Question
A 21-year-old woman comes to the physician for a follow-up examination. Four months ago, she underwent posterior arthrodesis for thoracolumbar scoliosis. She has recovered well from the surgery but noticed difficulties combing her hair with her right hand. A photograph of the patient’s back is shown. The nerve that was most likely injured in the surgery originates from which of the following spinal roots?
| A. |
C5–C7
|
| B. |
C6-C8
|
| C. |
C8-T1
|
| D. |
T2-T5
|
Show Answer
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Correct Answer � A
Explanation
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|
Answer A) C5–C7
Explanation:
The image shows winging of the scapula, which is characteristic of long thoracic nerve injury.
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The long thoracic nerve originates directly from the C5–C7 anterior spinal roots, enters the axillary cavity, and descends together with the lateral thoracic artery along the lateral surface of the thoracic cage.
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In surgeries that require the patient to be in a prone position (e.g., spinal surgery), improper positioning of the arms can compress and injure this nerve. This injury leads to paralysis of the serratus anterior muscle, which manifests with medial winging of the scapula and weakened abduction of the shoulder above 90° (manifesting, e.g., during hair combing), as seen here.
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Further common causes of long thoracic nerve injury include invasive procedures (e.g., axillary lymph node dissection), direct trauma to the shoulder, and prolonged nerve compression (e.g., carrying a heavy backpack).
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