What is the primary symptom of an infraspinatus injury?

What is the primary symptom of an infraspinatus injury?

• A. Deficit in internal rotation
• B. Pain and weakness in abduction
• C. Pain and weakness during external rotation of the arm
• D. Accumulation of porphobilinogen

Answer: (C)

An infraspinatus injury primarily results in pain and weakness during external rotation of the arm. The infraspinatus muscle, which is one of the rotator cuff muscles located on the posterior aspect of the shoulder, plays a crucial role in externally rotating the humerus. When this muscle is injured, individuals typically experience difficulty and discomfort when attempting to externally rotate the arm, which can greatly affect activities requiring arm movement, such as throwing or overhead activities. This pain and weakness experienced during external rotation are characteristic signs that indicate an injury to the infraspinatus. In contrast, issues like deficits in internal rotation are more closely associated with other muscles, such as the subscapularis, and pain during abduction would likely indicate involvement of the supraspinatus. The mention of porphobilinogen relates to metabolic conditions and is not relevant to shoulder injuries. Thus, the distinct symptom of pain and weakness during external rotation directly correlates with the function of the infraspinatus and is why it is recognized as the primary symptom of an infraspinatus injury.

An infraspinatus injury primarily results in pain and weakness during external rotation of the arm. The infraspinatus muscle, which is one of the rotator cuff muscles located on the posterior aspect of the shoulder, plays a crucial role in externally rotating the humerus. When this muscle is injured, individuals typically experience difficulty and discomfort when attempting to externally rotate the arm, which can greatly affect activities requiring arm movement, such as throwing or overhead activities. This pain and weakness experienced during external rotation are characteristic signs that indicate an injury to the infraspinatus.

In contrast, issues like deficits in internal rotation are more closely associated with other muscles, such as the subscapularis, and pain during abduction would likely indicate involvement of the supraspinatus. The mention of porphobilinogen relates to metabolic conditions and is not relevant to shoulder injuries. Thus, the distinct symptom of pain and weakness during external rotation directly correlates with the function of the infraspinatus and is why it is recognized as the primary symptom of an infraspinatus injury.