![]() The suprascapular notch is located lateral to the midpoint of the superior border. The three margins or borders of the scapula, named for their positions within the body, are the superior border of the scapula, the medial border of the scapula, and the lateral border of the scapula. The scapula has several important landmarks ( Figure 8.4). It is surrounded by muscles on both its anterior (deep) and posterior (superficial) sides, and thus does not articulate with the ribs of the thoracic cage. The scapula is located on the posterior side of the shoulder. The scapula is also part of the pectoral girdle and thus plays an important role in anchoring the upper limb to the body. The clavicle overlies many important blood vessels and nerves for the upper limb, but fortunately, due to the anterior displacement of a broken clavicle, these structures are rarely affected when the clavicle is fractured. Muscles acting across the shoulder will also pull the shoulder and lateral clavicle anteriorly and medially, causing the clavicle fragments to override. If the fracture is complete, the shoulder and lateral clavicle fragment will drop due to the weight of the upper limb, causing the person to support the sagging limb with their other hand. Because the sternoclavicular joint is strong and rarely dislocated, excessive force results in the breaking of the clavicle, usually between the middle and lateral portions of the bone. ![]() Such breaks often occur because of the force exerted on the clavicle when a person falls onto his or her outstretched arms, or when the lateral shoulder receives a strong blow. The clavicle is the most commonly fractured bone in the body. In men, the clavicle is heavier and longer, and has a greater curvature and rougher surfaces where muscles attach, features that are more pronounced in manual workers. In women, the clavicle tends to be shorter, thinner, and less curved. There are some sex differences in the morphology of the clavicle. The lateral or acromial end of the clavicle articulates with the acromion of the scapula, the portion of the scapula that forms the bony tip of the shoulder. The sternoclavicular joint is indirectly supported by the costoclavicular ligament (costo- = “rib”), which spans the sternal end of the clavicle and the underlying first rib. This joint allows considerable mobility, enabling the clavicle and scapula to move in upward/downward and anterior/posterior directions during shoulder movements. This forms the sternoclavicular joint, which is the only bony articulation between the pectoral girdle of the upper limb and the axial skeleton. The medial end, known as the sternal end of the clavicle, has a triangular shape and articulates with the manubrium portion of the sternum. The clavicle has three regions: the medial end, the lateral end, and the shaft. Finally, it serves to protect the underlying nerves and blood vessels as they pass between the trunk of the body and the upper limb. The clavicle also transmits forces acting on the upper limb to the sternum and axial skeleton. This in turn holds the shoulder joint superiorly and laterally from the body trunk, allowing for maximal freedom of motion for the upper limb. First, anchored by muscles from above, it serves as a strut that extends laterally to support the scapula. The clavicle has several important functions. The clavicle is the only long bone that lies in a horizontal position in the body (see Figure 8.3). This allows for the extensive mobility of the entire pectoral girdle, which in turn enhances movements of the shoulder and upper limb. In addition, the clavicle of each pectoral girdle is anchored to the axial skeleton by a single, highly mobile joint. The right and left pectoral girdles are not joined to each other, allowing each to operate independently. Both of these bones serve as important attachment sites for muscles that aid with movements of the shoulder and arm. Move your shoulder around and feel how the clavicle and scapula move together as a unit. By following along the clavicle, you can palpate out to the bony tip of the shoulder, and from there, you can move back across your posterior shoulder to follow the ridge of the scapula. This ridge extends out laterally, where it forms the bony tip of the shoulder and joins with the lateral end of the clavicle. The scapula is a flat, triangular-shaped bone with a prominent ridge running across its posterior surface. It is supported by the clavicle and articulates with the humerus (arm bone) to form the shoulder joint. The scapula (shoulder blade) lies on the posterior aspect of the shoulder. Figure 8.3 Pectoral Girdle The pectoral girdle consists of the clavicle and the scapula, which serve to attach the upper limb to the sternum of the axial skeleton.
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