Dr. Amit T. Suryawanshi

Oral and Maxillofacial Surgeon

Pune, India

Contact details :Email ID - amitsuryawanshi999@gmail.com

Mobile No - 9405622455

CONTENTS

BASIC NEUROANATOMY

Origin of nervous system

Divisions of nervous system

Cranial nerves

NEUROANATOMY

• Sensory stimuli

Sensory Nerves

• Correlation

• Coordination

BRAIN• Muscles

• Glands etc.

Motor Nerves

Basic organization of the nervous system

The nervous system is an organ system containing

a network of specialized cells called neurons that

transmit signals between different parts of the

body. coordinate the actions .

The nervous system consists of two parts,

1. Central nervous system

2. Peripheral nervous system.

The Nervous system

Origin Of Nervous System

NERVOUS SYSTEM

EMBRYONIC ECTODERM

NEURAL

PLATE

NEURAL

CREST CELLS

PNS ANS

NEURAL

TUBE

CNS

Origin Of Nervous System

Divisions of Nervous systemNervousrsystem

CENTRAL NERVOUS SYSTEMBrain & Spinal cord

PERIPHERAL NERVOUS SYSTEMCranial & Spinal nerves

and their associated ganglia

Autonomic

Nervous

system

Somatic

Nervous

system

Sensory

Divisions Motor

Divisions

Parasympathetic

N. system

Sympathetic

N. system

Enteric N.

System

Basic Functions of the Nervous System

1. Sensation- Events or changes occurring inside and outside the

body. Such changes are known as STIMULI and the cells that monitor them are RECEPTORS.

2. Integration- The parallel processing and interpretation of sensory

information to determine the appropriate response.

3. Reaction- Motor output.

The activation of muscles or glands (typically via the release of neurotransmitters (NTs))

1. Central Nervous System –

Organization of the Nervous System

2. Peripheral Nervous System -

The nervous system outside the brain and spinal cord

Consists of:31 Spinal nerves

- Carry information to and from the spinal cord.

12 Cranial nerves - Carry information to and from the brain.

- Ganglia

Divisions of Nervous System :

The brain the spinal cord

The Main center of integration and control

Divisions of Nervous System -

Receives sensory input from the spinal cord as well as

from its own nerves (e.g., Cranial nerves )

Devotes most of its volume (and computational power)

to processing its various sensory inputs and initiating

appropriate and coordinated — motor outputs.

1. Central Nervous System

The brain -

Spinal Cord -

- Conducts sensory information from

the peripheral nervous system (both somatic

and autonomic ) to the brain

- Conducts motor information from the brain to our

various effectors

-skeletal muscles

-cardiac muscle

-smooth muscle

-glands

Peripheral Nervous System

Responsible for communication between the CNS and the rest of the body .

It is divided into:

Sensory division ( Afferent division )

Motor division ( Efferent division )

Sensory division ( Afferent division ) –

-Conducts impulses from RECEPTORS to the CNS

-Informs the CNS about the state of the body

-( interior and exterior )

- Sensory nerve fibers can be ,

SOMATIC - Conduct impulses from skin, skeletal

muscles and Joints to CNS

VISCERAL –Conduct impulses from smooth muscles,

cardiac muscles, and glands (Internal organs) to CNS.

Motor Division ( Efferent Division ) -

It is divided into:

Somatic nervous system - VOLUNTARY (generally)

Conducts impulses from the CNS to skin , skeletal muscles , joints

Autonomic nervous system - INVOLUNTARY (generally)

Conducts impulses from the CNS to smooth muscles, cardiac muscles, and glands (Internal organs )

Autonomic Nervous System- Divided into:

Sympathetic Nervous System - “Fight or Flight”

Parasympathetic Nervous System - “Rest and Digest”

These 2 systems are antagonistic.

The

sympathetic

nervous

system aids in

the control of

most of the

body's internal

organs.

Stress — as in

the flight-or-

fight response.

Sympathetic Nervous System -

“Rest and Digest”

Phenomenon

- generally works

to promote

maintenance of

the body at rest.

Parasympathetic Nervous System -

The enteric nervous system is a

meshwork of nerve fibers that

innervate the

viscera

Enteric Nervous System

Gastrointestinal tract,

Pancreas

Gall bladder.

NEURON-

Neuron (nerve cell)–

It is basic structural and

functional unit of the

nervous system.

