Question

which muscle of the anterior thorax is responsible for flexion, adduction, and medial rotation of the shoulder? a.) latissimus dorsi b.) deltoid c.) supraspinatus d.) pectoralis major

Explanation:

• Latissimus Dorsi: It is located on the posterior (back) side of the body, not the anterior thorax. Its main actions include extension, adduction, and medial rotation of the shoulder, but it is not involved in shoulder flexion.
• Deltoid: It is a large, triangular muscle covering the shoulder. The anterior part of the deltoid is responsible for flexion of the shoulder, the middle part for abduction (opposite of adduction), and the posterior part for extension. So it doesn't meet all the criteria (adduction is not its main action for the whole muscle).
• Supraspinatus: It is one of the rotator cuff muscles. Its main function is to initiate abduction of the shoulder, not flexion, adduction, or medial rotation.
• Pectoralis Major: It is a large muscle in the anterior thorax. It has clavicular and sternocostal heads. The pectoralis major is responsible for flexion (clavicular head helps in flexing the shoulder), adduction (pulls the arm towards the mid - line of the body), and medial rotation of the shoulder.

Answer:

d. Pectoralis Major