| Origin |
Long head: infraglenoid tubercle of scapula
Lateral head: posterior surface of humerus, superior to radial groove
Medial head: posterior surface of humerus, inferior to radial groove |
| Insertion |
Proximal end of olecranon process of ulna and fascia of forearm |
| Action |
Chief extensor of forearm; long head steadies head of abducted humerus |
| Innervation |
Radial nerve (C6, C7 and C8)
|
Arterial
Supply |
Branches of deep brachial artery |