near the apex of the petrous part of the temporal bone in the pouch of thedura mater called the trigeminal cave.
from the middle cranial fossa
It is the fifth and largest cranial
nerve, which emerges from the
anterolateral surface of the pons as a
motor and sensory root.
The large sensory root expands to form
the “trigeminal ganglion”.
The motor root of trigeminal is situated
below the sensory ganglion and
completely separate from it and leaves the
skull through the foramen ovale
and, immediately below this foramen, joins
the mandibular nerve.
the trigeminal ganglion contain the cell
bodies of the sensory branches of the
From the anterior border of the
ganglion the three sensory branches are
arise which convey pain, touch and
thermal sensations from the face, oral
and nasal cavities to the CNS.
The branches are:
1- Ophthalmic nerve
2- Maxillary nerve
3- Mandibular nerve
The ophthalmic nerve enter the orbital
cavity through the superior orbital fissure
and divides into three branches (frontal,
lacrimal, and nasociliary nerves) which
supply the eyeball, cornea, lacrimal
gland, upper eyelid, skin of forehead,
scalp, nose, and nasal cavity.
The Maxillary nerve leave the cranial
fosse through the foramen rotundum,
and entering the pterygopalatine
fossa and divides into (meningeal
branch, ganglionic branches,
zygomatic nerve, superior alveolar
nerves) which supply the Skin of face
over maxilla and the upper lip, teeth of
upper jaw, mucous membrane of
nose, the maxillary air sinus, palate,
and lower eyelid.
The mandibular nerve is both motor and
sensory, leave the cranial fossa through
foramen ovale to enter the infratemporal
fossa and divides into (meningeal branch,
masseteric, deep temporal, lateral and medial
pterygoid, buccal, auriculotemporal, lingual,
and inferior alveolar nerves) which supply the
muscles of mastication, mylohyoid, anterior
belly of digastric, skin of cheek and over
mandible, lower lip, side of head, teeth of
lower jaw, mucous membrane of mouth and
anterior two thirds of tongue
1- Sensation Function
2- Motor Function
3- Corneal reflex
4- Test jaw jerk
We use sterile sharp item on forehead, cheek, and jaw
If any abnormality present we test the thermal
sensation and light touch
Ask the patient to clench their teeth.
Both masseters should feel firm and strong with
Take a clean piece of cotton wool and ask the patient
to look away gently touch the cornea with the cotton
wool and the patient will blink.
Doctor finger on tip of jaw, grip patellar hammer halfway
up shaft and tap finger lightly usually nothing happens, or
just a slight closure.