The nervous system Chapter two Dr. Haydar Muneer Salih

PARTS OF NERVOUS SYSTEM1. Central nervous system (CNS):a. Brain: b. Spinal cord: 2. Peripheral nervous system (PNS)It includes those parts of nervous system which lie outside the central nervous system. It consists of twelve pairs of cranial nerves, thirty one pairs of spinal nerves

CRANIAL NERVESI. Olfactory II. OpticIII. OculomotorIV. TrochlearV. TrigeminalVI. Abducent VII. FacialVIII. VestibulocochlearIX. GlossopharyngealX. VagusXI. AccessoryXII. Hypoglossal

5th cranial nerve

Trigeminal nerve

It is called trigeminal because it consists of three divisions, namely:1. Ophthalmic nerve2. Maxillary nerve3. Mandibular nerveThe three nerves arise from a large, semilunar trigeminal ganglion which lies in the trigeminal fossa on the anterior surface of the petrous temporal bone near its apex.

Attached to ventral surface of pons

Trigeminal fossa

Opthalmic Division

1. Ophthalmic divisionIt is the smallest of the three divisions of trigeminal nerve. It is purely sensory and It runs forward in the lateral wall of the cavernous sinus in the middle cranial fossa and divides into three branches, the lacrimal, frontal, and nasociliary nerves, which enter the orbital cavity through the superior orbital fissure.

Branches of ophthalmic nerve1. The frontal nerve runs forward on the upper surface of the levator palpebrae superioris muscle and divides into the supraorbital and supratrochlear nerves These nerves leave the orbital cavity and supply the frontal air sinus and the skin of the forehead and the scalp

Branches of ophthalmic nerveThe nasociliary nerve

crosses the optic nerve, runs forward on the upper border of the medial rectus muscle and continues as the anterior ethmoid nerve

Its gives offCiliary branchInfratrochlearPosterior ethmoid

Branches of ophthalmic nerveThe lacrimal nerve runs forward on the upper border of the lateral rectus muscle. It is joined by the zygomaticotemporal branch of the maxillary nerve, which contains the parasympathetic secret motor fibers to the lacrimal gland. The lacrimal nerve then enters the lacrimal gland and gives branches to the conjunctiva and the skin of the upper eyelid.

Maxillary Division

It is the second division of trigeminal nerve. It is also purely sensory.The nerve leaves the middle cranial fossa through foramen rotundum and reaches the pterygopalatine fossa• It enters orbit through the inferior orbital fissure where it is called as the infraorbital nerve, it appears on the face through the infraorbital foramen.• Therefore, in its course the maxillary nerve traverses in the middle cranial fossa, the pterygopalatine fossa and the orbit

Important Branches of maxillary division 1. Zygomatic nerve:a. Zygomatico-temporal nerveb. Zygomatico-facial nerve2. Posterior superior alveolar nerve:3. Middle superior alveolar nerve: 4. Anterior superior alveolar nerve: a. The dental branches b. The nasal branches.

Important Branches of maxillary division

On the face: These are also branches of 5. infra-orbital nerve after it emerges out from infra-orbital foramen.6. Superior labial branches: Supply the skin and mucous membrane of the upper lip

PTERYGOPALATINE GANGLIONSPHENOPALATINE GANGLIONIs the largest peripheral ganglion of the parasympathetic system. It serves as a relay station for the secretomotor fibres of the lacrimal glands and mucous glands of the nose, palate, pharynx and paranasal sinuses. Topographically, it is related to the maxillary nerve, but functionally, it is connected to the facial nerve through greater petrosal nerve.

PTERYGOPALATINE GANGLIONSPHENOPALATINE GANGLIONBranches■■ Orbital branches, which enter the orbit through the inferior orbital fissure■■ Greater and lesser palatine nerves , which supply the palate, the tonsil, and the nasal cavity■■ Pharyngeal branch, which supplies the roof of the nasopharynx

Mandibular Division

This is largest of the three divisions of the trigeminal nerve and is the nerve of the first branchial archIt is formed by two roots.1. Larger sensory root: 2. Small motor root:

Branches of Mandibular NerveFrom Main Trunk:1. Nervous spinosus (meningeal branch):2. Nerve to medial pterygoid

From Anterior Division:It gives rise to 3 motor branches and one sensory branch.1. Deep temporal nerves:2. Nerve to lateral pterygoid, 3. Masseteric nerve, 4. Buccal nerve: It is the sensory branch which supplies the skin and mucus membrane of cheek.

From Posterior Division:It gives rise to three nerves namely:1. Auriculotemporal nerve: It is a sensory nerve.2. Inferior alveolar nerve: It is the larger terminal branch of mandibular nerve and it is a mixed nerve.3. Lingual nerve: It is primarily sensory nerve:

OTIC GANGLION It is a parasympathetic ganglion connected to the mandibular division of trigeminal nerve which provides a relay station to the secretomotor parasympathetic fibers of the parotid gland. Topographically, it is connected to mandibular nerve but functionally, it is associated with glossopharyngeal nerve

7th cranial nerve

Facial nerve

Facial nerve is the seventh cranial nerve it has a motor root and sensory root (nervus intermedius which carry somatosensory fibers and parasympathetic secretomotor fibersThe nerve emerges on the anterior surface of the hindbrain between the pons and medulla oblongata

Terminal branches

Summary