Question

A PT student is assessing a patient with a chief complaint regarding the inability to completely raise the right arm. The student internally rotates the arm, slightly abducts, and brings the arm to 90 degrees of flexion. The student then asks the patient to resist the downward directed force on their arm. Which of the following responses would be MOST LIKELY if the patient is graded poorly on this test?

Select one:
a. Radial nerve injury
b. Suprascapular nerve injury
c. Long thoracic nerve injury
d. Musculocutaneous nerve injury

Answer 1

A poor grading on the muscle resistance test described, where muscles innervated by the musculocutaneous nerve are engaged, indicates a likely musculocutaneous nerve injury.

Step-by-step explanation:

When the physical therapy (PT) student assesses a patient who is unable to completely raise their right arm and performs a resistance test that engages muscles typically innervated by the musculocutaneous nerve, the most likely poor response would be due to a musculocutaneous nerve injury. The action of resisting a downward directed force on the arm in the position described (internally rotated, slightly abducted, and at 90 degrees of flexion) primarily tests the muscles of the anterior compartment of the arm, predominantly the biceps brachii, which is innervated by the musculocutaneous nerve. Therefore, if the patient has poor muscle grading on this test, it suggests a potential deficit in this nerve or its associated musculature.