Author: Dr Peter de Souza
Last modified: 14 December 2021

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.


  • Long head: infraglenoid tubercle of scapula
  • Lateral head: above the radial groove (posterior humeral surface)
  • Medial head: below the radial groove (posterior humeral surface)


  • Olecranon process of the ulna.


  • Primarily extends forearm at the elbow joint
  • Long head: extension and adduction of the arm at the shoulder joint


  • Radial nerve (C6,7,8)
  • Long head innervated by the axillary nerve


Blood Supply

  • Deep brachial artery
  • Posterior circumflex humeral artery