latissimus dorsi

latissimus dorsi

(lə-tĭs′ə-məs dôr′sī)

n. pl. latissimi dorsi (-mī′)

Either of two broad, flat, triangular muscles with origin from the spinous processes of the lower thoracic and lumbar vertebrae, the sacrum, and the iliac crest, that insert into the humerus and whose action adducts, medially rotates, and extends the arm.

latissimus dorsi

[latis′iməs dôr′sī]

Etymology: L, widest, dorsum, the back

one of a pair of large triangular muscles on the thoracic and lumbar areas of the back. The base of the triangle inserts through lumbar aponeuroses to the spines of lumbar and sacral vertebrae and in the supraspinous ligaments, posterior iliac crest, and the lower four ribs. The fibers of the muscle twist as they pass the scapula and converge at the base of the intertubercular groove of the humerus. The latissimus dorsi extends, adducts, and rotates the arm medially; draws the shoulder back and down; and, with the pectoralis major, draws the body up when climbing. It is innervated by the thoracodorsal nerve. Compare levator scapulae, rhomboideus major, rhomboideus minor, trapezius.

Latissimus dorsi

latissimus dorsi

The broadest muscle of the back. It arises from the spines of the six lower thoracic vertebrae and from the FASCIA attached to the lumbar vertebrae and back of the pelvis and sweeps up and forward to be inserted by a short, broad tendon into the back of the top of the upper arm bone (humerus). It acts to pull the body upward in climbing and assists in heavy breathing.

latissimus

[L.] widest, a broad structure.

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latissimus dorsi

the broad muscle of the back that serves to retract the forelimb.