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Cranial Nerves

Cranial Nerves. Sanjaya Adikari Department of Anatomy. 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). Summary of cranial nerves. Aspects to study

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Cranial Nerves

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  1. Cranial Nerves Sanjaya Adikari Department of Anatomy

  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)

  3. Summary of cranial nerves • Aspects to study • Position of nucleus • Emerging point from brain stem • Intracranial course • Point of exit from the cranial cavity • Extracranial course • Distribution

  4. Few terms: Somatic, branchial and visceral

  5. Branchial Branchial (Pharyngeal) Arches ectoderm • Core of mesodermal tissue covered by ectoderm and endoderm • Each of the arch will have its own bone/cartilage, muscles, nerve and artery endoderm

  6. Mandibular branch of trigeminal nerve (V) Facial nerve (VII) Premaxilla, maxilla, zygomatic bone, part of temporal bone and mandible Glossopharyngealnerve (IX) Superior laryngeal branch of vagusnerve (X) Recurrent laryngeal branch of vagusnerve (X)

  7. Visceral • In relation to internal organs • Heart • Lung • Intestines ……………… ……………..

  8. Few hints Nerve A Nerve B

  9. Sensory Motor Posterior horn Lateral horn Sensory Motor Anterior horn Posterior Somatic sensory Visceral sensory Visceral motor Somatic motor Spinal cord (thoracic or lumbar)

  10. Brain stem SpS SS GSS VS VM BM SM

  11. Types of sensations General Visceral sensory pain, temperature, touch, viration position sense Visceral sensory Special Visceral sensory taste General Somatic sensory pain, temperature, touch, vibration position sense Somatic sensory Special Somatic sensory hearing

  12. SS GSS VS VM BM SM III IV VI XII V VII IX X XI III VII IX X VII IX X V VII IX X VIII

  13. Functional components of cranial nerves III IV Somatic Motor Muscles of the orbit (III, IV, VI) Muscles of tongue (XII) VI XII

  14. BranchialMotor Muscles of mastication (V) Facial muscles (VII) Pharyngeal and laryngeal muscles (Nucleus ambiguusvia IX, X, XI nerves)

  15. Visceral Motor EdingerWestphal nucleus (accessory oculomotor) Salivary nuclei (NI part of VII, IX) Dorsal motor nucleus of vagus (for cardiac muscles, smooth muscles of alimentary tract)

  16. Sensory Consists of single nuclei for visceral and somatic sensory Visceral sensory with taste Nucleus of tractussolitariouswhich receives taste fibres from the tongue through VII, IX and sensory from heart, lungs and other viscera through X

  17. General somatic sensory Sensory nucleus of trigeminal nerve extending from the midbrain to the cervical spinal cord

  18. Special somatic sensory Hearing via VIII (vestibulocochlear nerve)

  19. SS GSS VS BM VM SM III IV VI XII III VII IX X V VII IX X XI VII IX X V VII IX X VIII

  20. Intracranial course and exit SanjayaAdikari Department of Anatomy

  21. Optic canal (II) Superior orbital fissure (III, IV, V1, VI) Foramen rotundum (V2) Foramen ovale (V3) Foramen spinosum Foramen lacerum Internal acoustic meatus (VII, VIII) Jugular foramen (IX, X, XI) Hypoglossal canal (XII)

  22. Olfactory Nerve (I) Anterior perforated substance Olfactory tract Uncus Olfactory bulb Nerve filaments Cribriform plate of ethmoid bone Bypass thalamus and goes directly into the taste area

  23. Optic Nerve (II) T N T

  24. Optic Nerve (II) Optic nerve Optic chiasma Optic tract Optic radiation Superior colliculus (body reflexes) Pretectal nucleus (pupillary reflexes) Internal capsule Lateral geniculate body of thalamus

  25. Oculomotor Nerve (III) Somatic motor nucleus Visceral motor nucleus (Edingerwestphalnucleus) Nerve emerges from ventral aspect of midbrain travel’s in the lateral wall of the cavernous sinus

  26. Oculomotor Nerve… cont. Levator palpabrae superioris Dilator pupillae Sympathetic from Internal carotid plexus Superior division Superior rectus Medial rectus, inferior rectus, inferior oblique Inferior division Parasympathetic from EW nucleus Ciliary muscle Sphincter pupillae Ciliary ganglion

  27. 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

  28. AbducensNerve (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

  29. Oculomotor N (III) Ventral midbrain Lateral wall Cavernous S Divide Sup. & Inf. divisions Sup/infraorbital 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

  30. Cavernous sinus 5- Maxillary branch of TN 6- Sympathetic plexus of N 7- Internal carotid A 8- Pituitary gland 1- Oculomotor N 2- Trochlear N 3- Abducent N 4- Ophthalmic branch of TN

  31. LR6(SO4)3

  32. Trigeminal nerve (V) Branchial motor nucleus Somatic sensory nucleus Emerge from the ventral aspect of pons Sensory and motor roots emerge separately

  33. Trigeminal nerve… cont. Somatic sensory nucleus Trigeminal ganglion Ophthalmic division Cell bodies of 1st order SA fibres Lat. Wall of cavernous sinous Maxillary division Mandibulardivision Mandibularnerve (mixed) Branchial motor nucleus Foramen ovale

  34. Facial Nerve (VII) Branchial motor nucleus Visceral motor nucleus (Superior salivary nucleus) Taste sensory nucleus (Tractussolitarius) Main facial nerve and the nervous intermediusparts emerge from the cerebellopontine angle

  35. Facial Nerve…cont. Internal acoustic meatus Geniculate ganglion (taste 1st order cell bodies) Branchialmotor nucleus Greater petrosal nerve Sup. salivary nucleus Chorda tympani nerve Nerve to stapedius Nervous intermedius Nucleus of Tractussolitarious Ear drum Stylomastoid foramen Pure branchial motor facial nerve Supply muscles of facial expression VE to submandibular gland and glands on the mouth floor Taste from anterior tongue

  36. Vestibulocochlear Nerve (VIII) Internal acoustic meatus Spiral ganglion of cochlea Cochlear nuclei in pons Cochlear nerve Hair cells of spiral organ Vestibular ganglion Vestibular nuclei in medulla Cerebellopontineangle Vestibular nerve Hair cells of utricle, saccule and semilunar canals

  37. Glossopharyngeal Nerve (IX) Branchialmotor 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 tractussolitarius VS from baroreceptors go to nucleus of tractussolitarius

  38. Vagus Nerve (X) Branchialmotor 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 tractussolitarius GSS goes to sensory nucleus of trigeminal nerve

  39. Accessory Nerve (XI) Branchialmotor nerve Cranial rootFrom nucleus ambiguus Fibres in the cranial root join the vagus nerve Somatic motor nerve Spinal rootAnterior horn cells of upper 5-6 cervical spinal segments Fibres in the spinal root supply sternocleidomastoid and trapezius muscles

  40. Hypoglossal Nerve (XII) Somatic motor nerve Leaves cranial cavity through the hypoglossal canal Supplies all muscles (intrinsic and extrinsic) of tongue except palatoglossus

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