1. Cranial nerves & Cranial nerve nuclei : The base of the brain showing locations of cranial nerves  There are 12, paired cranial nerves.  The first 2 cranial Ns. attach directly to forebrain, while the rest attach to brain stem.  Olfactory system is attached to forebrain and is referred to as the limbic system, / optic N. also is discribed in visual pathway.  Cranial Ns. from 3 - 12 have nuclei (cranial N.nucluei) in the brain stem, receiving afferents Fs. Or send efferent Fs. as the cranial Ns.

2. Superficial attachements of Cranial nerves : Superficial attachements of Cranial nerves : The base of the brain showing locations of cranial nerves  Occulomotor & trochlear Ns. are attached to midbrain.  Trigeminal N. is attached to antero-lateral surface of pons.  Abducent, Facial & vestibulo- cochlear Ns. are lying between pons & M.O. from medial to lateral.  Hypoglossal N. lies between olive & pyramid in the M.O. / but glossopharyngeal, vagus & accessory Ns. are attached to postero-lateral sulcus of M.O., lateral to olive.

3. Dorsal aspect of brain stem showing locations of Afferent cranial N. nuclei (left), and Efferent cranial N.nuclei (right), in which the same colours have a common embryological origin. Afferent Nerve Nuclei :  Large Trigeminal Sensory nucleus, extends the whole length of brain stem and cervical spinal cord. receiving general sensation from the head via trigeminal N.  Vestibular & Cochlear nuclei that are located in upper M.O., receiving hearing & positional sense via vestibulo-cochlear N.  Nucleus solitarius located in upper M.O., receiving taste sensation via facial & glossopharyngeal Ns.

4. Efferent Nerve Nuclei :  Somatic efferent column : supplies striated Ms. in head, including : 1- Oculomotor nucleus.2-Trochlear nucleus. 3-Abducent nucleus. 4-Hypoglssal nucleus.  Branchiomotor (special visceral) efferent column : supplies striated Ms. derived from branchial arches, including : 1- Trigeminal motor nucleus. 2- Facial motor nucleus. 3- Nucleus ambiguus.  Parasympathetic (general visceral) efferent column : supplies glands & smooth Ms. of viscera, including : 1- Edinger- Westphal nucleus. 2- Sup.& Inf. Salivary nuclei. 3- Dorsal nucleus of vagus.

5. Somatic efferent Nerve Nuclei  Oculomotor nucleus : lies at the base of periaqueductal grey of midbrain at the level of superior colliculus. Its efferent Fs. run in oculomotor N. to innervate levator palpebrae superiooris + all extraocular Ms. Except L.R & S.O  Trochlear nucleus : lies at the ventral part of periaqueductal grey of midbrain at the level of inferior colliculus. Its efferent Fs. run in trochlear N. to innervate S.O.muscle.

6. Somatic efferent Nerve Nuclei :  Abducent nucleus : lies in the caudal pons, beneath floor of 4 th vent. Its efferent Fs. run in abducent N. to supply L.R.  Hypoglossal nucleus : lies in the rostral M.O. its efferent Fs. run in hypoglossal N. to supply all Ms. of tongue Except palatoglossus muscle.

7. Branchiomotor efferent Nerve Nuclei  Trigeminal motor nucleus : lies in the tegmentum of the mid-pons and its motor Fs. run in mandibular branch of trigeminal N. to supply structures of 1 st pharyngeal arch as Ms. of mustication, mylohyoid, ant.belly of digastric, tensor tympani (middle ear) & tensor veli palatini.(soft palate).  Facial motor nucleus : lies in the caudal pontine tegmentum, its motor Fs. run in facial N. to innervate Ms. of facial expression, stapedius muscle (middle ear) & other Ms. derived from 2 nd pharygeal arch (stylohyoid, post.belly of digastric).  Nucleus ambiguus : it is a long nucleus lies in M.O., sending motor Fs. in 9 th,10 th & cranial root of 11 th nerves to innervate Ms. of pharynx & larynx derived from 3,4& 6 pharyngeal arches.

