sternum, superior six costal cartilages, aponeurosis of the external oblique muscle. Insertion - Lateral lip of bicipital (intertubercular) groove of humerus. Innervation - lateral pectoral and medial pectoral nerves. Action - Adducts and medial rotates the shoulder joint; flexes shoulder joint (clavicular head); extends shoulder joint from a flexed position (sternal head). Blood supply - pectoral branch of thoracoacromial trunk. |