Table 142 The Cranial Nerves continued

V. Trigeminal52 (tri-JEM-ih-nul) Nerve

Largest of the cranial nerves; consists of three divisions designated V! to V3

VI, Ophthalmic Division Composition: Sensory

Function: Main sensory nerve of upper face (touch, temperature, pain) Origin: Superior region of face as illustrated, surface of eyeball, tear gland, superior nasal mucosa, frontal and ethmoid sinuses Termination: Pons

Cranial passage: Superior orbital fissure Effects of damage: Loss of sensation

Clinical test:Test corneal reflex—blinking in response to light touch to eyeball

V2, Maxillary Division Composition: Sensory

Function: Same sensations as V! lower on face Origin: Middle region of face as illustrated, nasal mucosa, maxillary sinus, palate, upper teeth and gums Termination: Pons

Cranial passage: Foramen rotundum and infraorbital foramen Effects of damage: Loss of sensation

Clinical test:Test sense of touch, pain, and temperature with light touch, pinpricks, and hot and cold objects

V3, Mandibular Division Composition: Mixed

Function: Same sensations as V-,-V2 lower on face; mastication Sensory origin: Inferior region of face as illustrated, anterior two-thirds of tongue (but not taste buds), lower teeth and gums, floor of mouth, dura mater Sensory termination: Pons Motor origin: Pons

Motor termination: Anterior belly of digastric, masseter, temporalis, mylohyoid, pterygoids, and tensor tympani of middle ear Cranial passage: Foramen ovale Effects of damage: Loss of sensation; impaired chewing Clinical test: Assess motor functions by palpating masseter and temporalis muscles while subject clenches teeth; test ability of subject to move mandible from side to side and to open mouth against resistance

Infraorbital nerve Superior alveolar nerves

Lingual nerve

Inferior alveolar nerve

Distribution of sensory fibers of each division

Superior orbital fissure Ophthalmic division (V1) Trigeminal ganglion Trigeminal nerve (V) Mandibular division (V3) Foramen ovale Maxillary division (V2) Foramen rotundum

Distribution of sensory fibers of each division

Medial Pterygoid

Superior orbital fissure Ophthalmic division (V1) Trigeminal ganglion Trigeminal nerve (V) Mandibular division (V3) Foramen ovale Maxillary division (V2) Foramen rotundum

Anterior trunk to chewing muscles

Temporalis muscle Lateral pterygoid muscle Medial pterygoid muscle Masseter muscle

Anterior belly of digastric muscle

Inset shows motor branches of the mandibular division (V3)

Anterior trunk to chewing muscles

Temporalis muscle Lateral pterygoid muscle Medial pterygoid muscle Masseter muscle

Anterior belly of digastric muscle

Inset shows motor branches of the mandibular division (V3)

Figure 14.32 The Trigeminal Nerve.

Saladin: Anatomy & I 14. The Brain and Cranial I Text I © The McGraw-Hill

Physiology: The Unity of Nerves Companies, 2003 Form and Function, Third Edition

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