Trigeminal Nerve

Trigeminal nerve Largest & one of most complex cranial nerves Mixed nerve Large sensory part & much smaller motor part Sensory component has 3 divisions : ophthalmic, maxillary, mandibular. Motor & prinicipal sensory nuclei – midpons Spinal tract & nucleus (pain, temp) – pons to upper cervical cord

TRIGEMINAL NERVE Type: Mixed (sensory & motor). Fibers: General somatic afferent: Carrying general sensations from face. 2. Special visceral efferent: Supplying muscles developed from the 1st pharyngeal arch, (8 muscles).

TRIGEMINAL NERVE NUCLEI Four nuclei: (3 sensory + 1 Motor). General somatic afferent: Mesencephalic (midbrain & pons): receives proprioceptive fibers from face. Principal (main) sensory (pons): receives touch fibers from face. Spinal (pons, medulla & upper 2-3 cervical segments of spinal cord): receives pain & temperature sensations from face. Special visceral efferent: 4. Motor nucleus (pons): supplies: Four Muscles of mastication (temporalis, masseter, medial & lateral pterygoid). Other four muscles (Anterior belly of digastric, mylohyoid, tensor tympani & tensor palati). TRIGEMINAL NERVE NUCLEI

TRIGEMINAL 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.

TRIGEMINAL NERVE Emerge from middle of the ventral surface of the pons by 2 roots (large lateral sensory root & small medial motor root). Divides into 3 divisions (dendrites of trigeminal ganglion): 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

OPHTHALMIC (PURE SENSORY) Divides into:3 branches: frontal, lacrimal & nasociliary which pass through superior orbital fissure to orbit. Frontal: supplies skin of face & scalp. Lacrimal: supplies skin of face & lacrimal gland. Nasociliary: supplies skin of face, nasal cavity & eyeball.

MAXILLARY (PURE SENSORY) Supplies: Upper teeth, gums & maxillary air sinus: (posterior, middle & anterior superior alveolar nerves). 2. Face: (zygomaticofacial ,zygomatico temporal &infraorbital nerves).

MANDIBULAR (MIXED) SENSORY BRANCHES: Lingual: General sensations from anterior 2/3 the of tongue. 2. Inferior alveolar: Lower teeth, gums & face. 3. Buccal: Face(cheek on upper jaw) 4. Auriculotemporal: auricle, temple, parotid gland & TMJ. MOTOR BRANCHES: to 8 muscles ( 4 muscles of mastication & other 4 muscles).

Muscles of Mastication Masseter : close the jaw , protrude it slightly Temporalis : close the jaw , retract it slightly Medial pterygoids : close the jaw & protrude it Lateral pterygoids : open the jaw & protrude it - Unilateral pterygoid weakness – jaw deviates towards side of weak muscle

Also supplies Mylohyoid Ant.belly of digastric Tensor veli palatini Tensor tympani

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.