The Nervous System

山东大学医学院 解剖教研室李振华

Organizations

Central nervous system (CNS) 中枢神经系统

Peripheral nervous system (PNS) 周围神经系统

Major Division of the Central Nervous System (CNS)

Brain 脑 Telencephalon 端脑 Diencephalon 间脑 Cerebellum 小脑 Brain stem 脑干

Midbrain 中脑 Pons 脑桥 Medulla oblongata 延髓

Spinal cord 脊髓

Major Division of the Peripheral Nervous System (PNS)

Cranial nerves (12 pairs) 脑神经

Spinal nerves (31 pairs) 脊神经

Visceral nerves 内脏神经 Visceral sensory nerve

Visceral motor nerve

Sympathetic part 交感神经 Parasympathetic part 副交感神经

Cellular Organization

Neuron 神经元 Cell body 胞体 Axon 轴突 Dendrites 树突

Neuroglia － glial cel

l 胶质细胞

Classification of Neurons

Structural classification 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 peripher

al branch Multipolar neuron 多极神经元

has an axon and two or more dendrites

Classification of Neurons

Functional classification Sensory (afferent) neuron

感觉神经元 Motor (efferent) neuron

运动神经元 Association neuron

联络神经元

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 ↓ Motor neurons ↓ Effector

Reflex and Reflex Arc

Reflex and Reflex Arc

Basic Terminology in Nervous System

In the CNS Gray matter 灰质 : collection of nerv

e 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

Basic Terminology in Nervous System

In the CNS Nucleus 神经核 :

a collection ( group ) of cell bodies which have the same shape and function

Fasciculus ( tract ) 纤维束 : 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

Basic Terminology in Nervous System

In the PNS Ganglion 神经节 : a collec

tion 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

学习方法看断面，想立体，上下串联。

Position of the Spinal Cord

Lies in vertebral canal Continuous above with medulla

oblongata at level of foramen magnum

Ends below at the lower border of L1 in the adult; at birth the cord ends at level of L3

A long cylindrical structure and slightly flattened anteroposteriorly

Two enlargements Cervical enlargement 颈膨大 corre

sponds to the C4 to the T1 segments Lumbosacral enlargement 腰骶膨大 corre

sponds to the L2 to the S3 segments

Conus medullaris 脊髓圆锥 Filum terminale 终丝 Cauda equina 马尾

External Features of Spinal Cord

External Features of Spinal Cord

Fissure and sulci Anterior median fissure 前正中裂 Posterior median sulcus 后正中沟

Posterior median septum 后正中隔 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 cell-station of the sensory nerves

Segments of Spinal Cord

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 spinal Cord Segments to Vertebral Numbers

Spinal segments Vertebral levels (spines)

Upper cervical region (C1~C4) Lie opposite the corresponding vertebrae

Lower cervical and upper thoracic region (C5~T4)

One lower in number than corresponding vertebrae

Middle thoracic region (T5~T8) Two lower in number than corresponding vertebrae

Lower thoracic region (T9~T12) Three lower in number than corresponding vertebrae

Lumber segments T10~T12

Sacral and coccygeal segments L1

Relationship of spinal Cord Segments to Vertebral Numbers

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

Structure of Spinal Cord

Gray matter 灰质 White matter 白质 Central canal 中央管

Gray Matter of Spinal Cord Anterior horn (column) 前角（柱） Posterior horn (column) 后角（柱） Lateral horn (column) 侧角（柱）

is present in the thoracic and upper lumber segments of the cord (T1-L3)

Intermediate zone 中间带 Anterior gray commissures

灰质前连合 Posterior gray commissures

灰质后连合

Gray Matter of Spinal CordPosterior horn (column): Marginal layer 缘层 （后角边缘核） Substantia gelatinosa 胶状质

