1、Human Anatomy Nervous pathways are routes formed by chains of neurons.They are classified into:.Int,Ext EnvironmentResponses In most sensory pathways there are three orders of neurons involved:Lower sensory neurons Intermediate neurons Upper sensory neurons spinothalamicpathway two-point discriminat
2、ion1.躯干四肢意识性深感觉传导路躯干四肢意识性深感觉传导路 The conscious deep sensory pathways of trunk and limbsreceptors muscle,tendon,periosteum,joint,and skinperipheral processes spinal nerve spinal ganglia 1st neurons fasciculus gracilis&cuneatus central processes,posterior funiculus 2nd neurons gracile&cuneate nuclei de
3、cussation of lemniscus&medial lemnisci ventroposterior lateral nucleus 3rd neurons posterior limb of internal capsule thalamocortical tract brain stempostcentral gyrus,posterior part of paracentral lobule and precentral gyrus updown(1)(2)(1)Interruption of pathways by lesions numbness on the affecte
4、d side of body below the lesion level (2)Interruption -hemianesthesia on the opposite side of the bodydorsal column pathwayLHSspinal cord injuryLoss of sense of:fine touch proprioception vibrationin left leg Sensory ataxia Patient staggers cannot perceive position or movement of legs Visual clues he
5、lp movement2.躯干四肢非意识性深感觉传导路躯干四肢非意识性深感觉传导路 The unconscious deep sensory pathways of trunk and limbsmuscle,tendon,periosteum,and jointreceptors peripheral processes spinal nerve spinal ganglia 1st neurons central processes dorsal roots thoracic N.and intermedio-medial N.2nd neurons anterior or posteri
6、or spinocerebellar tracts superior and inferior cerebellar peduncles paleocerebellum or spinocerebellum to maintain the coordination movement and equilibrium and appropriate posture of the body 3.The deep sensory pathway of head and face The exact route of this pathway is still not known.No 3rd neur
7、on to cortex,hence unconscious(Carries unconscious proprioception signals)Spinal ganglion Posterior spinocerebellar tract Anterior Spinocerebellartract Lamina-Inferior cerebellar peduncleSuperior cerebellar peduncleNucleus thoracicusupdownPaleocerebellumPrimary somatosensory cortex(S1)Thalamus(Intra
8、laminar and VP nuclei)MedullaSpinothalamic tractSpinal cordSmall sensory fibres:Pain,temperature,some touch and pressure sensation receptors skinspinal nerve peripheral processes spinal ganglia 1st neurons central processes nucleus proprius lamina I.IV.V.2nd neurons cross to opposite side anterior w
9、hite commissure lateral&anterior spinothalamic tract lateral funiculus runs up to brain stem3rd neurons VPLpostcentral gyrus,posterior part of paracentral lobule posterior limb of internal capsule thalamocortical tract dorsal roots Lissauers fasciculus asend 12 segments Spinal ganglia1neuron nucleus
10、 proprius Lamina,2neuron Lateral spinothalamic tract anterior spinothalamic tract Spinal lemniscusVPL 3neurons Central thalamic radiationupdownpostcentral gyrus&posterior part of paracentral lobule nociceptornociceptorA nerveC nervespinothalamicpathwayto reticularformationreticular formationspinotha
11、lamicpathwaythalamussomato-sensorycortexImpulses transmitted to spinal cord by Myelinated A nerves:fast pain(80 m/s)Unmyelinated C nerves:slow pain(0.4 m/s)Impulses ascend to somatosensory cortex via:Spinothalamic pathway(fast pain)Reticular formation(slow pain)(1)Interruption of pathways by lesions
12、 at anterior white commissure to causes(2)Interruption of pathways by lesions in the lateral funiculus of the spinal cord (3)Interruption of pathways by lesions in the internal capsule to causes spinothalamic pathwayLHSspinal cord injuryLoss of sense of:TouchPainWarmth/coldin right legreceptors skin
13、 mucosa sensory branches of trigeminal nerve peripheral processes trigeminal ganglion 1st neurons central processes spinal nucleus&pontine nucleus of trigeminal n.2nd neurons cross to opposite side3rd neurons VPM inferior part of postcentral gyrusposterior limb of internal capsule thalamocortical tr
