Which set contributes to internal rotation with all listed muscles?

Which set contributes to internal rotation with all listed muscles?

• A. Subscapularis and pectoralis major.
• B. Pectoralis major, latissimus dorsi, and teres major.
• C. Subscapularis, pectoralis major, latissimus dorsi, teres major, and anterior deltoid.
• D. Subscapularis, latissimus dorsi, and teres major.

Answer: (B)

Internal rotation of the shoulder is produced by muscles that pull the humerus medially, bringing the front of the arm toward the body. The strongest contributors in this action are the pectoralis major, latissimus dorsi, and teres major. Pectoralis major sits on the chest and, when it contracts, pulls the humerus inward toward the midline and can also aid in adduction and flexion depending on the position. Latissimus dorsi runs from the back and side to the front of the upper arm, and its contraction medially rotates the humerus while also helping with extension and adduction. Teres major originates near the scapula and inserts with the latissimus on the same part of the humerus, providing a strong medial rotation alongside adduction. Each of these muscles reliably contributes to internal rotation across a range of arm positions, so a set consisting of these three muscles represents the core group that drives internal rotation. Subscapularis is also an internal rotator, but the combination listed here highlights the primary, widely recognized contributors. Anterior deltoid can assist in internal rotation in some positions, but it is not a primary internal rotator, which is why it’s not emphasized in this concise set.

Internal rotation of the shoulder is produced by muscles that pull the humerus medially, bringing the front of the arm toward the body. The strongest contributors in this action are the pectoralis major, latissimus dorsi, and teres major.

Pectoralis major sits on the chest and, when it contracts, pulls the humerus inward toward the midline and can also aid in adduction and flexion depending on the position. Latissimus dorsi runs from the back and side to the front of the upper arm, and its contraction medially rotates the humerus while also helping with extension and adduction. Teres major originates near the scapula and inserts with the latissimus on the same part of the humerus, providing a strong medial rotation alongside adduction.

Each of these muscles reliably contributes to internal rotation across a range of arm positions, so a set consisting of these three muscles represents the core group that drives internal rotation. Subscapularis is also an internal rotator, but the combination listed here highlights the primary, widely recognized contributors. Anterior deltoid can assist in internal rotation in some positions, but it is not a primary internal rotator, which is why it’s not emphasized in this concise set.