Peripheral Nerves

Overview

Peripheral nerves (43)

1. Cranial nerves: CN1-12

2. Cervical nerves: C1-C4

3. Brachial plexus: C5-T1

4. Thoracic nerves: T2-T12

5. Lumbosacral plexus: L1-S2

6. Sacral-coccyx nerves: S2-C1

Nerves functions:

1. Efferent: sensory

2. Afferent: motor

Peripheral Nervous System

• Somatic

• Autonomic

  • Sympathetic

  • Parasympathetic

Cranial Nerves

By Nerve: Motor and sensory functions

1. Olfactory

Sensory: smell

Motor: nil

Damage: loss of smell

2. Optic

Sensory: vision

Motor: nil

Cell bodies in retina (at start)

Passage: optic chiasm

Damage: loss of vision

3. Oculomotor

Sensory: nil

Motor: all eye muscles except superior oblique and lateral rectus (TOS RAL); ciliary muscle, sphincter pupillae

Motor function: eye movement, pupil constriction & lens accomodation

Passage: superior orbital fissure

Damage: down & out, ptosis, dilated

4. Trochlear

Sensory: nil

Motor: superior oblique (TOS RAL)

Passage: superior orbital fissure

5. Trigeminal

Divisions: 

Ophthalmic V1-  superior orbital fissure, sensory upper 1/3 face (orbit, nose)

Maxillary V2- foramen rotundum, sensory: zygomatic, upper lip

Mandibular V3- foramen ovale, sensory: lower lib, mandibular

Sensory: anterior 2/3 tongue (somatic)

Motor: mastication

Diseases: trigeminal neuralgia

6. Abducens

Sensory: nil

Motor:  Eye abduction- lateral rectus (TOS RAL)

Diseases: common palsy in raised ICP

7.  Facial 

Sensory: taste anterior 2/3 tongue

Motor: facial movements; lacrimal, submandibular glands

Passage: internal acoustic meatus, stylomastoid foramen

Diseases: common palsy, called Bell's Palsy

8. Vestibulocochlear

Sensory: hearing & balance/ motion

Motor: nil

Passage: internal acoustic meatus

9. Glossopharyngeal

Sensory: gag reflex, posterior 1/3 tongue, taste & sensation in mouth

Motor: swallowing, salivation

Passage: jugular foramen

10. Vagus

Sensory: thoracic and abdominal viscera, epiglottis, carotid body, posterior meninges

Motor: thoracic and abdominal viscera, laryngeal and pharyngeal muscles- gag reflex, gland secretion, peristalsis, 

Diseases: core nerve of the parsymathetic route

11. Accessory

Sensory: nil

Motor: sternocleidomastoid, trapezius, laryngeal muscles

Passage: jugular foramen

12. Hypoglossal

Sensory: nil

Motor: tongue movements- speech, swallowing

Passage: hypoglossal foramen

Thoracic Nerves of note

T4: sensory- nipples

T8: sensory- umbilicus

Somatic, Sympathetic & Parasympathetic Systems

Peripheral nerve functions can be divided into

• Somatic

• Autonomic

  • Sympathetic

  • Parasympathetic

Cranial nerves

• 3, 7, 9, 10- parasympathetic functions

The Sympathetic and Parasympathetic Nervous Systems' anatomy are illustrated below:

References

1. Illustration from Anatomy & Physiology, Connexions Web site. http://cnx.org/content/col11496/1.6/, Jun 19, 2013. 

2. https://www.kenhub.com/en/library/anatomy/the-12-cranial-nerves

Written 2024