Which muscle extends, medially rotates, and adducts the shoulder?

Which muscle extends, medially rotates, and adducts the shoulder?

• A. Latissimus Dorsi
• B. Supraspinatus
• C. Infraspinatus
• D. Serratus Anterior

Answer: (A)

Latissimus dorsi is the muscle that can extend, medially rotate, and adduct the shoulder. It’s a large posterior back muscle that pulls the humerus downward and backward (extension), rotates the arm inward toward the body (medial rotation), and brings the arm toward the midline (adduction). This combination of actions is a hallmark of the latissimus dorsi, especially in movements like pulling oneself up or climbing. Supraspinatus mainly initiates arm abduction, not extension or medial rotation. Infraspinatus is an external rotator, not a medially rotating one. Serratus anterior helps with scapular protraction and stabilization, not the primary movements of the glenohumeral joint described here.

Latissimus dorsi is the muscle that can extend, medially rotate, and adduct the shoulder. It’s a large posterior back muscle that pulls the humerus downward and backward (extension), rotates the arm inward toward the body (medial rotation), and brings the arm toward the midline (adduction). This combination of actions is a hallmark of the latissimus dorsi, especially in movements like pulling oneself up or climbing.

Supraspinatus mainly initiates arm abduction, not extension or medial rotation. Infraspinatus is an external rotator, not a medially rotating one. Serratus anterior helps with scapular protraction and stabilization, not the primary movements of the glenohumeral joint described here.