The trigeminal nerve Flashcards
The trigeminal is the … cranial nerve
Vth or 5th
Describe the trigeminal nerve. Which fibres does it contain?
The trigeminal nerve is the largest cranial nerve and contains both sensory and motor fibers
The trigeminal nerve receives 3 large sensory nerve, namely :
▪ upper(ophthalmic n.)
▪ middle (maxillary n.)
▪ lower (mandibular n.) (+motor)
Name the 4 nuclei of the trigeminal nerve.
- Main sensory nucleus
- Spinal nucleus
- Mesencephalic nucleus
- Motor nucleus
Where does the main sensory nucleus lie?
In the posterior part of pons lateral
to the motor nucleus
What is the spinal nucleus continuous with superiorly?
The spinal nucleus is 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
What is the mesencephalic nucleus composed of?
The mesencephalic nucleus is composed of unipolar cells situated in lateral part of gray matter around cerebral aqueduct and it extends inferiorly into pons as far as the main sensory nucleus
Where is the motor nucleus situated?
In the pons medial to the main sensory nucleus
The course of the trigeminal nerve(from the pons) :
❑Trigeminal nerve leaves
anterior aspect of pons as a
small motor root and a large
sensory root
❑Each root is ensheathed in
pia-arachnoid
❑It passes forward out of posterior cranial fossa and rests on apex of petrous bone in middle cranial fossa here sensory root expands to form trigeminal ganglion
❑Ophthalmic, maxillary, and
mandibular nerves arise from
the anterior border of ganglion
Course of the trigeminal nerve(from the skull) :
❑Ophthalmic nerve (V1) contains only sensory fibers leaves skull through superior orbital fissure to orbital cavity ❑Maxillary nerve (V2) also contains only sensory fibers leaves the skull through foramen rotundum ❑Mandibular nerve (V3) contains both sensory and motor fibers and leaves skull through foramen ovale ❑The sensory fibers to skin of face from each division supply a distinct zone with little or no overlap of dermatomes
What type of ganglion is the trigeminal ganglion?
A sensory ganglion
What is the trigeminal ganglion made up of?
The trigeminal ganglion is made up of pseudounipolar nerve cells, with a “T-shape” arrangement of
processes arising from the cell bodies, which divide to form the central and
peripheral processes
Where does the trigeminal ganglion lie?
Lies in the trigeminal impression on the anterior surface of the petrous temporal
bone near the apex
What does the trigeminal ganglion occupy?
It occupies a special space of dura called the Meckel’s cave or the Trigeminal cave
The relations of the trigeminal ganglion :
▪Medially – ICA and posterior part of cavernous sinus ▪Laterally – Middle meningeal artery ▪Superiorly – Parahippocampal gyrus ▪Inferiorly – Motor root of Vth CN; greater petrosal nerve; apex of petrous bone; foramen lacerum
SENSORY COMPONENT OF TRIGEMINAL NERVE : What are the branches of the unipolar cells of the trigeminal ganglion divided into?
Branches of the unipolar cells of the trigeminal ganglion are divided into central
and peripheral branches
Describe the peripheral processes of the unipolar cells.
The peripheral processes of the unipolar cells are sensory
What do the central processes of the unipolar cells form?
The central processes of the unipolar cells
form sensory root of trigeminal nerve
About half the fibers divide into…
ascending
and descending branches
when they enter the pons
Where do the ascending branches terminate?
Ascending branches terminate in
main sensory nucleus
Where do the descending branches terminate?
Descending branches terminate in
spinal nucleus
Where do the touch and pressure nerve fibers terminate?
Touch and pressure nerve fibers
terminate in the main sensory nucleus
Where does pain and temperature pass?
Pain and temperature pass to spinal
nucleus
The remaining fibers ascend or descend in the…
brainstem without division
What are the proprioceptive impulses from the muscles of mastication carried by?
Proprioceptive impulses from muscles of mastication are carried by fibers of unipolar cells of the mesencephalic nucleus that have bypassed the trigeminal ganglion
What happens to the axons in the main sensory nuclei and central processes of cells in the mesencephalic nucleus?
Axons in the main sensory nuclei, spinal nuclei and central processes of cells in mesencephalic nucleus crosses the median plane and ascend as the trigeminal lemniscus is going to terminate on nerve cells of ventral postero-medial nucleus of the thalamus.
