This document discusses the anatomy and functional components of the 12 cranial nerves. It provides names and classifications of each nerve as sensory, motor, or mixed. It describes the deep origin nuclei and fiber types of each nerve, including their development, branches to visceral arches, and types of sensations carried. Diagrams are included to illustrate cranial nerve nuclei and fiber classifications. The glossopharyngeal nerve section provides more detail on its afferent and efferent nuclear origins and fibers.

1. Cranial nerves
Functional components and deep origin nuclei
Anatomy
DR. Mohamed Elfiky
Professor of anatomy and embryology

2. Names Of The Cranial Nerves
1- OLFACTORY NERVE
2- OPTIC NERVE
3- OCCULOMOTOR NERVE
4- TROCHLEAR NERVE
5- TRIGEMINAL NERVE
6- ABDUCENS NERVE
7- FACIAL NERVE
8- VESTIBULOCOCHLEAR NERVE
9- GLOSSOPHARYNGEAL NERVE
10- VAGUS NERVE
11- ACCESSARY NERVE
12- HYPOGLOSSAL NERVE
Mohamed el fiky

3. SENSORY/
AFFERENT
OLFACTORY
OPTIC
VESTIBULO
COCHLEAR
MOTOR/
EFFERENT
OCCULOMOTOR
TROCHLEAR
ABDUCENS
ACCESSARY
HYPOGLOSSAL
MIXTURE
TRIGEMINAL
FACIAL
GLOSSOPHARYNGEAL
VAGUS
Cranial Nerves
Mohamed el fiky

4. DEVELOPMENT
➢ Pharyngeal arch is associated with a developing cranial nerve or its
branches.
➢1st arch CN 5 ( Mandibular)
➢ 2nd arch CN 7
➢3rd arch CN 9
➢4th arch Superior Laryngeal ( Branch of CN 10 )
➢6th arch Recurrent Laryngeal ( Branch of CN 10 )
Mohamed el fiky

5. CRANIAL NERVE FIBERS
Efferent - Motor Afferent - sensory
Skeletal muscles Visceral (smooth) muscles
Developed from
Somatic mesoderm
Developed from
Special visceral mesoderm
Branchial arches
General somatic Efferent
GSE
Special Visceral Efferent
SVE
General Visceral Efferent
GVE
General sensory Special sensory
Somatic Visceral
Somatic Visceral
General Visceral Afferent
GVA
general somatic Afferent
GSA
Special Somatic Afferent
SSA 2&8
Special Visceral Afferent
SVA 1& TASTE
Mohamed el fiky

6. TYPES OF MOTOR FIBERS (EFFERENT)
1. General somatic efferent (G.S.E.) to skeletal muscles
2. Special visceral efferent (S.V.E.) to skeletal muscles developed
from visceral arches
3. General visceral efferent (G.V.E.) to visceral muscles(smooth)
which are supplied by para-sympathetic
fibers.
N.B. there is no special somatic efferent nerve fibers.
Mohamed el fiky

7. TYPES OF SENSORY FIBERS
1- General somatic afferent (G.S.A) Skin & skeletal muscles.
2- General somatic afferent (G.S.A) Visceral (smooth) muscles.
3- Special somatic afferent (S.S.A) Vision & hearing. ( developed from
ectoderm)
4- Special visceral afferent (S.V.A) Sensation which related to
gastrointestinal tract- Olfaction& Taste.
Mohamed el fiky

8. CRANIAL NERVE FIBERS
Cranial nerve supply muscles of branchial arches ( SVE) :
1. Trigeminal nerve 1st arch
2. Facial 2nd arch
3. Glossopharyngeal 3rd arch
4. Vagus 4th & 6th arhes
Cranial nerve carry parasympathetic ( GVE) :
1. Oculomotor nerve
2. Facial
3. Glossopharyngeal
4. Vagus
Cranial nerve carry taste ( SVA) :
1. Facial
2. Glossopharyngeal
3. Vagus
Mohamed el fiky

