Pectoral Girdle Anatomy & Physiology Fundamentals > Skeletal > Skeletal

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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 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

1 / 2 • 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