Types of NEURON

NEUROANATOMY

Neuron consists of :

a cell body containing

nucleus – the

Neuronal soma.

Multiple number of

processes -dendrites

and axons

NEUROANATOMY

Dendrites conduct

information towards the

cell body

Axons conduct impulses

away from cell body

Function Of Neurons -

Neurons produce and

conduct nerve impulses.

A synapse is the site of

functional contact

between axon and

another neuron or

organ.

Neurotransmitters are

released at synapses

and they help in

transmission of

impulses.

Synapse and Neurotransmitters

Afferent neurons

- carry sensations of touch , pain, temperature

and pressure. Therefore they are called as

sensory fibers .

Efferent neurons

- carry impulses away from the central

nervous system.

NUCLEUS - is a compact group of nerve cell bodies of similar form and function, located inside the CNS.

GANGLION – is a similar group of nerve cell bodies located outside the CNS.

NUCLEUS & GANGLION

NEUROANATOMY

The PNS has three main types of nerves:

1. Cranial Nerves

2. Spinal Nerves and

3. Autonomic Nerves

All cranial nerves are attached to the

brainstem, except for cranial nerve XI,

Accessory Nerve.

which is attached to the spinal cord.

All spinal nerves are attached to the spinal cord.

All spinal nerves have dorsal and ventral roots.

spinal nerves -

The autonomic nerves run through the roots

of cranial or spinal nerves to ganglia or

autonomic plexuses in the walls of the viscera

(smooth muscles and glands)

They also return sensory impulses to CNS from

sensory receptors in viscera.

Cranial Nerves

I . Olfactory Nerve II . Optic Nerve III. Oculomotor Nerve IV. Trochlear Nerve V. Trigeminal Nerve VI. Abducent NerveVII. Facial Nerve VIII. Vestibulocochlear Or Auditory N.IX. Glossopharyngeal NerveX. Vagus Nerve XI. Accessory Nerve XII. Hypoglossal Nerve

Entirely sensory in function.

Arises from olfactory receptor nerve cells in the

mucous membrane of nasal cavity.

Bundles of these nerve fibers pass through

openings of cribriform plate of ethmoid bone

and synapse in the olfactory bulb.

OLFACTORY NERVE

From olfactory bulb ,the second order nerve fibers

pass through the olfactory tract to the olfactory

cortex in cerebrum.

The olfactory cortex in cerebrum is

responsible for appreciation of olfactory

sensations. i.e. Sensation of Smell.

• The Optic Nerve passes from the

eyeball through the optic canal into the

middle cranial fossa .

OPTIC NERVE

Entirely sensory in function.

The two optic nerves

join below the base of

the diencephalon to

form optic chiasma

and then divides into

two optic tracts

Optic nerve transmits visual information from light-

sensitive receptors on the retina of the eye to the brain

for analysis, interpretation .

Entirely motor in function.

Oculomotor nerve nuclei:

Two nuclei –

1. the main motor nucleus situated in midbrain.

2. the parasympathetic nucleus situated

posterior to the motor nucleus

OCULOMOTOR NERVE

Course of occulomotor nerve :

The occulomotor nerve emerges from themidbrain- then continues in the middle cranialfossa in the lateral wall of cavernous sinus.

Here it divides into superior and inferior ramuswhich enter the orbital cavity through superiororbital fissure.

The occulomotor nerve supplies parasympathetic innervation to

the intraocular muscles.

And somatic innervation to the extraocular muscles.

Parasympathetic fibers synapse in ciliary ganglion.

The occulomtor nerve supplies the following extrinsic muscles of eye :

1. Levator palpebraesuperioris

2. Superior, medial and inferior rectus

3. Inferior oblique

The oculomotor nerve is responsible for:

1. Lifting the upper eyelid.

2. Turning the eye upward, downward and medially.

3. Constricting the pupil and accomodating the eye.

Entirely motor in function.

Trochlear nerve nucleus –

Situated in midbrain and lies inferior to the

Oculomotor nucleus.

TROCHLEAR NERVE

Course of trochlear nerve :

Leaves the brainstem and immediately decussates

with the nerve of opposite side .

It passes through the middle cranial fossa in the

lateral wall of cavernous sinus and enters orbit

through superior orbital fissure.

