Notes on Vagus Nerve

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VAGUS NERVE

Function:

Mixed - motor and sensory.

1. General visceral efferent (parasympathetic): Heart, smooth muscle of lungs, GUT.

2. Special visceral efferent: Control of pharyngeal muscle movement.

3. General visceral afferent: Sensation from heart, lungs and GUT. Aortic arch baroreceptors and aortic body chemoreceptors.

4. Special visceral afferent: Taste function (epiglottis, pharynx).

5. General somatic afferent: Visceral reflexes (pain sensation from ear, pharynx and larynx.)

Nuclei:

(4, two motory - two sensory) - thus shared with glossopharyngeal and accessory nerves.

1. Nucleus ambiguous.

2. Nuclei of the tractus solitarius.

3. Sensory nucleus of the trigeminal.

4. Dorsal nucleus of vagus.

Origin:

1. Sulcus between the inferior cerebellar peduncle and olive.

2. Vagal triangle - floor of the 4th ventricle and nucleus ambiguous of the medulla.

Course:

Passes through the jugular foramen with the accessory nerve and forms the superior ganglion. On exiting the foramen it forms the inferior ganglion. The cranial root of the accessory nerve joins the inferior vagal ganglion. Passes down the neck on both sides in the carotid sheath. In the chest the right nerve forms the right posterior pulmonary plexus. Together with the opposite nerve it forms the esophageal plexus. Passes through the esophageal orifice in the diaphragm to enter the abdomen as the anterior aspect of the stomach and ends in the Coeliac ganglion.

Branches:

Come of at the level of the head, neck, thorax and abdomen.

1. Meningeal (dura of posterior cranial fossa).

2. Auricular (Arnold): Supplies (sensory) adjacent skin of the external auditory meatus and auricle and part of the tympanic membrane.

3. Pharyngeal: Motory to pharyngeal constrictors (striated) and soft palate muscles except palatoglossus and tensor veli palatini. The fibres are originally from the N. accessorius.

4. Superior laryngeal divides into:

a. External laryngeal nerve: supplies crico-thyroid and crico-pharyngeus and

b. Internal laryngeal nerve: to mucous membrane of the piriform fossa and larynx i.e. sensory to larynx superior to the vocal cords.

5. Recurrent laryngeal nerves (right and left). After hooking around the subclavian artery (right) and aortic arch (left) the nerves ascend in the groove between the trachea and esophagus to enter the larynx by passing under the inferior constrictor. Both sensory and motory function. Supplies all laryngeal intrinsic muscles (except crico-thyroid) and crico-pharyngeus. Sensory to larynx below the vocal cords.

6. Cervical and thoracic cardiac: carotid branches to the carotid sinus; cardiac plexus.

7. Bronchial: pulmonary plexus.

8. Esophageal.

9. Gastric (anterior and posterior).

Further Topics on Cranial Nerves:

1. Introduction to Cranial Nerves
2. Notes on Olfactory Nerve CN 1
3. Notes on Optic Nerve CN 2
4. Notes on Oculomotor Nerve CN 3
5. Notes on Trochlear Nerve CN 4
6. Notes on Trigeminal Nerve CN 5
7. Notes on Abducens Nerve CN 6
8. Notes on Facial Nerve CN 7
9. Notes on Vestibulocochlear Nerve CN 8
10. Notes on Glossopharyngeal Nerve CN 9
11. Notes on Vagus Nerve CN 10
12. Notes on Accessory Nerve CN 11
13. Notes on Hypoglossal Nerve CN 12
14. Summary of Cranial Nerve Nuclei
15. Summary of Cranial Nerve Functions

Additional Reading:

Basic Neurology

1. Peripheral Nervous System
2. Central Nervous System
3. The Ventricular System
4. The Spinal Cord
5. The Brain Stem
6. The Cerebellum
7. Visual Pathways
8. Diencephalon
9. Basal Ganglia
10. Cerebral Cortex
11. Sleep Disorders
12. Autonomic Nervous System
13. Cranial Nerves and Parasympathetic Ganglia
14. Cells of the Nervous System
15. Cerebrospinal fluid
16. Additional short notes on Cerebrum
17. Functions and Diseases of Cerebrum
18. Subcortical Grey Matter
19. Notes on The Spinal Cord
20. Regulation of Heart Rate by Autonomic Nervous System
21. Action Potentials, Axon Conduction, and Neuromuscular Junction
22. Types of Seizures
23. What is a Cough Reflex?
24. Notes on Congenital Prosopagnosia
25. Findings in Parkinson's Disease
26. Types of Heat Strokes
27. Types of Strokes
28. What is Benign Intracranial Hypertension?
29. What is Cauda Equina Syndrome?
30. Cranial Nerve Locations in Brain Stem

Neurology Videos

1. Video of Neurology Examination in a Clinical Setting

Medical Images

Useful Medical Images & Diagrams (link opens in a new window)

Related Topics

1. Nervous System Disorders
2. Histology of Nervous Tissue
3. Cranial Nerve Reflexes
4. Motor System Examination

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