The dorsal surface is slightly convex from superior to

inferior. It contains the two fossae for the supraspinatus and

infraspinatus, separated by the prominent spine of the

scapula. The supraspinatus fossa, which is much smaller

than the infraspinatus, is smooth, concave, and broader at

its medial aspect than its lateral border. It is bordered by the

spine inferiorly, the coracoid process laterally, and the superior and medial rim of the scapula superiorly and medially,

respectively. The supraspinatus muscle originates from the

medial two-thirds of the fossa (see Fig. 1.7).

The infraspinatus fossa is approximately three times

larger than the supraspinatus fossa. It has a slight concavity

superiorly to inferiorly, especially along the medial border.

There is a slight convexity throughout its central portion,

and a deep groove near the axillary border. The attachments

of the infraspinatus are located on the lateral third of the

fossa (see Fig. 1.7).

There is a slight bony ridge that runs along the lateral

border of the dorsal surface of the scapula. The ridge runs

from the lower part of the glenoid cavity, downward and

backward to the medial border, to an area approximately 2

to 3 cm superior to the tip of the inferior angle. This ridge

serves for the attachment of a fibrous septum that separates

the infraspinatus from the teres major and teres minor. The

surface between the ridge and the lateral border is narrow in

the superior two-thirds. In this area, the ridge is crossed

near its center by a groove that contains the circumflex

scapular vessels. This ridge provides attachment for the teres

minor superiorly and for the teres major inferiorly. The area

of origin of the teres major is broader and somewhat triangular. The latissimus dorsi muscle glides over the lower

region, and frequently a few muscle fibers arise at the inferior angle of the scapula. The teres muscles are separated

from each other by a fibrous septum that extends along an

1 Skeletal Anatomy 11

FIGURE 1.7. Right scapula, posterior surface, showing muscle origins (red) and

insertions (blue).

oblique line from the lateral border of the scapula to an elevated ridge (2,4,5).

Processes of the Scapula

The scapula has three main processes: the acromion, the

coracoid process, and the spine of the scapula (see Figs. 1.6

to 1.9).