skapula

Skapula, typically referred to in English as the scapula or shoulder blade, is a flat, triangular bone of the pectoral girdle positioned on the posterior thorax. It lies against the ribs between approximately the second and seventh, and forms part of the shoulder complex by connecting laterally with the humerus at the glenoid cavity and with the clavicle at the acromioclavicular joint.

Anatomy and features include the superior, medial (vertebral), and lateral (axillary) borders; the anterior (costal) and posterior surfaces; and the superior and inferior angles. The scapular spine runs across the posterior surface, creating the supraspinous and infraspinous fossa. The acromion and coracoid process extend from the scapula, with the glenoid cavity on its lateral angle serving as the socket for the head of the humerus.

The glenoid cavity forms the glenohumeral joint with the humerus, while the acromion participates in the acromioclavicular joint with the clavicle. The scapula’s orientation and movement are guided by multiple muscles, including the rotator cuff muscles, deltoid, trapezius, serratus anterior, and others, and it plays a central role in the range of motion of the shoulder through scapulohumeral rhythm.

Vascular supply arises from branches of the subclavian and axillary arteries, including the suprascapular and circumflex scapular arteries. Innervation is provided mainly by the suprascapular, axillary, and subscapular nerves. Developmentally, the scapula ossifies from a primary center in the body and several secondary centers in the processes, which fuse during adolescence.

Clinically, scapular injuries are uncommon but can include fractures, winging from nerve injury, and impingement or dyskinesis related to variations in scapular orientation or acromial shape.