28.Which statement about M. gluteus mealus 15 A. It allows lateral tilt of the pelvis. B. It maintains balance of the pelvis. C. When its insertion moves, it causes abduction of the hip. D. When its origin moves, it causes rotation of the trunk. E. It is innervated by N. gluteus superior. 29.Which of the following options correctly identifies a Rotator cuff muscle and its function? A. M. teres minor - shoulder flexion B. M. infraspinatus - shoulder external rotation C. M. teres major - shoulder abduction D. M. subscapularis - shoulder external rotation E. M. supraspinatus - first 15 degrees of adduction 30. Which of the following muscle-function pairings is incorrect? A. M. pectoralis major - arm adduction B. M. latissimus dorsi - arm flexion C. M. trapezius-scapular retraction D. M. biceps femoris - knee flexion E. M. erector spinae - trunk extension

28. The correct answer is B. It maintains balance of the pelvis.<br /><br />Explanation: The gluteus medius muscle is responsible for maintaining the balance of the pelvis during standing and walking. It does this by abducting the hip and tilting the pelvis laterally. When the insertion of the gluteus medius moves, it causes abduction of the hip. The gluteus medius is innervated by the superior gluteal nerve.<br /><br />29. The correct answer is B. M. infraspinatus - shoulder external rotation.<br /><br />Explanation: The rotator cuff muscles are a group of muscles that stabilize the shoulder joint. The infraspinatus muscle is one of the rotator cuff muscles and its primary function is to externally rotate the shoulder. The other options are incorrect: M. teres minor is involved in shoulder external rotation, not flexion; M. teres major is involved in shoulder adduction, not abduction; M. subscapularis is involved in shoulder internal rotation, not external rotation; M. supraspinatus is involved in shoulder abduction, not adduction.<br /><br />30. The correct answer is B. M. latissimus dorsi - arm flexion.<br /><br />Explanation: The latissimus dorsi muscle is responsible for arm extension, adduction, and internal rotation, not flexion. The other options are correct: M. pectoralis major is involved in arm flexion and adduction; M. trapezius is involved in scapular retraction and elevation; M. biceps femoris is involved in knee flexion and hip extension; M. erector spinae is involved in trunk extension.