The Latissimus dorsi is the large, flat, dorso-lateral muscle on the trunk, posterior to the arm, and partly covered by the spinotrapezius on its median dorsal region.

• Origin: neural spines of the last thoracic and most of the cervical vertebrae.
• Insertion: tendon on the medial surface of the humerus.
• Action: pulls the forelimb dorsally and caudally.