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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
of visceral sense
•General visceral sence
•Special visceral sense
•corticospinal tract
•pyramidal tract
•corticonuclear tract
Motor（descending）
conductive pathway
•Extracorticospinal
tract
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•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
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
middle and superior part of
internal capsule •The
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
funiculus lateralis
medullae spinalis
of homonymy
the lateral part of the 5th to 7th 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
The superficial sensory pathway of trunk and limbs
peripheral
process
skin
spinal
nerve
spinal
lemniscus
all parts of
brain stem
①
spinal ganglia
central
process
②
spinal cordⅠ、
Ⅳ～Ⅶ layer
spinothalamic tract
of opposite side
③
posterior limb of
ventral
internal capsule
posterolateral
nucleus of
dorsal thalamus
•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
peripheral
central
①
spinal nucleus of
skin
process
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
-6-
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 sides
→oculomotor nerve→
ciliary ganglion →postganglionic fibre
→pupil sphincter muscle→the contraction
of two pupils
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The pupillary light reflex representation of injury in
different position
ill eye
-10-
healthy eye
direct light
reflex
indirect light
reflex
direct light
reflex
indirect light
reflex
the injury of
optic nerve
loss（—）
exist
（+）
exist
（+）
loss
（—）
the injury of
oculomotor
nerve
loss
（—）
loss
（—）
exist
（+）
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.
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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 corticospinal
tract
anterior horn motor
neuron
spinal nerve
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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
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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
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only recept the corticonuclear
tract fiber of opposite side
The principal injury representation of upper motor
neurons and lower motor neurons
paralysis
muscular
atrophy;
tendon
reflex
pathologic
reflex
superficial
reflex
-16-
the lesion of upper motor
neuron
the lesion of lower
motoneurons
spastic paralysis
flaccid paralysis
obsolete
obvious
accentuation
（－）
positive
（－）
weaken or disappear
（－）
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
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