Upper limb
Triceps Brachii
Musculus triceps brachii
- Origin
- Long head: infraglenoid tubercle of the scapula. Lateral head and medial head: posterior surface of the humerus, above and below the radial groove respectively
- Insertion
- Olecranon of the ulna via a common tendon
- Function
- Extends the elbow; the long head also extends and adducts the shoulder
- Innervation
- Radial nerve, C6–C8
- Movement & chain
- The long head crosses two joints and is most active during combined shoulder extension/elbow extension, such as pushing up from a low position; the lateral and medial heads provide the force for pure elbow extension.
- Palpation
- The common tendon is easily palpated above the olecranon; the three bellies can be distinguished on the posterior upper arm during active resisted extension.
- Clinical
- The tendon can rupture from a fall on an outstretched arm or from eccentric overload; also a classic site for olecranon bursitis just distal to the insertion.
- Segmental innervation
- The triceps reflex runs through the C7 segment (with contribution from C6–C8); a diminished or absent reflex points to a radiculopathy at this level.
- In clinical practice
- The tendon above the olecranon is a landmark for intramuscular injections into the triceps and for assessing the triceps reflex (C7).
- Region in the model
- Upper limb