14、act sensory root of trigeminal n.spinal tract of trigeminal n.to join trigeminal lemniscus2.头面部的头面部的浅感觉传导路浅感觉传导路 The superficial sensory pathways of head and face Trigeminal ganglion1neuron Pontine nucleus of V 2neuronSpinal nucleus of V 2neuronTrigeminal lemniscus Spinal tract of trigeminal n.VPM 3
15、neurons Central thalamic radiation updown*Lesion and Appearance(2)receptors rod&cone cells external layer of retinaperipheral processes bipolar cells1st neurons central processes ganglionic cells2nd neurons optic nerve optic chiasma optic tract 3rd neurons lateral geniculate body both banks of the c
16、alcarine sulcusposterior limb of internal capsule optic radiation middle layer of retinadecussation of fibers from nasal halves of retina innermost layer of retinaaxons optic disc visual area Visual areaOptic nerveOptic chiasmaOptic tractLateral geniculate bodyOptic radiation*Lesion and AppearanceIn
17、terruption of pathways by lesions in:1.Optic nerve 2.Optic chiasma-pituitary tumor 3.Optic tract,Lateral geniculate body,and Optic radiation Complete blindness Bitemporal hemianopia hemianopia of opposite halves of both visual fieldspostganglionic fibersRetinaaxons of retinal ganglion cellsOptic ner
18、veOptic chiasmaBoth optic tractdecussation of fibers from nasal halvesbrachium of superior colliculusPretectal areaE-W nucleusto both sideOculomotor n.Ciliary ganglionSphincter of pupilspreganglionic fibers to formPretectal area E-W nucleusOccculomotor n.Ciliary ganglia Sphincter pupil muscle Respon
19、se in Stimulated eye-direct pupillary light reflex Opposite eye-indirect pupillary light reflex1.Optic nerve damage To disappear direct pupillary light reflex To be present indirect pupillary light reflex 2.Oculomotor nerve damage Both to disappear direct pupillary light reflex&indirect pupillary li
20、ght reflex*Lesion and Appearance12visual centerlightpretectal areaE-W nucleusvisual pathwaylight reflexlateral genicular body(area 17)sphincter of irisretina two sidesposterior limb of internal capsulevisual radiationcone&rod cellsBipolar cellsGanglionic cellsOptic NOptic chiasmaOptic tractSummary f
21、or visual pathway ciliary ganglionreceptors spiral organ(Cortis organ)in internal ear bipolar cellsperipheral processes cochlear ganglion 1st neurons central processes cochlear nuclei2nd neurons terminate directly or indirectly to 3rd neurons medial geniculate body both transverse temporal gyriposte
22、rior limb of internal capsule acoustic radiation cochlear nerveboth side fibers(decussed&undecussed fibers)acoustic centertrapezoid body lateral lemniscus Bipolar neuron of cochlear ganglion Cochlear nerveCochlear nucleiTrapezoid body Lateral lemniscus Medial geniculate body Acoustic radiation Trans
23、verse temporal gyrusSpiral organ receptors cristae ampullares,maculae of utricle and sacculebipolar cellsperipheral processes vestibular ganglion 1st neurons central processes vestibular nucleus2nd neurons vestibular nerve axons are grouped into five courses:joining medial longitudinal fasciculus fi
24、bers end in oculomotor,abducent,trochlear nuclei,and anterior horn cells of upper cervical cord joining vestibulospinal tract to anterior horn cells of spinal cord entering cerebellum via inferior cerebellar peduncle connecting with reticular formation of brain stem,vagus and glossopharyngeal nuclei
25、 connecting with temporal,parietal and frontal cortex of hemisphere ()It is concerned with voluntary movement of skeletal muscles.It is composed of two orders of neurons-upper and lower motor neurons.It is to form Corticonuclear tract&Corticospinal tract Giant pyramidal cells(Betzs cells)&Other pyra