What do the axons travel through?
Axons travel through genu internal
capsule to postcentral gyrus
MOTOR COMPONENT OF TRIGEMINAL NERVE : Where does the motor nucleus lie?
Motor nucleus lies in grey
matter beneath rhomboid
fossa
MOTOR COMPONENT OF TRIGEMINAL NERVE : What do the cells of the motor nucleus give rise to?
Cells of motor nucleus give
rise to axons that form motor
root
MOTOR COMPONENT OF TRIGEMINAL NERVE : What does the motor nucleus supply?
Motor nucleus lies in grey matter beneath ❑Motor nucleus supplies muscles of mastication, tensor tympani, tensor veli palatini, mylohyoid and anterior belly of digastric muscle.
Describe the ophthalmic nerve[Va]
- The ophthalmic nerve[Va] is the smallest of 3 peripheral branches of trigeminal
- The ophthalmic nerve is a sensory nerve
The cutaneous branches supplies structures derived from frontonasal
prominence i.e.
- Eyeball
- Lacrimal gland
- Conjunctiva
- Nasal & paranasal mucosa
- Skin of scalp, forehead, eyelids and nose
Course of the ophthalmic nerve(Va) :
❑ Passes forwards from trigeminal cave
❑ Through the lateral wall of cavernous sinus:
▪ above maxillary n.
▪ below trochlear n.
❑ Divides into three branches (Frontal; Lacrimal and Nasociliary nerves) prior to
entry into superior orbital fissure to enter into the orbit
BRANCHES OF OPHTHALMIC NERVE (Va) : Frontal nerve. Describe the frontal nerve.
The frontal nerve is the largest of 3 terminal branches of Va
BRANCHES OF OPHTHALMIC NERVE (Va) : The frontal nerve passes…
forwards in orbit just under its roof and ½ way through it divides into the:
- Supratrochlear nerve
- Supraorbital nerve
Describe the supratrochlear nerve.
The supratrochlear is the smallest terminal branch
Where and how does the supratrochlear nerve run?
The supratrochlear nerve runs anteromediallly in the roof of the orbit, passing above trochlear nerve
and emerges through the frontal notch
Which structures does the supratrochlear nerve supply?
The conjunctiva; skin of upper eyelid and skin of midline of forehead
above root of nose
Describe the supraorbital nerve.
The supraorbital nerve is a larger terminal branch
What does the supraorbital nerve transverse?
The supraorbital nerve transverses through the supra-orbital foramen
What does the supraorbital nerve supply?
The scalp up to vertex, rest of
forehead, central upper eyelid;
conjunctiva and frontal sinus
BRANCHES OF OPHTHALMIC NERVE (Va) : The lacrimal nerve. Describe the lacrimal nerve.
The lacrimal nerve is the smallest of the 3 terminal branches of Va
BRANCHES OF OPHTHALMIC NERVE (Va) : Where does the lacrimal nerve enter the orbit?
The lacrimal nerve enters the orbit through the lateral part of the superior orbital fissure
BRANCHES OF OPHTHALMIC NERVE (Va) : The lacrimal nerve receives communication from the…
zygomatico-temporal nerve and passes deep to
the lacrimal gland
BRANCHES OF OPHTHALMIC NERVE (Va) : Which structures does the lacrimal nerve supply?
▪ Conjuctiva and upper eyelid laterally
▪Parasympathetic and sensory to lacrimal gland
And the lacrimal nerve sends Secretomotor fibres to the gland
from the greater petrosal nerve
via the zygomatico-temporal
nerve
BRANCHES OF OPHTHALMIC NERVE (Va) : What is the nasociliary nerve?
The nasociliary nerve is the terminal branch of Va
BRANCHES OF OPHTHALMIC NERVE (Va) : Where does the nasociliary nerve begin?
The nasociliary nerve Begins in the lateral wall of the anterior part of the cavernous sinus
BRANCHES OF OPHTHALMIC NERVE (Va) : Where does the nasocillary nerve enter?
The nasociliary nerve Enters the orbit through SOF between the two division of the occulomotor nerve
BRANCHES OF OPHTHALMIC NERVE (Va) : What does the nasocillary nerve cross over to?
