Ulnar collateral ligament

At a glance

English

Ulnar collateral ligament

Latin (TA2)

Ligamentum collaterale ulnare cubiti

System

Ligament

Region

Upper limb

Side

Paired, left and right

About the ulnar collateral ligament

The ulnar collateral ligament, also called the medial collateral ligament of the elbow, thickens the inner wall of the elbow joint capsule. It spreads from the humeral medial epicondyle down to the upper end of the ulna and is the main restraint against the forearm being forced outwards at the elbow. It should be kept distinct from the lateral ulnar collateral ligament, a separate band on the outer side of the joint.

Three bands make up the ligament. The anterior band is the strongest: it runs obliquely forwards from the front of the medial epicondyle and fans out to the medial edge of the coronoid process. The posterior band, also roughly triangular, passes from the lower, rear surface of the epicondyle to the medial border of the olecranon. Between the two lies a thin intermediate sheet, and across the bottom of the notch separating olecranon from coronoid process runs a transverse band (sometimes called Cooper's ligament), which receives some of these middle fibres.

The ligament sits in a crowded neighbourhood. Triceps brachii lies behind it, flexor carpi ulnaris covers it, and the ulnar nerve runs directly over its posterior part as it passes behind the medial epicondyle. Part of flexor digitorum superficialis takes origin from the ligament itself, so the common flexor mass and the ligament work together to brace the inner elbow.

Repeated overhead throwing, as in baseball pitching or javelin, loads the inner elbow with large outward-bending forces, and the anterior band takes most of that strain. Over time it can stretch, fray or tear. The athlete then notices pain on the inside of the elbow, a feeling of looseness when the forearm is pushed outwards, tingling in the ulnar fingers from irritation of the nearby nerve, and a fall in throwing speed or accuracy. Treatment ranges from rest and rehabilitation to surgical reconstruction with a tendon graft.

Attachments and function

Attaches from

The humeral medial epicondyle: its front part for the anterior band and its lower, rear part for the posterior band.

Attaches to

The ulna: the inner edge of the coronoid process (anterior band) and the inner edge of the olecranon (posterior band), with a transverse band bridging the two.

Function

Resists valgus (outward-bending) force on the elbow and keeps the trochlear notch of the ulna seated against the humerus through flexion and extension.

Nerve supply

Twigs from the nerves crossing the elbow, chiefly the ulnar nerve, together with branches of the median and musculocutaneous nerves.

Blood supply

Branches of the anastomosis around the elbow, especially the superior and inferior ulnar collateral arteries and the posterior ulnar recurrent artery.