1. TRIGEMINAL NERVE
The trigeminal nerve, the largest cranial nerve (Fig 2.1), contains both
sensory and motor fibers. General somatic afferent fibers convey both
exteroceptive and proprioceptive impulses. Exteroceptive impulses of touch,
pain, and thermal senses are transmitted from the skin of the face and forehead
(Fig 2.2); mucous membranes of the nasal cavities, oral cavities, nasal sinuses,
and floor of the mouth; the teeth; the anterior two thirds of the tongue; and
extensive portions of the cranial dura. Proprioceptive impulses (deep pressure
and kinesthesis) are conveyed from the teeth, periodontium, hard palate, and
temporomandibular joint receptor. The nerve is also involved in conveying
afferent fibers from stretch receptors in the muscles of mastication. Special
visceral efferent fibers innervate the muscles, muscles of the eye, and facial
muscles. Afferent fibers constitute the sensory root (portio major), whereas the
efferent fibers form the smaller motor root (portio minor) (Fig 2.3).
The trigeminal nerve is attached to the lateral part of the pons by its two
roots, motor and sensory. The two roots enter the middle cranial fossa.
SENSORY ROOT OF THE TRIGEMINAL NERVE
The fibers of the sensory root of the trigeminal nerve arise from the
semilunar (gasserian) ganglion. They enter the brain stem through the side of
the pons.
1

2. The semilunar ganglion is developed from the neural crest. Like the
spinal ganglia it contains unipolar neurons. It is located in Meckel’s cavity.
The ganglion is crescent shaped. The ganglion, with its unipolar neurons,
forms central and peripheral processes.
The peripheral branches form the ophthalmic, maxillary, and
mandibular divisions of the nerve. The central branches are the sensory roots
of the trigeminal nerve. These central branches leave the semilunar ganglion
and pass back and enter the pons, where they divide into ascending and
descending fibers.
The ascending fibers terminate in the upper sensory nucleus in the pons
lateral to the motor nucleus. The upper nucleus is the sensory (main) nucleus
of the trigeminal nerve. These ascending fibers convey light touch, tactile
discrimination, sense of position, and passive movement.
The upper or main nucleus gives rise to the dorsal trigeminothalamic
tract. The sensory fibers of this tack ascend upward. Most fibers cross to the
opposite side and accompany the medial lemniscus to the thalamus.
The spinal (bulbospinal) nucleus of the trigeminal nerve gives rise to
the ventral trigeminothalamic tract. The spinal nucleus extends caudally from
the main sensory nucleus to the second cervical segment. The fibers of the
ventral trigeminothalamic tract cross to the opposite side and ascend to the
thalamus. They form a loosely arranged bundle in the medial leminscus. From
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3. the thalamus these fibers continue on to the cerebral cortex. These fibers
convey pain and temperature from the entire trigeminal area. (Table 2.1 for an
outline of sensory, motor, and sectretory nerve supply of certain head regions).
MOTOR ROOT OF THE TRIGEMINAL NERVE
The motor root (Fig. 2.4) of the trigeminal nerve consists of fibers that
have their origin in the motor nucleus located in the upper pons. These
filaments pass from the pons, along the medial side of the semilunar ganglion.
The motor root then passes below to the foramen ovale, through which it
passes to joint the mandibular division immediately below the base of the
skull. The nerve is chiefly motor, ad its fibers supply the muscles of
mastication. It is often called the masticator nerve.
MESENCEPHALIC ROOT OF THE TRIGEMINAL NERVE
The mesencephalic root consists of afferent fibers that accompany the
fibers of the motor root. Entering the pons from the peripheral distribution of
the mandibular division of the trigeminal nerve, these fibers ascend to the
mesencephalic nucleus of the trigeminal nerve. This nucleus serves as an
afferent station that receives proprioceptive impulses from the
temporomandibular joint, the periodontal membrane, the maxillary and
mandibular teeth, and the hard palate. The mesencephalic nucleus also
receives
3

4. Table 2.1: Outline of sensory, motor, and secretory nerve supply of certain
head regions.
Region Sensory nerves Secretory Motor nerves
Upper lip Superior labial fibers of
infraorbital nerve of V2
Buccal branches of
VII
Corner of mouth Superior labial fibers of
infraoral nerve of V2
Inferior labial fibers of
mental nerve of V3
Buccal and
mandibular branches
of VII
Lower lip Inferior labial fibers of
mental nerve
Mandibular branch of
VII
Cheek Long buccal nerve of V3 Buccal branches of
VII
Teeth
Maxillary Posterior superior alveolar
nerve of V2 to 6, 7, 8.
Middle superior alveolar
nerve of V2 to 4, 5 and
mesiobuccal root of 6.
Anterior superior alveolar
nerve of V2 to 1,2,3.
Mandibular Inferior alveolar nerve of
V3 to 1,2,3,4,5,6,7,8.
Gingivae Lateral side
Maxillary Posterior superior alveolar
nerve of V2
Superior labial nerve of
infraorbital nerve of V2
Palatal side
Greater palatine of V2
Nasopalatine of V2
Gingivae Lateral side
Mandibular Long buccal nerve of V3
Mental nerve of V3
Lingual side
Lingual nerve of V3
Mucus membrane
of maxillary
sainus
Anterior, middle, posterior
superior alveolar branches
of V2
Mucous glands via
sphenopalatine
ganglion
Greater superficial
petrosal nerve of VII
4

5. Table 2.1: Outline sensory, motor, and secretory nerve supply of certain head
regions – cont’d.
