Bone Review – Scapula

Scapula

The scapula, or shoulder blade, is a flat, triangular bone that serves as a key structure in the upper extremity. It connects the clavicle (collarbone) to the humerus (upper arm bone) and is part of the appendicular skeleton.

This bone plays a crucial role in shoulder movement and stability, providing attachment sites for multiple muscles that facilitate arm motion and posture. Key anatomical features of the scapula include:

• Glenoid fossa – A shallow, concave structure that forms the socket of the glenohumeral (shoulder) joint, where it articulates with the head of the humerus. The shallow depth and shape of the glenoid contribute to the shoulder’s wide range of motion but also make it susceptible to dislocation.
• Acromion process – A bony projection on the superior aspect of the scapula that extends laterally over the shoulder joint. It articulates with the clavicle, forming the acromioclavicular (AC) joint, and serves as an attachment site for the deltoid and trapezius muscles.
• Spine of the scapula – A prominent ridge running obliquely across the posterior surface of the scapula. It divides the supraspinous fossa (above the spine) from the infraspinous fossa (below the spine), which house the supraspinatus and infraspinatus muscles, respectively. These muscles are part of the rotator cuff and are essential for shoulder stability and movement.
• Coracoid process – A hook-like projection on the anterior aspect of the scapula, providing attachment for the pectoralis minor, short head of the biceps brachii, and coracobrachialis muscles. It also serves as an anchor point for the coracoacromial and coracoclavicular ligaments, which contribute to shoulder stability.
• Muscle attachment points – The scapula serves as an attachment site for numerous muscles that control shoulder motion, including the rotator cuff muscles (supraspinatus, infraspinatus, teres minor, and subscapularis), the serratus anterior, and the rhomboids.

Understanding the detailed anatomy of the scapula is crucial for recognizing its role in movement, stability, and common clinical conditions, such as shoulder impingement syndrome, scapular winging, and rotator cuff injuries.