Posterior Arm

Question 1

Triceps Brachii

Answer 1

Origin: long head - infraglenoid tubercle of scapula, lateral head - upper 1/2 of posterior humerus, medial head - distal 2/3 of medial and posterior humerus

Insertion: posterior surface of olecranon process of ulna

Innervation: radial nerve

Blood Supply: deep brachial artery

Action: extends forearm at elbow, long head stabilizes head of abducted humerus, extends arm at shoulder, and adducts arm at shoulder

(long head medial border of quadrangular space and lateral border of triangular space)