Chapter 19 the conductive pathway of nervous system the sensory conductive pathway the motor conductive pathway the chemical pathway of nervous system

The reflex path was referred to the conductive path of preceding or descending without via cerebral cortex. conscious nonconscious trunk、four limbs Head and facial part Conductive pathway of proprioceptive sense The conductive pathway of sensation of pain and warm, thick touch sensation and ressure sense Trunk, four limbs Head and facial part Sensory（preceding）conductive pathway Visual conductive pathway and pupillary light reflex Auditory conductive pathway Conductive pathway of equilibratory sensation General visceral sence Special visceral sense Conductive pathway of visceral sense corticospinal tract corticonuclear tract pyramidal tract Motor（descending）conductive pathway 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 Extracorticospinal tract

The sensory conductive pathway conductive pathway of proprioceptive sense the conductive pathway of conscious proprioceptive sense of trunk and four limbs and fine touch peripheral process ① Muscle, tendon, joint, skin central process spinal ganglia Goll's column Burdach's fibers spinal nerve ③ ② gracile nucleus Burdach's nucleus bulbar lemniscus of opposite side ventral posterolateral nucleus of dorsal thalamus posterior limb of internal capsule all parts of brainstem 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 C8～L2segment of thoracic nucleus the lateral part of the 5th to 7th of lumbosacral enlargement funiculus lateralis medullae spinalis of homonymy fiber of second class posterior spinocerebellar tract anterior spinocerebellar tract of opposite side and ipsolateral inferior cerebellar peduncle superior cerebellar peduncle cortex of palaeocerebellum cortex of palaeocerebellum

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

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

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.

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 sides →oculomotor nerve→ ciliary ganglion →postganglionic fibre →pupil sphincter muscle→the contraction of two pupils

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

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.

Motor pathways Upper motor neurons Lower motor neurons final common path pyramidal system cranial nerve motor nucleus corticonuclear tract pyramidal tract somatic motor area of cerebral cortex pyramidal cell 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.

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

（inferior part of anterior central gyrus） corticonuclear tract ① corticonuclear tract pyramidal cell （inferior part of anterior central gyrus） knee of internal capsule 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 ② extraocular muscles masseter muscle facial muscles（frontal muscle、orbicularis muscle) laryngeal muscle sternocleidomastoid trapezius

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

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

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.

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