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Cranial Nerves

2. Cerebral Cortex. Two hemispheresSeparated by longitudinal fissureRight and Left hemispheresConnected by Corpus CallosumOuter gray matter

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Cranial Nerves

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    1. 1 Cranial Nerves

    2. 2 Cerebral Cortex Two hemispheres Separated by longitudinal fissure Right and Left hemispheres Connected by Corpus Callosum Outer gray matter – neurones Inner white matter – nerve fibres, and neuroglia Sulci and gyri Frontal parietal temporal and occipital lobes

    3. 3 Brain Stem Midbrain Pons Medulla oblongata Midbrain connects the pons and the cerebellum with the cerebral hemispheres Cranial nerves III and IV originate in the midbrain Pons in front of cerebellum; between the midbrain and medulla and is a bridge between the two halves of the cerebellum and between the medulla and the cerebrum Cranial nerves V, VI, VII and VIII originate in the pons IX, X, XI and XII have their nuclei in medulla oblongata

    4. 4 Cerebellum Separated from the cerebral hemispheres by tentorium cerebelli Responsible for coordination of movement – balance position sense (awareness of where each part of the body is)

    5. 5 Cranial Nerves 12 pairs Emerge from the lower surface of the brain and pass through the foramina in the skull I, II, VIII – sensory III, IV ,V, XI and XII – motor V, VII, IX and X are – mixed

    6. 6 Cranial Nerves Olfactory – sensory - sense of smell Optic nerve – sensory – visual acuity Oculomotor – motor – eye ball movement, lid movement, pupillary constriction lens accommodation Trochlear – motor – muscles that move the eye Trigeminal – mixed – facial sensation, mastication Abducens – motor – muscle that move the eye Facial – mixed – facial expression, salivation, taste Vestibulocochlear – sensory – hearing and equilibrium Glossopharyngeal – mixed – taste, sensation in the pharynx and tongue, pharyngeal muscles Vagus – mixed – muscles of pharynx, larynx, soft palate, thoracic and abdominal viscera – parasympathetic innervation Spinal accessory – motor – sternocleidomastoid trapezius muscles. Hypoglossal – motor – movement of the tongue

    7. 7 Olfactory nerves Nerve of the sense of smell Nerve endings and fibres arise in the upper part of the mucous membrane of the nose Pass upwards through the cribriform plate of ethmoid bone These nerves pass to the olfactory bulb Thence proceed backwards as the olfactory tract, to the area of smell in the temporal lobe

    8. 8 Optic nerves Nerves of the sense of sight Fibres originate in the retina The fibres combine to form optic nerve Optic nerve passes through the optic foramina of the sphenoid bone Join optic chiasma above the pituitary gland The nerves proceede backwards as the optic tracts to the lateral geniculate bodies From LGB the impulses pass as optic radiations to the centre for sight in the occipital lobes and to the cerebellum In the occipital lobe sight is perceived The central retinal artery and vein enter the eye enveloped by the fibres of the optic nerve

    9. 9 Oculomotor nerve Arises from nerve cells near the cerebral aqueduct. It supplies the following extra-ocular muscles : superior rectus, medial retus, inferior rectus and the inferior oblique muscles of the eye It also supplies the following intra-ocular muscles also ciliary muscles – shape of lens circular muscles of the iris – constrict the iris It supplies the levator palpebrae muscle – raises the upper eyelid

    10. 10 Trochlear nerve This nerve arises from nerve cells near the cerebral aqueduct. It supplies the superior oblique muscle of the eye which moves the eye ball downwards and outwards

    11. 11 Trigeminal nerve Contains motor and sensory fibres Chief sensory nerve for the face and head Pain temperature and touch Motor action on muscles of mastication Three main branches – dermatomes as shown in the picture The ophthalmic branch – sensory – lacrimal glands, conjunctiva, forehead, eyelids anterior aspect of scalp and mucous membrane of the nose The maxillary branch – sensory – cheeks, upper gums, upper teeth aned lower eyelids The mandibular branch sensory and motor – teeth and gums of the lower jaw, pinnas lower lip and tongue – muscles of mastication

    12. 12 Abducent nerve From nerve cells lying under the floor of the fourth ventricle supplies lateral rectus muscle

    13. 13 Facial nerve Motor and sensory From nerve cells in the lower part of the pons varolii Supplies muscles of facial expression Sensations from taste buds on the anterior 2/3 of tongue to the taste perception area in the cerebral cortex

    14. 14 Vestibulocochlear nerve Two distinct sets of fibres – vestibular nerves and cochlear nerves Vestibular nerve arises from the semicircular canals go to cerebellum – associated with the manitenance of posture and balance The cochlear nerve originate in the organ of Corti – go to hearing areas of the cerebral cortex.

    15. 15 Glossopharyngeal nerve From nuclei in the medulla oblongata. Motor fibres – muscles of the tongue and pharynx and secretory cells of the parotid Sensory fibres – go to cerebral cortex from posterior 1/3 of tongue, the tonsils and pharynx. Nerves IX, X and XI go out of the cranium through the same foramen – the jugular foramen

    16. 16 Vagus nerve Aise from nerve cells in the medullar oblongata and other nuclei Pass through neck into the thorax and the abdomen Motor – smooth muscles and secretory glands of the pharynx, larynx, trachea, heart, oesophagus, stomach, intestines, pancreas, gall blader, bile ducts spleen, kidneys, ureter and blood vessels in the thoracic and abdominal cavities Sensory – lining membranes of the above structures.