8. Parasympathetic efferent Nerve Nuclei :  Edinger-Westphal nucleus lies in midbrain adjacent to oculomotor nucleus. It is the parasymp. part of oculomotor nucleus. It gives preganglionic parasymp. motor Fs. Via oculomotor N. into ciliary ganglion, which sends postganglionic Fs. to innervate sphincter pupillae & ciliary Ms. in the eye.  Superior salivary nucleus : lies in caudal pontine tegmentum, it gives preganglionic Fs. Via facial N. into pterygo- palatine & submandibular ganglia, which gives postganglionic Fs. to innervate lacrimal gl., Nasal and oral M.Ms. & submandibular and sublingual salivary glands…. respictevly

9. Parasympathetic efferent Nerve Nuclei :  Inferior salivary nucleus : lies in pontine tegmentum, sends pre- ganglionic Fs. Via glosso-pharyngeal N. into otic ganglion, which sends post-ganglionic Fs. to parotid gland. + via Vagus N. to supply mucous gland of G.I.T & respiratory glands.  Dorsal motor nucleus of vagus : lies in the rostral M.O. lateral to hypoglossal nucleus, it gives preganglionic parasymp.Fs. Via vagus N. to supply ms. of abdominal & respiratory viscera.

10. Cranial Nerves : III : Oculomotor N.  This N. contains 2-types of fibres : 1- Somatic motor efferent Fs. from oculomotor nucleus to all extrinsic eye Ms. Except S.O &L.R. 2- Preganglionic parasymp. motor Fs. from Edinger-Westphal nucleus into ciliary ganglion which sends postganglionic Fs. via short ciliary nerves into constrictor pupillae & ciliary ms.

11. T.S of midbrain at the level of sup.colliculus to illustrate the pathway of pupillary light reflex.  During the visual pathway,small Fs. leave the optic tract to synape in pretectal nucleus, which projects bilaterally Fs. to Edinger-Westphal nuclei of occulomotor,that send efferent parasympathetic Fs. Via oculomotor nerves on both sides to sphincter pupillae ms. Note that pretectal area involves in mediation of pupillary light reflex.

12. Accomodation Reflex :  Fixation upon a nearby object, involves contraction of ciliary muscles to increase the convexity of lens, thus focusing the image.  It is also accompanied by activation of sphincter pupillae m.  Fibres from visual frontal cortex activate the parasymp. Edinger- Westphal nuclei on both sides to supply ciliary & sphincter pupillae Ms. Optic pathway and Visual reflexes (pupillary light R.+ accomodation R.)

13. IV : Trochlear Nerve : T.S of midbrain at the level of inferior colliculus,showing the location of trochlear nucleus (at the base of periaquaductal grey matter) and course of trochlear N.Fs.  This N. carries only somatic motor efferent Fs. from the trochlear nucleus in midbrain (level of inferior colliculus) to supply the S.O. of opposite side.  Trchlear N.,the only nerve emerges from the post.surface of brain - stem,then appears on the ventral aspect of the midbrain.

14. VI : Abducens Nerve :  Contains only somatic motor neurones in the abducens nucleus,which located in caudal pons beneath the floor of 4 th ventricle.  Fibres emerge from the ventral surface of brain stem at the junction between the pons & pyramid of M.O  The nerve then passes in the cavernous sinus and enter orbit through sup. orbital fissure to supply L.R muscle to abduct the eyeball.

15. Lesions of cranial nerves III,IV and VI :  Oculomotor N. palsy by a lesion of occulomotor nucleus in midbrain or compression by aneurysm or tumour leads to ptosis, dilatation of pupil that is unresponsive to light & accommodation reflexes and inability to move eyeball upwards, downwards and inwards (adduction).  Abducens N. palsy leads to inability to move the eyeball outwards (abduction).  Combined unilateral palsies of III, IV,and VI during their course in cavernous sinus, sup. Orbital fissure or within the orbit, lead to: 1-ptosis. 2-dilatation of pupil. 3-paralysis of all eye movements  Note right ptosis.  Note with elevation of right eyelid, the eyeball can be seen abducted and the pupil dilated.  Note failure of left eyeball abduction due to lesion of left abducent N.