9. FUNCTIONAL CLASSIFICATION OF NERVE FIBRES
1- Efferent (G.S.E.):
• They are motor to the skeletal muscles developed from myotomes (somatic muscles).
• Cells of origin are in the anterior horn cells of the grey matter of the spinal cord, and in
the nuclei of somatic cranial nerves (III, IV, VI & XII).
SOMATIC
2- Afferent:
a- General (G.S.A.): They are sensory fibres for exteroceptive &
proprioceptive sensations. Their cells of origin are in dorsal ganglia, in the
trigeminal ganglion, geniculate ganglion, glossopharyngeal and vagal
ganglia (V, VII, IX&X).
b- Special (S.S.A.): The fibres of optic and vestibulo-cochlear nerves. They
arise from the bipolar cells of olfactory epithelium, retina, vestibular and
spiral ganglia ( VIII & II ). Mohamed el fiky

10. FUNCTIONAL CLASSIFICATION OF NERVE FIBRES
VISCERAL
1- Efferent:
a- General (G.V.E.): They are preganglionic efferent fibres of the autonomic nervous system. Their cell bodies lie in the lateral
horns of the spinal cord from T1-L2 (sympathetic) and in the lateral horns of S2-S4 and also in a number of cranial nerve
nuclei as: oculomotor, facial glossopharyngeal and vagus (para-sympathetic).
b- Special (S.V.E.): These fibres supply muscles derived from the branchial arches. Their cells of origin are the motor nuclei of
V & VII cranial nerves and nucleus ambiguus of IX, X & XI cranial nerves.
1- Trigeminal nerve: supplies muscles of 1st branchial arch.
2- Facial nerve: supplies muscles of 2nd branchial arch.
3- Glossopharyngeal nerve: the nerve of the 3rd arch.
4- External laryngeal nerve (vagus): the nerve of the 4th arch.
5- Recurrent laryngeal nerve (vagus): the nerve of the 6th arch.
2- Afferent:
a- General (G.V.A.): Their cell bodies are found in the dorsal root ganglia and in the sensory ganglia of certain cranial nerves
as glossopharyngeal and vagus nerves. Their peripheral processes pass to the receptors in the viscera and blood vessels
(for enteroceptive sensations).
b- Special (S.V.A.): They are the taste fibres and olfaction . They are found in facial, glossopharyngeal and vagus nerves.
Their cell bodies are found in the geniculate ganglion, ganglia of glossopharyngeal and vagus. Mohamed el fiky

11. Analysis of cranial nerves
Olfactory Nerve :
Q. What is the type ?
A. Sensory
Q. Any type of sensation ?
Special visceral Afferent
S. V .A .
S .V. A
Mohamed el fiky
S V A

12. Analysis of cranial nerves
Optic Nerve :
Q. What is the type ?
A. Sensory
Q. Any type of sensation ?
Special Somatic Afferent
S. S .A .
S .S. A
N.B. vestibulocochlear nerve the same Mohamed el fiky
S S A

13. Analysis of cranial nerves
Oculomotor Nerve :
Q. What is the type ?
A. Motor
Q. Supply visceral arches
No : G S E
Contain parasympathetic
Yes : G V E
Oculomotor nerve contains :
1- GSE for extraocular muscles
2. GVE it parasympathetic of constrictor pupil
Mohamed el fiky
G S E
G V E

14. Analysis of cranial nerves
Trochlear Nerve :
Q. What is the type ?
A. Motor
Q. Supply visceral arches
No : G S E
Contain parasympathetic
No : --------------
Trochlear nerve contains :
1- GSE for extraocular muscles
N. B. spinal accessory and hypoglossal the same
Mohamed el fiky
G S E
---------

15. Analysis of cranial nerves
Trigeminal Nerve :
Q. What is the type ?
A. Mixed
Motor
Sensory
Q. Supply visceral arches
Yes : SVE
A. Contain parasympathetic
No : XXXXXXXXXXXX
Trigeminal nerve contains :
1- S. V. E for muscles derived from 1st arch
2. G. S. A sensation from face and scalp
Q. Any type of sensation ?
General somatic sensation from
face and scalp GSA
SVE
------
GSA
Mohamed el fiky

