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AAAC36 21/5/05 10:49 AM Page 83
The elbow joint (Figs 36.1 and 36.2)
This is a pivot joint. It is formed by the articulation of the radial head
• Type: synovial hinge joint. At the elbow the humeral capitulum
and the radial notch of the ulna. The superior radio-ulnar joint commun-
articulates with the radial head, and the trochlea of the humerus with
icates with the elbow joint.
the trochlear notch of the ulna. Fossae immediately above the trochlea The superior radio-ulnar joint
and capitulum admit the coronoid process of the ulna and the radial
head, respectively, during full flexion. Similarly the olecranon fossa Movements at the elbow
admits the olecranon process during full elbow extension. The elbow Flexion/extension occur at the elbow joint. Supination/pronation occur
joint communicates with the superior radio-ulnar joint. mostly at the superior radio-ulnar joint (in conjunction with move-
• Capsule: the capsule is lax in front and behind to permit full elbow ments at the inferior radio-ulnar joint).
flexion and extension. The non-articular medial and lateral epicondyles • Flexion (140°): biceps, brachialis, brachioradialis and the forearm
are extracapsular. flexor muscles.
• Ligaments (Fig. 36.2): the capsule is strengthened medially and lat- • Extension (0°): triceps and to a lesser extent anconeus.
erally by collateral ligaments. • Pronation (90°): pronator teres and pronator quadratus.
• The medial collateral ligament is triangular and consists of ant- • Supination (90°): biceps is the most powerful supinator. This move-
erior, posterior and middle bands. It extends from the medial epi- ment is afforded by the insertion of the muscle on the posterior aspect
condyle of the humerus and the olecranon to the coronoid process of the radial tuberosity. Supinator, extensor pollicis longus and brevis
of the ulna. The ulnar nerve is adjacent to the medial collateral liga- are weaker supinators.
ment as it passes forwards below the medial epicondyle. Owing to
the close proximity of the ulnar nerve to the humerus it is at risk in The cubital fossa (Fig. 36.3)
many types of injury, e.g. fracture dislocations, compression and • This fossa is defined by: a horizontal line joining the two epi-
even during surgical explorations. condyles; the medial border of brachioradialis; and the lateral border of
• The lateral collateral ligament extends from the lateral epicondyle pronator teres. The floor of the fossa consists of brachialis muscle and
of the humerus to the annular ligament. The annular ligament is the overlying roof of superficial fascia. The median cubital vein runs in
attached medially to the radial notch of the ulna and clasps, but the superficial fascia and connects the basilic to cephalic veins.
does not attach to, the radial head and neck. As the ligament is not • Within the fossa the biceps tendon can be palpated. Medial to this lie
attached to the head this is free to rotate within the ligament. the brachial artery and the median nerve.
• The radial and ulnar nerves lie outside the cubital fossa. The radial
Elbow dislocation nerve passes anterior to the lateral epicondyle between brachialis and
The classical injury is a posterior dislocation caused by a fall on the brachioradialis muscles. The ulnar nerve winds behind the medial
outstretched hand. It is commonest in children whilst ossification is epicondyle.
incomplete.

The elbow joint and cubital fossa 83