The nasociliary nerve Crosses over to the medial wall of the orbit and ends at the anterior ethmoidal
foramen by dividing into the infratrochlear and anterior ethmoidal nerves
Name the branches of the nasociliary nerve.
*Communicating branch to ciliary
ganglion
- Two-three long ciliary nerves
- Posterior ethmoidal nerve
*Infratrochlear nerve
(smaller terminal br.)
*Anterior ethmoidal nerve
(larger terminal br.)
Which structures do each of the branches of the nasociliary nerve innervate?
*Communicating branch to ciliary
ganglion :
Sensory root to the ganglion
- Two-three long ciliary nerves : Cornea, iris and ciliary body
- Posterior ethmoidal nerve : Ethmoidal and sphenoidal air sinuses
*Infratrochlear nerve
(smaller terminal br.)
Conjunctiva, lacrimal sac and caruncle, medial ends of
the eye lids and upper half of the external nose
*Anterior ethmoidal nerve
(larger terminal br.)
Gives off two internal nasal branches, i.e. Medial and
lateral to supply the mucosa of the nose
It emerges at the lower border of the nose as the
external nasal nerve to supply the skin of the lower half
of the nose
Describe the maxillary nerve[Vb].
The maxillary nerve[Vb] is the peripheral branch of the trigeminal ganglion and it is a sensory nerve
State the course of the maxillary nerve[Vb].
❑ Passes through the lateral wall of the cavernous sinus below Va. ❑ Leaves MCF by traversing foramen rotundum ❑Maxillary nerve enters the pterygopalatine fossa (PPF) ❑Exiting PPF, it continues as infraorbital nerve and enters the orbit through the infraorbital fissure ❑It runs on the floor of the orbit, firstly in a shallow groove and then in the infraorbital canal ❑ Finally emerges through the infraorbital foramen
CUTANEOUS BRANCHES OF MAXILLARY NERVE
❑ Three cutaneous branches:
▪ Zygomaticotemporal nerve
▪Zygomaticofacial nerve
▪ Infraorbital nerve
CUTANEOUS BRANCHES OF MAXILLARY NERVE
❑ The cutaneous branches supplies structures derived from frontonasal
prominence i.e.
- Skin of the lower eye lids
- Prominence of the cheeks
- Alar part of the nose
- Part of the temple
- Upper lip
What does the zygomatico-facial transverse through?
The zygomatico-facial nerve transverses through the inferolateral angle of the orbit, and emerges on the face
through a foramen on the zygomatic bone
What does the zygomatico-facial nerve supply?
The zygomatico-facial nerve supplies the skin on the prominence of the cheeks
What does the zygomatico-facial nerve form?
The zygomatico-facial forms a plexus with the zygomatic branch of the facial nerve and the palpebral
branch of the maxillary nerve
Where does the zygomatico-temporal nerve enter?
The zygomatico-temporal nerve enters the orbit through the lateral
end of the inferior orbital fissure and
runs on the lateral wall to enter the
zygomatic bone
What does the zygomatico-temporal transverse with?
The zygomatico-temporal nerve then transverses with the zygomatic
canal to enter anterior part of the
temporal fossa
What does the zygomatico-temporal nerve supply?
The zygomatico-temporal nerve supplies the skin on the temples
What does the zygomatico-temporal nerve communicate with?
It communicates with the facial and
auriculotemporal nerves
What does the zygomatico-temporal nerve give off?
It Gives off a communicating branch
carrying parasympathetic postganglionic
fibres from pterygopalatine ganglion to
the lacrimal gland
What does the infraorbital nerve emerge onto?
Emerges onto the face through the infraorbital foramen
The infraorbital nerve gives off the following 5 branches :
- Middle superior alveolar nerve
- Anterior superior alveolar nerve
- Palpebral nerve[terminal branch]
- Nasal nerve[terminal branch]
- Superior labial nerve[terminal branch]
What do the branches of the infraorbital nerve innervate?
*Middle superior alveolar nerve :Upper premolar teeth
*Anterior superior alveolar nerve :Upper incisors and canine teeth; maxillary sinus;
antero-inferior aspect of nasal cavity
*Palpebral nerve
(terminal branch)
Skin over the lower eyelid
*Nasal nerve
(terminal branch)
Skin on the side of the nose and movable part of the
nasal septum
*Superior labial nerve
(terminal branch)
Skin over the anterior parts of the cheeks and upper
eyelids
The clinical significance of the infraorbital nerve :
The Infraorbital nerve is commonly implicated in trigeminal
neuralgia, which is amenable to cryotherapy where medical therapy fails
Describe the pterygopalatine ganglion[PPG].
