Which broad, flat muscle occupies most of the lower posterior thorax?

Which broad, flat muscle occupies most of the lower posterior thorax?

• A. Rhomboid Major
• B. Teres Minor
• C. Trapezius
• D. Latissimus Dorsi

Answer: (D)

The broad, flat muscle that forms much of the lower back and the posterior side of the thorax is the latissimus dorsi. It is a large, fan-shaped muscle originating from the lower spine, sacrum, iliac crest, and thoracolumbar fascia, then sweeping up to insert on the humerus. Because of its wide span and extensive attachments, it covers and occupies most of the lower posterior thorax, unlike the other muscles listed, which are smaller or located higher up on the back or near the shoulder.

The broad, flat muscle that forms much of the lower back and the posterior side of the thorax is the latissimus dorsi. It is a large, fan-shaped muscle originating from the lower spine, sacrum, iliac crest, and thoracolumbar fascia, then sweeping up to insert on the humerus. Because of its wide span and extensive attachments, it covers and occupies most of the lower posterior thorax, unlike the other muscles listed, which are smaller or located higher up on the back or near the shoulder.