    17. 17 Accessory nerve Arise from nerve cells in the medulla oblongata and in the spinal cord. Supplies sternocleidomastoid and trapezius muscles Branches join the vagus nerve and supply the pharyngeal and laryngeal muscles

    18. 18 Hypoglossal nerve Arise from cells in the medulla oblongata Supply the muscles of the tongue and muscles surrounding the hyoid bone and contribute to swallowing and speech

    19. 19 Assessing Cranial Nerve Function Olfactory Nerve : identify odors with eyes closed – coffee etc Optic Nerve : snellen eye chart; visual fields : ophthalmoscopic examination Oculomotor Nerve : III, IV and VI : ocular rotations, conjugate movements, nystagmus. Test for pupillary reflexes and inspect eyelids for ptosis Trochlear Abducens Trigeminal Nerve :

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    37. 37 Oculomotor nerve

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    40. 40 Brain stem - Cranial nerves - anterior view 1. Oculomotor nerve CN.III 2. Trochlear nerve CN.IV 3. Transverse pontine vein 4. Abducent nerve CN.VI 5. Trigeminal nerve CN.V 6. Facial and vestibulocochlear nerves CN.VII/VIII 7. Glossopharyngeal nerve CN.IX 8. Vagus nerve CN.X 9. Accesory nerve -spinal part CN.XI 10. Hypoglossal nerve CN.XII 11. Anterior cerebellar vein

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    42. 42 Trigeminal nerve Trigeminal nerve

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    44. 44 TRIGEMINAL NERVE

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    49. 49 Facial nerve

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    53. 53 Glosso pharyngeal nerve

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    69. 69 The End

    70. 70 a) Frontal bone. b) Frontal sinus. c) Internal frontal spine. d) Foramen caecum. e) Crista galli. f) Frontal bone, orbital portion. g) Cellulae of the ethmoidal bone. h) Body of the sphenoid bone. i) Greater wing of the sphenoid bone. k) Occipital bone, basilar portion. l) Temporal bone, squamous portion. m) Temporal bone, petrous portion. n) Optic foramen. o) Foramen rotundum. p) Foramen ovale. q) Foramen spinosum. r) Superior orbital fissure. s) Tympanic cavity. t) Internal auditory meatus (broken open from above). u) Malleus, hammer (s. capitulum). v) Incus (s. ambos). w) Cochlea. x) Superior semicircular canal. y) Ocular bulb. z) Lacrimal gland. a) m. Lateral rectus. b) m. Levator palpebrae superioris. g) m. Superior rectus. d) m. Superior oblique. d*) Trochlea for superior oblique. e) m. Medial rectus. z) m. Temporalis (medial surface). h) m. Lateral pterygoid. q) Hypophysis (pituitary gland). i) Foramen magnum. k) Jugular foramen. l) Hypoglossal canal (s. Anterior condyloid foramen). m) Occipital bone (fossae cerebelli). n) Transverse sinus. middle meningeal artery (branch of the maxillary artery). internal carotid artery. lacrymal artery. artery, muscle branch. supraorbital artery. ethmoidal artery. ophthalmic artery. optic nerve (CN II). oculomotor nerve (CN III). trochlear nerve (CN IV). trigeminal nerve (CN V). semilunar ganglion (s. Gasserian or trigeminal ganglion). mandibular nerve (s. maxillaris inferior) [branch of trigeminal nerve]. maxillary nerve (s. maxillaries superior) [branch of trigeminal nerve]. ophthalmic nerve, [branch of trigeminal nerve]. frontal branch, ophthalmic nerve. lacrymal branch, ophthalmic nerve. nasal branch, ophthalmic nerve. ethmoidal branch, nasal nerve. infratrochlear branch, nasal nerve. supratrochlear branch, frontal nerve. supraorbital branch, frontal nerve.

    71. 71 zygomatic branch, lacrymal nerve. lacrymal branch, lacrymal nerve. ciliary nerves (from the ciliary ganglion [s. ganglion opthalmicum]). nerve to the m. buccinator. deep temporal nerve. nerve to the m. masseter. superficial temporal nerve (s. auricularis anterior nerve). maxillary artery. nerves of the external auditory meatus. chorda tympani (of facial nerve). petrosus minor nerve [NA] (s. lesser superficial petrosal nerve). petrosus major nerve [NA] (s. greater superficial petrosal nerve, nervus Vidianus, nervus petrosus superficialis major) [carried in the genu of the facial nerve]. abducens nerve (CN VI). facial nerve (CN VII) inner half of the internal auditory meatus. genu (facial nerve). facial nerve in the Fallopian canal. cochlear nerve (CN VIII). vestibular nerve (CN VIII). glossopharyngeal nerve (CN IX). vagus nerve (CN X). spinal accessory nerve of Willis (CN XI). hypoglossal nerve (CN XII). vertebral artery.

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