The nerve supplies superior oblique musleof eyeball.

It assists in turning eye downward and laterally.

Course & relations

Anterior aspect of Pons ( sensory and Motor Root )

Middle Cranial Fossa

Meckel’s cavity ( Trigeminal Ganglion)

Superior orbitalfissure

Ist DivisionOphthalmic

IInd DivisionMaxillary

Foramen Rotundum

IIIrd DivisionMandibular

Foramen Ovale

TRIGEMINAL NERVE

OPHTHALMIC DIVISION

Course & relations

Trigeminal Ganglion

Middle Cranial Fossa

Lateral wall of Cavernous Sinus

Superior Orbital Fissure

Orbit

-Lacrimal -Frontal -Nasociliary

OPHTHALMIC DIVISION

LACRIMAL NERVE

Superior Orbital Fissure

Lateral wall of Orbit

Above the Lateral Rectus muscle

Lacrimal Gland

Course & Relations

Course & relations

Superior Orbital Fissure

Rim of Orbit

Levator Palpebrae Superioris

Supra-orbital Supra-trochlear

Supra-orbital Foramen

Frontal nerve

NASO-CILIARY NERVE

Course & relations

Superior Orbital Fissure

Within common tendinous ring of Recti

Optic Nerve

Below superior rectus & superior oblique

Medial orbital wall

AnteriorEthmoidal

PosteriorEthmoidal

LongCiliary

Infra-trochlear

External nasal Internal nasal

MAXILLARY NERVE

Gasserion Ganglion

Foramen Rotundum

Pterygopalatine Fossa

Infra –Orbital Canal

Infra –Orbital Foramen

Face

Middle Meningeal N.

-Pterigopalatine N-Posterior superioralveolar N

-Zygomatic N

-Inferior palpebral-External nasal-Superior labial

Anterior superior alveolar N Middle superior alveolar N

- Branches and Course -

MAXILLARY DIVISION

Maxillary Nerve Branches (within pterigopalatine fossa )

Zygomatic N

Inferior OrbitalFissure

Zygomatico-facial

Supplies-Facial prominenceOf cheek

Supplies-Skin of temple

Zygomatico-temporal

Pterygopalatine Nerves

Orbital Nasal Palatine

Continued -

Nasopalatine N. Greater palatine n.

middle palatine n.

posteriorpalatine n.

Posterior superior Alveolar N.

PosteriorHard palate

Soft palate,Tonsil,uvula

Softpalate

Maxillary molars , buccalMucosa in molar region

Maxillary Nerve Branches( within infraorbital canal )

Middle superior alveolar nerve

Anterior superioralveolar nerve

Supplies-Maxillary Incisors,canine

Supplies –Maxillary premolars

Maxillary Nerve Branches ( on the face )

InferiorPalpebralbranches

External nasal branches

Superior labial branches

LowerEyelid

UpperLip,cheekSide of

Nose

- Superior dental plexus -

MANDIBULAR NERVE Course & Relations

Gasserion Ganglion

Motor rootForamen Ovale

Maintrunk

Nerve to medial pterygoid

Anteriordivision

Posteriordivision

Buccal

Nerve to MasseterNerve To TemporalisNerve to LateralPterygoid

Auriculo-temporal

MylohyoidNerve

SuperficialtemporalCutaneous

Mental

Incisive

Lingual

Inferior alveolar

sensory root

Nervous spinosus-

ABDUCENT NERVE

Entirely motor and supplies the lateral rectus

muscle of the eyeball.

Abducent nerve nucleus :

situated in pons

ABDUCENT NERVE -

Course of abducent nerve :

The nerve fibers emerge from the pons from the

groove between pons and medulla oblongata.

It passes through cavernous sinus and lies below

the internal carotid artery.

The nerve enters the orbit through superior orbital

fissure.

Abducent nerve :

FACIAL NERVE

Course and Branches of Facial Nerve

PONS

INTERNAL AUDITORY MEATUS

PETROUS PART OF TEMPORAL

BONE

FACIAL CANAL

STYLOMASTOID FORAMEN

Motor

root

PAROTID GLAND

FACIAL MUSCLES

(GENICULATE GANGLION )

Medulla oblongata

PAROTID PLEXUS

GREATER PETROSAL

NERVE TO STAPEDIUS

CHORDA TYMPANI

POSTERIOR AURICULAR

N . POST. BELLY OF DIGASTRIC

N . STYLOHYOID

-Course-

Sensory

root

• Greater petrosal nerve -

- provides motor innervation to lacrimal

gland , mucosal glands of the nose, palate, and

pharynx.

