Triceps brachii
Musculus triceps brachii
MuscularSuperficial musclesArmLeft and right
View left in 3D View right in 3D
- What it is
- The only muscle on the back of the arm, with three heads: the long head from the infraglenoid tubercle of the scapula, the lateral head from the posterior humerus above the radial groove and the deep medial head from below it. They join a broad flat tendon on the olecranon of the ulna.
- Function
- The main extensor of the elbow; the long head also extends and adducts the shoulder.
- Size
- About 30 cm long; the bulkiest muscle of the arm.
- Clinical note
- The radial nerve spirals between its lateral and medial heads in the radial groove, where humeral shaft fractures injure it (wrist drop); the triceps reflex tests C7.