A physical therapist examines a patient who complains of forearm pain and weakness in the hand. During the examination, the therapist identifies weakness with wrist flexion, finger flexion, and thumb adduction. Froment’s sign is positive. Which of the following nerves is MOST likely affected?

1. Ulnar
2. Radial
3. Median
4. Musculocutaneous

Transcript

Welcome back to the Scorebuilders’ Question and Answer Podcast! This podcast provides members of the Scorebuilders’ team with the opportunity to explore challenging multiple-choice examination questions with students actively preparing for the licensing examination. My name is Scott Giles and I will be your host for today’s journey.

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A physical therapist examines a patient who complains of forearm pain and weakness in the hand. During the examination, the therapist identifies weakness with wrist flexion, finger flexion, and thumb adduction. Froment’s sign is positive. Which of the following nerves is MOST likely affected?

1. Ulnar
2. Radial
3. Median
4. Musculocutaneous

Peripheral Nerve Entrapment
Peripheral nerve entrapments in the arm occur when a nerve is compressed or irritated as it passes through narrow spaces (e.g., muscles, connective tissue). Common sites include the carpal tunnel, cubital tunnel, and radial tunnel. Symptoms can include pain, tingling, numbness or weakness in the areas the nerve supplies.

This particular question requires you to have specific knowledge related to nerve function and anatomy as well as familiarity with Froment’s sign. Let’s review this special test.

Froment’s Sign
A patient is asked to hold a piece of paper between the thumb and index finger as the therapist attempts to pull the paper away.  A positive test is indicated by the patient flexing the distal phalanx of the thumb due to adductor pollicis muscle paralysis.

Let’s explore each of the options:

Option 1 -  Ulnar 
The ulnar nerve is most commonly compressed in the cubital tunnel at the elbow. Since the ulnar nerve innervates the flexor carpi ulnaris, flexor digitorum profundus, and adductor pollicis, compression of the nerve can result in weakness with wrist flexion, finger flexion, and thumb adduction. In addition, ulnar nerve involvement would be associated with a positive Froment’s sign. 

Option 2 - Radial
The radial nerve innervates the wrist and finger extensors in the forearm, as well as the brachioradialis and supinator muscles. Compression of this nerve would more likely result in weakness with wrist and finger extension. A patient with radial nerve palsy would exhibit a wrist drop deformity. Radial nerve involvement would not be associated with a positive Froment’s sign.

Option 3 - Median
The median nerve is most commonly compressed in the carpal tunnel at the wrist. Since the median nerve innervates many of the wrist and finger flexors (e.g., flexor carpi radialis, flexor digitorum superficialis and profundus), it too could result in weakness with wrist and finger flexion. The median nerve does not innervate the adductor pollicis and therefore, Froment’s sign would be negative.

Option 4 – Musculocutaneous 
The musculocutaneous nerve innervates the biceps brachii, brachialis, and coracobrachialis muscles. Compression of this nerve would more likely result in weakness with elbow flexion and forearm supination. Musculocutaneous nerve involvement would not be associated with a positive Froment’s sign.

The correct answer is Option 1.

Let’s explore the all student data:
60% of students selected Option 1 - Ulnar - the correct response
10% of students selected Option 2 - Radial
25% of students selected Option 3 - Median
5% of students selected Option 4 - Musculocutaneous

System Classification
This question is a Neuromuscular and Nervous Systems question which represents approximately 24% of all exam items.

Content Outline Classification
This question is a Physical Therapy Examination question which represents approximately 24% of all exam items.

Level Classification
This question is a Level 2 question since the question requires students to integrate numerous pieces of information or to apply knowledge in a given clinical scenario. Remediation of Level 2 questions occurs by increasing flexibility with academic content and by carefully analyzing decision making processes when answering applied examination questions.

Academic Focus Area
Looking to review related academic content? Check out pages 109 and 271 in PTEXAM: The Complete Study Guide.

Thanks for joining us on the Scorebuilders Q and A podcast! See you next week!