Trigeminal Nerve D.Nimer D.Rania Gabr D.Safaa D.Elsherbiny

Objectives List the trigeminal nerve nuclei and their location Follow up the course of trigeminal nerve from its point of central connections to exit and down to its target areas. Describe the sensory and motor components of the trigeminal nerve.

Trigeminal nerve Type: mixed nerve formed of a large sensory root and a small motor root. The largest cranial nerve Origin: 1. Sensory root: arise from the trigeminal ganglion ( Gasserian , semilunar ganglion). a. The peripheral branches form the 3 divisions of the trigeminal nerve: ophthalmic, maxillary and mandibular. b. The central branches form the sensory root of the trigeminal nerve. 2. Motor root: from the motor nucleus in the pons. It joins the mandibular nerve.

Fibers: General somatic afferent: Carrying general sensations from face. 2. Special visceral efferent: Supplying muscles developed from the 1st pharyngeal arch, (8 muscles).

Nuclei: 4 nuclei (motor and 3 sensory) 1. One motor nucleus: in the lateral part of the pontine tegmentum (mid pons). 2. Three sensory nuclei: a. Mesencephalic nucleus: in the midbrain, for proprioception from the face. b. Main sensory nucleus: in the pons, for discriminative touch from the face. c. Spinal trigeminal nucleus: in the medulla, for pain and temperature sensations from the face.

Trigeminal Nerve Emerges from the middle of the ventral surface of the pons Divisions: Ophthalmic. Maxillary. Mandibular. Axons of cells of motor nucleus join only the mandibular division.

Areas of Distribution of Trigeminal Nerve in the Face Pure Sensory Pure Sensory C2,3 Great auricular N. Mixed Nerve Areas of Distribution of Trigeminal Nerve in the Face

Trigeminal Ganglion (Gasserian ganglion) Site: Occupies a depression in the middle cranial fossa. Importance: Contains cell bodies: Whose dendrites carry sensations from the face. Whose axons form the sensory root of trigeminal nerve.

Ophthalmic nerve (Pure Sensory) Type: purely sensory nerve. Origin: It arises from the trigeminal ganglion. Course: It passes in the lateral wall of the cavernous sinus and divides into 3 branches that enter the orbit through the “superior orbital fissure”. Branches: Frontal: supplies skin of face & scalp. Lacrimal: supplies skin of face & lacrimal gland. Nasociliary: supplies skin of face, nasal cavity & eyeball.

Maxillary nerve (Pure Sensory) Type: purely sensory nerve. Origin: It arises from the trigeminal ganglion. Course: It passes in the lateral wall of the cavernous sinus → passes through foramen rotundum → enters the pterygopalatine fossa → passes through the inferior orbital fissue to continue as the infraorbital nerve → passes through the infraorbital groove, infraorbital canal and the infraorbital foramen.

Maxillary nerve Supplies the: Upper teeth, gums & maxillary air sinus: (posterior, middle & anterior superior alveolar nerves). Face: (zygomaticofacial ,zygomaticotemporal & infraorbital nerves). Branches

Maxillary nerve block (Dentists)

Mandibular nerve (Mixed) Type: mixed nerve. Origin: It arises by two roots, motor and sensory: Motor root (small): from the motor nucleus of the trigeminal nerve in the pons. 2. Sensory root (large): from the trigeminal ganglion. Course: The 2 roots pass through foramen ovale → unite below foramen ovale to form a short mandibular nerve trunk → divides into anterior and posterior divisions.

Mandibular nerve SENSORY BRANCHES: 1. Lingual: General sensations from anterior 2/3 the of tongue. 2. Buccal: Face(cheek on upper jaw) 3. Auriculotemporal: auricle, temple, parotid gland & TMJ. 4. Inferior alveolar: Lower teeth, gums & face. MOTOR BRANCHES: 1.Four muscles of mastication: Masseter, Temporalis, Medial And Lateral Pterygoid. 2. Other 4: Anterior belly of Digastric, Mylohyoid, Tensor Palati and Tensor Tympani.

Clinical Anatomy Paralysis of lateral pterygoid muscles causes the jaw to deviate towards the paralysed side on opening the mouth as a result of action of normal muscle.

Trigeminal Neuralgia Compression, degeneration or inflammation of the 5th cranial nerve may result in a condition called trigeminal neuralgia or tic douloureux. This condition is characterized by recurring episodes of intense stabbing , excoriating pain radiating from the angle of the jaw along a branches of the trigeminal nerve. Usually involves maxillary & mandibular nerves, rarely in the ophthalmic division.

Trigeminal block A trigeminal nerve block is an injection of medication e.g carbamazepine, that helps relieve facial pain. It’s used to treat: 1-Trigeminal neuralgia 2- Herpes zoster infection (or “shingles”) affecting the face 3- Other atypical facial pain syndromes

Inferior alveolar block (Dentists)