TRIGEMINAL NERVE and its course intracranially.pptx

trigeminal nerve and its course

1. TRIGEMINAL NERVE - V DR ASHIUNDU E.M SOM-HUMAN ANATOMY MMUST

2. Largest Cranial Nerve Motor to Muscles of 1 st Pharyngeal arch;- all the muscles of mastication, the anterior belly of the digastric, the mylohyoid , tensor tympani, and tensor veli palatini . Sensory to face, oral and nasal cavity, paranasal sinuses, orbit, dura mater, TMJ

3. NUCLEI NUCLEUS LEVEL OF NUCLEUS FUNCTION OF FIBRES Mesencephalic Mesencephalon(midbrain) GSA Principal/Pontine Pons GSA Motor Nucleus of V. Nerve Pons SVE Nucleus of Spinal Germinal Tract Pons & Medulla Oblongata GSA

4. COURSE -Originates from 4 nuclei extending from midbrain to medulla -Exits brainstem via ventral surface of pons by two roots- motor & sensory -In the middle cranial fossa, the sensory root expands into the trigeminal ganglion located lateral to the cavernous sinus, in a depression of the temporal bone called trigeminal cave / Meckels cave

5. The peripheral aspect of the trigeminal ganglion gives rise to 3 divisions: ophthalmic (V1), maxillary (V2) and mandibular (V3 ). The motor root passes inferiorly to the sensory root, along the floor of the trigeminal cave. Its fibres are only distributed to the mandibular division . The ophthalmic nerve and maxillary nerve travel lateral to the cavernous sinus exiting the cranium via the superior orbital fissure and foramen rotundum respectively. The mandibular nerve exits via the foramen ovale entering the infra-temporal fossa.

6. OPHTHALMIC NERVE Course After arising from the trigeminal ganglion, the ophthalmic nerve travels laterally to the cavernous sinus and gives rise to the recurrent tentorial branch (which supplies the tentorium cerebelli ). The nerve then then exits the cranium via the superior orbital fissure, where it divides into its three main branches : frontal, lacrimal nasociliary , which innervate the skin and mucous membrane of derivatives of the frontonasal prominence derivatives: Forehead and scalp Frontal and ethmoidal sinus Upper eyelid and its conjunctiva Cornea Dorsum of the nose

7. Parasympathetic Supply: Lacrimal gland: Post ganglionic fibres from the pterygopalatine ganglion (derived from the greater petrosal n of facial nerve), travel with the zygomatic branch of V2 and then join the lacrimal branch of V1. The fibres supply parasympathetic innervation to the lacrimal gland.

8. MAXILLARY NERVE V2 Wholly sensory Course : Traverse foramen rotundum P osterior wall of pterygopalatine fossa E nters the inferior orbital fissure E nter infra orbital canal E merges on face as infraorbital nerve

9. Maxillary nerve gives rise to 14 terminal branches, which innervate the skin, mucous membranes and sinuses of derivatives of the maxillary prominence of the 1st pharyngeal arch: Lower eyelid and its conjunctiva Cheeks and maxillary sinus Nasal cavity and lateral nose Upper lip Upper molar, incisor and canine teeth and the associated gingiva Superior palate

10. Parasympathetic Supply: Lacrimal gland : Post ganglionic fibres from the pterygopalatine ganglion (derived from the facial nerve), travel with the zygomatic branch of V2 and then join the lacrimal branch of V1. The fibres supply parasympathetic innervation to the lacrimal gland. Nasal glands : Parasympathetic fibres are also carried to the mucous glands of the nasal mucosa. Post-ganglionic fibres travel with the nasopalatine and greater palatine nerves (branches of V2)

11. Maxillary nerve-Branches In the cranial cavity: •Middle Meningeal nerve (to dura mater ) In pterygopalatine fossa: •Ganglionic- connected to PterygoPalatine ganglion; contain lacrimal secretomotor & sensory fibres from orbital periosteum and mucosa of nose, palate and pharynx------named below Greater and lesser palatine nerve Nasopalatine nerve Pharyngeal nerve • Zygomatic - enters orbit; divides in to zygomaticotemporal and zygomaticofacial branches. • Posterior Superior alveolar nerves In the infraorbital canal : Middle & Anterior superior alveolar nerves Infraorbital nerve On face :- Inferior palpebral lateral nasal superior labial

12. MANDIBULAR NERVE V3 The mandibular nerve contains both sensory and motor axons, arising from three sensory nuclei ( mesencephalic , principal sensory and spinal nuclei of trigeminal nerve) and one motor nucleus (motor nucleus of the trigeminal nerve) respectively . Course The motor root runs along the floor or the trigeminal cave, beneath the ganglion, joining the sensory root before leaving the cranium through the foramen ovale . Once the mandibular branch has emerged from the cranium, it courses through the infratemporal fossa, branching into four tributaries buccal nerve, inferior alveolar nerve, auriculotemporal nerve and lingual nerve .

13. Branches V3 T runk • meningeal • medial pterygoid nerve- otic /tensor tympani/tensor palatini A nterior division (4 branches, all motor except one) deep temporal nerves lateral pterygoid nerves masseteric nerve buccal nerve

14. P osterior division (3 branches, all sensory except one) - auriculotemporal nerve (TMJ )-Motor - lingual nerve - inferior alveolar nerve - incisive nerve/ mental nerve/ mylohyoid nerve

15. These branches innervate the skin, mucous membrane and striated muscle derivatives of the mandibular prominence of the 1st pharyngeal arch . Sensory supply : Mucous membranes and floor of the oral cavity External ear Lower lip Chin Anterior 2/3 of the tongue (only general sensation; special taste sensation supplied by the chorda tympani, a branch of the facial nerve) Lower molar, incisor and canine teeth and the associated gingiva

16. Motor Supply: Muscles of mastication; medial pterygoid , lateral pterygoid , masseter, temporalis Anterior belly of the digastric muscle and the mylohyoid muscle (these are suprahyoid muscles) Tensor veli palatini Tensor tympani

17. Parasympathetic Supply : Submandibular and Sublingual glands: Post-ganglionic fibres from the submandibular ganglion (derived from the facial nerve), travel with the lingual nerve to innervate these glands. Parotid gland: Post-ganglionic fibres from the otic ganglion (derived from the glossopharyngeal nerve, CN IX), travel with the auriculotemporal branch of the V3 to innervate the parotid gland .

18. SUMMARY OF GANGLIONIC SYNAPSES 1.Greater petrosal of CN VII- pterygopalatine ganglion- Zygomatic nerve fibers of V2-Lacrimal nerve-Lacrimal gland(G.V.E) 2.Chorda tympani of CN VII-Lingual nerve of V3-Submandibular ganglion-Sublingual and submandibular gland.(G.V.E) 3.Lesser petrosal nerve of CN IX – Otic ganglion – auriculotemporal (posterior trunkV3)-parotid gland(G.V.E)