Alexis Ortiz, PT, MS, CSCS
The elbow joint is a compound synovial hinge or uniaxial joint between the lower end of the
humerus and the upper end of the ulna and radius. Its articular surfaces are the trochlea and
capitulum of the lower end of the humerus proximally, and the upper surface of the head of the
radius and the trochlear notch of the ulna distally. Its joint cavity and synovial membrane is
shared with that of the superior radioulnar joint. Ligaments strengthening the joint include
capsular, ulnar collateral and radial collateral.
Due to the medial flange of the trochlear of the humerus being slightly lower than the lateral,
the forearm is angled laterally up to 15 degrees in men and up to 25 degrees in women, termed
"the carrying angle".
This surrounds the joint attaching proximally around the lower end of the humerus to both
lateral and medial epicondyles, a line above the coronoid and radial fossae anteriorly, and on a
line above the olecranon fossa posteriorly. Distally, it attaches to the edge of the olecranon
posteriorly, around the upper edge of the annular ligament, which surrounds the head of the
radius, and to the anterior, medial and lateral edges of the coronoid process anteriorly. The
capsule is made up of circular, vertical and oblique fibers.
Synovial membrane lines the capsule, passing upwards from the anterior and posterior
margins of the articular surfaces of the humerus to cover all three fossae until it reaches the
attachment of the capsule. It is then reflected down the inner surface of the capsule attaching
to the lip of the coronoid and olecranon and lining the inner surface of the annular ligament. As
it passes over the fossae it is thickened by pads of fat.
Interactive Skeleton - Sports & Kinetic
©1999 Primal Pictures Ltd.
The ulnar collateral ligament is triangular in shape with its apex attached to the medial
epicondyle and its base to the ulna. It is made up of thre