Anatomy Exam Muscles of the Rotator Cuff 5 — Questions and Answers
Question 1: Which rotator cuff muscle is most commonly torn in rotator cuff injuries?
- Supraspinatus (Correct answer)
- Infraspinatus
- Subscapularis
- Teres minor
Correct answer: Supraspinatus
The supraspinatus is the most commonly torn rotator cuff muscle, typically at its insertion on the greater tubercle.
Question 2: The 'drop arm test' is positive when a patient cannot slowly lower the arm from 90° abduction. This indicates injury to which structure?
- Supraspinatus tendon (Correct answer)
- Subscapularis tendon
- Axillary nerve
- Long head of biceps
Correct answer: Supraspinatus tendon
A positive drop arm test indicates a complete supraspinatus tear, as the muscle cannot control the eccentric lowering of the arm.
Question 3: From which cord of the brachial plexus does the upper subscapular nerve originate?
- Posterior cord (Correct answer)
- Lateral cord
- Medial cord
- Anterior division
Correct answer: Posterior cord
The upper subscapular nerve originates from the posterior cord (C5, C6) of the brachial plexus.
Question 4: Which of the following clinical tests is most specific for infraspinatus and teres minor pathology?
- External rotation lag sign (Correct answer)
- Neer impingement sign
- Speed's test
- Yergason's test
Correct answer: External rotation lag sign
The external rotation lag sign tests external rotation strength, isolating the infraspinatus and teres minor.
Question 5: The interval between the supraspinatus and subscapularis tendons is called the rotator interval. What structure passes through this interval?
- Long head of the biceps tendon (Correct answer)
- Short head of the biceps tendon
- Coracobrachialis
- Pectoralis minor
Correct answer: Long head of the biceps tendon
The long head of the biceps tendon passes through the rotator interval before entering the bicipital groove.
Question 6: Which rotator cuff muscle has the largest cross-sectional area and is therefore the most powerful?
- Subscapularis (Correct answer)
- Infraspinatus
- Supraspinatus
- Teres minor
Correct answer: Subscapularis
The subscapularis has the largest cross-sectional area of the rotator cuff muscles, making it the most powerful internal rotator.
Question 7: When performing a 'bear hug test,' the examiner tries to pull the patient's hand off the opposite shoulder while the patient resists. This specifically tests which muscle?
- Subscapularis (Correct answer)
- Supraspinatus
- Infraspinatus
- Teres minor
Correct answer: Subscapularis
The bear hug test places the subscapularis under maximal load by testing its ability to maintain internal rotation against resistance.
Anatomy Exam Muscles of the Rotator Cuff 5
Which rotator cuff muscle is most commonly torn in rotator cuff injuries?