Region Sensory nerves Secretory Motor nerves
Hard palate Major portion greater
palatine V2
Premaxillary portion
nasopalatine V2
Mucous glands via
sphenopalatine
ganglion
Greater superficial
nerve of VII
Soft palate Middle palatine nerve of
V2 and palatine branches
of IX
Same as for hard
palate
Tensor palatine by V3
all others by cranial
part of XI
Pharynx Pharyngeal branches of V2
and IX
Pharyngeal branch of
sphenopalatine
ganglion and by
pharyngeal branches
IX and X from
pharyngeal plexus
Stylopharyngeal by
IX
All others by cranial
part of IX
Floor of mouth Sensory branches of
lingual nerve of V3
By submandibular
ganglion from VII via
chorda tympani
5

6. afferent impulses from stretch receptors in the muscles of mastication. These
fibers are concerned with perfect synchronization on controlling the biting
force of the jaws.
During mastication, proprioceptors in the muscles, tendons, periodontal
membrane, and joints send impulses through afferent fibers in the rigeminal
nerve that enter the brain stem, pass through the mesencephalic nucleus, and
synapse (first) in the main nucleus of the trigeminal nerve.
Secondary fibers cross the brain stem and ascend to the thalamus. The
secondary fibers constitute the dorsal trigeminothalamic fibers of the
bulbothalamic tract. They carry impulses of tactile perception from the
afferent fibers of the trigeminal nerve.
The third synapse occurs as these afferent fibers leave the thalamus and
proceed to the postcentral gyrus in the cortex (sensory).
These impulses permit awareness of motion in the jaws and the position
of the mandible and maxilla during chewing movements. Finally, some of the
proprioceptive impulses pass from the main sensory nucleus by means of the
secondary trigeminocerebellar fibers to the dentate and emboliform nuclei.
The cerebellium, in turn, conveys impulses to the motor cortex.
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7. DIVISIONS OF THE TRIGEMINAL NERVE
Three large nerves proceed from the convex border of the semilunar
ganglion: ophthalmic nerve, V1; maxillary nerve, V2; mandibular nerve, V3.
The ophthalmic nerve, or first division of the trigeminal nerve, is a
sensory nerve. It is the smallest of the three divisions, and passes forward and
enters the orbit through the superior orbital fissure.
The maxillary nerve, or second division of the trigeminal nerve, is a
sensory nerve. It begins at the middle of the semilunar ganglion and leaves the
skull through the foramen rotundum.
The mandibular nerve, the largest of the three divisions of the
trigeminal nerve, consists of two roots: a large sensory root arising from the
semilunar ganglion and a smaller motor root, which passes beneath the
ganglion to unite with the sensory root just after it emerges through the
foramen ovale.
Ophthalmic division
The ophthalmic division (Fig 2.5) is the smallest of the three branches
of the semilunar ganglion. It leaves the anterior medial part of the ganglion
and passes forward in the lateral wall of the cavernous sinus. Its fibers are
sensory, or afferent, from the scalp, the skin of the forehead, the upper eyelid
lining the frontal sinus, the conjuctiva of the eyeball, the lacrimal gland, and
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8. the skin of the lateral angle of the eye. It also transmits sensory impulses from
the sclera of the eyeball and the lining of the ethmoid cells. In the middle
cranial fossa, the nervus tentorii branches from the ophthalmic division to
supply the dura. The ophthalmic division also gives off communication
branches to the oculomotor, trochlear, and abducent cranial nerves.
As the ophthalmic division passes forward from the cavernous sinus, it
divides into three branches: lacrimal, frontal, and nasociliary nerves.
I. Lacrimal nerve
The lacrimal nerve is the smallest of the three branches. It passes into
the orbit at the lateral angle of the superior orbital fissure. It then courses in an
anterolateral direction to reach the lacrimal gland. Here it supplies sensory
fibers to the gland and adjacent conjuctiva.
In the orbit, postganglionic secretory fibers from the sphenopalatine
ganglion meet and travel along with he lacrimal nerve. These fibers are from
the zygomatic nerve.
II. Frontal nerve
The largest of the three branches, the frontal nerve, appears to be a
direct continuation of the ophthalmic division. It enters the orbit by way of the
superior orbital fissure. At about the middle of the orbit, the frontal nerve
divides into two branches: supraorbital and supratrochlear nerves.
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9. A. Supraorbital nerve
The supraorbital nerve is the largest branch of the frontal nerve. It
passes forward and leaves the orbit through the supraorbital foramen, or notch,
to supply the skin of the upper eyelid, the forehead, and the anterior scalp
region to the vertex of the skull.
B. Supratrochlear nerve
The smallest branch of the frontal nerve is the supratrochlear nerve. It
passes toward the upper medial angle of the orbit. Here it pierces the fascia of
the upper eyelid to supply the skin of the upper eyelid and lower medial
portion of the forehead.
III. Nasociliary nerve
The nasociliary nerve is the third main branch of the ophthalmic
division. It enters the orbit through the superior orbital fissure. Branches of the
nasociliary nerve are divided into those arising in the orbit, in the nasal cavity,
and on the face.
A. Branches in the orbit
1. Long Root Of The Ciliary Ganglion: The long, or sensory, root arises
from the nasociliary nerve. It contains sensory fibers, which pass
through the ganglion without synapsing and continue on to the eyeball
by means of the short ciliary nerves.
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10. 2. Long Ciliary Nerves: There are usually two or three long ciliary nerves
branching from the nasociliary nerve. They are distributed to the iris
and cornea.
In addition, the long ciliary nerves contain postganglionic fibers, from
the superior cervical sympathetic ganglion.
3. Posterior Ethmoid Nerve: The posterior ethmoid nerve enters the
posterior ethmoid canal to be distributed to the mucous membrane
lining the posterior ethmoidal cells and the sphenoid sinus.
4. Anterior Ethmoid Nerve: The nasociliary nerve continues anteriorly
along the medial wall of the orbit. In its course, the anterior ethmoid
nerve gives off filaments that supply the mucous membrane of the
anterior ethmoid cells and frontal sinus. In the upper part of the nasal
cavity, the ethmoid nerve divides into two sets of anterior nasal
branches, the internal and external nasal branches.
a. Internal nasal branches: The internal nasal branches, in turn,
divide in the upper anterior part of the nasal cavity into two divisions.
