Pectoral Girdle

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

Pectoral Girdle

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