Dr. Amit T. Suryawanshi
Oral and Maxillofacial Surgeon
Pune, India
Contact details :Email ID - [email protected]
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