Long head of triceps brachii
Caput longum musculi tricipitis brachii
- Related terms: Long head; Triceps brachii: Long head; Triceps brachii : Long head; Triceps brachii - Long head
Definition
Long head of triceps brachii | |||
Origin | Infraglenoid tubercle of the scapula | ||
Insertion | Olecranon process of the ulna | ||
Artery | Profunda brachii artery | ||
Innervation | Radial nerve | ||
Action | Extends the forearm, extends and adducts the shoulder | ||
Antagonist | Biceps brachii and brachialis muscles | ||
The long head of triceps brachii is a unique component of the triceps muscle, originating from the infraglenoid tubercle of the scapula.
Its muscle fibers converge with those of the lateral and medial heads in the distal arm, contributing to the formation of the common triceps tendon. This tendon then functionally inserts as a single, confluent unit onto the olecranon process of the ulna.
Distinguishing it from the other two heads, the long head is the only one that crosses the glenohumeral (shoulder) joint. Consequently, its actions extend beyond mere elbow extension; it also assists with extension and adduction of the arm at the shoulder joint. Furthermore, when the arm is adducted, the long head helps to stabilize the humeral head within the glenoid cavity, thus preventing displacement.
References
Tiwana MS, Sinkler MA, Bordoni B. Anatomy, Shoulder and Upper Limb, Triceps Muscle. [Updated 2023 Aug 28]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK536996/
Negrão JR, Mogami R, Ramirez Ruiz FA, Wagner FV, Haghighi P, Ward SR, Resnick DL. Distal insertional anatomy of the triceps brachii muscle: MRI assessment in cadaveric specimens employing histologic correlation and Play-doh® models of the anatomic findings. Skeletal Radiol. 2020 Jul;49(7):1057-1067. doi: 10.1007/s00256-020-03382-3. Epub 2020 Jan 28. Erratum in: Skeletal Radiol. 2020 Jul;49(7):1069-1071.
