Home » Anatomy » Upper Extremity Muscles » Brachial Muscles » Triceps Brachii – Functional Anatomy

Triceps Brachii – Functional Anatomy

Triceps brachii, as the name implies, is a 3 headed muscle on the posterior upper arm. It has a lateral, medial, and long head.

Brief Anatomy Overview


  • long head – infraglenoid tubercle of the scapula
  • medial head – posterior humeral shaft, medial to the radial groove
  • lateral head – posterior humeral shaft superolateral to the radial groove

Insertion – olecranon process of the ulna


  • extension of the elbow
  • assists in extension and adduction of the shoulder joint

The long head attaches to the scapula and ulna, trapping the humerus in-between them.

The Triceps brachii is woven with the muscles and neurovascular bundle of the shoulder.

Details of Attachments

Its attachments provide important landmarks for surgeons and bodyworkers. The long head trails along the radial nerve and leads to the radial groove of the humerus. This head also separates the teres major and minor as they extend from the scapula to connect on opposite sides of the humerus.

  • The long head attaches to the scapula at the base of the glenoid fossa. It blends with the capsule in this area. The blending both stabilizes the capsule and creates so potential for a torn labrum in jerky accidents.
  • The medial head attaches broadly on the surface of the humerus below the groove for the radial nerve. It also attaches to the intermuscular septum.
  • The lateral head attaches a ridge along the upper border of the radial groove. This ridge starts just medial to the attachment of teres minor. It extends interiorly and laterally to the deltoid tuberosity. This head also attaches to the intermuscular septum.
  • All three heads insert into the olecranon process of the ulna. This broad fascial attachment extends over the anconeus and blends with the fascial of the posterior forearm.

Anomalies, Etc.

Variations are reported as rare. Occasionally a fourth head is found in a cadaver study. The location of the 4th head is very inconsistent. They are mostly of interest in cases where they are positioned to compress the radial or ulna nerves.

This site is undergoing changes. Starting in early 2020, we began improving the format. We are also adding more extensive self-care, illustrations, therapist notes, anatomy, and protocols. We appreciate your input and feedback. You will see us adding posts and updating older posts as time permits.

Weekly Featured Post

This patient had recovered from a frozen shoulder but developed shoulder pain at the end of his golf swing. More traditional neuromuscular techniques weren’t working. Chiropractic wasn’t working. Integrative Craniosacral was the right solution for lasting relief.

Tony Preston has a practice in Atlanta, Georgia where he sees clients. He has written and taught about anatomy, trigger points, and cranial therapies since the mid-90s.

Question? Comment? Typo?
(404) 226-1363

*This site is undergoing major changes. We are reformatting and expanding the posts to make them easier to read. The result will also be more accessible and will include more patterns with better self-care. In the meanwhile, there may be inconsistency in formatting, content presentation, and readability. Until we get older posts updated, please excuse our mess.