16. Analysis of cranial nerves
Facial Nerve
Q. What is the type ?
A. Mixed
Motor
Sensory
Q. Supply visceral arches
Yes : SVE
A. Contain parasympathetic
Yes : GVE
Facial nerve contains :
1. S. V. E : for muscles derived from 2nd arch
2. G. v . E : parasympathetic to submandibular , sublingual and lacrimal glands
3. G. S. A : general sensation from auricle of the ear
4. S. V. A : taste sensation from anterior 2/3 of tongue ( chorda tympani )
Q. Any type of
sensation ?
SVE
GVE
GSA
Taste
sensation
General
sensation
from ear
SVA
Mohamed el fiky

17. Analysis of cranial nerves
Facial Nerve
Q. What is the type ?
A. Mixed
Motor
Sensory
Q. Supply visceral arches
Yes : SVE
A. Contain parasympathetic
Yes : GVE
Glossopharyngeal nerve contains :
1. S. V. E : for muscles derived from 3rd arch
2. G. v . E : parasympathetic to parotid glands
3. G. S. A : general sensation from auricle of the ear
4. S. V. A : taste sensation from posterior 1/3 of tongue
Q. Any type of
sensation ?
SVE
GVE
GSA
Taste
sensation
General
sensation
from ear
SVA
Mohamed el fiky

18. Analysis of cranial nerves
Vagus Nerve
Q. What is the type ?
A. Mixed
Motor
Sensory
Q. Supply visceral arches
Yes : SVE
A. Contain parasympathetic
Yes : GVE
Vagus nerve contains :
1. S. V. E : for muscles derived from 2nd arch
2. G. v . E : parasympathetic to submandibular , sublingual and lacrimal glands
3. G. S. A : general sensation from auricle of the ear
4. S. V. A : taste sensation from root of tongue ( chorda tympani )
5. G. V. A : general sensation from abdominal & thoracic organs
Q. Any type of
sensation ?
SVE
GVE
GSA
Taste
sensation
General
sensation
from ear
SVA
Visceral
sensation
Of
thorathic &
abd.
Organs
GVA

19. CRANIAL NERVE NUCLEI
MOTOR
EFFERENT
SENSORY
AFFERENT
Motor fibres ( Efferent :
1. G S E to skeletal muscles of
general mesoderm
2. S V E to skeletal muscles of
visceral arches
3. G V E to visceral ( smooth)
muscle( parasympathetic )
Sensory fibres ( Afferent :
1. G S A pain temp. touch from skin and
proprioceptive from sk. Muscles
2. G V A as colic sensation from viscera
3. S V A olfaction and taste
4. S S A vision and hearing
Mohamed el fiky

20. CRANIAL NERVE NUCLEI
MOTOR
EFFERENT
General somatic efferent column.
3 , 4, 6,11(spinal) &12
General visceral efferent column (parasympathetic)
3, 7,9 &10.
Special visceral efferent column ( branchial arches )
5,7,9 , 10 and 11(cranial)
SENSORY
AFFERENT
General somatic afferent column
5 , 7 , 9, 19 .
General visceral & special visceral afferent
column. ( taste ) 7,9 &10
Special somatic afferent hearing & vision
2 & 8
Mohamed el fiky

21. CRANIAL NERVE NUCLEI
I- General somatic efferent Column (GSE)
Medulla:
Hypoglossal nucleus Motor nucleus: present in the floor of the 4th ventricle,
adjacent to midline.
Pons:
Abducent nucleus:
- It is a motor nucleus present in the motor column of the brain stem.
- It is located in the floor of the 4th ventricle surrounded by fibers of the facial nerve,
forming with it the facial colliculus
Midbrain:
1- Trochlear nerve nucleus: - It lies close to the midline at the level of inferior
colliculus. - It projects motor fibers to the superior oblique muscle.
2- Occulomotor nerve nucleus: - It lies close to the midline at the level of superior
colliculus.
Mohamed el fiky

