Key points:

• The superficial muscles of the back stabilize and also move the pectoral girdle and humerus.
• The muscles of the superficial back are symmetrically paired, and trapezius lies superficially over the others.

Trapezius:

• Originates on the skull (the external occipital protuberance, superior nuchal line) and the spines and connective tissues of C7-T12.
• Inserts on the lateral 1/3rd of the clavicle, and on the spine and acromion of the scapula.
• Because the fibers of trapezius are convergent, trapezius adducts, rotates, elevates, or depresses the scapula, depending on which fibers contract.

Levator scapulae:

• Originates on the transverse processes of vertebrae C1-C4.
• Inserts on the medial border of the scapula.
• It elevates and rotates the scapula.

Rhomboid minor:

• Originates on the spines of vertebrae C7-T1.
• Inserts on the scapula at the medial border, adjacent to its spine.
• It adducts the scapula.

Rhomboid major

• Originates on the spines of vertebrae T2-T5
• Inserts on the medial border of the scapula.
• It adducts the scapula.

Latissimus dorsi

• Originates on the spines of vertebrae T7-T12, the thoracolumbar fascia (which overlies the lumbar vertebrae and sacrum), ribs 9-12, and the iliac crest (of the ilium).
• Inserts on the floor of the bicipital groove of the humerus.
• Adducts, extends, and medially rotates the humerus, and also depresses the scapula.