The pterygopalatine ganglion[PPG] is the Largest parasympathetic peripheral
ganglion in the head region
What does the pterygopalatine ganglion serve as?
It serves as a relay station for
preganglionic, secretomotor fibres to glands
What do the postganglionic fibres of the pterygopalatine ganglion join?
Its postganglionic fibres join all
‘ganglionic’ branches of Vb
The pterygopalatine ganglion is ultimately secretomotor to the..
lacrimal gland & mucus glands of paranasal
sinuses, nose, palate and pharynx.
Where does the pterygopalatine lie?
It lies in the PTERYGOPALATINE FOSSA below the Vb
What is the pterygopalatine ganglion related to and what is it functionally connected to?
The Pterygopalatine ganglion is related to the
maxillary nerve, but functionally connected
to the facial nerve via its greater petrosal
branch
Where does the sensory root come from and what does it traverse?
Sensory root – comes from Vb and merely
traverse the ganglion
BRANCHES OF MAXILLARY NERVE via PPG. Orbital branches - Where do they pass and what do they supply?
❑ Passes through the inferior orbital fissure
❑ Supplies the periosteum of the orbit and orbitalis muscle
BRANCHES OF MAXILLARY NERVE via PPG. Name the palatine branches.
- Greater palatine nerve
* Lesser palatine nerves
What does the greater palatine nerve traverse and supply?
❑ Greater palatine nerve ▪ Traverses through the greater palatine canal ▪ Supplies: Postero-inferior quadrant of lateral nasal wall and adjacent floor of nose; hard plate and maxillary sinus
What do the lesser palatine nerves traverse and supply?
❑ Lesser palatine nerves
▪Traverse through the palatine
foramina
▪ Supplies: soft palate and tonsil
BRANCHES OF MAXILLARY NERVE via PPG. Where do the nasal branches enter?
Nasal branches:
❑ Enter the nasal cavity through the sphenopalatine foramen
Name the nasal branches.
- Lateral posterior superior nasal nerves
- Medial posterior superior nasal nerves
- Nasopalatine nerve
What do each of the nasal branches supply?
❑ Lateral posterior superior nasal nerves:
▪ Supplies: Posterior parts of the superior and middle conchae
❑ Medial posterior superior nasal nerves
▪ Supplies: Posterior aspect of the roof of the nose and nasal septum
❑ Nasopalatine nerve
▪ Supplies: Gum behind the incisors
What does the pharyngeal branch traverse and supply?
Pharyngeal branch:
▪ Traverses through the palatinovaginal canal
▪ Supplies: Part of the nasopharynx behind the auditory tube
What does the lacrimal branch supply?
Lacrimal branch:
▪ Supplies: Secretomotor fibres to lacrimal gland
Describe the mandibular nerve[Vc].
The mandibular nerve[Vc] is :
❑ The largest peripheral branches of trigeminal ganglion
❑ A Mixed nerve (sensory + motor)
What does the mandibular nerve[Vc] supply?
The mandibular nerve[Vc] Supplies all structures derived from the mandibular or first branchial arch
State the course of mandibular nerve[Vc].
❑ Begins in the MCF through a large sensory root and a small motor root ❑ Sensory root arises from the lateral part of the trigeminal ganglion and leaves the cranial cavity via foramen ovale ❑ Motor root lies deep to the trigeminal ganglion and sensory root ❑ It also passes through foramen ovale to join the sensory root thus forming the main trunk ❑ The main trunk lies in the infratemporal fossa and divides into a small anterior trunk and a large posterior trunk
BRANCHES OF MANDIBULAR NERVE. Main trunk branches:
- Meningeal branch
* Nerve to medial pterygoid
Where does the meningeal branch enter and what does it supply?
▪ Meningeal branch
✓ Enters the skull through foramen spinosum with the Middle meningeal artery
✓ Supplies: dura mater in Middle cranial fossa
Where does the nerve to the medial pterygoid arise and what does it supply?
