The triceps brachii muscle is the only muscle in the posterior compartment of the arm. It consists of three heads: lateral, medial and long head and serves primarily to extend the forearm. Learn more about the anatomy of the triceps brachii using the narrated video tutorial and interactive 3D anatomy model.

Origin
  • Long head: infraglenoid tubercle of scapula
  • Lateral head: above the radial groove (posterior humeral surface)
  • Medial head: below the radial groove (posterior humeral surface)
Insertion
  • Olecranon process of the ulna.
Innervation
  • Radial nerve (C6,7,8)
  • Long head innervated by the axillary nerve

 

Blood Supply
  • Deep brachial artery
  • Posterior circumflex humeral artery
Action
  • Primarily extends forearm at the elbow joint
  • Long head: extension and adduction of the arm at the shoulder joint