Nervous system Chapter 19 the conductive pathway of

Nervous system Chapter 19 the conductive pathway of nervous system • the sensory conductive pathway • the motor conductive pathway • the chemical pathway of nervous system 1

The reflex path was referred to the conductive path of preceding or descending without via cerebral cortex. • Conductive pathway of proprioceptive sense • conscious • trunk、four limbs • nonconscious • Head and facial part • The conductive pathway of sensation of pain • Trunk, four limbs and warm, thick touch sensation and ressure • Head and facial part Sensory（preceding） sense • Visual conductive pathway and pupillary light reflex conductive pathway • Auditory conductive pathway • Conductive pathway of equilibratory sensation • Conductive pathway • General visceral sence of visceral sense • Special visceral sense • corticospinal tract • pyramidal tract • corticonuclear tract Motor（descending） conductive pathway • Extracorticospinal tract 2 • cortical substance－neostriatum－dorsal thalamus －circuit loop of cortex • neostriatum－circuit of black substance • pallidum－circuit loop of subthalamus • cortex －bridge of varolius－cerebellum－ circuit of cortex

The sensory conductive pathway of proprioceptive sense the conductive pathway of conscious proprioceptive sense of trunk and four limbs and fine touch Muscle, tendon, joint, skin peripheral process spinal nerve ① central process spinal ganglia Goll's column Burdach's fibers ③ ② gracile nucleus Burdach's nucleus bulbar lemniscus of opposite side all parts of brainstem 3 ventral posterolateral nucleus of dorsal thalamus posterior limb of internal capsule • The middle and superior part of posterior central gyrus • The posterior part of paracentral lobule

（二）The conductive pathway of unconscious proprioceptive sense in trunk and four limbs The proprioceptor of muscle, tendon, and joint the medial part of radix posterior spinal cord C 8～L 2 segment of thoracic nucleus funiculus lateralis medullae spinalis of homonymy the lateral part of the 5 th to 7 th of lumbosacral enlargement fiber of second class posterior spinocerebellar tract inferior cerebellar peduncle cortex of palaeocerebellum 4 anterior spinocerebellar tract of opposite side and ipsolateral superior cerebellar peduncle cortex of palaeocerebellum

The superficial sensory pathway of trunk and limbs skin ① peripheral process spinal nerve spinal lemniscus all parts of brain stem spinal ganglia ③ central process ② spinal cordⅠ、 Ⅳ～Ⅶ layer posterior limb of ventral internal capsule posterolateral nucleus of dorsal thalamus spinothalamic tract of opposite side • the middle and superior part of posterior central gyrus • the posterior part of paracentral lobule （二） The superficial sensory pathway of head and face ② ① peripheral central spinal nucleus of skin process trigeminal ganglion and mucosa trigeminal nerves ③ posteromedial nucleus of dorsal thalamusventral 5 ascends 1 to 2 segment trigeminal nerve pontine nucleus of trigeminal nerve posterior limb of internal capsule trigeminal lemniscus the inferior part of posterior central gyrus

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visual pathway and pupillary light reflex pathway visual pathway ① visual cone rod chiasm opticum visual tract bipolar neuron external geniculate body ③ ② nodal cell optic nerve posterior limb of internal capsule optic radiation the two sides of calcarine fissure • In the chiasm opticum, the fiber derived from retina of two eyes’ nasal side intersect, while the temple side ones don’t intersect. 7

The damaging of conductive pathway in different position can induce different visual filed defect: ①The injury of retina can induce visual field defect, which is related to the position and scope of injury; ②The optic nerve injury of ones side can induce absolute blindness of this eye； ③The lesion of decussating fiber of chiasm opticum can induce the half blindness in temple side of binocular visual field； ④the lesion of non-decussating fiber of chiasm opticum’s lateral part can induce the half blindness in nasal side of binocular visual field; ⑤the lesion of visual tract in one side can induce homonymous hemianopsia of opposite side. 8

The pupillary light reflex pathway The route of pupillary light reflex： direct light reflex indirect light reflex retina→optic nerve→chiasm opticum→ the visual tract of two sides→brachium of superior colliculus→pretectal area→ accessory nucleus of oculomotor nerve of two →oculomotor nerve→ sides ciliary ganglion →postganglionic fibre →pupil sphincter muscle→the contraction of two pupils 9

The pupillary light reflex representation of injury in different position ill eye 10 healthy eye direct light reflex indirect light reflex the injury of optic nerve loss（—） exist （+） loss （—） the injury of oculomotor nerve loss （—） exist （+）

The auditory pathway organ of Corti →bipolar cell (exchange neuron） →cochlear nerve →ventral cochlear nucleusdorsal and cochlear nucleus (exchange neuron） →trapezoid body of pons overlaps to the opposite side →lateral lemniscus →the dorsi-lateral part of tegmentum of midbrain →inferior colliculus (exchange neuron） →brachium of inferior colliculus →medial geniculate body (exchange neuron） →acoustic radiation →posterior limb of internal capsule →transverse temporal gyri of auditory field in cerebral cortex The auditory impulsion is conducing of two sides. If one side path above lateral lemniscus is damaged, the obvious symptom wouldn’t happen. But if the cochlear nerve, internal ear or middle ear is damaged, auditory handicap will be induced. 11

Motor pathways Upper motor neurons Lower motor neurons final common path pyramidal system somatic motor area of cerebral cortex pyramidal cell pyramidal tract corticonuclear cranial nerve motor tract nucleus corticospinal tract anterior horn of spinal cord motor neuron pyramidal tract The giant pyramidal cell of paracentral lobule’s anterior part and precentral gyrus and the pyramidal cells of other type as well as the axon of pyramidal cell which lie at the frontal lobe and apical lobe constitute pyramidal tract. 12

corticospinal tract the middle and superior ① part of anterior central gyrus pyramidal cell the anterior part of paracentral lobule midbrain, pons medulla oblongata ② posterior limb of internal capsule lateral corticospinal tract anterior horn motor neuron spinal nerve 13 trunk muscle, limbs muscle

corticonuclear tract ① corticonuclear tract pyramidal cell （inferior part of knee of internal capsule anterior central gyrus） • nucleus of oculomotor nerve • nucleus of trochlear nerve • nucleus of abducent nerve • motor nucleus of trigeminal nerve • the superior part of nucleus of facial nerve • nucleus ambiguus • accessory nucleus 14 ② • extraocular muscles • masseter muscle • facial muscles（frontal muscle、orbicularis muscle) • laryngeal muscle • sternocleidomastoid • trapezius

• the inferior half of facial nucleus → cheek muscle、 orbicularis oris • nucleus of hypoglossal nerve→ lingual muscle • supranuclear paralysis of facial nerve • infranuclear paralysis of facial nerve • supranuclear paralysis of hypoglossal nerve • infranuclear paralysis of hypoglossal nerve 15 only recept the corticonuclear tract fiber of opposite side

The principal injury representation of upper motor neurons and lower motor neurons 16

extrapyramidal system It is referred to the influence outside of pyramidal system and all the conductive pathways controlling body movement. Its structure is very complex, which includes cerebral cortex, striate body, dorsal thalamus, red nucleus, substantia nigra， vestibular nucleus, cerebellum and so on. The main functions of the extrapyramidal system in man are to regulate the tonicity of the muscles, coordinate the muscular activities, maintain the normal body posture and produce habitual and rhythmic movements. 17

The extrapyramidal system concludes the following four circuits: cortex－neostriatum－dorsal thalamus－cortex neostriatum－substantia nigra corticoponto－cerebellar－cortex globus pallidus－subthalamus 18