- Forms a synovial hinge joint , consisting of the humeroradial and humeroulnar joints , and allows flexion and extension.
- Also includes the proximal radioulnar (pivot) joint , within a common articular capsule.
- Is innervated by the musculocutaneous, median, radial, and ulnar nerves.
- Receives blood from the anastomosis formed by branches of the brachial artery and recurrent branches of the radial and ulnar arteries.
- Is reinforced by the following ligaments:
Annular ligament
- Is a fibrous band that forms nearly four fifths of a circle around the head of the radius; the radial notch forms the remainder.
- Forms a collar around the head of the radius, fuses with the radial collateral ligament and the articular capsule, and prevents withdrawal of the head of the radius from its socket.
Radial collateral ligament
- Extends from the lateral epicondyle to the anterior and posterior margins of the radial notch of the ulna and the annular ligament of the radius.
Ulnar collateral ligament
- Is triangular and is composed of anterior, posterior, and oblique bands.
- Extends from the medial epicondyle to the coronoid process and the olecranon of the ulna.
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