Page 195 - Clinical Anatomy

ECA3 7/18/06 6:45 PM Page 180

180 The upper limb

Fig. 131◊The deformity of shoulder dislocation. The dislocated head of the humerus
is held adducted by the shoulder girdle muscles and internally rotated by
subscapularis.

traction and adduction being applied to the forearm; in this way the
humeral head is levered outwards into its normal position.

The elbow joints (Figs 132, 133)
The elbow joint, although a single synovial cavity, is made up of three dis-
tinct articulations, which are:
1◊◊the humero-ulnar, between the trochlea of the humerus and the trochlear
notch of the ulna (a hinge-joint);
2◊◊the humeroradial, between the capitulum and the upper concave surface
of the radial head (a ball and socket joint);
3◊◊the superior radio-ulnar, between the head of the radius and the radial
notch of the ulna, the head being held in place by the tough annular liga-
ment (a pivot joint).
The capsule of the elbow joint is closely applied around this complex
articular arrangement; the non-articular medial and lateral epicondyles are
extracapsular. The capsule is thin and loose anteriorly and posteriorly to
allow flexion and extension, whereas it is strongly thickened on either side
to form the medial and lateral collateral ligaments. The lateral ligament is