▪ Nerve to medial pterygoid
✓ Arise close to the optic ganglion
✓ Supplies: medial pterygoid muscle (deep surface); tensor veli palatini;
tensor tympani muscles
BRANCHES OF MANDIBULAR NERVE. Anterior trunk branches :
*Buccal nerve
*Masseteric nerve
*Deep temporal nerves
*Nerve to the lateral pterygoid
*
Anterior trunk branches: The buccal nerve is the…
only sensory branch of anterior division of Vc
Anterior trunk branches : Where does the buccal nerve pass and what does it supply?
The Buccal nerve :
✓Passes between the two head of lateral pterygoid
✓Supplies: skin and mucous membrane related to buccinator muscle + labial
aspect of gums of molar and premolar teeth
Masseteric nerve : Where is the upper border of the lateral pterygoid muscle situated?
The Upper border of lateral pterygoid
muscle just in front of the Temporomandibular joint
Where does the masseteric nerve pass and what does the supply?
The masseteric nerve : ✓Passes laterally through the mandibular notch to the deep surface of the masseter muscle ✓ Supplies: masseter muscle +Temporomandibular joint
❑ Anterior trunk branches: How many deep temporal nerves are present?
▪ Deep temporal nerves
✓ Two nerves: anterior & posterior
Where do the deep temporal nerves pass?
The deep temporal nerves pass between the skull and lateral pterygoid and enters the deep surface
of temporalis
Where does the nerve to the lateral pterygoid enter?
The nerve to the lateral pterygoid enters the deep surface of the muscle
BRANCHES OF MANDIBULAR NERVE
❑ Posterior trunk branches:
- Lingual nerve
* Inferior alveolar nerve
❑ Posterior trunk branches:
Where does the auriculotemporal nerve emerge?
The auriculotemporal nerve emerges onto the face behind the TMJ within the superior surface of the
parotid gland
Where does the auriculotemporal nerve ascend, pass over and divide into?
The auriculotemporal nerve ascends posterior to the superficial temporal vessels, passing over the
posterior root of zygoma and divides into superficial branches:
*Auricular part
*Temporal part
*Auriculotemporal nerve
What do each of the superficial branches supply?
➢Auricular part supplies: skin over tragus; upper part of pinna; External acoustic meatus;
tympanic membrance
➢ Temporal part supplies: skin over temple
➢ Auriculotemporal nerve supplies: parotid gland (secretomotor) + Temporomandibular joint
❑ Posterior trunk branches: The lingual nerve is one of…
the two terminal branches of the posterior division of Vc
Where does the lingual nerve lie and what does it supply?
The lingual nerve :
✓ lies between the mandibular ramus and the muscles in
the pterygomandibular space
✓Supplies: Sensory anterior two-thirds of the tongue and floor of the mouth
The fibres from the chorda tympani is…
secretomotor to submandibular and
sublingual glands
❑ Posterior trunk branches: Describe the inferior alveolar nerve.
The inferior alveolar nerve is the Largest terminal branches of the posterior division of Vc
Where does the inferior alveolar nerve run?
The inferior alveolar nerve runs lateral to the medial pterygoid and sphenomandibular ligament
Where does the inferior alveolar nerve enter?
The inferior alveolar nerve enters the mandibular foramen and runs in the mandibular canal
Branches of the inferior alveolar nerve :
- Mylohyoid branch
- Inferior alveolar nerve
- Mental nerve
- Incisive branch
What does each branch of the inferior alveolar nerve supply?
➢Mylohyoid branch (motor): supplies mylohyoid muscle + anterior belly of digastric ➢ Inferior alveolar nerve: supplies lower teeth and gums ➢Mental nerve: supplies skin of the chin + skin and mucous membrane of the lower lip ➢Incisive branch: labial aspect of gums of canines and incisor teeth
CLINICAL SIGNIFICANCE. What is trigeminal neuralgia?
Trigeminal neuralgia is a chronic pain condition that affects the trigeminal nerve, which carries
sensation from your face to your brain
What does trigeminal neuralgia cause?
Trigeminal neuralgia causes even mild stimulation of your face, such as from
brushing your teeth or putting on makeup to trigger a jolt of excruciating pain
Who does trigeminal neuralgia affect?
Trigeminal neuralgia affects women more often than men, and it’s more likely to occur in people
who are older than 50
What does the treatment of trigeminal neuralgia include?
The treatment of trigeminal neuralgia includes surgery, injections or medication
