Sx006-神經(jīng)總論脊髓.ppt

1、人體解剖學(xué) Human Anatomy,吉林大學(xué)解剖學(xué)教研室 石岫昆 2006年9月,供五、七年制用 （據(jù)王云祥 呂衡發(fā)主編人體解剖學(xué)第八版吉林科學(xué)技術(shù)出版社出版）,第六篇 神經(jīng)系統(tǒng) Nervous system,Chapter 1 總論 Introduction,Human nervous system is most complex anatomical and physical system in body; it regulates and integrates activities of all bodily systems for benefit of organism as a

2、whole; and makes balance of external and internal environments in body. 基本要求 掌握神經(jīng)系統(tǒng)的區(qū)分和常用術(shù)語。 了解神經(jīng)系統(tǒng)的組成。,I.神經(jīng)系統(tǒng)的區(qū)分 Divisions of Nervous System,中樞神經(jīng)系統(tǒng)central nervous system (CNS),周圍神經(jīng)系統(tǒng)Peripheral nervous system (PNS),按相連部位,按分布區(qū)分,按功能區(qū)分,內(nèi)臟神經(jīng)的傳出部分又稱為自主神經(jīng)系統(tǒng)或植物神經(jīng)系統(tǒng)Autonomic nervous system (交感神經(jīng) Sympathetic

3、 n. 多極神經(jīng),元 Multipolar neuron has an axon and two or more dendrites. Functional classification: 感覺神經(jīng)元 Sensory (afferent) neuron 運(yùn)動神經(jīng)元 Motor (efferent) neuron 聯(lián)絡(luò)神經(jīng)元Association neuron., 神經(jīng)元分類 Classification of neuron, 神經(jīng)元分類 Classification of neuron,3.神經(jīng)纖維 Nerve fibers Longer processes of neuron envelop

4、ed by myelin sheath and neurilemma are termed nerve fibers. 有髓纖維 Myelinated fibers are surrounded by a myelin sheath and neurilemma. 無髓纖維 Unmyelinated fibers are not, however,insulated by a myelin sheath. Oligodendrocytes form myelin in central nervous system while Schwann cells form myelin in perip

5、heral nerves.,4.突觸 Synapses Within nervous system impulses are conducted from one part to another along a chain of neurons. Terminal arborizations of axon of one neuron ramify in close contact with cell body or dendrites, less frequently with axonic terminals of many others.,These structural and fun

6、ctional areas of contact are termed synapses. Each synapse involves close apposition of a presynaptic element with a postsynaptic element from which it is separated by a synaptic cleft.,Presynaptic element contains numerous synaptic vesicles in which chemical substance neurotransmitter is present. W

7、hen an impulse arrives at presynaptic element, neurotransmitter diffuses across synaptic cleft and binds to receptor molecules in postsynaptic membrane. As a result, postsynaptic neuron,is activated and impulse is conducted from one neuron to others. The “chemical synapse” involving release of trans

8、mitter substance is most common type in mammalian nervous sys.,II)神經(jīng)膠質(zhì) Neuroglia Neuroglial cells outnumber neurons in central nervous system 10:1. These cells appear to play a number of important roles, including myelin formation, guidance of developing neurons, maintenance of extracellular K+ leve

9、ls, and reuptake of transmitters after synaptic activity. 1.星形膠質(zhì)細(xì)胞 Astrocytes have many radiating processes,some of which end at nerve cells and others at capillaries. They are neuroectodermal in origin and may assist in transfer of nutrients and metabolic products between neurons and blood.,2.寡突膠質(zhì)細(xì)

10、胞 Oligodendrocytes are smaller and have fewer branching processes; they tend to lay in rows between nerve fibers and are concerned with production and nourishment of myelin sheaths especially those surround axon in central nervous system. They are neuroectodermal in origin. 3.小膠質(zhì)細(xì)胞 Microglia are dim

11、inutive cells, which,permeate entire central nervous system. They are modified macrophages and form part of reticulo-endothelial system and are probably mesodermal in origin.,III. 反射與反射弧 Reflex and Reflex Arc Reflexes are automatic, subconscious responses to stimuli within or outside body. Reflex ar

12、c, a linkage of afferent and efferent neurons, is defined as entire neural pathway that is involved in a reflex. Reflex arc has 5 basic components: Receptor Sensory neurons CNS Moter neurons Effector,Interruption of this reflex arc at any point abolishes response.,Receptor,Effector,Centre,Efferent,A

