cranial nerves sanjaya adikari department of anatomy
TRANSCRIPT
Cranial Nerves
Sanjaya AdikariDepartment of Anatomy
12 pairs of cranial nerves
III to XII attached to brain stem
Their cell bodies form nuclei in the brain stem
First cell body of sensory nerves lie out side CNS(form ganglia)
Summary of cranial nerves
Aspects to study
1. Position of nucleus
2. Emerging point from brain stem
3. Intracranial course
4. Point of exit from the cranial cavity
5. Extracranial course
6. Distribution
Few terms: Somatic, branchial and visceral
Branchial (Pharyngeal) Arches
• Core of mesodermal
tissue covered by
ectoderm and
endoderm
• Each of the arch will
have its own
bone/cartilage,
muscles, nerve and
artery
endodermectoderm
Branchial
Premaxilla, maxilla, zygomatic bone, part of temporal bone and mandible
Mandibular branch of trigeminal nerve (V)
Facial nerve (VII)
Glossopharyngeal nerve (IX)
Superior laryngeal branch of vagus nerve (X)Recurrent laryngeal branch of vagus nerve (X)
Visceral
• In relation to internal organs
– Heart
– Lung
– Intestines
………………
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Few hints
Nerve A
Nerve B
Posterior horn
Lateral horn
Anterior horn
Motor
Sensory
Motor
Sensory
Posterior
Spinal cord (thoracic or lumbar)
Somatic sensory
Visceral sensory
Visceral motor
Somatic motor
SMVM
VS
BM
SS
Brain stem
SpSGSS
Types of sensations
Visceral sensory
Somatic sensory
General Visceral sensory pain, temperature, touch, viration position sense
Special Visceral sensory taste
General Somatic sensory pain, temperature, touch, vibration position sense
Special Somatic sensory hearing
SM
VSGSS
SS
IIIIVVIXII
BM
VVIIIXXXI
VM
IIIVIIIXX
VIIIXX
VVIIIXX
VIII
Functional components of cranial nerves
Somatic Motor
Muscles of the orbit (III, IV, VI)
Muscles of tongue (XII)
IIIIV
VI
XII
Branchial Motor
Muscles of mastication (V)
Facial muscles (VII)
Pharyngeal and laryngeal muscles (Nucleus ambiguus via IX, X, XI nerves)
Visceral Motor
Edinger Westphal nucleus(accessory oculomotor)
Salivary nuclei (NI part of VII, IX)
Dorsal motor nucleus of vagus (for cardiac muscles, smooth
muscles of alimentary tract)
SensoryConsists of single nuclei for visceral and somatic sensory
Visceral sensory with taste
Nucleus of tractus solitarious
which receives taste fibres from
the tongue through VII, IX
and sensory from heart, lungs
and other viscera through X
General somatic sensory
Sensory nucleus of
trigeminal nerve extending
from the midbrain to the
cervical spinal cord
Special somatic sensoryHearing via VIII (vestibulocochlear nerve)
SM VMVS
BM
GSSSS
VVIIIXXXI
IIIIVVIXII
IIIVIIIXX
VIIIXX
VVIIIXX
VIII
Intracranial course and exit
Sanjaya AdikariDepartment of Anatomy
Superior orbital fissure(III, IV, V1, VI)
Foramen rotundum(V2)
Foramen ovale(V3)
Foramen spinosum
Foramen lacerum
Internal acoustic meatus(VII, VIII)
Jugular foramen(IX, X, XI)
Hypoglossal canal(XII)
Optic canal(II)
Olfactory Nerve (I)
Olfactory bulb
Olfactory tractAnterior perforatedsubstance
Uncus
Bypass thalamus and goes directly into the taste area
Nerve filaments
Cribriform plate of ethmoid bone
Optic Nerve (II)
T
N
T
Optic Nerve (II)
Optic nerve
Optic chiasma
Optic tract
Superior colliculus(body reflexes)
Pretectal nucleus(pupillary reflexes)
Lateral geniculate bodyof thalamus
Internalcapsule
Optic radiation
Oculomotor Nerve (III)
Somatic motor nucleus
Visceral motor nucleus
(Edinger westphal nucleus)
Nerve emerges from ventral
aspect of midbrain
travel’s in the lateral wall of
the cavernous sinus
Oculomotor Nerve… cont.
