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Cranial Nerves Sanjaya Adikari Department of Anatomy

Cranial Nerves Sanjaya Adikari Department of Anatomy

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Cranial Nerves Sanjaya Adikari Department of Anatomy Slide 2 12 pairs of cranial nerves III to XII attached to brain stem Their cell bodies form nuclei in the brain stem First cell body of sensory nerves lie out side CNS (form ganglia) Slide 3 Summary of cranial nerves Aspects to study 1.Position of nucleus 2.Emerging point from brain stem 3.Intracranial course 4.Point of exit from the cranial cavity 5.Extracranial course 6.Distribution Slide 4 Few terms: Somatic, branchial and visceral Slide 5 Branchial (Pharyngeal) Arches Core of mesodermal tissue covered by ectoderm and endoderm Each of the arch will have its own bone/cartilage, muscles, nerve and artery endoderm ectoderm Branchial Slide 6 Premaxilla, maxilla, zygomatic bone, part of temporal bone and mandible Mandibular branch of trigeminal nerve (V) Facial nerve (VII) Glossopharyngeal nerve (IX) Superior laryngeal branch of vagus nerve (X) Recurrent laryngeal branch of vagus nerve (X) Slide 7 Visceral In relation to internal organs Heart Lung Intestines .. Slide 8 Few hints Nerve A Nerve B Slide 9 Posterior horn Lateral horn Anterior horn Motor Sensory Motor Sensory Posterior Spinal cord (thoracic or lumbar) Somatic sensory Visceral sensory Visceral motor Somatic motor Slide 10 SM VM VS BM SS Brain stem SpS GSS Slide 11 Types of sensations Visceral sensory Somatic sensory General Visceral sensory pain, temperature, touch, viration position sense Special Visceral sensory taste General Somatic sensory pain, temperature, touch, vibration position sense Special Somatic sensory hearing Slide 12 SM VM VS BM SS SpS SM VM VS BM SpS SS Slide 13 SM VS GSS SS III IV VI XII BM V VII IX X XI VM III VII IX X VII IX X V VII IX X VIII Slide 14 Functional components of cranial nerves Somatic Motor Muscles of the orbit (III, IV, VI) Muscles of tongue (XII) III IV VI XII Slide 15 Branchial Motor Muscles of mastication (V) Facial muscles (VII) Pharyngeal and laryngeal muscles (Nucleus ambiguus via IX, X, XI nerves) Slide 16 Visceral Motor Edinger Westphal nucleus (accessory oculomotor) Salivary nuclei (NI part of VII, IX) Dorsal motor nucleus of vagus (for cardiac muscles, smooth muscles of alimentary tract) Slide 17 Sensory Consists of single nuclei for visceral and somatic sensory Visceral sensory with taste Nucleus of tractus solitarious which receives taste fibres from the tongue through VII, IX and sensory from heart, lungs and other viscera through X Slide 18 General somatic sensory Sensory nucleus of trigeminal nerve extending from the midbrain to the cervical spinal cord Slide 19 Special somatic sensory Hearing via VIII (vestibulocochlear nerve) Slide 20 SM VM VS BM GSS SS V VII IX X XI III IV VI XII III VII IX X VII IX X V VII IX X VIII Slide 21 Intracranial course and exit Sanjaya Adikari Department of Anatomy Slide 22 Slide 23 Slide 24 Superior orbital fissure (III, IV, V 1, VI) Foramen rotundum (V 2 ) Foramen ovale (V 3 ) Foramen spinosum Foramen lacerum Internal acoustic meatus (VII, VIII) Jugular foramen (IX, X, XI) Hypoglossal canal (XII) Optic canal (II) Slide 25 Olfactory Nerve (I) Olfactory bulb Olfactory tract Anterior perforated substance Uncus Bypass thalamus and goes directly into the taste area Nerve filaments Cribriform plate of ethmoid bone Slide 26 Optic Nerve (II) T N T Slide 27 Optic nerve Optic chiasma Optic tract Superior colliculus (body reflexes) Pretectal nucleus (pupillary reflexes) Lateral geniculate body of thalamus Internal capsule Optic radiation Slide 28 Oculomotor Nerve (III) Somatic motor nucleus Visceral motor nucleus ( Edinger westphal nucleus) Nerve emerges from ventral aspect of midbrain travels in the lateral wall of the cavernous sinus Slide 