Pectoral Girdle
The body has two pectoral or shoulder girdles that attach the bones of the upper limbs to the axial skeleton.
– Each consists of a clavicle and a scapula. The clavicle is the anterior bone that articulates with the manubrium of the sternum at the sternoclavicular joint.
– The scapula articulates with the clavicle at the acromioclavicular joint and with the humerus at the glenohumeral or the shoulder joint.
Clavicle
-It is an S-shaped collarbone, that horizontally across the anterior part of the thorax superior to the first rib.
-Its medial end is called the sternal end that articulates with the manubrium of the sternum to form the sternoclavicular joint.
– The broad, flat, lateral end is the acromial end that articulates with the acromion of the scapula to form the acromioclavicular joint.
-There is a conoid tubercle on the inferior lateral end is a point of attachment for the conoid ligament, which attaches the clavicle and scapula.
Scapula
-It is a large triangular flat shoulder blade situated in the superior part of the posterior thorax between the levels of the second and seventh ribs.
-A prominent ridge, the spine runs diagonally across the posterior surface of the scapula.
-Superior and inferior to the spine are two fossae-The supraspinous fossa is a surface of attachment for the supraspinatus muscle of the shoulder, and the infraspinous fossa provides an attachment for the infraspinatus muscle of the shoulder.
-On the anterior surface of the scapula is a subscapular fossa, a surface of attachment for the subscapularis muscle.
-The lateral end of the spine projects as a flat process called the acromion this is the highest point of the shoulder, this articulates with the acromial end of the clavicle to form the acromioclavicular joint.
-Inferior to the acromion is a shallow depression, the glenoid cavity, that articulates with the head of the humerus to form the glenohumeral or shoulder joint.
-The edge of the scapula toward the vertebral column is the medial border and the edge toward the arm is the lateral border. The medial and lateral borders join at the inferior angle.
-The superior edge is the superior border, which joins the medial border at the superior angle. At the lateral end of the superior border is a projection called the coracoid process to which the tendons of muscles and ligaments attaches.
