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Trigeminal nerve

Slide in bold and please go back to see the pictures , if I skipped any part of record that because it wasn’t clear to me

Hala nsour

2/26/2018

this lecture contain two topics :

1-face and palate development and malformations (we will discuss it briefly )

2- Trigeminal nerve

Development of the Face: Premordia and derivatives

• Swellings surrounding stomodeum *Mandibular prominences (paired)(blue ) • Soft tissue • Bone * Maxillary prominences (paired)(yellow) • Soft tissue • Bone • Secondary palate

* Frontonasal prominence (unpaired)(green) • Soft tissue • Bone

The face developed from fusion of five prominence (two mandibular and two maxillary from first pharyngeal arch while Frontonasal get down from skull)

Slide 4 • In the frontonasal prominence.. Nasal placodes appear and then become nasal pits which will separate the prominences to two nasal prominences : 1• Medial nasal prominences • Fleshy nasal septum nasal septum get down from roof and form the division of nasal cavity

• Intermaxillary segment

• Philtrum

• Premaxilla (upper lip), jaw and gingival associated withupper incisor teeth

• Primary palate = median palatine process

2• Lateral nasal prominences They will bind to the maxillary nasal prominences

• Soft tissue • Bone

• Nasolacrimal groove : site of lateral nasal prominence fusion with maxillary

prominence and its will become later on nasolacrimal canal and duct • Labiogingival laminae: it has contribution in development of hard palate

Development of the Palate Hard palate is fusion of:

1• Primary palate pre maxilla which is anterior part of hard palate

(median palatine process) 2• Secondary palate – posterior part of hard palate (lateral

palatine processes) >>called palatal process and its come from maxillary prominence

Fusion → secondary palate

Malformations: Cleft Lip and Palate

• May be unilateral or bilateral May involve Lips only, Palate only , Lip & palate also its may be Anterior/posterior to incisive foramen Unilateral/bilateral Isolated/associated with cleft lips

Incisive fossa will separates the palate anterior and posterior parts

Anterior clefts – unilateral (E) or bilateral (F)

Complete vs. incomplete

Posterior clefts–unilateral (C) or bilateral (D)

Complete vs. incomplete

The Causes of palate clefts is failure of fusion between different

prominences and processes • Cleft lip (with (E‐H) or without cleft palate)

1/1000, 75% males

Maxillary with medial nasal prominences

• Cleft palate (with (E‐H)or without (C‐D) cleft

lip)

1/2500, ⅔ females

Lateral palatine processes with each other & with nasal septum & with median

palatine process

• Primary(anterior ) palate clefts (E‐F) • Secondary (posterior) palate clefts (C‐D) • Primary and secondary palate clefts (G‐H)

If the two palate not fuse superiorly, the oral cavity will be opened on the nasal cavity and

this will make problem in breathing and eating (sucking problem to baby: because sucking

need complete ceiling) These anomalies need complicated surger (take long stages )

Malformations:

Facial clefts:

Failure of the embryonic facial prominences to fuse properly 1• Oblique (orbitofacial fissure) (E) If the fusion between Maxillary and lateral nasal prominences didn’t happen completely

2• Lateral (macrostomia) If the Mandibular and maxillary Prominences fuse far from each other

3 • Median Between medial nasal prominences pic in slide 7 A….incomplete cleft lip B….bilateral cleft lip C….cleft lip ,jaw, and palate D …. Cleft palate

Trigeminal Nerve (V) • Mixed nerve • Largest of the cranial nerves • Three branches: • Ophthalmic nerve (GSA) (supply upper third of the head) ←

Leave from superior orbital fissure go and supply the orbit

• Maxillary nerve (GSA) (supply middle third of the head) ← will leave from foramen rotundum ← to pterygopalatine fossa this fossa is v. important area in skull because it’s the connection between many parts its

connect

1-cranial cavity by foramen rotundum

2- base of the skull by infra temporal fossa by pterygomaxillary canal

3- orbit by inferior orbital fissure

4- oral cavity directly just posterior to alveolar process of maxilla

5-nasal cavity by sphenopalatine foramen

6-pharnex

• Mandibular nerve (GSA, SVE) (supply lower third of the head) foramen ovale ...

infratemporal foss

Trigeminal Nerve (V) mainly GSA , Part of it is motor usually in SVE (to masticatory

muscle ) and its with mandibular nerve It’s out from mid of pons laterally and the Cell body of it in the trigeminal ganglion trigeminal ganglion found in the middle cranial fossa >>have depressed area called trigeminal impression located posterior lateral of the cavernous sinus Trigeminal cave : the name of it within dura matter > cover the ganglion with some extensions from dura matter mostly tentorium cerebelli

• Emerges from two roots on the ventrolateral surface of the pons • The large sensory root (GSA) ‐ trigeminal ganglion in the trigeminal cave of the dura matter • The small motor root (SVE) originates from the pons pass beneath the ganglion • Join the mandibular branch for Mastication

The motor and sensory nerve get out from the pons totally separated and the fusion occur in

the trigeminal ganglion

Trigeminal Nerve Nuclei • Motor nucleus of trigeminal nerve (SVE) superior to abducent &facial nucleus • Location in pons •connect to Cortex bilaterally • Reticular formation, red nucleus, tectum Actually all the sensory nucleus of trigeminal nerve contentious to each other and in the same direction (rostral &caudal )

Trigeminal Nerve Sensory Nuclei *****there is slide number 11 not included in the sheet because the doctor say we have

already talk about it in previous lecture*****

• 1st order neurons: in the Trigeminal ganglion >there is an exception in the nerve

that transport proprioception information which have first order neuron in the mesencephalic nucleus