26、midal cells located-upper motor neuron Effector posterior limb of internal capsule intermediate 3/5 of crus cerebri basilar part of pons pyramid of medulla oblongata Pyramidal tract-Corticospinal tract 7090%of tract crosses to opposite side to form pyramidal decussatlon lateral corticospinal tract (
27、lateral funiculus)(anterior funiculus)anterior corticospinal tract smaller part of crossed fibers of tract Lower motor neuronspinal nerve Corticospinal tractDecussation of pyramid Lateral corticospinal tractAnterior corticospinal tract upper motor neuron Lower motor neuronupper motor neuron Effector
28、 genu of internal capsule brain stem to bilateral oculomotor,trochlear,trigeminal motor,ambiguus,accessory nuclei and superior part of facial nucleus,Pyramidal tract Lower motor neuron corresponding cranial nerves and to contralateral hypoglossal nucleus and inferior part of facial nucleusCorticonuc
29、lear tractOculomotor Nucleus Trochlear Nucleus Trigeminal Motor Nucleus Abducent NucleusSup.part of Facial NucleusInf.part of Facial NucleusAmbiguus NucleusAccessory Nucleus Hypoglossal Nucleus-Injury of unilateral facial nerve or hypoglossal nerve Paralysis of homolateral facial muscles and glossal
30、 muscles -Injury of unilateral corticonuclear tract Paralysis of contralateral glossal muscles and facial muscles below palpebral fissure-Injury of unilateral(left)facial nerve 1.Uni-paralysis(cerebral paralysis)Motor Area 2.Alternate Paralysis Brain Stem (1)Alternating oculomotor hemiplegia-Webers
31、syndrome (2)Alternating abducent hemiplegia (3)Alternating hypoglossal hemiplegia3.Paraplegia-Spinal Cord 4.Infantile Paralysis-Anterior horn motor cells of spinal cord 1.cerebral paralysis2.alternate paralysis3.paraplegia4.infantile ParalysisPyramidal tractUpper motor neuronsInferior motor neuronse
32、ffectorsParalysisTonicityTendon reflexPathologic reflex (Babinski sign)Muscle atrophyspastic(hard)paralysis flaccid(soft)paralysis (+)No(in short period)()Yes(下神经元不断发放冲动下神经元不断发放冲动 保证肌肉的营养代谢保证肌肉的营养代谢)Interruption of reflex arc 锥体束对下神经元锥体束对下神经元 的抑制性影响消失的抑制性影响消失 disappearMotor areaLesion for pyramidal
33、systemPeripheral nerves Somatic motor F.Signs of Upper Motor Neuron(UMN)and Lower Motor Neuron(LMN)LesionsSignUMN LesionsLMN Lesions ParalysisHard paralysisFlaccid paralysisToneIncreasedDecreasedTendon reflexDisappearBabinski signYesNoAtrophyNo*Yes*Mild atrophy may develop due to disuse.Increased1.T
34、he definition:descending pathways except pyramidal system 2.The features:发生古老发生古老,多次中继多次中继,联系复杂联系复杂,形成若干形成若干反馈通路反馈通路3.The functions:Regulate the tonicity of the muscles Coordinate the muscular activity Maintain the normal posture Produce habitual and rhythmic movement4.The constituent for extrapyram
35、idal system:The cortico-neostriatum-dorsalthalamic circuit The neostriatum-substantia nigra circuit The corticopoto-cerebellum-cortex circuit Cortical cells of frontal,parietal,and temporal lobes caudate nucleus&putamen globus pallidus dorsal thalamus somatomotor areas of cortex(feedback inhibition)
36、Substantia nigra producting and releasing dopamine Pyramidal cells of cortex frontopontine,parieto-occipito-temporopontine tracts internal capsule&crus cerebri pontine nuclei pontine brachium neocortex of cerebellum dentate nucleus superior cerebellar peduncle ventrolateral nucleus of thalamus&red n
37、ucleus rubrospinal tract Anterior horn motor cells of spinal cord环路环路 环路环路 2.Corticoponto-cerebellar system 1.Neostriatum-glubus pallidus system 1.Lesion for neostriatum-Chorea Sydenhams chorea(Thomas sydenham,English physician,sometimes called“the English Hippocrates”,16241689)2.Lesion for paleostr
38、iatum-Shaking Palsy 2.Lesion for corticoponto-cerebellar system-loss of coordination 1817,James Parkinson(English physician,17551824)first observed this disease and called it The Shaking Palsy.Cardinal symptoms-resting tremor,bodily rigidity,marked slowness of movement,gait disturbances,and difficulty initiating voluntary movementThanks
