The pre-plexus nerves discussed include Dorsoscapular and which other nerve?

The pre-plexus nerves discussed include Dorsoscapular and which other nerve?

• A. Long Thoracic
• B. Nerve to Subclavius
• C. Spinal Accessory nerve
• D. Phrenic nerve

Answer: (A)

The main idea here is identifying nerves that originate from the nerve roots before the brachial plexus forms—the pre-plexus nerves. Dorsal scapular nerve and long thoracic nerve both come off the ventral rami at the root level. The dorsal scapular nerve comes from C5 and supplies the rhomboids and levator scapulae, while the long thoracic nerve arises from C5–C7 and travels to innervate the serratus anterior. These roots-before-trunks origins classify them as pre-plexus nerves. The other options don’t fit that pattern: the nerve to the subclavius arises from the upper trunk (after the roots, i.e., post-plexus); the spinal accessory nerve is a cranial nerve outside the brachial plexus; and the phrenic nerve comes from the cervical plexus and isn’t a pre-plexus nerve of the shoulder region.

The main idea here is identifying nerves that originate from the nerve roots before the brachial plexus forms—the pre-plexus nerves. Dorsal scapular nerve and long thoracic nerve both come off the ventral rami at the root level. The dorsal scapular nerve comes from C5 and supplies the rhomboids and levator scapulae, while the long thoracic nerve arises from C5–C7 and travels to innervate the serratus anterior. These roots-before-trunks origins classify them as pre-plexus nerves.

The other options don’t fit that pattern: the nerve to the subclavius arises from the upper trunk (after the roots, i.e., post-plexus); the spinal accessory nerve is a cranial nerve outside the brachial plexus; and the phrenic nerve comes from the cervical plexus and isn’t a pre-plexus nerve of the shoulder region.