22. CRANIAL NERVE NUCLEI
II- General visceral efferent column- Parasympathetic (GVE)
Medulla:
1- Dorsal nucleus of vagus:
- Lies lateral to the hypoglossal nucleus in the floor of 4th ventricle raising the vagal
trigone.
2- Inferior salivatory nucleus: - It is present at the higher level of open medulla.
Pons:
Superior salivary nucleus: - Gives the parasympathetic fibres of the facial nerve.
Midbrain:
Edinger-westephal nucleus: The parasympathetic part of oculomotor nucleus.
Mohamed el fiky

23. CRANIAL NERVE NUCLEI
III- Special visceral efferent column – arches (SVE)
Medulla:
1- Nucleus ambiguus:
- It is a branchio-motor nucleus lying lateral to the dorsal nucleus of vagus.
- It gives motor fibres to the cranial nerves 9, 10 & 11(cranial part ) .
- It supplies the branchial arch muscles of palate, larynx & pharynx.
Pons:
1- Facial motor nucleus:
- Its fibres curve round the abducent nucleus forming the facial colliculus.
- Gives motor fibres to the muscles of the 2nd branchial arch (muscles of facial
expression & stapedius).
2- Trigeminal motor nucleus:
- It is the highest nucleus in the SVE column.
- It projects motor fibres to muscles of mastication through the mandibular nerve
(muscles of 1st arch).

24. CRANIAL NERVE NUCLEI( Sensory )
I- General somatic afferent column (GSA)
Sensory nuclei of trigeminal nerve:
a- Spinal trigeminal nucleus: Located in spinal cord (C l-3) & extends through medulla to the pons. Receives general
sensations from the face via 5, 7, 9, 10 cranial nerves.
b- Main sensory nucleus: Carries touch & pressure sensations from the face.
c- Mesencephalic nucleus: it extends from the upper pons to the level of superior colliculus of midbrain. It receives
proprioceptive sensation from the face.
II- Special somatic afferent column (SSA)
Special somatic afferent column (SSA): consists of nuclei that lie at pontomedullary junction; 2 cochlear nuclei & 4
vestibular nuclei.
General and special visceral afferent column (GVA & SVA)
Solitary nucleus: Presents in pons & medulla medial to the inferior cerebellar peduncle. Its medial part represents the
G.V.A. area receiving enteroceptive sensations carried by 9 & 10 cranial nerves. Its lateral part represents the S.V.A. area
receiving taste sensation carried by 7, 9 & 10 cranial nerves.
Mohamed el fiky

25. GLOSSO-PHARYNGEAL NERVE
Deep nuclear origin:
A. Two nuclei receiving two types of afferent sensations :
1- Spinal nucleus of trigeminal N. receives pain and temperature
from the posterior 1/3 of the tongue, oropharynx and middle ear.
2- Nucleus solitarius receives taste sensation from the posterior
1/3 of the tongue and circumvallate papillae.
B. Two nuclei give rise to two types of efferent fibers :
1- Nucleus ambiguus (upper part):
- It receives bilateral cortico-nuclear fibres.
- It gives branchio-motor efferent fibres to stylo-pharyngeus
muscle.
2- Inferior salivary nucleus : - It gives preganglionic
parasympathetic fibres, which relay in the otic ganglion to supply
the parotid gland. Exit from medulla: between olive and I.C.P.
Mohamed el fiky

26. Functional components:
1- S.V.E. fibres: Arise from nucleus ambiguus. Supply the
stylo-pharyngeus muscle.
2- G.V.E. fibres: Consist of parasympathetic fibres to parotid
gland via tympanic branch & lesser petrosal nerve to otic
ganglion.
3- G.V.A. fibres: End in the medial part of solitary nucleus.
Carry enteroceptive sensations from the mucous
membrane of the posterior 1/3 of the tongue, tonsil,
nasopharynx, soft palate, auditory tube & tympanic cavity.
It also carries paroreceptor fibres from the carotid sinus &
chemo-receptors from the carotid body via the sinus nerve
4- S.V.A. fibres: End in the lateral part of solitary nucleus.
Carry taste sensation from posterior 1/3 of the tongue.
5- G.S.A. fibres: End in the spinal tract & nucleus of
trigeminal. Carry general sensations from the external
auditory meatus & tympanic membrane via auricular
branch of vagus nerve.
GLOSSO-PHARYNGEAL NERVE
Mohamed el fiky