13、fferent, Reflex Arc,Int, Ext Environment,Higher Centre,Responses,IV.神經(jīng)系統(tǒng)的常用術(shù)語 Basic terminology in nervous sys. In the CNS,灰質(zhì) Gray matter collection of nerve cell bodies and their dendrites, gray color during fresh condition. 皮質(zhì) Cortex matter outermost layer of gray matter in cerebrum and cerebellum

14、. 白質(zhì) White matter collection of nerve fibers, white color during fresh condition. 髓質(zhì) Medulla matter a central core of white matter beneath cortex of cerebrum and cerebellum., Neuroanatomical terms in common usage,神經(jīng)核 Nucleus a collection ( group ) of cell bodies which have same shape and function. 纖

15、維束 Fasciculus ( tract ) a bundle of nerve fibers which have the same origin, termination, pathway and function. 網(wǎng)狀結(jié)構(gòu) Reticular formation an admixture of cross-crossing fibers with larger or smaller groups of nerve cells occupying the meshes., In the PNS 神經(jīng)節(jié) Ganglion a collection of neuronal cell bod

16、ies outside the CNS. 神經(jīng) Nerve a bundle of nerve fibers held together by connective tissue sheath.,Chapter 2 中樞神經(jīng)系統(tǒng) Central Nervous Sys. Section 1 脊髓 Spinal Cord, 基本要求 掌握脊髓的外形；脊髓灰質(zhì)的分部、主要核團(tuán)的名稱、位置和功能；脊髓白質(zhì)的分部，后索和外側(cè)索通過纖維束的名稱和功能。 熟悉脊髓的位置；脊髓節(jié)與椎骨的對應(yīng)關(guān)系；脊髓灰質(zhì)的分層；前索通過的纖維束；脊髓的前角、后角、白質(zhì)前連和半離斷時出現(xiàn)的癥狀或體征。 了解脊髓網(wǎng)狀結(jié)構(gòu)的位置

17、；脊髓的功能。, Spinal cord is about 18 inches (40 45 cm ) long, 1/2 inch (14 mm) wide 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. It consists of centrally located gray matter, involved in ref

18、lexes, and peripherally located ascending and descending tracts of white matter that conduct impulses to and from brain., I.脊髓的外形 External features A long cylindrical structure and slightly flattened anteroposteriorly Two prominent enlargements can be seen,in a posterior view: 頸膨大 Cervical enlargeme

19、nt is located between C3 and T2 vertebrae Nerves emerging from this region serve upper extremities; 腰骶膨大 Lumbar enlargement lies between T9 and T12 vertebrae Nerves from lumbar enlargement supply lower extremities.,Caudal to lumbosacral enlargement, spinal cord tapers gradually and becomes conical t

20、ermination known as 脊髓圓錐 conus medullaris. A condensation of pia mater forms 終絲filum terminale that descends from conus medullaris to level of,S2 vertebra; from here it is enveloped by dura mater and continues to posterior surface of coccyx. Some spinal roots surround film terminale and extends infe

21、riorly referred to as 馬尾 cauda equina, because they resemble a horses tail.,A longitudinal fissure and some sulci are shown on surface of naked spinal cord: 前正中裂 Anterior median fissure on median line of anterior surface, where anterior spinal artery and companion vein are lodged. 后正中溝 Posterior med

22、ian sulcus On posterior surface. 前外側(cè)溝 Anterolateral sulcus anterior (motor) roots emerge serially. 后外側(cè)溝 Posterolateral sulcus posterior (sensory) roots,enter spinal cord, each bear a spinal ganglion which constitutes first cell-station of sensory nerves., External features of spinal cord,脊髓節(jié)段與椎骨的對應(yīng)關(guān)

23、系 Relationship of segments of spinal cord to vertebrae 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, and 1 coccygeal. Embryonic spinal cord develops more slowly than associated vertebral colu

24、mn; thus in adult, cord does not extend beyond L1. Spinal cord is markedly shorter than vertebral column, each spinal cord segment at lower levels is located above similarly numbered vertebral body., Relationship of spinal cord with vertebral body in adults, II.脊髓的內(nèi)部結(jié)構(gòu) Internal structures In cross-s

25、ection spinal cord appears as a white oval with a gray, butterfly-shaped area in centre. White matter surrounds grey matter, and is composed of myelinated (sheathed) fibres, or axons; Gray matter consists of cell columns or horns and contains cell bodies, unsheathed motor-neuron fibres, and interneu

