The infraspinatous fossa (infraspinatus fossa, infraspinous fossa) of the scapula

Scapula

In anatomy, the scapula , omo, or shoulder blade, is the bone that connects the humerus with the clavicle ....

 is much larger than the supraspinatous fossa

Supraspinatous fossa

The supraspinatous fossa of the posterior aspect of the scapula is smaller than the infraspinatous fossa, concave, smooth, and broader at its vertebral than at its humeral end. Its medial two-thirds give origin to the Supraspinatus....

; toward its vertebral margin a shallow concavity is seen at its upper part; its center presents a prominent convexity, while near the axillary border is a deep groove which runs from the upper toward the lower part.

The medial two-thirds of the fossa give origin to the Infraspinatus; the lateral third is covered by this muscle.