Dorsal scapular nerve supplies:
**Core Concept**
The dorsal scapular nerve is a branch of the brachial plexus that arises from the C5 root and supplies muscles involved in scapular rotation and elevation. It plays a crucial role in the movement and stability of the scapula.
**Why the Correct Answer is Right**
The dorsal scapular nerve innervates the rhomboids (major and minor) and the levator scapulae muscles. These muscles are responsible for scapular rotation, elevation, and stabilization. The nerve's course and distribution allow it to innervate these muscles, facilitating their functions in scapular movement. The rhomboids, in particular, are key to scapular rotation and stabilization, while the levator scapulae assists in scapular elevation.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because the suprascapular nerve, not the dorsal scapular nerve, primarily innervates the supraspinatus and infraspinatus muscles.
**Option B:** This option is incorrect because the long thoracic nerve, not the dorsal scapular nerve, innervates the serratus anterior muscle, which is crucial for scapular rotation and upward rotation.
**Option C:** This option is incorrect because the accessory nerve, not the dorsal scapular nerve, primarily innervates the sternocleidomastoid and trapezius muscles.
**Clinical Pearl / High-Yield Fact**
A key point to remember is that the dorsal scapular nerve is often at risk during surgical procedures involving the brachial plexus, such as thoracocervical sympathectomy or brachial plexus repair. Injury to this nerve can result in weakness or paralysis of the scapular muscles, leading to scapular winging.
**Correct Answer:** C. Rhomboids (major and minor) and levator scapulae.