(1) Medial or Septal Branches: These branches travel
downward to supply sensory innervation to the mucous membrane of that
area.
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11. (2) Lateral Branches: These branches gives off twigs to the
mucous membrane of the anterior ends of the superior and middle nasal
conchae and to the anterior lateral nasal wall.
b. External nasal branches: At the end border between the lower
edge of the nasal bone and the upper edge of the lateral nasal cartilage, the
external nasal branch passes externally to supply the skin over the tip of the
nose and the skin over the ala of the nose.
B. Branches arising in the nasal cavity
The branches of the nasociliary nerve that arise in the nasal cavity
supply the mucous membrane lining the cavity.
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12. C. Terminal branches of the ophthalmic division on the face
These terminal branches course below the trochlear nerve to supply
sensory fibers to the skin of the medial parts of both eyelids, the lacrimal sac,
and the lacrimal caruncle. These terminal fibers supply the skin over the side
of the bridge of the nose.
IV. Autonomic ganglion associated with the ophthalmic division of the
trigeminal nerve.
These terminal branches course below the trochlear nerve to supply
sensory fibers to the skin of the medial parts of the both eyelids, the lacrimal
sac, and the lacrimal caruncle. These terminal fibers supply the skin over the
side of the bridge of the nose.
A. Motor or Short (preganglionic, parasympathetic) Root
These motor fibers arise from cells in the nucleus of Edinger-Westphal.
The oculomotor nucleus lies in the gray substance in the mesencephalon. The
axons of the autonomic nucleus course with the fibers of the oculomotor nerve
to the ciliary ganglion. They are the visceral efferent bundle that carries
preganglionic fibers to the ciliary ganglion.
In the ganglion, the preganglionic fibers synapse with postganglionic
fibers whose neurons form the short ciliary nerves that innervate the sphincter
pupillae and ciliary muscles of the iris.
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13. B. Sensory or long (postganglionic, sympathetic) root
The sensory fibers of the ciliary ganglion are derived from the
nasociliary nerve of the trigeminal nerve. This root also carries many
postganglionic fibers from cell bodies of the superior cervical sympathetic
ganglion. They join the nasociliary nerve. They pass through the ganglion
without synapse to innervate the radial fibers of the dilator pupillae muscle in
the iris.
C. Sympathetic root
As already mentioned, the sympathetic fibers may come from the
sensory root of the nasociliary nerve or direcly from the internal carotid
plexus. Short ciliary nerves emerge from the anterior border of the ciliary
ganglion and continue on to the posterior surface of the eyeball. Fibers of the
short ciliary nerves contain sensory, parasympathetic, and sympathetic fibers.
They run in theinner surface of the sclera toward the iris. The postganglionic
fibers of the parasympathetic group innervate the circular, or sphincter, muscle
fibers of the iris, which causes the pupil to constrict. They also innervate the
ciliary muscle, which changes the convexity of the crystalline lens.
Postganglionic fibers of the sympathetic group pass to the radial fibers of the
dilator pupillae muscle in the iris, which causes the pupil to dilate. The sensory
fibers are afferent from all parts of the eyeball and the conjunctiva.
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14. Maxillary division
The maxillary division of the trigeminal nerve (Fig 2.6) is entirely
sensory in function. The maxillary nerve originates at the middle of the
semilunar ganglion and continues forward in the lower part of the cavernous
sinus. It then passes to the foramen rotundum, through which it leaves the
cranial fossa and enters the pterygopalatine fossa. It enters the inferior orbital
fissure to pass into the orbital cavity. Here it turns laterally in a groove on the
orbital surface of the maxilla, called the infraorbital groove. Continuing
forward, the second division emerges on the anterior surface of the maxilla
through the infraorbital foramen, where it divides.
The maxillary division of the trigeminal nerve transmits sensory
(afferent) impulses from the lower eyelid, the side of the nose, and the upper
lip. It is sensory to all maxillary teeth and their gingivae, the mucous
membrane of most of the nasal cavity, the hard and soft palate regions, part of
the tonsillar region, and form the region of the pharynx near the opening of the
auditory (Eustachian) tube. In addition, afferent fibers arising in the mucous
membrane lining the maxillary sinus transmit sensory impulses by this
division of the fifth cranial nerve.
In its course from the semilunar ganglion, the maxillary division gives
off branches in four regions: in the middle cranial fossa, in the pterygopalatine
fossa, in the infraorbital groove and canal, and on the face (terminal branches).
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15. I. Branches given off in the middle cranial fossa
In the middle cranial fossa a small branch, the middle meningeal nerve,
passes with the middle meningeal artey and its branches to supply the dura
with sensory fibers
II. Branches in the pterygopalatine fossa
A. Zygomatic nerve
The zygomatic nerve leaves the second division in the pterygopalatine
fossa and passes anteriorly and laterally through the inferior orbital fissure into
the orbit. Here it divides into two parts: zygomaticofacial nerve and
zygomaticotermporal nerve.
1. Zygomaticofacial Nerve: The zygomaticofacial nerve passes forward on
the lateral orbital foramen. The nerve pierces the orbicularis oculi
muscle and supplies sensory fibers on the skin over the prominence of
the zygomatic bone.
2. Zygomaticotemporal Nerve: The zygomaticotemporal nerve leaves the
orbit between the great wing of the sphenoid and the zygomatic bone to
enter the temporal fossa. It supplies sensory fibers to the skin over the
anterior temporal fossa region.
B. Pterygopalatine (spehnopalatine) nerves
15

16. The pterygopalatine nerves are two short nerve trunks that unite at the
pterygopalatine ganglion and are then redistributed into several branches. since
a great majority of the fibers in the trunks are trigeminal somatic afferent
fibers, which merely pass beside or through the ganglion without synapsing,
the branches are listed here as belonging to the maxillary nerve rather than the
pterygopalatine ganglion.
