Question

Which of the following nerves does not arise from the brachial plexus?

1) median
2) phrenic
3) radial
4) ulnar

Answer 1

The phrenic nerve does not arise from the brachial plexus but from the cervical plexus. It controls the diaphragm, essential for breathing, while the brachial plexus gives rise to nerves that innervate the arms.

Step-by-step explanation:

The nerve that does not arise from the brachial plexus is the phrenic nerve. This question is examining your understanding of the human peripheral nervous system, specifically in relation to the origins of certain nerves. The phrenic nerve arises from the cervical plexus (spinal nerves C1 through C5) and innervates the diaphragm, which is crucial for breathing. Meanwhile, the brachial plexus, comprised of spinal nerves C4 through T1, is responsible for the innervation of the arms and gives rise to the median, radial, and ulnar nerves. Therefore, the correct answer to the question is 2) phrenic nerve, as it comes from the cervical plexus, not the brachial plexus.