Answer:
The latissimus dorsi is a large flat triangular muscle covering the posterior inferior half of the trunk with its origins in the spine of the lower six thoracic vertebra, sacral vertebra, supraspinal ligament, and posterior iliac crest. It inserts into the intertubercular groove of the humerus. The dominant pedicle is the thoracodorsal artery with secondary pedicles from a lateral row of posterior intercostal artery and a medial row of lumbar artery. The reversed lat flap is based on the secondary pedicles, after division of its insertion and dominant pedicle. It can be rotated as a complete or segmental muscle flap to reach across the midline to cover the posterior trunk or mid thoracic.