1. Trigeminal Nerve Anatomy 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.

2. the trigeminal ganglion contain the cell bodies of the sensory branches of the trigeminal nerve. 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 Ophthalmic nerve maxillary nerve mandibular nerve 3. 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. 4. 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 5. 1- Sensation Function 2- Motor Function 3- Corneal reflex 4- Test jaw jerk 6. We use sterile sharp item on forehead, cheek, and jaw If any abnormality present we test the thermal sensation and light touch 7. Ask the patient to clench their teeth. Both masseters should feel firm and strong with contracting temporalis. 8. 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. 9. Doctor finger on tip of jaw, grip patellar hammer halfway up shaft and tap finger lightly usually nothing happens, or just a slight closure.