Angles of the Scapula

The scapula has three angles: the superior, inferior, and lateral angles (see Figs. 1.9A, 1.16, 1.17, 1.19A). The superior

angle is formed by the junction of the superior and medial

(vertebral) borders. This region is thin, smooth, and

rounded, and gives attachment for a portion of the levator

scapulae muscle. It measures approximately 80 degrees.

The inferior angle is formed by the junction of the

medial (vertebral) border and the lateral (axillary) borders.

It measures approximately 25 degrees. The inferior angle, in

contrast to the superior angle, is thick and rough. The dorsal surface provides attachment for the teres major and, in

some individuals, a few fibers of the latissimus dorsi (see

Fig. 1.17).

The lateral angle is the thickest part of the bone, and the

adjacent broadened portion of the bone sometimes is

16 Systems Anatomy

referred to as the head of the scapula. It measures approximately 90 degrees. The broadened area is connected to the

rest of the scapula by a slightly constricted neck. This area

of the scapula forms part of the shoulder joint. The most

lateral portion becomes the glenoid, an oval, slightly concave surface. The surface of the glenoid is relatively shallow.

The mean size of the glenoid is 2.9 cm in anteroposterior

width by 3.6 cm in superoinferior length (26) (Table 1.1).

It faces posteriorly by approximately 8 degrees (26). Its laterally facing articular surface is deepened and broadened by

the glenoid labrum, which is a circumferential rim of fibrocartilage. The glenoid labrum plays an important role in

stabilizing the shoulder. Superior to the glenoid, near the

base of the coracoid process, there is a slight elevation, the

supraglenoid tubercle, which provides the origin of the long

head of the biceps brachii.