神经科学讲义 林国伟 编授

1、神經科學講義 林國偉 編授Spinal cord I. Development :A. neural plate ® neural tube :1. ventricular layer (surrounds central canal) : ependymal cells2. mantle layer (® gray matter) : neuroblasts and glioblastsa. alar lamina ® dorsal hornb. basal lamina ® ventral hornu sulcus limitans3. margin

2、al layer (® white matter) : glioblasts and processes of mantle layer neuroblastsB. neural crest ® dorsal root ganglionII. Gross anatomyA. segments : 8 cervical,12 thoracic, 5 lumbar, 5 sacral, 1 cocygeal1. limb enlargements : cervical enlargement (C4 T1) lumbosacral enlargement (L1 S2)l co

3、nus medullaris (L1 or L2); lumbar cistern; cauda equina (dorsal and ventral roots of L2 Coc1)2. dorsal rootlets ® dorsal rootventral rootlets ® ventral rootB. spinal meninges :1. dura mater : form “dura sac” :a. cranial : attaches the rim of foramen magnum b. caudal : anchors to the coccyx

4、 by the filum terminale externum (coccygeal ligament) - S2 to coccyx2. arachnoid 3. pial epidural space : contains venous plexus and fatl subarachnoid space : contains cerebrospinal fluid (CSF)l denticulate ligament (pia-arachnoid tissue) : from foramen magnum to L2 (21 pairs)l filum terminales inte

5、rnum (pia tissue) : from L2 to coccyx² lumbar puncture (between L3 and L4) : collects CSF for diagnosisIII. Internal structure of the spinal cordA. Fissure and sulcus : 1. ventral median fissure2. dorsal median sulcus 3. dorsal intermediate sulcus : divides cuneate fasciculus and gracile fascic

6、ulus4. ventrolateral/dorsolateral sulcus : ventral and dorsal roots throughB. Gray matter : dorsal horn, ventral horn, and intermediate zone lateral horn (T1-L2)1. 3 types of neuron : tract cell, interneurons and motor cell2. neuronal architecture (laminae of Rexed) :a. lamina I (posteromarginal nuc

7、leus) : receives incoming dorsal root fibers; tract cells ® contralateral spinothalamic tractb. lamina II (substantia gelatinosa) : editing of sensory inputc. lamina III and lamina IV nucleus proprius (dorsal proper sensory nucleus) : axon of tract cells cross the midline and enter the contrala

8、teral spinothalamic tract u lamina III (Barr : most interneuron)d. lamina V-VI : tract cells (Barr : laminae IV-VI form nucleus proprius)e. lamina VII : most interneuron; tract cells form 3 nuclei :1. dorsal nucleus of Clarkes nucleus (Clarkes nucleus; nucleus thoracicus, nucleus dorsalis)(T1-L2) &#

9、174; dorsal spinocerebellar tract 2. intermediolateral cell column (T1-L2) : cell bodies of the preganglionic neurons of the sympathetic nucleus; §sacral visceromotor nucleus (S2-4) : cell bodies of the preganglionic neurons of the parasympathetic nucleus3. intermediomedial cell column : viscer

10、al reflexf. lamina VIII : termination of descending fibers of vestibulospinal and reticulospinal tractsg. lamina IX : several clusters of large motor neurons innervate the skeletal muscle; somatotopic organization medial/lateral : proximal/distal dorsal/ventral : flexor/extensorh. lamina X : surroun

11、ds the central canal; decussating axons B. White matter : 3 funiculi1. posterior (dorsal) funiculus : a. gracile fasciculus (from below T6)b. cuneate fasciculus (from above T6)² sensory nerve via dorsal root :¨medial division (large A axons) ® gracile and cuneate fasciculi (ascending

12、fibers); septomarginal fasciculus and interfascicular fasciculus (descending fibers); dorsal horn (collateral fibers)¨lateral division (Ad and C fibers) ® dorsalateral tract (of Lissauer) ® laminae I, IV-VI ® contralateral anterolateral system ® ascending2. lateral funiculus

13、 : a. dorsalateral fasciculus : 1. lateral corticospinal tract (form contralateral frontal and parietal lobes)2. posterior spinocerebellar tract (above L2) : from nucleus thoracicus (Clarkes nucleus); ipsilaterally3. rubrospinal tract : from red nucleus of the midbrain, excite flexor motor neuron4.

14、hypothalamospinal tract5. raphespinal tractb. ventrolateral fasciculus :1. anterior spinocerebellar tract : from contralateral laminae V to VIII and spinal border cells of the lumbosacral segments; ® superior cerebellar peduncle ; cross the midline twice 2. spinothalamic tract : from contralate

15、ral nucleus proprius3. spinomesencephalic tract ® cross the midline ® periaqueductal gray matter, superior colliculus, and reticular formation of the midbrain 4. spinoreticular tract ® pontine reticular formation (crossed fibers); medullary reticular formation (uncrossed fibers)5. spi

16、nohypothalamic tractl (2)-(5) : anterolateral system6. reticulospinal fibers : from medullary reticular formation; excite extensor motor neuron3. anterior (ventral) funiculus :a. anterior corticospinal tract : did not cross midline in the medullab. medial longitudinal fasciculus (MLF) : includes med

17、ial vestibulospinal, tectospinal, and interstitiospinal fibers);e.g. : medial vestibulospinal tract : from medial vestibular nucleus; maintaining equilibrium (head movement) e.g. : tectospinal tract : from contralateral superior colliculusc. vestibulospinal tract : from the lateral vestibular nucleu

18、s; uncrossed pathway ® lamina VIII and medial part of lamina VII; mediate equilibratory reflexes ( axial musculature and extensors of the limbs)4. fasciculus proprius : spinospinalis fibers; concerning intersegmental spinal reflexesC. Blood supply :1. arterial supply :a. anterior spinal artery : ® central branchb. posterior spinal artery : ® peripheral branchesc. anterior and posterior medullary and radicular arteries : ® peripheral branchesd. arterial vasocorona 2. Veins : a. same as arterial supplyb. anterior and posterior internal venous plexuses