GENERAL HISTOLOGY

Detailed explanation-1: -The most important motor branch of the cervical plexus is the phrenic nerve. The plexus also provides motor fibers to the spinal accessory nerve and to the paravertebral and deep muscles of the neck. Each nerve, with the exception of the first cervical nerve, provides significant cutaneous sensory innervation.

Detailed explanation-2: -Origin. The phrenic nerve originates mainly from the 4th cervical nerve, but also receives contributions from the 3rd and 5th cervical nerves (C3-C5) in humans. Thus, the phrenic nerve receives innervation from parts of both the cervical plexus and the brachial plexus of nerves.

Detailed explanation-3: -The phrenic nerve originates from the anterior rami of the C3 through C5 nerve roots and consists of motor, sensory, and sympathetic nerve fibers. It provides complete motor innervation to the diaphragm and sensation to the central tendon aspect of the diaphragm.

Detailed explanation-4: -The phrenic nerve is among the most important nerves in the body due to its role in respiration. The phrenic nerve provides the primary motor supply to the diaphragm, the major respiratory muscle. Phrenic nerve injury, such as may occur from cardiothoracic surgery, can lead to diaphragmatic paralysis or dysfunction.