16. V : Trigeminal Nerve : V : Trigeminal Nerve : Superficial distribution of sensory fibres of the 3 divisions of trigeminal nerve.  It is the largest cranial N., it has both sensory Fs. that are distributed via ophthalmic, maxillary and mandibular to the head --- & motor Fs. Via mandibular N. to ms. of mastications (Ms.of 1 st arch).  It attaches to the ventrolateral aspect of pons by 2 roots (a large sensory laterally & a smaller motor medially).

17. V : Sensory components of Trigeminal Nerve : Brain stem and location of trigeminal sensory nucleus & its major connections.  Trigeminal sensory nucleus consists of 3-subnuclei : 1-Chief (principle) sensory nucleus lies in pontine tegmentum (mid- pon), it recevies touch sensation. 2-Spinal nucleus extends caudally through the medulla and upper cervical spinal cord to become continuous with substantia gelatinosa, it recevies pain & temp.sensation from face & scalp. 3-Mesencephalic nucleus in midbrain, it recevies proprioception (deep) sensation from head.

18. Sensory components of Trigeminal nerve (for touch/pressure & pain/temperature) : Sensory components of Trigeminal nerve (for touch/pressure & pain/temperature) : Brain stem and location of trigeminal sensory nucleus & its major connections.  Afferent Fs. of touch, pressure, pain & temperature are recevied from skin of face,scalp, via peripheral processes (ophthalmic,maxillary+sensory part of mandibular)… whose cell bodies (first neurones) are situated in trigeminal ganglion (located at the convergence of ophthalmic, maxillary and mandibular nerves).  Afferent Fs.(centeral axons) conveying touch terminate in principal nucleus, and those carrying pain & temp. end in nucleus of spinal tract of trigeminal.

19. Sensory components of Trigeminal nerve (for proprioceptive sensation) : Brain stem and location of trigeminal sensory nucleus & its major connections.  1 st neurone for Proprioceptive : peripheral afferents (via mandibular nerve) from Ms.of mustication & temporo- mandibular joint have their cell bodies not in trigeminal ganglion but in mesencephalic nucleus of trigeminal ( the only primary afferents to have cell bodies within C.N.S).  The centeral axons of the cells of mesencephalic nucleus descend medially to synapse around Motor Nucleus of Trigeminal (2 ND neurone) in pons.  Axons arising from 2 nd neurones in trigeminal nuclei decussate to form contralateral trigemino-thalamic tract, which terminates in contralateral (VP) nucleus of thalamus that sends Fs. to sensory cortex.

20. Motor components of Trigeminal Nerve :  The motor Fs.of trigeminal N. arise from the trigeminal motor nucleus, which lies in pontine tegmentum.  The axons leave the pons to join the mandibular division of trigeminal, to innervate 1 st pharyngeal arch drevatives : 1- 4 Ms. of mastication. 2- 4 other Ms. : mylohyoid, anterior belly of digastric, tensor palati (soft palate) & tensor tympani (middle ear). T.S of pons at the level of Trigeminal nuclei.

21. Lesions of Trigeminal Nerve : Lesions of Trigeminal Nerve : Herpes Zoster infection of sensory root of trigeminal N. ….. Leads to severe stabbing pain & eruption of vesicles localised to skin supplied by its branches : ophthalmic, or maxillary or mandibular N….. Trigeminal Neuralgia. Herpes Zoster infection of sensory root of trigeminal N. ….. Leads to severe stabbing pain & eruption of vesicles localised to skin supplied by its branches : ophthalmic, or maxillary or mandibular N….. Trigeminal Neuralgia. Syringo-bulbia,it is a disease of unknown etiology which affects the closed M.O, causes central cavitation of medulla caudal to 4 th V., leading to destruction & damage of decussating trigemino-thalamic Fs., causing selective loss of pain & temp. sensation in the face ( dissociated sensory loss), mostly leading to destruction of the cervical spinal cord (syringomyelia) =cavitation of spinal cord. Syringo-bulbia,it is a disease of unknown etiology which affects the closed M.O, causes central cavitation of medulla caudal to 4 th V., leading to destruction & damage of decussating trigemino-thalamic Fs., causing selective loss of pain & temp. sensation in the face ( dissociated sensory loss), mostly leading to destruction of the cervical spinal cord (syringomyelia) =cavitation of spinal cord.