26、rons connecting either two sides of the cord or dorsal and ventral ganglia.,I)灰質(zhì) Gray matter Projections of gray matter within spinal cord are called horns or column, and named according to direction in which they project. 前角(柱) Anterior horn (column) project anteriorly; 后角(柱) Posterior horn (column

27、) project,posteriorly; 中間帶 Intermediate zone lies between posterior and anterior horns, 側(cè)角(柱) Lateral horn (column) is a spike-like grey extension of intermediate zone, from T1 to L3 segments.,灰質(zhì)連合 Gray commissure transverse bar of gray matter that connects horns across center of spinal cord. 中央管 Ce

28、ntral canal, a longitudinal canal, traverses center of grey commissure. It continues superiorly with central canal of medulla oblongata.,Grey matter of spinal cord contains an enormous number of neurons of varying size and shape. Main nuclei of spinal cord are as follows:, 1.后角 Posterior horn (colum

29、n): 1)后角邊緣核 Nucleus posteromarginalis forms a thin layer of cells covering tip of posterior horn. These cells are found throughout cord and their axons pass into lateral funiculus, probably forming intersegmental pathways. 2)膠狀質(zhì) Substantia gelatinosa forms outer cap-like portion,of head of posterior

30、 horn. They are presented at all spinal levels and may be excited by primary afferent fibers related to nociceptive stimuli.,3)后角固有核 Nucleus proprius is located deeply in substantia gelatinosa. Dendrites of cells radiate into substantia gelatinosa where they make synaptic contact with primary affere

31、nt fibers. Axons of nucleus cross in anterior white commissure and contribute to spinothalamic tracts. 4)胸核 Nucleus thoracicus is situated in medial portion of,base of posterior horn. It begins to be well defined in C8L3 segments and receives collateral branches of primary afferent fibers. Axons con

32、tribute fibers to posterior spinocerebellar tracts., 2.中間帶 Intermediate zone 1)中間內(nèi)側(cè)核 Intermediomedial nucleus receives collateral branches of posterior root fibers and gives rise to fibers that constitute spinocerebellar tract of both sides of spinal cord, regard sensation of viscera. 2)中間外側(cè)核 Interm

33、ediaolateral n.(lateral horn) lies in segments T1L3, containing sympathetic preganglionic neurons.,3)骶副交感核 Sacral parasympathetic nucleus lies in segments S2S4, containing parasympathetic preganglionic neurons., 3.前角Anterior horn (column) containing: 1)Three kinds of neuron -motor neuron: larger mul

34、tipolar neuron, innervates extrafusal fibers of skeletal m., producing contraction of m.; -motor neuron: smaller neuron, innervates intrafusal fibers regulating muscular tonus; Renshaws cell: negative feedback mechanism. 2)Two groups of nuclei 內(nèi)側(cè)群 Medial nuclear group:,present in most segments of sp

35、inal cord, innervating axial m. 外側(cè)群Lateral nuclear group: present only in cervical and lumbosacral enlargements, innervating limb muscles., 4.板層 Rexeds lamina In cross section of spinal cord, based on neuronal size, shape, cytological features and density in different regions, ten laminae has been d

36、istinguished, which are arrayed more or less parallel with dorsal and ventral limits of grey matter and extend throughout most of length of spinal cord. Briefly, structure of laminae is as follows: Posterior horn is formed by lamina I to VI; Intermediate,zone corresponding to lamina VII; Anterior ho

37、rn is composed laminae VIII and IX; Lamina X is gray matter surrounding central canal., Important Subdivision of Spinal Cord Gray Matter, Important Subdivision of Spinal Cord Gray Matter,II)白質(zhì) White matter It surrounds grey matter, and is composed of myelinated and unmyelinated nerve fibers. It is u

38、sually divided into three pairs of funiculi. Each funiculus is composed of many tracts. 前索anterior funiculus lies between the anterior median,fissure and anterolateral sulcus; 外側(cè)索 lateral funiculus lies between posterolateral sulcus and anterolateral sulcus;,后索 posterior funiculus lies between poste

39、rolateral sulcus and posterior median septum. 白質(zhì)前連合Anterior white commisure is a bundle of transverse fibers, anterior to grey commissure. It is composed of crossing fibers arising from nerve cells or extending from nerve fibers of opposite side.,White matter contains three kinds of fibers: ascendin

40、g, descending, and proprius tracts. 1.上行纖維束 Ascending tracts carry sensory impulses from spinal cord to brain or suprasegmental structures. (1)薄束和楔束 fasciculus gracilis and cuneatus are large proportion of myelinated fibers of posterior root enter,ipsilateral posterior funiculus. Fibers arising from

41、 sacral, lumbar and lower eight thoracic segments make up fasciculus gracilis,while fibers arising from upper four thoracic and cervical segments make up fasciculus cuneatus. After reaching medulla oblongata, fasciculi gracilis and cuneatus, terminate upon nuclei gracilis and cuneatus respectively.

