Which of the following nerves originates from the cervical plexus?
A Radial
B Mediam
C Phrenic
D Axillary
E Femoral
The correct answer and explanation is:
The correct answer is C. Phrenic.
The cervical plexus is a network of nerves formed by the anterior rami (branches) of the first four cervical spinal nerves (C1 to C4). It provides motor and sensory innervation to various structures in the neck, upper chest, and diaphragm. One of the most important nerves originating from the cervical plexus is the phrenic nerve.
The phrenic nerve is primarily responsible for motor control of the diaphragm, the muscle essential for breathing. This nerve arises from the C3, C4, and C5 spinal nerves, with the majority of its fibers coming from C4. The phrenic nerve travels down through the neck and into the chest, where it innervates the diaphragm. Damage to the phrenic nerve can lead to difficulty in breathing due to paralysis or weakening of the diaphragm, which can be life-threatening if not addressed.
Other nerves listed in the options are not associated with the cervical plexus:
- The radial nerve originates from the brachial plexus, which is a network of nerves formed by the anterior rami of C5 to T1.
- The median nerve also originates from the brachial plexus, arising from the combination of the lateral and medial cords.
- The axillary nerve originates from the brachial plexus, specifically from the posterior cord.
- The femoral nerve originates from the lumbar plexus, specifically from the L2 to L4 spinal nerves.
Thus, the phrenic nerve is the only one originating from the cervical plexus in this list. Its role in respiratory function underscores its vital importance in maintaining basic life-supporting processes.