Situated at the apex of posterior horn throughout the length of spinal cord

Concerns the sensations of pain and temperature

Nucleus proprius 后角固有核 Situated anterior to the substantia gel

ationnosa throughout the length of spinal cord

Receives fibers that are associated with the senses

Nucleus thoracicus 胸核 Situated at the base of posterior horn

and extending from segments C8~L3 Associated with proprioceptive endin

gs

Gray Matter of Spinal Cord

Intermediate zone Intermediaolateral nucleus

中间外侧核 (lateral horn) Extents from segments T1~L3, Containing sympathetic preganglioni

c neurons Sacral parasympathetic nucleus

骶副交感核 Extents from segments S2~S4, Containing parasympathetic pregan

glionic neurons Intermediomedial nucleus

中间内侧核 Throughout the length of spinal cord Associated with receiving viscera aff

erent information

Gray Matter of Spinal Cord Anterior horn (column): Two kinds of motor neurons

α-motor neuron: large multipolar neuron, innervates skeletal muscles, producing contraction of muscles

γ-motor neuron: smaller multipolar neuron, innervates intrafusal muscle fibers of neuromuscular spindles, regulating muscular tonus

Interneuron —Renshaw’s cell: negative feedback mechanism

Two groups of nuclei Medial nuclear group: present in mo

st 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 Posterior horn is formed b

y lamina to Ⅰ Ⅵ ； Intermediate zone corres

ponding to lamina Ⅶ ； Anterior horn is compose

d laminae and Ⅷ Ⅸ ； lamina is the gray mattⅩ

er 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

Intermediate zone

Ⅶ Nucleus thoracicus (C8~L3)

Ⅶ Intermediolateral nucleus (T1~L3)

Ⅶ Sacral parasympathetic nucleus (S2~S4)

Ⅶ Intermediomedial nucleus

Anterior horn Ⅸ Motor neuron

White Matter of Spinal Cord White matter contains three kinds of fibers: ascending, d

escending, and fasciculus proprius

Anterior funiculus 前索

Lateral funiculus外侧索

Posterior funiculus 后索

Anterior white commissure白质前连合

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）

Fasciculus gracilis

Fasciculus cuneatus

Spinothalamic tract

Ascending tracts

Tract Site of origin Funiculus Termination Function

Fasciculus gracilis

Spinal ganglia below segment T5

Posterior Gracile nucleus

Conscious proprioceptive (vibratory sense, and muscle joint sense) and fine touch sensation of trunk and limbsFasciculus cu

neatusSpinal ganglia above segment T4

Cuneate nucleus

Posterior spinocerebellar

Homolateral nucleus thoracicus

Lateral Cerebellum Unconscious proprioception from lower limb and lower portion of trunk

Anterior spinocerebellar

Contralateral Laminae Ⅴ~Ⅶ

Spinothalamic Laminae , ~Ⅰ Ⅳ Ⅶ

Lateral and anterior

Dorsal thalamus

Pain, temperature and crude touch sensation of trunk and limbs

Descending Tracts

Lateral corticospinal tract（皮质脊髓侧束）

Anterior corticospinal tract （皮质脊髓前束）

Rubrospinal tract （红核脊髓束）

Vestibulospinal tract （前庭脊髓束）

Reticulospinal tract（网状脊髓束）

Medial longitudinal fasciculus （内侧纵束）

Tectospinal tract （顶盖脊髓束）

Fasciculus proprius （固有束）

Descending tractsTract Site of origin Funiculus Termination Function

Lateral corticospinal

Cerebral cortex Lateral Laminae Ⅳ~Ⅸanterior horn

Voluntary movement

Anterior corticospinal

Cerebral cortex Anterior

Rubrospinal Red nucleus Lateral Laminae Ⅴ~Ⅶ

Facilitates activity of flexor muscles

Vestibulospinal Homolateral vestibular nuclei

Anterior Laminae Ⅶ~Ⅷ

Facilitates activity of extensor muscles

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

Conduction of excitations Reflex activity