29 Oculomotor Nerve cont. Levator palpabrae superioris Dilator pupillae Superior rectus Medial rectus, inferior rectus, inferior oblique Ciliary muscle Sphincter pupillae Ciliary ganglion Superior division Inferior division Sympathetic from Internal carotid plexus Parasympathetic from EW nucleus Slide 30 Trochlear Nerve (IV) Somatic motor nucleus Emerges from the dorsal aspect of midbrain Travels in the lateral wall of the cavernous sinus Supplies the superior oblique muscle Slide 31 Abducens Nerve (VI) Somatic motor nucleus Nucleus lies in lower pons near midline Emerge between pons and pyramid of medulla Travels through the cavernous sinus Supply the lateral rectus muscle Slide 32 Oculomotor N (III) Ventral midbrain Lateral wall Cavernous S Divide Sup. & Inf. divisions Sup/infrao rbital fissure Trochlear N (IV) Dorsal midbrain Lateral wall Cavernous S Superior orbital fissure Abducent N (VI) Between Pons & pyramid of medulla within Cavernous S Superior orbital fissure Slide 33 Cavernous sinus 1- Oculomotor N 2- Trochlear N 3- Abducent N 4- Ophthalmic branch of TN 5- Maxillary branch of TN 6- Sympathetic plexus of N 7- Internal carotid A 8- Pituitary gland Slide 34 LR 6 (SO 4 ) 3 Slide 35 Trigeminal nerve (V) Branchial motor nucleus Somatic sensory nucleus Emerge from the ventral aspect of pons Sensory and motor roots emerge separately Slide 36 Trigeminal nerve cont. Cell bodies of 1 st order SA fibres Trigeminal ganglion Somatic sensory nucleus Branchial motor nucleus Foramen ovale Ophthalmic division Maxillary division Lat. Wall of cavernous sinous Mandibular division Mandibular nerve (mixed) Slide 37 Facial Nerve (VII) Branchial motor nucleus Visceral motor nucleus (Superior salivary nucleus) Taste sensory nucleus (Tractus solitarius) Main facial nerve and the nervous intermedius parts emerge from the cerebellopontine angle Slide 38 Geniculate ganglion (taste 1 st order cell bodies) Nucleus of Tractus solitarious Chorda tympani nerve Taste from anterior tongue Nervous intermedius Facial Nervecont. Branchial motor nucleus Nerve to stapedius Stylomastoid foramen Pure branchial motor facial nerve Supply muscles of facial expression Ear drum VE to submandibular gland and glands on the mouth floor Greater petrosal nerve Sup. salivary nucleus Internal acoustic meatus Slide 39 Vestibulocochlear Nerve (VIII) Cochlear nerve Vestibular nerve Hair cells of spiral organ Hair cells of utricle, saccule and semilunar canals Spiral ganglion of cochlea Vestibular ganglion Internal acoustic meatus Cerebellopontine angle Cochlear nuclei in pons Vestibular nuclei in medulla Slide 40 Glossopharyngeal Nerve (IX) Branchial motor nucleus (Nucleus ambiguus) supplies stylopharyngeus muscle Parasympathetic nucleus (Inferior salivary nucleus) supplies parotid gland Sensory nuclei GSS from posterior tongue goes to sensory nucleus of trigeminal nerve Taste from the posterior tongue goes to the tractus solitarius VS from baroreceptors go to nucleus of tractus solitarius Slide 41 Vagus Nerve (X) Branchial motor nucleus (Nucleus ambiguus) supplies pharyngeal constrictors Visceral motor nucleus (Dorsal motor nucleus of vagus) supplies muscles of heart, bronchi, oesophagus, stomach and intestines Visceral sensory nucleus VS from larynx, heart, lung goes to nucleus of tractus solitarius GSS goes to sensory nucleus of trigeminal nerve Slide 42 Accessory Nerve (XI) Branchial motor nerve Cranial root From nucleus ambiguus Fibres in the cranial root join the vagus nerve Somatic motor nerve Spinal root Anterior horn cells of upper 5-6 cervical spinal segments Fibres in the spinal root supply sternocleidomastoid and trapezius muscles Slide 43 Hypoglossal Nerve (XII) Somatic motor nerve Leaves cranial cavity through the hypoglossal canal Supplies all muscles (intrinsic and extrinsic) of tongue except palatoglossus Slide 44 Slide 45 Slide 46 BE VE BA GSA Slide 47 BE VE BA GSA