Difference between Vagus and Phrenic Nerves

Vagus Nerves

The vagus nerve is the 10th cranial nerve that is also denoted as CN X. It is composed of sensory, motor and parasympathetic nerves. It has approximately 80% afferent fibres and 20% efferent fibres. It is one of the longest and most complex nerves of the cranial nerves. The vagus nerve runs through the brain to the face and from thorax to the abdomen.

The vagus nerves affect the respiratory, gastrointestinal and cardiovascular systems. It divides and spread to different parts, such as Inferior cervical cardiac branch, Pharyngeal nerve, Hering–Breuer reflex in alveoli etc.

Functionally, the vagus nerve sends motor impulses to different parts, such that it controls the rate of heartbeat, constriction of bronchi, peristalsis stimulation, sweating, speech and gastrointestinal secretions.

Damage to the vagus nerve can lead to hyperphagia (increases hunger), decreases antral contractions, inpaired pyloric relaxation and defective gastroduodenal coordination.

Phrenic Nerves

The phrenic is a mixed nerve that originates from the C3 to C5 spinal nerves in the neck. It originates as left and right nerve from the neck to travel through the chest between heart and lungs upto the diaphragm. The phrenic nerves are composed of sensory, motor and sympathetic neurons.

The major function of the phrenic nerves is to control the contraction of the diaphragm and help in the breathing process. The phrenic nerves supply motor neurons to the diaphragm, mediastinal pleura and pericardium. The nerve induces the activation of the diaphragm contraction, thus expanding the lungs. This draws air into them.

Injury to the phrenic nerve can cause diaphragmatic paralysis, and irritation to the nerve causes a reflex of hiccups.

Vagus vs Phrenic Nerves

Vagus Nerves

Phrenic Nerves

Description

The vagus nerve is a mixed nerve that is also the tenth cranial nerve.

The phrenic nerve is a mixed nerve that arises from the C3-C5 spinal nerves in the neck.

Type of Nerve

Cranial Nerve

Spinal Nerve

Mixed Nerves

It is composed of sensory, motor and parasympathetic fibres.

It is composed of sensory, motor and sympathetic fibres.

Occurrence

The vagus nerve runs from the brain to the face, and from thorax to the abdomen.

It originates from the neck to travel through the chest between heart and lungs upto the diaphragm.

Function

The vagus nerve controls the heartbeat, peristaltic movements, and gastrointestinal secretions.

The phrenic nerves innervate the diaphragm with motor impulses to allow respiration.

Damage to the Nerve

Damage to the vagus nerve can cause:

  • Hyperphagia
  • Impaired pyloric relaxation
  • Defective gastroduodenal coordination.

Damage to the phrenic nerve can cause:

  • Diaphragmatic paralysis
  • Hiccup reflex

Visit BYJU’S Biology for more interesting topics

Also Read:

Frequently Asked Questions on Difference between Vagus and Phrenic Nerves

Is the phrenic nerve autonomic or somatic?

The phrenic nerve is a mixed somatic nerve.

What’s the longest nerve in the human body?

The sciatic nerve is the longest nerve in the human body.

Leave a Comment

Your Mobile number and Email id will not be published. Required fields are marked *

*

*

DOWNLOAD

App Now