Download The Nervous System

The Nervous System
Divisions
 Central
nervous system (CNS)
 Peripheral
nervous system (PNS)
Central nervous system (CNS)
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Brain 脑

Telencephalon 端脑

Diencephalon 间脑

Cerebellum 小脑

Brain stem 脑干
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Midbrain 中脑
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Pons 脑桥
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Medulla oblongata 延髓
Spinal cord 脊髓
Peripheral nervous system (PNS)
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Cranial n. (12 pairs) 脑神经
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Spinal n. (31 pairs) 脊神经
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Visceral n. 内脏神经
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Visceral sensory n.
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Visceral motor n
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Sympathetic part 交感神经
Parasympathetic part 副交感神经
Cellular organization
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Neurons 神经元

Cell body 胞体

Axon 轴突

Dendrites 树突
Neuroglia －glial cell胶质细胞
Structural classification
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Bipolar neuron 双极神经元
has an axon and a dendrite
Pseudounipolar neuron
假单极神经元 has a central
branch and a peripheral branch
Multipolar neuron多极神经元
has an axon and two or more
dendrites
Functional classification

Sensory (efferent) neuron

Motor (afferent) neuron

Association neuron 联络神经元
感觉神经元
运动神经元
Reflex and reflex arc
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Reflex: a reaction of the organism
by the nervous system in response to
a stimulus
Reflex arc: has 5 basic components
Receptor
↓
Sensory neurons
↓
CNS
↓
Moter neurons
↓
Effector
Basic terminology in nervous system
In the CNS
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Gray matter 灰质: collection
of nerve cell bodies and their
dendrites, gray color during
fresh condition
Cortex皮质: the outermost
layer of gray matter in
cerebrum and cerebellum
White matter白质: collection
of nerve fibers, white color
during fresh condition
Medulla髓质: a central core of
white matter beneath cortex of
cerebrum and cerebellum
Nucleus神经核: a collection
( group ) of cell bodies which
have the same shape and
function
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Fasciculus 纤维束
( tract ): a bundle of
nerve fibers which have
the same origin,
termination, pathway
and function
Reticular formation
网状结构: an admixture
of cross-crossing fibers
with larger or smaller
groups of nerve cells
occupying the meshes
In the PNS
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
Ganglion 神经节: a
collection of neuronal
cell bodies outside the
CNS
Nerve 神经: a bundle
of nerve fibers held
together by connective
tissue sheath
The Spinal Cord 脊髓
Position
 Lies in vertebral canal
 Continuous above with medulla
oblongata at level of foramen
magnum
 Ends below at lower border of
L1 in adult; at birth at level of
L3
External features
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A long cylindrical structure and
slightly flattened anteroposteriorly,
Conus medullaris （脊髓圆锥）
Filum terminale （终丝）
Cauda equina （马尾）
Two enlargements
Cervical enlargement （颈膨大）:
corresponds to the C4 to the T1
segments
Lumbosacral enlargement
（腰骶膨大）: corresponds to the
L2 to the S3 segments
Fissure and sulci
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Anterior median fissure 前正中裂
Posterior median sulcus 后正中沟
Anterolateral sulcus 前外侧沟－anterior (motor) roots emerge serially
Posterolateral sulcus 后外侧沟－posterior (sensory) roots enter spinal
cord, each bear a spinal ganglion which constitutes the first cellstation of the sensory nerves
Relationship of segments
of spinal cord to vertebrae
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
A portion of the cord that gives
rise to a pair of spinal nerve
constitutes a segment.
There are 31 segments
8 cervical
12 thoracic
5 lumbar
5 sacral
1 coccygeal
Relationship of segments of spinal cord to vertebrae
Spinal segments
Vertebral levels (spines)
Upper cervical region (C1~C4)
= C1 ~ C4
Lower cervical and upper thoracic
region (C5~T4)
— 1 = C4 ~ T3
Middle thoracic region (T5~T8)
— 2 = T3 ~ T6
Lower thoracic region (T9~T12)
— 3 = T6 ~ T9
Lumber segments
= T10 ~ T12
Sacral and coccygeal segments
= L1
Internal structures
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Central canal 中央管
Gray matter
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Anterior horn (column) 前角（柱）
Posterior horn (column)后角（柱）
Intermediate zone 中间带
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Lateral horn (column) 侧角（柱）
Anterior gray commissures
灰质前连合

