The Scapula is a roughly triangular bone lying on the posterior aspect of the rib cage and tied in to the vertebral column and ribs by a complex system of muscles.

A strong, more or less horizontal ridge extends across its posterior surface. This is the scapular spine.

The scapular spine terminates laterally in a prominent projection, the acromion which articulates with the clavicle. Palpate the scapular spine on a friend's back, and locate the joint between the acromion and the clavicle.

Below the acromion is a shallow depression, the glenoid cavity which has a smooth surface for articulation with the humerus.

The short hook like process medial to the glenoid fossa is the coracoid. It is firmly anchored to the clavicle by ligaments and serves as an important base for the attachment of muscles of the arm.

Note that there is NO articulation between the scapula and the vertebral column or between the scapula and the thoracic cage.