The pterygopalatine nerves also serve as important functional
communications between the ganglion and the maxillary nerve. Postganglionic
secretomotor fibers from the pterygopalatine ganglion pass by means of these
nerves back along the maxillary nerve to the zygomatic nerve, through which
they are routed to the lacrimal nerve and the lacrimal gland.
Table 2.2: Distribution of branches of the spnenopalatine ganglion.
Secretory to Sensory from
Lacrimal gland
Mucous glands of nasal region via
nasopalatine and posterior superior
lateral nasal nerves.
Mucous glands of hard palate region
by nasopalatine and greater palatine
nerves.
Mucous glands of soft palate region
by middle palatine nerve; also
branches from pharyngeal plexus of
IX and X.
Mucous membrane of pharynx by
pharyngeal branch; also by IX and
X.
Lacrimal gland, VI; lacrimal nerve
Nasal mucosa, V2 nasopalatine and
posterior superior lateral nasal
branches.
Mucosa of hard palate by nasopalatine
and greater palatine branches of
V2.
Mucosa of soft palate by middle
palatine branch of V2; also
branches of pharyngeal plexus by
IX and X.
Mucous membrane of pharynx by
pharyngeal branch; also by IX and
X.
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17. The branches of distribution of the pterygopalatine nerves are divided
into three groups: orbital, nasal, and palatine.
1. Orbital Branches: Two or three lines filaments enter the orbit by
means of the inferior orbital fissure and supply the periosteum of the orbit
and the mucous membrane of part of the posterior ethmoid cells and the
sphenoid sinus.
2. Nasal Branches: In the nasal cavity, the branches divide into the
posterior superior lateral branches and the medial or septal branch.
a. Posterior superior lateral nasal branches: These branches
transmit sensory impulses from the mucous membrane of the nasal
septum and posterior ethmoid cells.
b. Medial or septal branch: This branch passes downward and
forward. It transmits sensory impulses from the mucous membrane over
the vorner. It then descends in the incisal canal and ramifies in the
mucous membrane of the premaxillary region of the hard palate.
3. Palatine Branches: The palatine branches descend in the
pterygopalatine canal, where the fibers usually divide into three stands:
greater or anterior palatine, middle palatine, and posterior palatine.
a. Greater of anterior palatine nerve: This nerve emerges on the
hard palate by passing through the greater palatine foramen and courses
17

18. in an anterior direction between the osseous hard palate and the
mucoperiosteum to supply the major part of the hard palate and the
palatine gingivae.
It breaks up into numerous branches in its course and finally
extends as far forward as the premaxillary palatine mucosa, which is also
supplied by terminal branches of the nasopalatine nerve.
b. Middle palatine nerve: This nerve emerges from the lesser
palatine foramen. Its fibers are sensory to the mucous membrane of the
soft palate.
c. Posterior palatine fibers: These nerve fibers, emerging from the
lesser palatine foramen, go to the mucous membrane of the tonsiller area
as part of the sensory supply to the tonsil itself.
C. Posterior superior alveolar braches
Two or three branches leave the maxillary division just before it enters
the inferior orbital fissure. They pass downward and continue on the posterior
surface of the maxilla. An internal branch of the posterior superior alveolar
nerve goes along with a branch of the internal maxillary artery through the
posterior superior alveolar canal, which opens on the posterior surface of the
maxilla.
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19. In those bone, the nerve passes down the posterior or posterolateral wall
of the maxillary sinus, giving off sensory fibers to the mucous membrane of
the sinus. It then supplies the maxillary molars and their gingivae. Within the
depths of the alveoli, or tooth sockets, some nerve filaments pass to supply the
periodontal membranes; whereas others, the pulpal fibers, pass through the
apical foramina of the roots of the molar teeth to supply the dental pulps.
D. Branches in the infraorbital groove and canal
The nerve in the infraorbital groove and canal becomes known as the
infraorbital nerve. From this groove serval fibers leave the infraorbital nerve
and descend.
1. Middle Superior Alveolar Nerve: The middle superior alveolar nerve
branches within the mucous membrane of the maxillary sinus to join with
other alveolar nerves in forming the superior dental plexus of nerves. In some
cases the middle superior alveolar nerve leaves the infraorbital nerve in the
posterior part of the floor of the infraorbital canal and passes in a downward
and anterior direction toward the apices of the maxillary bicuspids. In other
cases the middle superior alveolar nerve leaves the main trunk in the floor of
the infraorbital canal near the infraorbital foramen and passes downward in the
anterior or anterolateral wall of the sinus. Some authorities claim that the
middle superior alveolar nerve may be missing and that the maxillary
bicuspids receive their sensory innervation from the superior dental plexus.
19

20. Whether the maxillary bicuspids can be anesthetized by the infraorbital
injection or by the posterior superior alveolar injection depends on the point
where the middle superior alveolar nerve leaves the infraorbital nerve. In some
cases infiltration anesthesia about the maxillary bicuspids may be necessary.
2. Anterior Superior Alveolar Nerve: The anterior superior alveolar nerve
descends from the infraorbital nerve just inside the infraorbital foramen in the
anterior part of the infraorbital canal. The anterior superior alveolar nerves
descend in fine canals in the maxilla to pass to the roots of the maxillary
central and lateral incisors and cuspid teeth. They also send connecting fibers
to the superior dental plexus of nerves within the maxilla. Fibers of the
anterior superior alveolar nerves also supply sensory innervation to the
mucous membrane of the anterior part of the maxillary sinus as well as the
labial gingivae of the incisors and cuspid teeth.
E. Terminal branches of the maxillary division on the face
As the infraorbital nerve is about to emerge from the infraorbital
foramen on the front of the maxilla, it divides into three terminal nerve
branches: the inferior palpebral, external or lateral nasal, and superior labial
branches.