Levator palpabrae superioris
Dilator pupillae
Superior rectus
Medial rectus, inferior rectus, inferior oblique
Ciliary muscleSphincter pupillae
Ciliary ganglion
Superior division
Inferior division
Sympathetic fromInternal carotid plexus
Parasympathetic fromEW nucleus
Trochlear Nerve (IV)
Somatic motor nucleus
Emerges from the dorsal aspect of midbrain
Travels in the lateral wall of the cavernous sinus
Supplies the superior oblique muscle
Abducens Nerve (VI)
Somatic motor nucleus
Nucleus lies in lower pons near
midline
Emerge between pons and
pyramid of medulla
Travels through the cavernous
sinus
Supply the lateral rectus muscle
Oculomotor N (III)
Ventral midbrain
Lateral wallCavernous S
Divide Sup. & Inf.divisions
Sup/infraorbital fissure
Trochlear N (IV)
Dorsalmidbrain
Lateral wallCavernous S
Superior orbital fissure
Abducent N (VI)
BetweenPons & pyramid of medulla
withinCavernous S
Superior orbital fissure
Cavernous sinus
1- Oculomotor N2- Trochlear N3- Abducent N4- Ophthalmic branch of TN
5- Maxillary branch of TN 6- Sympathetic plexus of N7- Internal carotid A8- Pituitary gland
LR6(SO4)3
Trigeminal nerve (V)
Branchial motor nucleus
Somatic sensory nucleus
Emerge from the ventral aspect of
pons
Sensory and motor roots emerge
separately
Trigeminal nerve… cont.
Cell bodies of 1st orderSA fibres
Trigeminal ganglion
Somatic sensory nucleus
Branchial motor nucleus
Foramen ovale
Ophthalmic division
Maxillary division
Lat. Wall ofcavernoussinous
Mandibulardivision
Mandibularnerve(mixed)
Facial Nerve (VII)
Branchial motor nucleus
Visceral motor nucleus (Superior salivary nucleus)
Taste sensory nucleus (Tractus solitarius)
Main facial nerve and the
nervous intermedius parts
emerge from the
cerebellopontine angle
Geniculate ganglion (taste 1st order cell bodies)
Nucleus ofTractus solitarious
Chorda tympaninerve
Taste from anterior tongue
Nervousintermedius
Facial Nerve…cont.
Branchial motornucleus
Nerve to stapedius
Stylomastoid foramen
Pure branchial motor facial nerveSupply muscles of facial expression
Ear drum
VE to submandibular gland and glands on the mouth floor
Greater petrosal nerveSup.
salivarynucleus
Internal acoustic meatus
Vestibulocochlear Nerve (VIII)
Cochlear nerve
Vestibular nerve
Hair cells of spiral organ
Hair cells of utricle, saccule and semilunar canals
Spiral ganglion of cochlea
Vestibular ganglion
Internal acoustic meatus
Cerebellopontine angle
Cochlear nucleiin pons
Vestibular nucleiin medulla
Glossopharyngeal Nerve (IX)
Branchial motor nucleus (Nucleus ambiguus)
supplies stylopharyngeus muscle
Parasympathetic nucleus (Inferior salivary nucleus)
supplies parotid gland
Sensory nucleiGSS from posterior tongue goes to sensory nucleus of trigeminal nerve
Taste from the posterior tongue goes to the tractus solitarius
VS from baroreceptors go to nucleus of tractus solitarius
Vagus Nerve (X)
Branchial motor nucleus (Nucleus ambiguus)
supplies pharyngeal constrictors
Visceral motor nucleus (Dorsal motor nucleus of vagus)
supplies muscles of heart, bronchi,
oesophagus, stomach and intestines
Visceral sensory nucleus
VS from larynx, heart, lung… goes to nucleus of tractus solitarius
GSS goes to sensory nucleus of trigeminal nerve
Accessory Nerve (XI)
Branchial motor nerve
Cranial root From nucleus ambiguusFibres in the cranial root join the
vagus nerve
Somatic motor nerve
Spinal root Anterior horn cells of upper 5-6 cervical spinal segments
Fibres in the spinal root supply sternocleidomastoid and
trapezius muscles
Hypoglossal Nerve (XII)
Somatic motor nerve
Leaves cranial cavity through the hypoglossal canal
Supplies all muscles (intrinsic and extrinsic) of tongue except palatoglossus