Which muscle originates from the spinous processes of the inferior thoracic and all lumbar vertebrae and inserts into the intertubercular groove of the humerus?

Which muscle originates from the spinous processes of the inferior thoracic and all lumbar vertebrae and inserts into the intertubercular groove of the humerus?

• A. Deltoid
• B. Latissimus Dorsi
• C. Pectoralis Minor
• D. Serratus Anterior

Answer: (B)

The muscle being tested is identified by where it starts and where it ends. Originating from the spinous processes of the lower thoracic vertebrae and all lumbar vertebrae, with connection to the thoracolumbar fascia, and inserting into the intertubercular groove of the humerus, points to the latissimus dorsi. This configuration lets it pull the arm downward and backward, performing actions that extend, adduct, and medially rotate the humerus. The other muscles have different origins and insertions—deltoid attaches to the shoulder girdle and inserts on the humerus itself, pectoralis minor to ribs and the coracoid, and serratus anterior to the medial border of the scapula—so they don’t match this specific origin–insertion pattern.

The muscle being tested is identified by where it starts and where it ends. Originating from the spinous processes of the lower thoracic vertebrae and all lumbar vertebrae, with connection to the thoracolumbar fascia, and inserting into the intertubercular groove of the humerus, points to the latissimus dorsi. This configuration lets it pull the arm downward and backward, performing actions that extend, adduct, and medially rotate the humerus. The other muscles have different origins and insertions—deltoid attaches to the shoulder girdle and inserts on the humerus itself, pectoralis minor to ribs and the coracoid, and serratus anterior to the medial border of the scapula—so they don’t match this specific origin–insertion pattern.