27. VGAUS NERVE
Deep nuclear origin:
Deep nuclear origin:
A- Two nuclei receiving three types of afferent sensations :
1- Spinal nucleus of trigeminal N.: receives pain and temperature from the
external ear, back of tongue, laryngopharynx and larynx
2- Nucleus solitarius : a. It receives visceral sensations from the thoracic
organs, foregut and midgut. b. It receives taste sensation from the root of
the tongue and epiglottis.
B- Two nuclei giving two types of efferent fibers :
1- Nucleus ambiguus (middle part): Its fibers share cranial accessory nerve
in the motor nerve supply of the muscle of the palate, pharynx & larynx.
2- Dorsal vagal nucleus (parasympathetic):
▪ It lies in the vagal trigone in the floor of the 4th ventricle.
▪ It gives efferent preganglionic parasympathetic fibres to thoracic
organs, foregut and midgut.
▪ The nerve leaves the medulla from the posterolateral sulcus & the
skull through the jugular foramen.
▪ It has 2 ganglia one in the jugular foramen & the other just below it.
▪ It is the nerve of the 4th & 6th branchial arches.
Mohamed el fiky

28. VGAUS NERVE
Functional components:
1- S.V.E. fibres: Arises from nucleus ambiguus. Receives its fibres
from the cranial division of accessory nerve. Distributed to the 4th &
6th branchial arch muscles (muscles of pharynx, larynx & soft palate).
2- G.V.E. fibres: Arise from dorsal nucleus of vagus. Consist of
parasympathetic fibres to thoracic & abdominal viscera (heart,
trachea, lung & G.I.T down to Rt. 2/3 of transverse colon).
3- G.V.A. fibres: End in the medial part of the solitary nucleus. Carry
general sensations from mucous membrane of pharynx, larynx,
oesophagus, thoracic & abdominal viscera (down to Rt. 2/3 of
transverse colon).
4- S.V.A. fibres: End in the lateral part of the solitary nucleus. Carry
taste sensation from epiglottis.
5- G.S.A. fibres: End in the spinal tract & nucleus of trigemina. Carry
general sensations from the infra-tentorial dura, dorsal surface of the
external ear, external auditory meatus & tympanic membrane.
Mohamed el fiky

29. Accessory Nerve
❑ It arises from the lower part of nucleus ambiguus.
❑ It lies in the open medulla. o It receives bilateral cortico-
nuclear fibers.
❑ The cranial accessory N. joins the vagus N. and distributed
through the vagal branches to muscles of the palate
(except tensor palate), pharynx (except stylo-pharyngeus)
& larynx. Exit from the medulla: between olive and I.C.P.
❑ Spinal root of accessory nerve :
❑ It arises from the spinal nucleus of accessory N. in the
anterior horn of C1-5 spinal segments
❑ The nucleus receives bilateral cortico-spinal fibres.
❑ The nerve emerges from the side of the spinal cord
between the dorsal and ventral roots, ascends via the
foramen magnum and joins the cranial accessory N.
❑ Outside the skull, it separates from the cranial accessory
N. to supply sternomastoid and trapezius.
Mohamed el fiky

30. Hypoglossal Nerve
❑ Hypoglossal nucleus gives rise to somatic efferent fibers.
▪ It lies in the hypoglossal trigone in the floor of the 4th
ventricle.
▪ It receives bilateral cortico-nuclear fibres for voluntary
movements of the tongue.
▪ It supplies all intrinsic and extrinsic muscles of the
tongue except palatoglossus muscle.
❑ Exit from the medulla: between pyramid and olive.
Mohamed el fiky

31. Facial Nerve
Deep nuclear origin:
A- Two nuclei receive two types of afferent sensations:
1. Spinal nucleus of trigeminal nerve: receives somatic pain from the concha of the external ear.
2. Nucleus solitarius: receives taste sensation from the anterior 2/3 of the tongue (by chorda tympani) and from soft palate
(by greater petrosal N.).
B- Two groups of nuclei give rise to two types of efferent fibers:
1. Motor nucleus of facial nerve:
a. It lies in the lower pons.
b. Its upper part receive bilateral, while its lower part receives only contralateral corticonuclear fibers.
c. The axons of the motor nucleus loop around the abducent nucleus before emerging as the motor root of the facial
nerve.
d. The motor fibers supply muscles developed from the second branchial arch: occipito-frontalis, buccinator, platysma,
posterior belly of digastric, stylohyoid and stapedius.
Mohamed el fiky

