Triceps brachii
Latin: M. triceps brachii sinistra
Location: Arm
Paired structure: one on the left and one on the right side of the body.
View the triceps brachii in 3DOrigin
Long head: infraglenoid tubercle of the scapula. Lateral head: posterior humerus above the radial groove. Medial head: posterior humerus below the groove.
Insertion
Olecranon of the ulna.
Action
The elbow's sole extensor — straightening the arm for pushing, throwing and locking out overhead lifts; the long head also extends and adducts the shoulder.
Nerve supply
Radial nerve (C6–C8) — branches to each head.
Blood supply
Profunda brachii (deep brachial) artery.
Clinical relevance
The radial nerve spirals in the radial groove between the lateral and medial heads — humeral shaft fractures here cause wrist drop; the triceps reflex tests C7–C8. Gymnasts rupture its distal tendon on rings.
Educational anatomy reference, not medical advice. About this content.