Question

the brachial plexus can be palpated at the lower lateral border of the sternocleidomastoid muscle. injury to the brachial plexus could cause weakness or paralysis to all of the following except the ______.

○ biceps brachii muscle
○ deltoid muscle
○ muscles that flex the wrist and fingers
○ sternocleidomastoid muscle

Explanation:

The brachial plexus supplies nerves to muscles of the upper limb (like biceps brachii, deltoid, and wrist/finger flexors). The sternocleidomastoid muscle is innervated by the accessory nerve (cranial nerve XI), not the brachial plexus. So injury to the brachial plexus won't affect it.

Answer:

D. sternocleidomastoid muscle