- carries special sensory taste fibers from

the palate .

• Nerve to stapedius -provides motor innervation

for stapedius muscle in middle ear

• Chorda tympani -carries special sensory taste fibers from

the anterior 2/3rd of the tongue.

Outside skull -

(Distal to stylomastoid foramen)

• Posterior auricular nerve -

• Nerve to Posterior belly of Digastric

• Nerve to Stylohyoid muscle .

Facial nerve enters parotid gland and forms parotid plexus

Parotid

Plexus

• Its main function is motor

control of most of the muscles of

facial expression.

• The facial nerve also

supplies parasympathetic fibers

to the submandibular

gland and sublingual

glands via chorda tympani

Functions -

-It is Sensory nerve .

-It consists of two

roots

- Vestibular root

- Cochlear root

Vestibulocochlear Nerve Or Auditory Nerve

Course -

Vestibular root transmits impulses from

vestibular apparatus ( Balance )

Cochlear root transmits impulses from

auditory apparatus (Sound )

Vestibular root --

Cochlear root --

• Auditory nerve transmits sound and

equilibrium (balance) information from

the Internal ear to the Brain .

Functions -

Glossopharyngeal nerve

It originates from medulla oblongata

Inferior salivatory nucleus

Nucleus ambiguus

Nucleus of solitory tract

Nuclei -

Glossopharyngeal nerve

Glossopharyngeal nerve

Superior Ganglion

Inferior Ganglion•Branches -

•Tympanic nerve (s)

•Branch to carotid

sinus (s)

•Branch to

Stylopharyngeus

muscle (m)

•Tonsillar branches

(s)

Lingual Branches

•(S)

•Pharyngeal branches

(m)

•Tympanic nerve -

Sensory fibers supply the middle ear.

Secretory fibers supply the parotid gland

•Nerve to carotid sinus -

Receives sensory information from ‘

Chemoreceptors in Carotid body .

Baroreceptors in carotid sinus .

•Nerve to Stylopharyngeus muscle

•Tonsillar branches (s)

Lingual Branches -

Receives sensory information from posterior 1/3rd of the tongue.

•Pharyngeal branches -

Innervate constrictor muscles of the pharynx.

Nuclei -

-Nucleus ambiguus

-Nucleus of solitory tract

( superior part & inferior part )

It originates from medulla oblongata

COURSE OF VAGUS NERVE

VAGUS NERVE (MIXED)

Superior Ganglion- Meningeal nerve

- Auricular nerve

Inferior Ganglion - Pharyngeal branches

- Superior laryngeal nerve

- external laryngeal n.

- internal laryngeal n.

- Recurrent laryngeal

- Cervical Carotid branches

-Anterior esophageal plexus

-gastric, celiac, hepatic branches

BRANCHES -

•Cricothyroid muscle

Levator veli palatini muscle

•Salpingopharyngeus muscle

•Palatoglossus muscle

•Palatopharyngeus muscle

•Superior, middle and

inferior pharyngeal constrictors

•Muscles of the larynx (speech)

•It supplies -

Accessory nerve (motor)Course -

Cranial root –

Cranial root joins Vagus nerve and innervates

- all laryngeal muscles except cricothyroid

Spinal root -Spinal root innervates

-Trapezius

-Sternocleidomastoid

Hypoglossal nerve (motor)

Medulla Oblongata

(Hypoglossal Nucleus)

Hypoglossal Canal

Behind Vagus Nerve

Between IJV & ICA

Posterior Belly of Digastric

Tongue(Intrinsic and extrinsic muscles)

COURSE & RELATIONS

Extrinsic musclesGenioglossus

Hyoglossus

Styloglossus

Intrinsic musclesSuperior longitudinal

Inferior longitudinal

Verticalis

Transversus

It supplies --

Except Palatoglossus which is supplied by cranial part of accessory nerve

References Gray’s Anatomy

Oral and maxillofacial surgery – Laskin

Atlas of Anatomy - Anne Gilroy

LA – Malamed

Guyton (physiology )

Ganong (physiology )

Internet

Thank you