42、These two tracts conduct discriminating tactile ( ability to,recognize size, shape and texture of an object ) and kinesthetic senses ( sense of position and movement ).,Lesion of posterior funiculus naturally abolishes or diminishes discriminating tactile and kinesthetic senses (sensory ataxia),and

43、symptoms appear on same side as lesion. Tactile localization is poor, and two-point discrimination and vibratory sense are lost or diminished.,(2)脊髓小腦后束 posterior spinocerehellar tract is situated along posterolateral periphery of spinal cord. It arises from ipsilateral dorsal nucleus and ascends th

44、rough spinal cord to medulla oblongata in which it becomes incorporated in inferior cerebellar peduncle. It conveys subconscious proprioceptive impulses to cerebellum. (3)脊髓小腦前束 anterior spinocerebellar tract is anterior to posterior one. Its fibers arise from intermediomedial nucleus,cross spinal c

45、ord and ascend through medulla oblongata and pons, then enter cerebellum by coursing along sup. cerebellar peduncle. Its function is same as that of the posterior one.,(4)脊髓丘腦束spinothalamic tract includes lateral and anterior spinothalamic tracts. 脊髓丘腦側(cè)束 lateral spinothalamic tract Nucleus proprius

46、receives fibers from dorsolateral fasciculus and gives rise to most of axons that cross in anterior white commissure and ascend in opposite lateral funiculus Ends directly in thalamus.,Unilateral lesion of this tract produces a complete loss of pain and thermal sense on opposite side of body.,脊髓丘腦前束

47、 anterior spinothalamic tract arises also from nucleus proprius, crossing anterior white commissure, and ascending contralaterally anterior to lateral spinothalamic tract. A small number of uncrossed fibers may ascend in ipsilateral anterior spinothalamic tract. This tract transmits impulses associa

48、ted with rough touch ., Ascending tracts, 2.下行纖維束 Descending tracts are concerned with somatic movement, visceral innervation and modification of muscle tone. (1)皮質(zhì)脊髓束 Corticospinal tract arises from cerebral cortex, descends through internal capsule and brain stem, and divides into two tracts.,皮質(zhì)脊髓

49、側(cè)束 lateral corticospinal tract decussates in medulla oblongata and descends medially to posterior spinocerebellar tract in spinal cord.,The tract extends to most caudal part of spinal cord and progressively diminishes in size as more and more fibers leave to terminate in anterior horn of grey matter

50、. 皮質(zhì)脊髓前束 anterior corticospinal tract occupies a strip adjacent to anterior median fissure and normally extends only to upper thoracic spinal segments. Most of these fibers,decussate in anterior white commissure before they terminate in ant. horn.,(2)紅核脊髓束 Rubrospinal tract lies anterior to lateral

51、corticospinal tract. Fibers arise from red nucleus of midbrain, and cross median raphe immediately, then descend to spinal level. Their terminals contact flexor motor neurons in posterior horn and controls muscle tone of flexor muscle groups. (3)頂蓋脊髓束 Tectospinal tract arise from neurons in superior

52、 colliculus, then decussate to opposite side and descend through brain stem to reach cervical spinal segments.,Rubrospinal tract,Tectospinal tract,Anterior corticospinal tract,Medial longitudinal fasciculus,In spinal cord they are in anterior funiculus near anterior median fissure. Fibers innervate

53、anterior horn cell indirectly, and may mediate reflex postural movements in response to visual and perhaps auditory stimuli. (4)前庭脊髓束 Vestibulospinal tract arises from lateral vestibular nucleus of same side and descends through entire length of spinal cord in anterior funiculus. Fibers enter base o

54、f anterior horn. Function of this tract is to increase extensor muscle tone and inhibit motor neurons of flexors.,Vestibulospinal tract,Tectospinal tract,(5)網(wǎng)狀脊髓束 Reticulospinal tract Pontine and medullary reticular formations give off fibers to form reticulospinal tract descending to spinal levels, but its position has not been esta