What is the origin of latissimus dorsi?

• A. Spinous processes of C7-T1 and nuchal ligaments.
• B. Spinous processes of T7-L5, thoracolumbar fascia, iliac crest, and inferior ribs (9-12).
• C. Medial border of scapula.
• D. Lateral clavicle.

Answer: (B)

The main idea being tested is where latissimus dorsi attaches at its origin, which explains why it can pull the arm in powerful ways. Latissimus dorsi originates from a broad set of attachments: spinous processes from the lower thoracic to lumbar spine (T7 through L5), the thoracolumbar fascia, the iliac crest, and the inferior ribs (typically ribs 9–12). This wide origin gives the muscle a strong, sweeping pull toward the humerus, enabling extension, adduction, and medial rotation of the arm. It inserts on the intertubercular groove of the humerus, so its pull from that expansive origin translates into those movements efficiently. The other potential origins—such as regions near the upper spine with the nuchal ligament, the medial border of the scapula, or the lateral clavicle—belong to other muscles and do not match latissimus dorsi’s established attachment pattern.