22. 1. All of the following are corresponding to parasympathetic efferent nuclei EXCEPT: a.Superior salivary nucleus. b.Inferior salivary nucleus. c.Abducent nucleus. d.Edinger-Westphal nucleus. e.Dorsal motor nucleus of vagus. 2. Which of the following is Corresponding to branchiomotor efferent nuclei ? a.Edinger-Westphal nucleus. b.Dorsal motor nucleus of vagus. c.Oculomotor nucleus. d.Nucleus ambiguus. e.Hypoglossal nucleus.

23. 3.Bulbar palsy is confirmed by degeneration of one of the following Nuclei : a.Oculomotor nucleus. b.Mesencephalic nucleus. c.Abducent nucleus. d.Trochlear nucleus. e.Nucleus ambiguus. 4.Syringobulbia leads to destruction of : a.The lateral lemniscus. b.The trigeminal lemniscus. c.The corticobulbar tract. d.The spinothalamic tract. e.The trapezoid body.

25. VII : Facial Nerve : 1-The lateral root (Nervous intermedius) contains sensory & parasymp.Fs. 2- The medial root is the motor root.  It consists of 2 roots :

26. VII : Facial Nerve :  It carries 3-types of fibres : 1- Efferent motor (branchiomotor) Fs. From facial motor nucleus in pons to : Ms. of 2 nd arch, Ms. of facial expression & stapedius. 2-Efferent parasympathetic secretomotor Fs. Carried by lateral root of facial nerve (nervus intermedius) From sup. salivary nucleus in pons : to pterygopalatine & submandibular ganglia to lacrimal gland, palate, nasal & oral m.m, /and submandibular & sublingual salivary glands. 3- Sensory Taste Fs. from anterior 2/3 of tongue, cell bodies in sensory geniculate ganglion in middle ear, and run in nervus intermedius to end in Nucleus Solitarius in M.O. projecting into (v.p) of thalamus then to sensory cortex

27. VII : Facial Motor Nerve :  Motor Fs. of facial nucleus in pons, via facial N. looping over abducens nucleus, then leaving the brain stem to supply : Ms.of facial expression,platysma,stylohyoid, post.belly of digastric & stapedius of middle ear.  Facial motor nucleus receives other afferents from brain stem for mediation of certain reflexes and from cerebral cortex for cortico-bulbar pyramidal tract.

28. VII : Facial Motor Nerve :  Reflex connections mediate 1- protective eye closure in response to sudden strong stimuli via facial N. to supply orbicularis oculi to close & protect the eye. 2- corneal reflex through Fs. from trigeminal sensory nucleus, to motor nucleus of facial, then via facial N. to orbicularis oculi in response to tactile stimulation of cornea.  Afferents from cortical motor areas (cotico-bulbar Fs.) supply Ms. of upper face which are distributed bilaterally (from Rt.& left C.hemispheres), but those supplying Ms. of lower face are crossed. So, Unilateral upper motor neurone lesion (UMNL) leads to lower facial Ms. paralysis of opposite side only, but upper Ms. are intact.

29. Bell’s Palsy :LMN facial paralysis It is due to acute unilateral inflammation of facial nerve within the skull (in facial canal). It is due to acute unilateral inflammation of facial nerve within the skull (in facial canal).  Manifested by paralysis of facial muscles of upper & lower parts of face on the same side of lesion..  Manifested by pain around ear, - failure to close eye, absent corneal reflex, - loss of taste sensation in anterior 2/3 of tongue, & hyperacusis =increased sound perception due to paralysis of stapedius. (action of stapedius = damping down the intensity of high pitched sounds by damping down movement of stapes)  If herpes zoster virus is the inflammatory agent, a vesicular rash appear in ext. auditory canal & m.m of oropharynx (Ramsay Hunt syndrome).