Posterior gray commissures
灰质后连合
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White matter
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Anterior funiculus 前索
lateral funiculus 外侧索
Posterior funiculus 后索
Anterior white commisure
白质前连合
Posterior horn (column):
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Marginal layer （缘层）
Substantia gelatinosa
（胶状质）
Nucleus proprius
（后角固有核）
Nucleus thoracicus（胸核）
in segments C8~L3
Intermediate zone
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Intermediaolateral nucleus
（中间外侧核）(lateral horn or
column): lies in segments T1~L3,
containing sympathetic
preganglionic neurons
Sacral parasympathetic nucleus
（骶副交感核）: lies in
segments S2~S4, containing
parasympathetic preganglionic
neurons
Intermediomedial nucleus
（中间内侧核） : for sensation
of viscera
Anterior horn (column): contain motor

neurons
Three kinds of neuron
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α-motor neuron: larger multipolar neuron,
innervates extrafusal fibers of skeletal m.,
producing contraction of m.
γ-motor neuron: smaller neuron,
innervates intrafusal fibers regulating
muscular tonus
Renshaw’s cell: negative feedback
mechanism
Two groups of nuclei


Medial nuclear group: present in most
segments of spinal cord, innervating axial
muscles
Lateral nuclear group: present only in
cervical and lumbosacral enlargements,
innervating limb muscles
Rexed’s lamina 板层
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posterior horn is formed
by lamina Ⅰ to Ⅵ；
Intermediate zone
corresponding to
lamina Ⅶ；
Anterior horn is
composed laminae Ⅷ
and Ⅸ；
lamina Ⅹ is the gray
matter surrounding the
central canal.
Important Subdivision of Spinal Cord Gray Matter
Region
Lamina
Nucleus
Posterior horn
Ⅰ
Marginal layer
Ⅱ
Substantia gelatinosa
Ⅲ, Ⅳ
Nucleus proprius
Ⅶ
Nucleus thoracicus (C8~L3)
Ⅶ
Intermediolateral nucleus (T1~L3)
Ⅶ
Sacral parasympathetic nucleus (S2~S4)
Ⅶ
Intermediomedial nucleus
Ⅸ
Motor neuron
Intermediate zone
Anterior horn
Ⅲ) White matter
White matter contains three kinds of fibers:
ascending, descending, and fasciculus proprius
Ascending tracts
Fasciculus gracilis（薄束）
Fasciculus cuneatus （楔束）
Posterior spinocerebellar tract
（脊髓小脑后束）
Anterior spinocerebellar tract
（脊髓小脑前束）
Spinothalamic tract
（脊髓丘脑束）
Ascending tracts
Tract
Site of origin
Funiculus Termination
Fasciculus
gracilis
Spinal ganglia Posterior
below segment
T5
Gracile
nucleus
Fasciculus
cuneatus
Spinal ganglia
above segment
T4
Cuneate
nucleus
Posterior
spinocerebellar
Homolateral
nucleus
thoracicus
Anterior
spinocerebellar
Contralateral
Laminae
Ⅴ~Ⅶ
Spinothalamic
Laminae Ⅰ,
Ⅳ~Ⅶ
Function
Convey
proprioceptive
and fine touch
sensation of
trunk and limbs
Lateral
Cerebellum
Unconscious
proprioception
from lower limb
and lower
portion of trunk
Lateral
and
anterior
Dorsal
thalamus
Pain,
temperature and
simple touch
sensation of
trunk and limbs
Descending tracts
Fasciculus proprius （固有束）
Lateral corticospinal tract
（皮质脊髓侧束）
Rubrospinal tract
（红核脊髓束）
Reticulospinal tract
（网状脊髓束）
Vestibulospinal tract
（前庭脊髓束）
Tectospinal tract
（顶盖脊髓束）
Medial longitudinal fasciculus （内侧纵束）
Anterior corticospinal tract （皮质脊髓前束）
Descending tracts
Tract
Site of origin
Funiculus
Termination
Function
Lateral
corticospinal
Cerebral cortex
Lateral
Voluntary movement
Anterior
corticospinal
Cerebral cortex
Anterior
Laminae
Ⅳ~Ⅸ
anterior
horn
Rubrospinal
Red nucleus
Lateral
Laminae
Ⅶ~Ⅶ
Excitatory of flexors
Vestibulospinal
Homolateral
vestibular
nuclei
Anterior
Laminae
Ⅶ~Ⅷ
Excitatory of extensors
Reticulospinal
Reticular
formation
Anterior
and lateral
Laminae
Ⅶ~Ⅷ
Voluntary movement
Medial
longitudinal
fasciculus
Vestibular
nuclei
Anterior
Laminae
Ⅶ~Ⅷ
Coordinate neck with eye
movement
Tectospinal
Superior
colliculus
Anterior
Laminae
Ⅵ~Ⅷ
Fasciculus
proprius
Spinal cord
Anterior,
lateral and
posterior
Spinal cord
Intrinsic reflex
mechanism of spinal cord
Main functions of spinal cord
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Conduction of excitations
Reflex activity