20

21. 1. Inferior Palperbral Branches: Usually two or three in number, the
branches pass upward and supply sensory fibers to the skin of the lower
eyelid and its conjunctiva.
2. External or Lateral Nasal Branches: The external or lateral nasal
branches pass to the skin of the side of the nose.
3. Superior Labial Branches: Usually three or more in number, the
branches are distributed to the skin and mucous membrane of the upper lip.
III. Automic ganglion associated with the maxillary division of the
trigeminal nerve
A. Sphenopalatine ganglion
The sphenopalatine ganglion is associated with the great superficial
petrosal nerve. It is a part of the seventh cranial nerve and is a parasympathetic
ganglion relaying chiefly secretomotor impulses from the nerve (Fig. 2.7). It
contains cell bodies of afferent taste fibers. The ganglion is stellate and lies
deep in the pterygopalatine fossa, suspended from the maxillary division of the
trigeminal nerve by two roots.
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22. Fibers of the great superficial petrosal nerve arise in the central nucleus,
which is called the superior salivatory nucleus. Form this nucleus, fibers pass
laterally and caudally and are joined by sensory fibers of the facial nerve to
form the intermediate nerve.
The facial nerve and the intermediate nerve cross the petrous part of the
temporal bone and traverse the facial canal. The canal curves, and at its sharp
curve, or genu, the intermediate nerve expands and becomes the geniculate
ganglion. From this ganglion preganglionic parasympathetic fibers leave as the
greater superficial petrosal nerve passes from the hiatus of the facial canal on
the anterior slope of the petrous portion to enter the middle cranial fossa. It
then passes anteriorly and medially beneath the semilunar ganglion of the
trigeminal nerve and passes through the foramen lacerum. At the lower end of
this foramen the greater superficial petrosal nerve is joined by the deep
petrosal nerve. The deep petrosal nerve is superficial petrosal and the deep
petrosal nerves are then called the nerve of the pterygoid canal, or vidian
nerve.
The vidian nerve passes through the pterygoid canal, to enter the
pterygopalatine fossa, to enter the sphenopalatine ganglion. This ganglion
hangs suspended from the maxillary nerve by two roots (pterygopalatine
neves). They contain sensory fibers from the maxillary nerve and do not
22

23. synapse within the ganglion. They continue on their way to the mucous
membrane of the nasal cavity and palate.
The pterygopalatine nerve trunks are communications for the pterygopalatine
ganglion, since they are traversed by postganglionic fibers on their wayto the
maxillary nerve, which continue on their way to the mucous membrane of the
nasal cavity and palate.
The pterygopalatine nerve trunks are communications for the
pterygopalatine ganglion, since they are traversed by postganglionic fibers on
their way to the maxillary nerve, which continue to the lacrimal gland and
other glands of the nasal cavity and palate.
The sensory fibers pass through the ganglion, whereas the
parasympathetic fibers synapse in the ganglion.
1. Branches From The Sphenopalatine (Pterygopalatine)
Ganglion
a. Orbital branches: Orbital branches are made up of afferent fibers and
convey sensory or afferent impulses from the periosteum of the orbit.
Others supply the mucous membrane of the posterior ethmoid cells and the
sphenoid sinus.
b. Nasal branches: These nerves are divided into two groups: posterior
superior lateral nerves and nasopalatine (long sphenopalatine) nerve.
23

24. (1) Posterior Superior Lateral Nerves: These nerves innervate the
mucosa over the posterior parts of the nasal conchae.
(2) Nasopalatine (Long Sphenopalatine) Nerve: The nasopalatine
nerve (Fig. 2.8) passes downward and forward between the periosteum
and the mucous membrane in the region of the vomer bone and, as it
continues downward and forward, reaches the floor of the nasal cavity. It
then descends in the incisal canal to appear in the anterior part of the hard
palate and supply the mucous membrane of the premaxilla.
c. Palatine branches (Fig. 2.9): From the sphenopalatine ganglion the
palatine branches descend in the pterygopalatine fossa and the
24

25. pterygopalatine canal. In the canal the palatine branches separate into these
strands: greater (anterior) palatine, middle palatine, and posterior palatine.
(1) Greater or Anterior Palatine Nerve: This nerve emerges from the
greater palatine foramen in the region of the lateral margin of the palatine
bone and medial to the upper third molar. It then continues forward and
splits into numerous branches between the osseous roof of the oral cavity
and the mucoperiosteum. It carries sensory and secretory fibers to the
major part of the mucous membrane of the hard palate and palatal
gingivae. Its anterior terminal fibers extend forward as far as the
premaxillary palatine mucosa.
(2) Middle Palatine Nerve: This nerve emerges from a small
foramen in the medial aspect of the pyramidal part of the palatine bone to
supply sensory and secretory fibers to the mucosa membrane of the soft
palate.
(3) Posterior Palatine Nerve: This nerve usually emerges from a
lesser foramen posterior and slightly lateral to the middle palatine nerve.
The fibers of the posterior palatine nerve convey sensory and secretory
fibers to the mucous membrane in the tonsillar area.
25

26. d. Pharyngeal branch: This branch conveys sensory and secretory fibers
to the mucous membrane of the nasopharynx about the opening of the
auditory tube.
e. Secretory fibers to the lacrimal gland: Preganglionic parasympathetic
fibers arising in the lacrimal nucleus pass to the geniculate ganglion and
then to the sphenopalatine ganglion. The sympathetic postganglionic fibers
from the deep petrosal nerve continue on through the ganglion.
From the sphenopalatine ganglion, the parasympathetic and the
sympathetic fibers pass back to the maxillary nerve and enter the zygomatic
nerve. They leave the zygomatic nerve in the orbit, join the lacrimal nerve, and
then go to the lacrimal gland to control its secretion.
