1. Trigeminal Nerve (V)

2. Lecture Objectives Discuss briefly how the face is developed.
Follow up the course of trigeminal nerve from its point of central connections, exit and down to its target areas.
Describe briefly important cranial reflexes involving the face and trigeminal nerve.

3. Development of the Face: Premordia and derivatives
Swellings surrounding stomodeum
Mandibular prominences (paired)
Soft tissue
Bone
Maxillary prominences (paired)
Secondary palate
Frontonasal prominence (unpaired)

4. Development of the Face: Premordia and derivatives
Nasal placodes – nasal pits
Medial nasal prominences
Fleshy nasal septum
Intermaxillary segment
Philtrum
Premaxilla, jaw and gingiva associated with upper incisor teeth
Primary palate = median palatine process
Lateral nasal prominences
Soft tissue
Bone
Nasolacrimal groove
Labiogingival laminae

5. Development of the Palate
Primary palate (median palatine process)
Secondary palate – lateral palatine processes
Fusion → secondary palate

6. Malformations: Cleft Lip and Palate
Incisive fossa separates anterior and posterior parts
Anterior clefts – unilateral (E) or bilateral (F)
Complete vs. incomplete
Posterior clefts–unilateral (C) or bilateral (D)
Causes of palate clefts
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 palate clefts (E‐F)
Secondary palate clefts (C‐D)
Primary and secondary palate clefts (G‐H)

7. Malformations: Facial clefts
Oblique (orbitofacial fissure) (E)
Maxillary with lateral nasal prominences
Lateral (macrostomia)
Mandibular with maxillary prominences
Median (A)
Between medial nasal prominences

8. Trigeminal Nerve (V) Mixed nerve Largest of the cranial nerves
Three branches:
Ophthalmic nerve (GSA) ← superior orbital fissure
Maxillary nerve (GSA)← foramen rotundum ← pterygopalatine fossa
Mandibular nerve (GSA, SVE) ← foramen ovale ← infratemporal fossa
trigeminal ganglion
Pons

9. Trigeminal Nerve (V)
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

10. Trigeminal Nerve Nuclei
Motor nucleus of trigeminal nerve (SVE)
Location – pons
Connections
Cortex
Reticular formation, red nucleus, tectum
Fibers course

11. Trigeminal Nerve Sensory Nuclei
Main sensory nucleus (GSA)
Touch & pressure
Location, Extention
Relation to
Motor nucleus
Spinal nucleus
Spinal nucleus* (GSA)
Pain & tempreture
Location
Extentions
Medulla – C2
Somatotopic organisation
Ophthalmic – most caudal
Mandibular – most rostral
*receive GSA from other cranial nerves
Mesencephalic nucleus (GSA)
Proprioception
Location, Extension

12. Trigeminal Nerve Sensory Nuclei
1st order neurons
Trigeminal ganglion
2nd order neurons
Trigeminal nerve sensory nuclei
Central axons cross midline
Form trigeminal lemniscus
3rd order neurons
VPM nucleus of thalamus
Internal capsule

13. Maxillary Nerve: Branches
Menengial branches
Zygomatic branch – inferior orbital fissure
Zygomaticotemporal n. ‐
Zygomaticotemporal foramen
Zygomaticofacial n. ‐ Zygomaticofacial foramen
Posterior superior alveolar n. –
posterior superior alveolar foramen
Infraorbital nerve – inferior orbital fissure – infraorbital groove – infraorbital foramen
Middle superior alveolar n.
Anterior superior alveolar n.

14. Maxillary Nerve: Branches
Ganglionic branches (pterygopalatine nerves)
Greater &lesser palatine nn. – Greater & lesser palatine canals/foramens
Nasal branches (posterior superior lateral, posterior superior medial, & nasopalatine nn.) – sphenopalatine foramen
Pharyngeal branch – pharyngeal canal

16. Mandibular Nerve: Branches
Meningeal branch –
foramen spinosum
Nerve to medial pterygoid
Anterior division
Masseteric n.
Deep temporal nn.
Nerve to lateral pterygoid
Buccal nerve

17. Mandibular Nerve: Branches
Posterior division
Auriculotemporal n.
Relations – TMJ, middle menengeal a.
Lingual n.
Relations – submandibular duct
Inferior alveolar n. – mandibular foramen
Mylohyoid n. (GSE)
Mental n. – mental foramen

19. 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

20. Ophthalmic Nerve: Branches
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)

23. Trigeminal Nerve (V): Lesion
Loss of general sensation (hemianesthesia) from face and oral & nasal cavities
Loss of corneal reflex (V1) (afferent limb)
Paralysis of the muscles of mastication
Deviation of the mandible to the weak side
Paralysis of the tensor tympani muscle – 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

24. Corneal Reflex