30. VIII : Vestibulocochlear Nerve :  It is purely sensory nerve.  It has 2-components, 1- Vestibular N., which carries balance sensation from utricle, sacule & semicircular canals. 2- Cochlear N., which carries hearing sensation.  It emerges from ponto-medullary junction at cerebello-pontine angle

31. VIII : Vestibular Nerve : VIII : Vestibular Nerve : Distribution of Vestibular Nerve  Cells of origin : vestibular ganglion,lying in internal acoustic meatus.  The peripheral process : carries sensation from utricle,saccule & semicircular canals (membranous labyrinth).  Central process : leaves vestibular ganglion and joins cochlear N.  It enters the brain in groove between pons & M.O. to end in the Vestibular nuclei in M.O.

32. Vestibular Nerve Fibres : Vestibular nerve nuclei & their central connections (rostral M.O.) 1-Efferent Fs. From the 4 vestibular nuclei to cerebellum ( flocculo-nodular lobe) through inferior cerebellar peduncle to control balance. 2-Efferent Fs. descend uncrossed to spinal cord from lateral vestibular (Deiter’s)nucleus to form vestibulo-spinal tract, assist to maintain balance by influencing muscle tone of body. 3-Efferent Fs. to ocular nuclei of oculomotor, trochlear & abducent through medial longitudinal fasciculus, for coordination of head & eye movements.

33. Vestibular Nerve Fibres : Vestibular nerve nuclei & their central connections 4-Efferent Fs. ascend from vestibular nuclei to relay in (VP) nucleus of thalamus to reach the cerebral cortex, at the vestibular area of sensory cortex which adjacent to primary sensory cortex in parietal lobe at inferior parietal lobule just above lateral fissure.

34. Lateral aspect of cerebral hemisphere location of vestibular area in cerebral cortex : adjacent to primary sensory cortex in inferior parietal lobe/ or above lateral fissure, adjacent to auditory cortex in temporal lobe.

35. Ascending connections of auditory component of vestibulo-cochlear nerve. Cochlear Nerve :  1 st order neurones : it is formed by the cells of spiral ganglion.  Peripheral Fs. conduct sound from the organ of Corti in the cochlea.  The axons of these cells bifurcate to end in dorsal & venteral cochlear nuclei, which lie close to inf.cerebellar peduncle.

36. Ascending connections of auditory component of vestibulo-cochlear nerve.  At trapezoid body, some Fs.may terminate in superior olivary nucleus.  Most Fs. Ascend from sup.olivary nuclei to form the lateral lemniscus then ascend to end in inferior colliculus of midbrain.  2nd order neurones : it is formed of cells of cochlear nuclei.  Most axons of these cells Cross to opposite side of pons as trapezoid body.  The inferior colliculus sends axons to medial geniculate nucleus of thalamus.

37. Ascending connections of auditory component of vestibulo-cochlear nerve.  3 rd order neurone : axons arise from MGN pass through internal capsule to primary auditory cortex, which is located in Heschl’s gyri lying in superior temporal gyrus and hidden within the lateral fissure  Auditory association cortex ( Wernick’s area) is an area of temporal lobe surrounding the primary auditory cortex, in which the auditory information is interpreted ( for knowing the meaning of sounds).

38. Lateral aspect of cerebral hemisphere Note primary auditory cortex & Wernicke’s area in superior temporal gyrus.

39. Acoustic Neuroma : It is a benign tumour of vestibulocochlear nerve in cerebello-pontine angle. It is a benign tumour of vestibulocochlear nerve in cerebello-pontine angle. So, there is attacks of dizziness, deafness & So, there is attacks of dizziness, deafness & ataxia (disturbances of voluntary movement).

40. IX : Glossopharyngeal Nerve Fibres : Glossopharyngeal nerve nuclei & their central connections. Red= motor, brown= parasymp., blue = sensory 1-Afferent Sensory Fs. for Taste sensation from post.1/3 of tongue+ general sensation from phartnx end in trigeminal sensory nucleus. 2-Afferent visceral (chemo-& baroreceptors in carotid body+ sinus)& taste Fs. : end in Nucleus Solitarius of medulla.  It is a mixed N.,attached lateral to olive in rostral medulla and leaves the skull through jugular foramen.  It contains :

41. IX : Glossopharyngeal Nerve Fibres : Glossopharyngeal nerve nuclei & their central connections. Red= motor, brown=parasymp.,blue=sensory 3-Efferent motor Fibres : arises from its main motor nucleus in the rostral part of nucleus ambiguus of medulla to supply stylopharyngeus involved in swallowing. 4-Efferent Parasympathetic Fibres : arises from inferior salivary nucleus of rostral medulla to synapse in otic ganglion, then via post- ganglionic Fs.innervate parotid gland.