Mandibular division
The mandibular division of the trigeminal nerve (Fig. 2.10) is the
largest of the three divisions. It is formed by the union of the large sensory
(afferent) bundle of fibers and a small motor (efferent) bundle of fibers.
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27. The sensory (afferent) root fibers are peripheral extensions of unipolar
cells located in the semilunar ganglion. The motor (efferent) root ribers are
derived from motor cells located in the medulla oblongata. These fibers
become incorporated with the sensory fibers in the mandibular trunk. The
large sensory root arises from the semilunar ganglion. Its fibers are distributed
to the dura, skin, and mucous membrane of the chin, cheek, and lower lip; the
external ear region; parotid gland; temporomandibular articulation; the scalp
over the region of the temporal bone; to the lower teeth and their gingivae; and
to the anterior two thirds of the tongue. The motor root innervates the muscles
of mastication. It supplies the temporal, internal and external pterygoid,
masseter, and mylohyoid muscles and the anterior belly to the diastric
muscles. Some of its fibers innervate the tensor veli palatini and the tensor
tympari muscles.
The motor root is located in the middle cranial fossa. It joins the
sensory root after the latter leaves the semilunar ganglion. The two roots pass
side by side in the dura of the middle cranial fossa to the foramen ovale.
Leaving the foramen ovale, the two roots unite to form a short single trunk.
The branches of the mandibular division may be divided into two
groups: branches from the undivided nerve and branches from the divided
nerve.
I. Branches from the undivided nerve
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28. A. Nervus spinosus
The nervus spinosus arises outside the skull and then passes into the
middle cranial fossa to supply the dura and the mastoid cells.
B. Nerve to internal pterygoid muscle.
A branch of the motor root passes to innervate the internal pterygoid
muscle. This branch passes without interruption to innervate the tensor veli
palatini and the tensor tympani muscles.
II. Branches from the divided nerve
Below the level of the undivided part of the mandibular division, the
trunk separates into two parts: anterior and posterior divisions.
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29. A. Anterior divsion
The anterior division is smaller then the posterior division. It receives
sensory and motor fibers that supply the muscles of mastication, the skin and
mucous membrane of the cheek, and the buccal gingivae and lower molars. It
passes downward and forward, where it divides:
1. Branch to external pterygoid muscle
2. Branch to masseter muscle
3. Branches to temporal muscles
a. Anterior deep temporal nerve
b. Posterior deep temporal nerve
4. Buccal (long buccal) nerve
1. Pterygoid nerve
The pterygoid nerve enters the medial side of the external pterygoid
muscle to provide its motor nerve supply.
2. Massetter nerve
The massetter nerve passes above the external pterygoid to traverse the
mandibular notch and enter the deep side of the massetter muscle.
3. Nerves to the Temporal Muscle
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30. a. Anterior deep temporal nerve: This nerve passes upward and crosses
the infratemporal crest of the sphenoid bone. It ends in the deep part of
the anterior portion of the temporal muscle.
b. Posterior deep temporal nerve: This nerve passes upward to the deep
part of the temporal muscle.
4. Buccal Nerve
Usually the buccal nerve passes downward, anteriorly and laterally
between the two heads of the external pterygoid muscle. At about the level of
the occlusal plane of the mandibular second and third molars, it divides several
branches that ramify on the buccinator muscle. It then sends fibers to the
mucous membrane of the cheek region. Other fibers distribute sensory
innervation to the skin of the cheek. These fibers are purely sensory. Still other
sensory fibers to the buccal gingivae about the mandibular molars and the
mucous membrane of the lower part of the buccal vestibule. The buccal nerve
occasionally contributes to the nerve supply of the second bicuspid and the
first molar of the lower jaw. Almost the entire mucosa of the cheek is supplied
by the buccal nerve.
B. Posterior division
The larger posterior division is mainly sensory but also carries some
motor components. This division extends downward and medially and then
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31. branches into the auriculotemporal, the lingual, and the inferior alveolar
nerves.
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32. 1. Auriculotemporal Nerve
The auriculotemporal nerve arises by a medial and a lateral root. These
roots embrace the middle meningeal artery and unite behind the artery just
below the foramen spinosum. The united nerve passes posteriorly, deep to the
external pterygoid muscle, and then between the sphenomandibular ligament
and the neck of the condyle of the mandible. It traverses the upper deep part of
the parotid gland or its fascia and then crosses the posterior root of the
zygomatic arch. It passes with the superficial temporal artery in its upward
course and divides into numerous branches, to the tragus of the pinna of the
external ear, to the scalp about the ear, and as far upward as the vertex of the
skull.
a. Communications of the auriculotemporal nerve
(1) Two roots of the nerve: Each root receives communicating fibers from
the otic ganglion. These fibers are postganglionic, parasympathetic
secretory fibers that have come from the glossopharyngeal nerve by
way of the lesser superficial petrosal nerve. They control secretion of
the parotid gland.
(2) Communicating branches to the facial nerve: These fibers are purely
sensory from the auriculotemporal nerve.
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33. c. Branches of the auriculotemporal nerve: The auriculotemporal nerve
divides into parotid, articular, auricular, meatal, and terminal branches.
(1) Parotid branches: As the auriculotemporal nerve passes the
parotid gland, it gives off sensory, secretory, and vasomotor fibers to
the gland. The secretory fibers have passed as postganglionic
parasympathetic fibers to the gland. The vasomotor sympathetic
postganglionic fibers have accomplished the parasympathetic fibers to
the gland.
(2) Articular branches: One or two twigs of sensory fibers pass from
the auriculotemporal nerve and enter the posterior part of the
temporomandibular joint.
(3) Auricular branches: The anterior auricular branches are usually
two in number. They are sensory fibers supplying the skin of the helix
and tragus.
(4) Meatal branches: Two small branches usually supply the skin
lining the meatus and the tympanic membrane.
(5) Terminal branches: The major part of the filaments of the
auriculotemporal nerve pass to supply the scalp over the temporal
region.
