After a 26-year-old man’s car was roadsided by a large truck, he is brought to the emergency depament with multiple fractures of the transverse processes of the cervical and upper thoracic veebrae. Which of the following muscles might be affected?
**Core Concept**
The levator scapulae muscle is a key muscle in the neck and shoulder region, originating from the transverse processes of the cervical and upper thoracic vertebrae. It plays a crucial role in scapular elevation, rotation, and stabilization.
**Why the Correct Answer is Right**
The levator scapulae muscle is innervated by the spinal accessory nerve (cranial nerve XI) and its primary function is to elevate the scapula and rotate it downward. Given that the patient has multiple fractures of the transverse processes of the cervical and upper thoracic vertebrae, the levator scapulae muscle is likely to be affected due to its attachment to these bones. The muscle's function and innervation make it particularly susceptible to injury in the event of such fractures.
**Why Each Wrong Option is Incorrect**
**Option A:** The trapezius muscle is primarily responsible for scapular elevation, depression, and rotation, but it originates from the external occipital protuberance, superior nuchal line of the occipital bone, and the spinous process of the seventh cervical vertebra. Its attachment points are not directly related to the fractured transverse processes.
**Option C:** The rhomboid major muscle originates from the spinous processes of the second to fifth thoracic vertebrae and inserts into the medial border of the scapula. Although it is attached to the thoracic vertebrae, its primary function and attachment points make it less likely to be directly affected by the described fractures.
**Option D:** The serratus posterior superior muscle originates from the lower border of the ligamentum nuchae, spinous processes of the seventh cervical and first to third thoracic vertebrae, and inserts into the upper border of the second to fifth ribs. Its attachment points are not directly related to the fractured transverse processes.
**Clinical Pearl / High-Yield Fact**
It's essential to remember that the levator scapulae muscle's attachment to the transverse processes of the cervical and upper thoracic vertebrae makes it particularly susceptible to injury in cases of spinal trauma or fractures. This can lead to muscle weakness, pain, and limited scapular movement.
**✓ Correct Answer: B. Levator scapulae**