The primary muscle running from the shoulder to the elbow is the triceps brachii.
The triceps brachii, often simply called the triceps, is a large, three-headed muscle located on the posterior (back) side of the upper arm. It is the only muscle on the back of the upper arm, and its main function is to extend the forearm at the elbow joint.
- Location: Posterior compartment of the upper arm.
- Origin: It has three heads:
- Long head: Originates from the infraglenoid tubercle of the scapula (shoulder blade).
- Lateral head: Originates from the posterior surface of the humerus, superior to the radial groove.
- Medial head: Originates from the posterior surface of the humerus, inferior to the radial groove.
- Insertion: All three heads converge to insert onto the olecranon process of the ulna (the bony prominence at the elbow).
- Function: Elbow extension. The triceps is crucial for straightening the arm. The long head also assists in shoulder adduction and extension.
In summary, while other smaller muscles may influence or support the movement of the upper arm and elbow, the triceps brachii is the main muscle that spans from the shoulder region to the elbow.