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34. 2. Lingual Nerve
The lingual nerve is the smaller of the two terminal branches of the
posterior division of the mandibular nerve. At first it passes medially to the
external pterygoid muscle and, as it descends, lies between the internal
pterygoid muscle and the ramus of the mandible in the pterygomandibular
space. It gives off small branches to the interior alveolar nerve that pass as
sensory fibers to part of the tonsil and mucous membrane of the posterior part
of the oval cavity.
In the pterygomandibular space the lingual nerve lies parallel to the
inferior alveolar nerve but medial and anterior to it. It then passes deep to
reach side of the base of the tongue. At the side of the tongue it lies below the
lateral lingual sulcus.
In the lateral lingual sulcus it is separated from the tongue by the
alveololingual groove. As it passes forward, it loops downward and medially
beneath the submandibular duct.
The lingual nerve contributes many sensory fibers to the mucous
membrane of the floor of the mouth and gingiva on the lingual surface of the
mandible. It occasionally supplies sensory fibers to the bicuspids and first
molar teeth.
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35. a. Communications of the lingual nerve with the chorda tympani branch of the
facial nerve: As the lingual nerve passes medially to the external pterygoid
muscle, it is jointed from behind by the chorda tympani nerve. This nerve
conveys secretory fibers from the facial nerve. The parasympathetic secretory
fibers control the submandibular and sublingual salivary glands. The secretory
fibers of the chorda tympani nerve fibers to the submandibular ganglion,
where they synapse. The secretory nerve fibers to the sublingual gland join in
a small branch from the submandibular ganglion to rejoin the lingual nerve
and pass with this nerve to the sublingual gland.
3. Inferior alveolar nerve
The inferior alveolar nerve is the largest of the branches of the posterior
division of the mandibular part of the trigeminal nerve. It passes downward on
the medial side of the external pteryoid muscle and the medial side of the
mandibular ramus. On the medial side of the ramus in the pterygomandibular
space, it enters the mandibular foramen. Within the mandible the inferior
alveolar nerve descends in the inferior alveolar canal and is distributed
throughout the body of the mandible. In the inferior alveolar canal it gives off
branches to the mandibular teeth as apical fibers that enter the apical foramina
of the lower teeth to supply the dental pulps. Some of the fibers are distributed
to the periodontal membrane of the various lower teeth.
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36. Before the inferior alveolar nerve enters the mandibular foramen it
gives off a branch, the mylohyoid branch, which contains sensory and motor
fibers. The mylohyoid nerve continues downward and forward in the
mylohyoid groove. It passes forward below the mylohyoid muscle, to which it
sends motor fibers, and it supplies motor fibers to the anterior belly of the
digastric muscle. There is some claim that a twig of sensory fibers of the
mylohyoid nerve may enter the mandible in the area of the chin to aid in the
sensory nerve supply to the mandibular incisors.
III. Autonomic ganglia associated with the mandibular division of the
trigeminal nerve.
Two ganglia are associated with the mandibular division (Fig. 2.10):
submandibular and otic ganglia.
A. Submandibular (Submaxillary) ganglion
The submandibular ganglion is a small ovoid body that is suspended
from the lingual nerve above the submandibular salivary gland. It is suspended
by two nerves from the lingual nerve. These parasympathetic fibers are
preganglionic, having their origins in the superior salivatory nucleus in the
medulla. They course within the intermediate nerve and in the facial canal and
group together to form the chorda tympani nerve. The chorda tympani nerve
continues down and forward to join the lingual nerve and passes with it to the
submandibular ganglion.
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37. The preganglionic parasympathetic fibers enter the ganglion, and there
they synapse. Most of the postganglionic parasympathetic fibers are short.
They supply secretory fibers to the submandibular gland. Other
parasympathetic fibers turn upward to rejoin the lingual nerve and pass with it
to the sublingual gland. The submandibular ganglion also receives
postganglionic sympathetic fibers from the plexus on the external maxillary
artery.
B. Otic ganglion
The otic ganglion is a flattened ovoid body located on the medial side
of the undivided mandibular division of the trigeminal nerve. It is below the
foramen ovale and in front of the middle meningeal artery. It has two main
roots: parasympathetic and sympathetic.
1. Parasympathetic Preganglionic (Secretory) Fibers: These parasympathetic
fibers arise in the inferior salivatory nucleus. This group of cells lies in the
floor of the fourth ventricle in the medulla. The efferent fibers pass by way to
the glossopharyngeal nerve through the jugular canal. Immediately below the
canal, they leave the nerve at its petrosal ganglion in the tympanic nerve
(Jacobson’s nerve) to pass into the middle ear region. The lesser superficial
petrosal nerve emerges from the tympanic plexus. Then it passes on the upper
surface of the petrous part to the foramen ovale. The lesser superficial petrosal
nerve is the parasympathetic root of the otic ganglion. In the otic ganglion the
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38. postganglionic fibers join the auriculotemporal nerve and with it go to the
parotid gland.
2. Sympathetic Root: The sympathetic root is made up of post ganglionic fibers
that have originated in the superior cervical sympathetic ganglion and the
plexus on the middle meningeal artery. These sympathetic fibers pass
uninterruptedly through the otic ganglion. With the postganlionic
parasympathetic fibers, they join the auriculotemporal nerve and, with its
glandular branches, continue to the parotid gland.
Afferent, or sensory, fibers from the parotid gland pass by way of the
auriculotemporal nerve.
Summary of Functions of the Trigeminal (Fifth Cranial) Nerve
A. Ophthalmic division
1. Supratrochlear nerve – Sensory from the medial part of the upper
eyelid and the lower medial part of the forehead; sensory from the
conjuctive of the upper eyelid.
2. Supraorbital nerve – Sensory from the skin of the upper eyelid
and the skin of the forehead and scalp as far back as the vertex of the
skull; sensory from the lining of the frontal sinus.
