Teres Minor Muscle - Attachments, Actions & Innervation
Pectoralis Major Muscle – Attachment, Action & Innervation
Pectoralis major is a thick, fan-shaped muscle contributing to the thoracobrachial motion.
It consists of a clavicular part and a sternal part, both converging into a flat tendon that inserts on the humerus. It’s innervated by both medial and lateral pectoral nerves.
Pectoralis Major Muscle
Looking to advance your muscle identification skills? Try these free muscle labeling diagrams.
Attachments of Pectoralis Major Muscle: Origin & Insertion
Origin: (proximal attachments)
a. Clavicular head: medial half of the clavicle.
b. Sternal head: sternum, upper costal cartilages (1-6), and the aponeurosis of the external oblique.
Insertion: (distal attachments)
a. Lateral lip of the intertubercular (bicipital) groove of the humerus.
b. Crest of the greater tubercle of the humerus.
Actions of Pectoralis Major Muscle:
Both heads working together:
a. Medially rotate the arm at the shoulder (glenohumeral) joint.
b. Adduct the arm at the shoulder (glenohumeral) joint.
Innervation of the Pectoralis Major:
b. C8 and T1 (medial pectoral nerve to the sternal head).