42. X : Vagus Nerve : Vagus nerve Nuclei & their central connections.  It is mixed nerve, attached lateral to olive of medulla caudal to glosso-pharyngeal N. in groove between olive & inf. cerebellar peduncle.  It recevies afferent Fs.from : 1-Receptors for general sensation in pharynx, larynx, tympanic membrane, ext.acoustic meatus. 2- Chemoreceptors in aortic bodies and baroreceptors in aortic arch. 3- Visceral receptors in thoracic & abdominal viscera.

43. X : Vagus Nerve Fibres : Vagus nerve Nuclei & their central connections. 1-Afferent Fs.for general sensation : end in sensory nucleus of trigeminl and - visceral sensory afferents end in nucleus solitarius. 2-Efferent Motor Fs. : arise from nucleus ambiguus of medulla (main motor nucleus of vagus) to innervate Ms. of soft palate, pharynx, larynx to control swallowing and speech. 3-Efferent Parasymp. Fs. : arise from dorsal motor nucleus of vagus to supply CVS, RS, & GITS.

44. XI :Accessory Nerve : Diagram of caudal medulla & rostral spinal cord to illustrate origin and course of vagus & accessory nerves.  It is purely motor, consists of cranial part & spinal part.  The cranial part emerges from lateral aspect of medulla below vagus N. It arises from caudal part of nucleus ambiguus of medulla. -At the level of jugular foramen it joins vagusN. to supply Ms. of soft palate, pharynx & larynx.  Spinal root of accessory arises from upper 5 cervical spinal cord segments. It ascends to the side of medulla to join the cranial root till the jugular F., it separates to supply sternomastoid & trapezius Ms.

45. XII : Hypoglossal Nerve : T.S.of medulla to illustrate origin & course of hypoglossal nerve.  It is purely motor, supplying all extrinsic & intrinsic Ms. of tongue except palatoglossus (by pharyngeal plexus).  It arises from hypoglossal nucleus in medulla ( beneath floor of 4 th V.).  It emerges from M.O. between olive & pyramid.

46. Motor neurone disease and lesions of cranial nerves IX-XII : Occures in those over 50 years due to chronic degeneration of cortico-bulbar tracts projecting to nucleus ambiguus (sends motor Fs.in 9,10,11 nerves) & hypoglossal nucleus, leading to dysphonia (difficulty in phonation), dysphagia (difficulty in swallowing), dysarthria ( difficulty in articulation) and weakness & spasticity of tongue (pseudobulbar palsy). Occures in those over 50 years due to chronic degeneration of cortico-bulbar tracts projecting to nucleus ambiguus (sends motor Fs.in 9,10,11 nerves) & hypoglossal nucleus, leading to dysphonia (difficulty in phonation), dysphagia (difficulty in swallowing), dysarthria ( difficulty in articulation) and weakness & spasticity of tongue (pseudobulbar palsy). There is also degeneration of nucleus ambiguus & hypoglossal nucleus themselves, leading to dysphonia,dysphagia, dysarthria and weakness, wasting & fasciculation of tongue (bulbar palsy). There is also degeneration of nucleus ambiguus & hypoglossal nucleus themselves, leading to dysphonia,dysphagia, dysarthria and weakness, wasting & fasciculation of tongue (bulbar palsy). IX-XII nerves can be damaged by tumours in skull foramina, lead to dysphonia, dysphagia, + wasting of sternomastoid & trapezius Ms. + Weakness & wasting of tongue. IX-XII nerves can be damaged by tumours in skull foramina, lead to dysphonia, dysphagia, + wasting of sternomastoid & trapezius Ms. + Weakness & wasting of tongue.