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39. 3. Lacrimal nerve – Sensory from the skin of the upper eyelid and
lateral part of the eyebrow region; sensory from the conjunctiva of the
lateral part of the upper eyelid.
4. Nasociliary nerve
a. Long ciliary branch – Sensory from the eyeball and
ciliary ganglion.
b. Infratrochlear nerve – Sensory from the upper and lower
eyelids and from the side of the nose; sensory from the conjunctiva
and the lacrimal sac.
c. Ethmoid branches
(1) Anterior ethmoid branch – Sensory from the lining of the frontal
sinus and of the anterior ethmoid cells.
(2) Posterior ethmoid branches – Sensory from the lining of the
posterior ethmoid cells and the sphenoid sinus.
d. Internal branches – Sensory from the anterior portion of
the septum and lateral walls of the nasal cavity.
e. External nasal branch – Sensory from the tip of the
nose.
B. Maxillary division – Middle meningeal branch
39

40. 1. In the cranial cavity the maxillary division sends a
sensory branch to the dura.
2. In the pterygopalatine fossa he maxillary division gives
off two branches.
a. Zygomatic nerve and branches.
(1) Zygomaticofacial branch – Sensory from the skin over the
zygomatic bone.
(2) Zygomaticotemporal branch – Sensory from the skin of the side
of the forehead and of the anterior part of the temporal region.
b. Sphenopalatine nerves (pterygopalatine).
(1) Orbital branches – Sensory from the periosteum of the orbit and
from the lining of the sphenoid sinus and posterior ethmoid
cells.
(2) Greater palatine branch (anterior palatine) – Sensory from the
mucous membrane of the major part of the hard palate and
adjacent part of the soft palate.
(3) Lesser palatine branches – Sensory from the mucous membrane
of the soft palate and tonsil area.
(4) Posterior lateral nasal branches – Sensory over the nasal
conchae.
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41. (5) Nasopalatine branches – Sensory from the mucous membrane of
the lower and posterior part of the nasal septum and from the
premaxillary part of the hard palate.
(6) Pharyngeal branch – Sensory from the mucous membrane of the
nasopharynx and the area behind the auditory tube.
c. Posterior superior alveolar nerve.
(1) Gingival branches- Sensory from the buccal gingiva of the upper
molar region and from the mucous membrane of part of the
cheek.
(2) Alveolar branches – Sensory from the maxillary molars, except
the mesiobuccal root of the upper first molar and their gingivae,
and from the mucous membrane of the maxillary sinus.
(3) In the infraorbital canal region.
a) Middle superior alveolar nerve – Sensory from the
maxillary bicuspids and the mesiobuccal root of the first
molar; sensory from the lining of the maxillary sinsu.
b) Anterior superior alveolar nerve – Sensory from the
maxillary incisors and cuspid and from the lining of the
maxillary sinus.
(4) Terminal branches on the face (infraorbital branches).
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42. a) Inferior palpebral branches – Sensory from the skin of the
lower eyelid.
b) Lateral nasal branches – Sensory from the skin of the side
of the nose.
c) Superior labial branches – Sensory from the skin of the
upper lip.
C. Mandibular division
1. Nervus tentorii – Sensory from the dura of the
posterior cranial fossa and from the lining of the mastoid cells.
2. Buccal (long buccal) nerve – Sensory from the
mucous membrane and the skin of the cheek region; sensory from buccal
gingavae of the mandibular molar region.
3. Auriculotemporal nerve.
a. Sensory from the skin over the areas
supplied by the branches of the facial (VII) nerve, that is, zygomatic,
buccal, and mandibular areas.
b. Sensory from the perotid gland by means of
the parotid branch.
c. Sensory from the temporomandibular
articulation.
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43. d. Sensory from the skin lining the external
auditory meatus and from the lateral surface of the tympanic membrane.
e. Sensory from the skin and scalp over the
upper part of the external ear and the side of the head up to the vertex of
the skull.
4. Lingual nerve – Sensory from the mucous
membrane covering the anterior two thirds of the tongue; sensory from the
mucous membrane of the floor of the mouth and of the lingual side of the
mandibular gingivae; sensory from the submandibular and sublingual
glands and their ducts.
The lingual nerve conveys special sense of the taste from the anterior
two thirds of the tongue. It also contains secretomotor fibers to the
submandibular and sublingual salivary glands and the mucous glands in the
floor of the mouth.
5. Inferior alveolar nerve.
a. Dental branches – Sensory from all of the
lower molar and bicuspid (mandibular) teeth and their periodontal
membranes.
43

44. b. Mental nerve – Sensory from the skin of the
lower lip and chin regions and from the mucous membrane lining of the
lower lip region.
c. Incisive nerve – Sensory from incisors,
cuspid teeth, and their periodontal membranes.
The trigeminal nerve has a distinct motor root that conveys efferent
fibers to muscles derived from the first branchial arch. The motor fibers join
with fibers of the mandibular and pass as:
1. Internal pterygoid nerve – Innervates the internal
pterygoid muscle, the tensor veli palatini muscle, and the tensor tympani
muscle.
2. Masseter nerve – Innervates the masseter muscle.
3. Deep temporal branches – Pass as the anterior and
posterior deep temporal branches to the temporal muscle.
4. External pterygoid nerve – Supplies the external
pterygoid muscle.
5. Mylohyoid nerve – Innervates the mylohyoid and the
anterior belly of the digastric muscles.
In passing from the neck to head the somatic sensory functions of the
cervical nerves are taken over by the trigeminal nerve.
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45. The central processes of the previously mentioned branches of the
nerve send their impulses of pain and temperature backward and downward
through the lateral part of the pons, forming the spinal tract of the trigeminal
nerve.
Those impulses subserving tactile sensibilities of the trigeminal nerve
pass to the semilunar ganglion and then into the main nucleus of the trigeminal
nerve located in the pons.
45