PERIPHERAL NERVOUS SYSTEM by All India ayush

PERIPHERAL NERVOUS SYSTEM 

1. Central Nervous System (CNS)

Brain

Spinal Cord

2. Peripheral Nervous System (PNS)

Cranial Nerves

Spinal Nerves

Divisions of PNS:

a. Sensory (Afferent) Nervous System

Carries sensory input from sense organs to the CNS.

b. Motor (Efferent) Nervous System

Carries motor output from CNS to muscles and glands.

3. Motor Nervous System Subdivisions

a. Somatic Nervous System

Controls voluntary movements

Communicates with skeletal muscles and sense organs

b. Autonomic Nervous System (ANS)

Controls involuntary functions

Communicates with internal organs and glands

Divisions of ANS:

Sympathetic Division – Arousing (“fight or flight” response)

Parasympathetic Division – Calming (“rest and digest”)

Cranial nerves

➢ Like spinal nerves, cranial nerves are part of the peripheral 

nervous system.

➢ There are 12 pairs of cranial nerves, 

➢ They are designated with roman numerals and with names

➢ The roman numerals indicate the order (anterior to posterior) in 

which the nerves emerge from the brain. 

➢ The names indicate the distribution or function.

CRANIAL NERVES (I–XII)

I. Olfactory Nerve

Component: Sensory

Function: Smell

II. Optic Nerve

Component: Sensory

Function: Vision

III. Oculomotor Nerve

Component: Motor (Somatic + Parasympathetic)

Function: Eye movement, eyelid elevation, pupil constriction, lens accommodation

IV. Trochlear Nerve

Component: Motor

Function: Eye movement (superior oblique muscle – down & lateral)

V. Trigeminal Nerve

Component: Mixed (Sensory + Motor)

Function:

Sensory: Touch, pain, temp from face

Motor: Chewing muscles

VI. Abducens Nerve

Component: Motor

Function: Eye movement (lateral rectus muscle – abduction of eyeball)

VII. Facial Nerve

Component: Mixed (Sensory + Motor + Parasympathetic)

Function:

Sensory: Taste (anterior 2/3 of tongue)

Motor: Facial expression

Parasympathetic: Salivary & lacrimal glands

VIII. Vestibulocochlear Nerve

Component: Sensory

Function: Hearing and balance (equilibrium)

IX. Glossopharyngeal Nerve

Component: Mixed (Sensory + Motor + Parasympathetic)

Function:

Sensory: Taste (posterior 1/3 of tongue), BP monitoring

Motor: Swallowing

Parasympathetic: Salivation (parotid gland)

X. Vagus Nerve

Component: Mixed (Sensory + Motor + Parasympathetic)

Function:

Sensory: From thoracic & abdominal organs

Motor: Speech, swallowing

Parasympathetic: Control of heart, lungs, GI tract

XI. Accessory Nerve (Spinal Accessory)

Component: Motor

Function: Movement of head & shoulders (sternocleidomastoid & trapezius muscles)

XII. Hypoglossal Nerve

Component: Motor

Function: Tongue movement (speech & swallowing)

SPINAL NERVES

Spinal nerves and the nerves that branch from them are part of the 

peripheral nervous system (PNS). 

They connect the CNS to sensory receptors, muscles, and glands in all 

parts of the body. 

The 31 pairs of spinal nerves are named and numbered according to the 

region and level of the vertebral column from which they emerge

All other spinal nerves leave the vertebral column by passing through the 

intervertebral

foramina, the holes between vertebrae

There are 

✓ 8 pairs of cervical nerves, 

✓ 12 pairs of thoracic nerves, 

✓ 5 pairs of lumbar nerves,

✓ 5 pairs of sacral nerves, and 

✓ 1 pair of coccygeal nerves. 

✓ A typical spinal nerve has two connections to the cord: 

✓ A posterior root and 

✓ An anterior root

✓ The posterior and anterior roots unite to form a spinal nerve at the 

intervertebral foramen.

✓ As the posterior root contains sensory axons and the anterior root 

contains motor axons, a spinal nerve is classified as a mixed 

nerve.

Autonomic Control

Cranial Nerves – Parasympathetic Control

Heart

Gastrointestinal organs

Spinal Cord Levels and Autonomic Control

T1–L5 – Sympathetic Control

Cardiovascular system

Lungs

Gastrointestinal tract

Kidneys

Sweat glands

L5–S3 – Parasympathetic Control

Bowel

Bladder

FUNCTIONAL ABILITY 

C3-C6

• Voluntary movement limited to Diaphragmand partial triceps only

• No grip function but may be able to performed limited arm cranking with hand/wrist straps

Torso support necessary for stability in wheelchair

C5-C8

All or most triceps functions present

• Wrist flexion and extension present

• Most/all finger flexion and extension present permitting grasp mad release functions

• Are able to perform arm crank exercise with/without wrist/hand straps

• Torso support necessary for stability in wheelchair

T1-L5

• Some upper extremity and back muscle function present

• Able to perform arm cranking with no wrist/hand straps

Little or no abdominal muscle function

• Torso support may be necessary for stability in wheelchair

T6-T10

Most or all upper extremity and back muscle functions present

• Good muscle upper abdominal muscles

• Greater power output possible due to increased contribution of trunk musculature

• Good or normal stability in wheelchair

T11-T12

• Good abdominal and spinal extensor function

• Some hip flexor and adductor function

• Trunk musculature and increased "bracing" from hip flexors and adductors contributes to increased arm crank power output

• Good or normal stability in wheelchair

L1-S2

• Good/fair lower limb function

• Some walking possible

• Little or no physiological limitation on arm crank power output

•Normal stability in wheelchair