Phrenic nerve is A. Cranial nerve B. Spinal nerve C. Sciatic nerve D. Lumbar nerve
Hint: A mixed motor / sensory nerve is the phrenic nerve. The nerve is essential for breathing because it provides the diaphragm, the primary muscle of respiration, with exclusive motor control.
Complete Answer: - Phrenic nerves derive from the spinal nerves of C3-C5 in the neck. The right and left phrenic nerves are mainly given by the spinal nerve C4 in humans, but there is also a contribution from the spinal nerves C3 and C5. - The nerve passes downward through the chest from its origin in the neck to pass between the heart and lungs into the diaphragm.The nerve occurs at the lateral edge of the anterior scalp muscle. It moves below the anterior surface of the anterior scalp, deep to the anticipated layer of the cervical fascia. - The nerve runs at the back of the subclavian vein on both sides. From here, the direction of the phrenic nerve varies between the left and the right. - Cranial nerves are nerves that originate directly from the brain (including the brainstem) and are conventionally known to be twelve pairs. Cranial nerves convey information between the brain and areas of the body, mainly to and from the regions of the head and neck, including special senses of vision, taste, smell , and hearing. - The sciatic nerve, also known as the ischiadic nerve, is a large nerve in humans and other vertebrate animals, which is the main branch of the sacral plexus and travels between the hip joint and the lower limb.This nerve provides a connexion to the nervous system for the skin of the lateral leg and the entire foot, The muscles of the back of the thigh, the muscles of the leg and the foot.
Thus the correct answer is option(B) Spinal nerve.
Note: The phrenic nerve triggers motor innervation to the diaphragm. If the nerve is impaired, the diaphragm can be paralysed.