• 2nd order neurons: Trigeminal nerve sensory nuclei > Central axons cross

midline Form trigeminal lemniscus • 3rd order neurons :VPM nucleus of thalamus ……Internal capsule

Maxillary Nerve: Branches

1• Menengial branches (the meningeal branch may exit before or after exiting of cranial cavity)

All trigeminal division can give menengial branch * In general fibers of maxillary nerve will deliver the post ganglionic nerves (which will descend from pterygopalatine ganglia (the ganglia itself receive postganglionic signals form the

nerve that pass through pterygoid canal and form from the fusion of greater and deep petrosal nerves)) to there targets Lets take the details From pterygopalatine fossa it will give many branches :

2• Zygomatic branch its target the face above zygomatic bone ,its will inter the

orbit from inferior orbital fissure and its will give two branches: A• Zygomaticotemporal n…. Zygomaticotemporal foramen B• Zygomaticofacial n…. Zygomaticofacial Foramen The zygomatic branch carry postganglionic fiber to lacrimal nerve of ophthalmic in its way to the orbit

3• Posterior superior alveolar n. – posterior superior alveolar foramen Supply the posterior third of the upper jaw

4• Infraorbital nerve Its inter the orbit by inferior orbital fissure to infra orbital groove(floor of orbit )…exit from infraorbital foramen to area above maxilla (anteriorly )

Give two branches :

A• Middle superior alveolar n. B• Anterior superior alveolar n. All upper jaw will take supply from the three alveolar n

5• Ganglionic branches (pterygopalatine nerves) The function of them is to carry postganglionic neurons towered nasal cavity and palate • Greater &lesser palatine nn. – Greater & lesser palatine canals/foramens

-to posterior two third of hard palate and soft palate

-postganglionic neuron to small salivary gland of palate

• Nasal branches (posteriorsuperior lateral, posterior superior medial, & nasopalatine(premaxilla) nn. (enter the premaxilla trough incisive foramen)) – sphenopalatine foramen to nasal cavity

-postganglionic neuron to mucus gland in nasal cavity and to small salivary gland in

premaxilla

• Pharyngeal branch– pharyngeal canal: mostly to nasopharynx and upper part of oropharynx

# sympathetic innervations to head important to blood vessels and erector pilli muscle in

skin

Mandibular Nerve(motor fiber) : Branches • Meningeal branch – Through foramen spinosum(if after exiting) the meddle meningeal artery pass through foramen spinosum

• Nerve to medial pterygoid sometimes it appear after division as branch of the

anterior division but its mostly appear before the division of mandibular nerve (ant &post) **Sometime if it appear before the division it carry branches for : 1- tensor tympani 2- tensor palatine (part of soft palate) 3- medial pterygoid muscle • Anterior division • Masseteric n. to masseter muscle

• Deep temporal nn. To temporal

• Nerve to lateral pterygoid • Buccal nerve (GSA) (TO Cheek region ) • Posterior division

• Auriculotemporal n. Very unique nerve its divide and surround middle menengeal a then fuse again ,it pass deep to TMJ . then supply the upper part of the mandible (lateral part of the head)

• Lingual n (GSA to toungh). (general sensation of touch and temperature of anterior 2/3 of tounge)

Its will fuse with the chorda tympani which is from facial nerve inferior to submandibular duct

• Inferior alveolar n. Supply all lower jaw – mandibular foramen

• Mylohyoid n. (GSE)

• leave as Mental n. from mental foramen

The doctor skip the next two slides because we already cover them in the orbit lecture

Ophthalmic Nerve: Branches

Superior orbital fissure

• Frontal nerve

Scalp

• Branches: • Supraorbital & Supratochlear nn. • Lacrimal nerve

Lateral part of upper eyelid

• Carry parasympathetic fibers to lacrimal gland via zygomaticotemporal nerve

• Nasociliary nerve‐ Branches: • Comunicating branch to ciliary ganglion‐ sensory fibers from short ciliary nn. • Long ciliary nn.‐ carry sympathetic fibers (dilator pupillae m.) • Posterior ethmoidal n. (ethmoid & sphenoid sinuses)

• Anterior ethmoidal n. • External nasal branch (tip of nose) • Infratrochlear n. (medial part of upper eyelid & part of nose)

Trigeminal Nerve (V): Lesion

• Loss of general sensation in anterior two third of head (hemianesthesia) from face and oral (soft palate so may affect swallowing ) & nasal cavities • Loss of corneal reflex (V1) Corneal reflex : (afferent limb from trigeminal and efferent limb from facial nerve)

when you touch the corneal the eyelid will close because of contraction of orbicularis oculi muscle which innervated by facial n Remember that the target of trigeminal n toward the motor nuclei of facial n in the pons is bilaterally so if you touch the cornea in the right eye both eyes will close For example : -if you make a lesion on right trigeminal and touch the right cornea guess the result?? No thing (because you cut the sense totally ) - if you make a lesion to one of the facial nerve there will be effect on the corresponding eye ( in other word the eye which you cut facial motor nerve will not close ) • Paralysis of the muscles of mastication • Deviation of the mandible to the weak side • Paralysis of the tensor tympani muscle so may affect on hearing and cause partial deafness to low‐pitched sounds • Trigeminal neuralgia • Test • Sensory – by touching face using cotton ball

• Motor – by assisting masticatory muscles (masseter & temporalis) on clenching