Lecture'3'Rules!for!sensory!pathways!!Rules!for!motor!pathways!!Functional!components!and!organizational!principles!for!cranial!nerves!!Cranial!nerves!

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Cranial!Nerve! Cranial!exit! Peripheral!pathway!! Function!Olfactory!(1)! Foramina!in!

cirbiform!plate!of!ethmoid!bone!

Olfactory!epithelium!(nose)!:>!olfactory!bulb!

Pure!Sensory:!smell!

Optic!!(2)! Optic!canal! Retina:>!diencepthalon! Pure!Sensory!:vision!Oculomotor!(3)! Superior!orbital!

fissure!Mesencephalon!:>!superior!oblique!

Motor:eye!movement!

Trochlear(!4)! Superior!orbital!fissure!!

Mesencepthalone!:>!superior!oblique!!

Motor!:!eye!movement!

Trigeminal!(5)!!Opthalmic!(v1)!!!Maxillary!(v2)!!!!Mandibular!(v3)!

!!Superior!orbital!fissure!!Foramen!Rotundum!!!Foramen!ovale!

!!Upper!eyelid/face!:>!pons!!Midface:>!pons!!!!Pons:>!mastication!muscles!

!!Sensory:!forehead,!nose,!nasal!cavity!!Sensory:!lower!eyelid,!upper!teeth,!lip!cheek!!!Sensory:!tongue,!lower!teeth/chin/mastication!muscles!Motor:!chewing!etc!

Abducent!(6)! Superior!orbital!fissure!

Pons!:>lateral!rectus! Motor:!eye!abduction!

Facial!(7)! Internal!acoustic!meatus,!facial!canal,!stylomastoid!foramen!

Pons!:>!facial!muscles,!anterior!tongue.!

Sensory:!taste!Motor!:!muscles!of!scalp/ear!

Vestibulocochlear!!(8)!

Internal!acoustic!meatus!

Inner!ear!:>!pons!:>!medulla!

Sensory:!balance,!equilibrium!and!hearing!

Glossopharyngeal!(9)!

Jugular!foramen! Posterior!tongue!:>!carotid!art.!Phlarynx!<:>!medulla!

Sensory:!taste,!blood!pressure,!blood!oxygen!Motor:!swallowing!!

Vagus!(10)! Jugular!foramen! Heart!,!phlarynx,!visceria!<:>!medulla!

Sensory:!viscera,!phlarynx!Motor:!heart,!gut!!

Spinal!Accessory!(11)!

Jugular!foramen! Medulla/spinal!chord!:>!neck!and!back!muscles!

Motor:!neck!and!back!muscles!

Hypoglossal!(12)! Hypoglossal!canal! Medulla!:>tongue!muscles!

Motor:!tongue!muscles!

!Basal!ganglia!disorders!Parkinson’s!Disease:!

• problems!with!substrate!niagra!to!dopameinegic!system!• hypokenisia,!bradykinesia,!rigidity!and!resting!tremor!

Huntingtons!chorea:!• ach!and!GABBA!decreased!in!striatum!• coriform!movements!and!dementia!!

Ballism!and!Hemiballism:!• from!destruction!of!subthalamic!nucleus!!• violent!flinging!movements!of!one!or!both!limbs!

Tardive!Dyskenesia!• side!effect!of!many!antipsychotics!• repetitive!choleric!movements!of!face!or!trunk.!

!Limbic!system!

• adds!emotional!slant!to!basic!or!instinctive!drives!and!behaviors!• links!somatic!and!visceral!brain!• strongly!associated!with!olfactory!inputs!!• olfaction!projects!directly!to!telencephalon!• olfaction!involved!in!primitive!behaviors!• located!on!medial!rim!of!brain!• olfactory!structure!complete!a!circle!

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Somatic!sensation!• touch,!vibration,!fine!pressure,!

proprioception!info!covered!by!dorsal!column!pathway!

• tonotopic!representation!of!body!and!nucleu!and!cortex!

o gracile!nucleus!(lower!limbs!and!torso)!

o cuneate!nucleus!(upper!limbs!and!torso)!

!Spinocerebellar!tracts!Dorsal!(posterior)!spinocerebelar!tract!

• origin:!clarke’s!nucleus!(T1:L2/3)!• Enters!cb!via!inferior!peduncle!• Conveys!infor!from!trunk!and!lower!

extremity!Ventral!(anterior)!spinocerebellar!tract!

• Origin:!spinal!border!cells!(T12:L5)!• Crosses:!in!SC!at!level!of!entry!and!again!

in!Cb!• Enters!Cb!via!superior!peduncle!• Conveys!info!from!trunk!and!lower!

extremity!Cuneocerebellar!Tract!

• Origin:!lateral!cuneate!nucleus!• Enters!Cb!via!inferior!peduncle!• Conveys!info!from!trunk!and!upper!extremity!

Pain!• Nociception:!detection!of!tissue!damage!that!may!ultimately!result!in!the!perception!of!pain.!

!Major!components!of!pain:!

• Perception:!implies!higher!brain!functioning!• Nociception:!driven!by!tissue!damage:generates!signals!that!tracel!into!the!CNS!and!up!the!

neuroaxis!• Perception!and!Nocieption!CAN!BE!SEPEPERATED.!E.g!battlefield!and!sports!injuries,!hypnosis!

!Pain!definitions:!

• Superficial!pain:!o Skin,!subcutaneous!tissues!and!mucous!membranes!o Localized!o Sharp,!pricking,!throbbing!or!burning!

• Deep!somatic!pain:!o Arises!from!muscles,!tendons,!joints,!bones!o Less!localised!than!superficial!o Dull!aching/cramping!

• Visceral!o Arises!from!a!disease!process!or!abnormal!function!of!an!internal!organ!o Poorly!localised!o Dull!aching/cramping!!

Nociceptors!can!sense!noxiuous!mechanical,!thermal!and!chemical!stimuli!• Mechanical:!deformation!sensitive!channels!

Vestibulospinal!tracts!• Medial!VST!• Lateral!VST!• Differces!in!SC!regions!they!project!• MVST!–!as!far!as!cervical!region!,!vestibule:collic!

reflexes!also!innervate!antigravity!extensors!important!for!balance!and!posture!!

!!Clinical!relevance!

• Balance!disorders!encountered!350,000/year!• Many!65+!• Present!with!dizziness,!vertigo,!unbalanced!gait:!huge!

impact!=falls!• Most!common!disorders!!• Benign!paraoxysmal!positional!vertigo!• Superior!canal!dehiscence!• Acute!vestibular!neuronitis!or!labyinthitis!• Vestibular!migraine!• Meniere’s!disease!

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Lecture'8'!Motor!systems!Divisions:!

• Somatic!and!autonomic!nervous!systems!(ANS)!• Motor!neurons!can!innervate!3!types!of!target!

o Skeletal!mm,!derived!from!somites!!o Skeletal!muscles!derived!from!brachial!arch!mesoderm!(gill/brachial!arches;!cranial!

nerves!only!5,7,9,10,11!o Smooth!muscle!or!grandular!tissue!(ie!effectors!of!the!autonomic!nervous!system)!

• Motor!neurons!(nuclei)!are!located!in!different!places!in!nervous!system!! !

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