The =shoulder-joint= is an arthrodial or ball-and-socket joint. The
bones entering into its formation are the scapula and the humerus.
The =capsular ligament= or =articular capsule= is very ample and allows
for extended movement of the humerus. It is attached to the edge of the
glenoid fossa of the scapula and passing distad covers the head of the
humerus and is inserted at the line of junction of the shaft and the
epiphysis which forms the head of the bone. On the lateral side of the
ventral surface of the humerus the attachment continues distad about two
centimeters along the lateral edge of the bicipital groove. On the
medial side the insertion passes over the proximal end of the lesser
tuberosity. A strong transverse band passes from the greater tuberosity
to the lesser tuberosity and bridges the bicipital groove, converting it
into a canal. The lateral and medial parts of the capsule are
strengthened by thicker bands of fibres, the more prominent medial one
of which passes from the coracoid process of the scapula to the lesser
tuberosity. To the capsule are closely united parts of the
supraspinatus, infraspinatus, coracobrachialis, and subscapularis
muscles. A synovial membrane lines the capsule within and forms a sheath
around the biceps tendon, so that the latter does not actually enter the
synovial capsule.
The =elbow-joint= (Figs. 52 and 53) is a ginglymus or hinge-joint. The
bones which enter into it are the humerus, radius, and ulna.
The capsule of the joint forms a sac, with the following attachments to
the bones: (1) To the humerus it is attached at the proximal edge of the
coronoid and radial fossæ; to the sides of the capitulum and trochlea
distad of the two epicondyles, and to the distal edge of the olecranon
fossa. (2) To the ulna it is attached at the edges of the radial and
semilunar notches; (3) to the radius around the articular facet, two or
three centimeters distad of the border. Many of the muscles of this
region are closely attached to the capsule.
[Illustration: FIG. 52.--LIGAMENTS OF ELBOW-JOINT, MEDIAL SIDE.