Pectoral Girdle - Gross Anatomy Flashcards

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Pectoral girdle • Connects the upper limb to the axial skeleton and provides muscle attachment sites for both the arm and back • Comprises the clavicle (collarbone) and the scapula (shoulder blade) Clavicle Anatomy: • Sternal end - flat medial
Pectoral girdle • Connects the upper limb to the axial skeleton and provides muscle attachment sites for both the arm and back • Comprises the clavicle (collarbone) and the scapula (shoulder blade) Clavicle Anatomy: • Sternal end - flat medial end, articulates with manubrium of sternum • Conoid tubercle - small bony projection where the conoid ligament attaches • Acromion end – rounded lateral end, articulates with acromion of scapula • Costal tuberosity (aka impression) - provides an attachment site for the costoclavicular ligament • Superior surface - smooth • Inferior surface - rough due to muscular attachments Key Points: • Cannot withstand heavy forces; fractures are common and can cause damage to the underlying brachial plexus and associated vessels. • The clavicle is one of the first bones to begin ossification during fetal development, but is the last to complete ossification, during the mid-twenties. • It is the only long bone that ossifies intramembraneously. Scapula Anatomy: • Supraspinous fossa - superior to the spine • Infraspinous fossa - inferior to the spine • Body – triangular surface of scapula • Superior angle – projects superomedially • Inferior angle - projects inferiorly • Lateral angle – projects laterally; includes the glenoid cavity • Superior border - extends from the glenoid cavity to the superior angle • Lateral (aka axillary) border - extends from the inferior angle to the lateral angle • Medial (aka vertebral) border - extends from the superior angle to the inferior angle • Subscapular fossa - anterior surface of the scapula; it is the attachment site for subscapularis • Acromion - the most-superior extension of the scapula and arises from the scapula's posterior surface • Coracoid process - extends from the superior aspect of the scapula and projects laterally • Glenoid cavity (aka fossa) - laterally oriented cup-shaped depression where the humerus articulates with the pectoral girdle • Glenoid labrum - rim of the glenoid cavity, composed of fibrocartilage and aids in humeral stabilization • Supra- and infraglenoid tubercles - raised portions of bone above and below the glenoid cavity that provide muscle attachment sites for the biceps brachii and triceps brachii • Scapular neck - the portion of the scapula that extends toward the glenoid cavity • Spine of the scapula - prominent ridge of bone that separates the posterior scapula into superior and inferior portions • Acromion process - projects laterally; it is a continuation of the spine of the scapula • Suprascapular notch - a small indentation in the superior border medial to the coracoid process • Superior transverse ligament - closes off this notch superiorly to create a foramen through which the suprascapular nerve traverses. - Calcification of the superior transverse ligament can compress the suprascapular nerve and impair innervation to the posterior scapular muscles • The scapula articulates with the acromial end of the clavicle and the head of the humerus (upper arm). Additional Images: Pectoral Girdle Clavicle Clavicle Muscles Scapula