A patient presents with marked weakness during resisted testing of right shoulder extension and medial rotation. Which of the following nerve lesions would MOST likely produce the described impairments?

1.    Thoracodorsal nerve
2.    Suprascapular nerve
3.    Spinal accessory nerve
4.    Axillary nerve

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 patient presents with marked weakness during resisted testing of right shoulder extension and medial rotation. Which of the following nerve lesions would MOST likely produce the described impairments?

1.    Thoracodorsal nerve
2.    Suprascapular nerve
3.    Spinal accessory nerve
4.    Axillary nerve

Nerve Lesions

A lesion of the nerve can occur through many mechanisms of injury. Possible etiologies include mechanical (e.g., compression injury), crush (e.g., fracture, compartment syndrome), laceration (e.g., contact with sharp object), penetrating trauma (e.g., stab wound), stretch (e.g., traction injury), high velocity trauma (e.g., motor vehicle accident), and cold (e.g., frostbite). 

Peripheral nerve lesions may result in total loss of muscle over time. Recovery is based on the degree of injury and potential for regeneration of the nerve.

Let’s explore each of the options:

Option 1- Thoracodorsal nerve

The thoracodorsal nerve originates from the posterior cord of the brachial plexus and innervates the latissimus dorsi muscle. The latissimus dorsi extends, adducts, and medially rotates the shoulder and is a depressor of the scapula. Marked weakness to resisted shoulder extension and medial rotation is characteristic of a thoracodorsal nerve lesion.

Option 2 – Suprascapular nerve

The suprascapular nerve originates from the trunks of the brachial plexus and innervates the supraspinatus and infraspinatus muscles. The supraspinatus abducts the shoulder and the infraspinatus laterally rotates and horizontally abducts the shoulder. Pain is frequently worsened with cross-body adduction and internal rotation.

Option 3 – Spinal accessory nerve

The spinal accessory nerve (cranial nerve XI) innervates the sternocleidomastoid and trapezius muscles. It is commonly tested with resisted shoulder shrugs. Due to the role of the upper and lower fibers of the trapezius as part of the force couple in upward rotation of the scapula, inability to abduct the shoulder beyond 90 degrees is characteristic of a lesion to the spinal accessory nerve.

Option 4 – Axillary nerve

The axillary nerve originates from the posterior cord of the brachial plexus and innervates the deltoid and teres minor muscles. Marked weakness with abduction of the shoulder in neutral rotation and weakness in shoulder external rotation is characteristic of an axillary nerve lesion.

The correct answer is Option 1.

Let’s explore the all student data:

63% of students selected Option 1 – Thoracodorsal nerve – the correct response
18% of students selected Option 2 - Suprascapular nerve
2% of students selected Option 3 - Spinal accessory nerve
17% of students selected Option 4 - Axillary nerve

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 1 question since the question requires students to possess basic foundational academic knowledge. Remediation of Level 1 questions occurs through academic review of entry-level content using textbooks, review books, Basecamp, and flash cards.

Academic Focus Area
Looking to review related academic content? Check out page 260 in PTEXAM: The Complete Study Guide.

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