32. 2. Parasympathetic nuclei:
a. Special lacrimatory nucleus: gives greater petrosal N. to
relay in pterygo-platine ganglion to lacrimal gland, nasal,
palatine, nasopharyngeal glands.
b. Superior salivary nucleus : give chorda tympani N. to relay
in submandibular ganglion, sublingual & submandibular
salivary glands.
c. These nuclei lie in lower pons and receive descending fibers
from hypothalamus.
Exit of facial nerve from pons: facial N. emerges from the
lower pons at the cerebello-pontine angle as two roots: 1.
Motor root: contains axons of the motor nucleus. 2. Nervus
intermedius root: contains all the sensory and preganglionic
parasympathetic nerve fibers. This root lies between motor
root of facial nerve (medial) and vestibulo-cochlear nerve
(lateral).
Facial Nerve
Mohamed el fiky

33. Facial Nerve
Functional components:
1- S. V. E. fibres: Arises from the facial motor nucleus. Its fibers curve around the abducent nucleus forming the facial
colliculus before leaving the pons. It supplies the muscles of the 2nd arch (muscles of facial expression, stapedius,
stylohyoid and posterior belly of digastric)
• Connections of the nucleus: The upper part of the nucleus receives corticobulbar fibers from both sides. The lower
part of the nucleus receives corticobulbar fibers from the opposite side only. Both parts of the nucleus receive extra-
pyramidal fibers for emotional movements.
2- G.V.E. fibers: - Arises from the superior salivary nucleus. - It carries para-sympathetic secreto-motor functions for
salivation and lacrimation
• Salivation:
Transmitted through the chorda tympani branch of the facial nerve that relays in the submandibular ganglion from
which postganglionic fibers reach the submandibular and sublingual salivary glands.
• Lacrimation: Transmitted through the greater superficial petrosal nerve to the sphenopalatine ganglion from which
postganglionic fibers join the zygomatic nerve then the lacrimal nerve to the lacrimal gland.
3- S.V.A. fibers: - End in the lateral part of solitary tract & nucleus. - Carry taste sensation from the anterior 2/3 of the
tongue through chorda tympani then the lingual nerve.
4- G.S.A. fibers: - End in the spinal tract & nucleus of trigeminal. - Innervate the posterior surface of the auricle.
Mohamed el fiky

34. Abducent Nerve
❑ Its single motor nucleus gives somatic efferent fibers to a
single muscle, lateral rectus of the eye ball.
❑ It lies in lower pons deep to facial colliculus. Its nucleus &
the motor nuclei of trochlear and oculomotor nerves
receive the following :
▪ Bilateral cortico-nuclear fibers from the frontal eye
field (area 8) for voluntary conjugate eye movements
as in reading a fixed object like a newspaper.
▪ Bilateral occipito-nuclear fibers from visual association
cortex of occipital lobe for involuntary conjugate eye
movements as in tracing a moving object.
❑ Exit from the brain: between lower border of pons and
medullary pyramid Mohamed el fiky

35. • Trigeminal Nerve Nuclei: It has four
nucleus:
• (1) Main sensory nucleus.
• (2) Spinal nucleus.
• (3)Mesencephalic nucleus.
• (4) Motor nucleus.
• Main sensory nucleus lies in posterior part of pons
lateral to the motor nucleus.
• Spinal nucleus continuous superiorly with main
sensory nucleus and extends inferiorly through
medulla oblongata and into upper part of spinal
cord as far as second cervical segment.
• Mesencephalic Nucleus composed of unipolar cells
situated in lateral part of gray matter around
cerebral aqueduct.
• It extends inferiorly into pons as far as main
sensory nucleus.
• Motor nucleus is situated in pons medial to main
sensory nucleus.
Mohamed el fiky

