Scapular

The scapular, commonly known as the shoulder blade, is a flat, triangular bone located on the posterior aspect of the upper thorax. It forms part of the pectoral girdle and rests over the upper ribs, with the glenoid cavity facing laterally to articulate with the humeral head. The scapula is not directly connected to the sternum; its position is maintained by muscles and by the clavicle via the acromioclavicular joint.

Anatomy and features: The scapula has a smooth costal (anterior) surface and a broad posterior surface divided by the spine. It presents three borders—the superior, medial (vertebral), and lateral (axillary)—and three angles—the superior, inferior, and lateral. The spine runs diagonally across the posterior surface and ends in the acromion, a projection that forms the highest point of the shoulder and articulates with the clavicle at the acromioclavicular joint. The coracoid process projects anteriorly and serves as an attachment for ligaments and muscles. On the lateral aspect lies the glenoid cavity, which articulates with the humeral head to form the glenohumeral joint.

Function and attachments: The scapula acts as a movable platform for many muscles, including the rotator cuff muscles (supraspinatus, infraspinatus, teres minor, subscapularis) and extrinsic muscles such as the serratus anterior, trapezius, rhomboids, and latissimus dorsi. Neurovascular supply includes branches from the subclavian and axillary arteries, with innervation from the suprascapular, dorsal scapular, and axillary nerves.

Clinical notes: Scapular fractures are relatively uncommon. Winged scapula may result from damage to the serratus anterior or spinal accessory nerve, and snapping scapula syndrome involves abnormal scapulothoracic contact.