Question

Which of the following is a motor branch of the cervical plexus?

a) Ansa cervicalis (C1-C3 loop)
b) Spinal accessory nerve (CNXII)
c) Phrenic nerve (C3, C4, C5)
d) Supraclavicular nerves (C3,C4)

Answer 1

The motor branch of the cervical plexus in question is the phrenic nerve (C3, C4, C5), which controls the diaphragm and is essential for breathing.

Step-by-step explanation:

The motor branch of the cervical plexus being asked about is the phrenic nerve (C3, C4, C5). The cervical plexus is composed of axons from spinal nerves C1 through C5. Among its branches, the phrenic nerve is crucial as it connects to the diaphragm at the base of the thoracic cavity, enabling breathing by controlling the diaphragm's movements. The spinal accessory nerve (CNXII) is not a branch of the cervical plexus, but rather one of the cranial nerves which innervates the sternocleidomastoid and trapezius muscles, assisting in movements relating to the head and shoulders.