36. Trigeminal Nerve
Functional components:
1-S.V.E. fibers: to the first branchial arch muscles.
2- G.S.A. fibers: carry general sensations from the face & scalp.
Deep nuclear origin:
1- Spinal nucleus of trigeminal N. : It extends from the lower pons where it
is continuous with the main sensory nucleus and extends through the whole
medulla down to the upper two cervical spinal segments, where it is
continuous with the Substantia Gelatinosa of Rolandi.
❑ Afferent: (from 5,7,9,10 cranial nerves).
▪ Trigeminal nerve afferent: from the anterior part of scalp, most of
the face, cornea, teeth, T.M.J., oro-nasal mucosa and supratentorial
dura mater.
▪ Facial afferent from the concha of the auricle of the external ear.
▪ Glossopharyngeal nerve afferent from the tympanic cavity,
posterior 1/3 of the tongue and oropharynx.
▪ Vagal nerve afferent from the external ear, back of the tongue
laryngo-pharynx and larynx.
❑ Efferent: axons of the spinal nucleus cross to opposite side to share in
the trigeminal lemniscus.
❑ Function: the nucleus is concerned with pain, temperature and crude Mohamed el fiky

37. Trigeminal pathwaysPathway of proprioceptive sensation from the
trigeminal area:
First neurone: The cells of origin are located in the mesencephalic
nucleus (not in the trigeminal ganglion). The cell processes probably reach
the main sensory nucleus.
Second neurone: The fibers cross the midline & ascend in the trigeminal lemniscus.
Third neurone: from the PMVN of thalamus to the postcentral gyrus.
Pathway of exteroceptive sensation (pain, touch,
temperature) from the trigeminal area:
First neurone: The trigeminal ganglion. Their peripheral
processes receive sensory fibers from the face anterior to the
coronal plane passing through the ears. Their central processes
enter the pons & descend downwards ending in the spinal
trigeminal nucleus.
Second neurone: The spinal trigeminal nucleus. The fibers cross
the midline to ascend as the trigeminal lemniscus to the thalamus.
Third neurone: from the PMVN of thalamus to the postcentral
gyrus.
Mohamed el fiky

38. First neurone: Trigeminal ganglion. Their peripheral processes form the 3
divisions of the trigeminal nerve. Their central processes form the sensory
root of the nerve which relay in the main sensory nucleus.
Second neurone: The main sensory nucleus. From it, fibers cross the
midline to join the trigeminal lemniscus which ascends to the thalamus.
Third neurone: from the PMVN of thalamus to the postcentral gyrus.
Pathway of touch and pressure from the trigeminal
area:
Trigeminal pathways
Mohamed el fiky

39. Mohamed el fiky
Trigeminal pathways

40. Trochlear Nerve
❑ Its single somatic efferent nucleus lies in the tegmentum of the
midbrain at level of inferior colliculus. It innervates superior
oblique muscle of the eye ball.
❑ The nucleus receives the same afferents as those described for
abducent nerve nucleus.
❑ Exit from the midbrain: its fibers pass dorsally and decussate with
opposite one before emerging from the dorsal surface of midbrain
just below the inferior colliculus.
Mohamed el fiky

41. The oculomotor Nerve
The oculomotor nerve has two nuclei: motor and parasympathetic, both lie in the
tegmentum of the midbrain at level of superior colliculus.
❑ Motor nucleus:
▪ It is a somatic efferent nucleus, formed of several nuclei whose fibers supply
all extra-ocular muscles except lateral rectus and superior oblique.
▪ Its central connections are similar to those of abducent and trochlear nuclei.
❑ Parasympathetic nucleus called Edinger-Westphal nucleus,whose preganglionic
parasympathetic fibers pass in the oculomotor nerve, relay in the cilliary ganglion
to supply constrictor pupillae and cilliary muscles of the eye ball. It receieves
bilateral afferent fibers from the pretectal nucleus for execution of the light reflex.
Exit from the brain: oculomotor nerve passes ventrally to emerge from midbrain
medial to crus cerebri.
Mohamed el fiky

42. Mohamed el fiky

43. Mohamed el fiky