神经解剖学课件：internal structures of spinal cord

1、The Internal Structure of Spinal Cord Gray Matter White Matter Conscious Sensory & Motor TractsOUTLINEFunctions of Spinal Cord transmitting spinal reflexInternal Structure of Spinal Cord white matter grey matter central canalThe Cytoarchitectural Lamination (Rexeds Laminae)The Gray Matter of Spinal

2、CordThe Anterior Horn motor neuron extrafusal muscle fibres (voluntary movement) motor neuron intrafusal muscle fibers (muscle tonus) Renshaw cell: motor neuron (axon collaterals) Renshaw cell motor neuron (negative feedback mechanism) medial nuclear group (lamina ) axial muscles lateral nuclear gro

3、up (lamina ) distal musclesNuclei in the Anterior Horn Medial Group: extends throughout the whole length of spinal cord, supplies axial muscles Lateral Group: exists in the 2 enlargements, supplies distal musclesNuclei in Cervical, Lumbar EnlargementsThe Nuclei in Posterior Horn marginal layer (lami

4、na ) substantia gelatinosa (lamina ) nucleus propris (laminae & ) nucleus thoracicus (lamina ) throughout the whole length of spinal cordthoracic regionLissauers TractFunctions of Nuclei in Posterior Horn marginal layer & substantia gelatinosa: pain, temperature, crude touch & pressure - spinothalam

5、ic tract nucleus propris: discriminative touch, vibratory sense & conscious muscle joint sense - fasciculi gracilis & cuneatus nucleus thoracicus: proprioceptive information to cerebellum - spinocerebellar tractThe Nuclei in Lateral (Intermediolateral) Horn intermediolateral nucleus - visceral motor

6、 intermediomedial nucleus - fibers constitute spinocerebellar tract visceral grey - visceral sensory sacral parasympathetic nuclusCoronal Section of the Spinal Cord at the Upper & Lower Cervical LevelsCoronal Section of the Spinal Cord at the Thoracic LevelsCoronal Section of the Spinal Cord at the

7、Lumbar & Sacral LevelsThe White Matter of Spinal Cord 3 funiculi (columns): anterior (ventral), lateral & posterior (dorsal) 2 commissures: ant. & post. long tracts: ascending & descending tracts short tracts: fasciculus propriusFasciculus Proprius & Anterior CommissureConscious Long Tracts descendi

8、ng tract - corticospinal tract ascending tracts - fasciculi gracilis & cuneatus - spinothalamic tractSubconscious Long Tracts ascending tracts - spinocerebellar tract - spinoreticular tract descending tracts - rubrospinal tract - vestibulospinal tract - reticulospinal tract1st Sensory NeuronLower Mo

9、tor NeuronConscious Descending Tract: Corticospinal Tract (System) anterior corticospinal tract - axial muscles lateral corticospinal tract - distal muscles Upper Motor Neuron - cerebral cortex Lower motor neuron - ant. horn of spinal cord Decussation - lateral corticospinal tract decussates at the

10、medulla oblongataPyramidal DecussationCorticospinal SystemConscious Ascending Tracts fasciculus gracilis fasciculus cuneatus (above T4 segment) proprioception & discriminative (fine) touch 1st sensory neuron - spinal ganglion 2nd sensory neuron - medulla oblongata Decussation - no decussation in spi

11、nal cordFasciculi Gracilis & Cuneatus anterior spinothalamic tract - non-discriminative touch & pressure lateral spinothalamic tract - pain & thermal sense (temperature)Spinothalamic Tract 1st sensory neuron - spinal ganglion, fiber doesnt decussate 2nd sensory neuron - posterior horn, fiber decussa

12、tes to opposite side by passing through anterior commissureLateral Spinothalamic TractAnterior Spinothalamic Tract Lissauers Tract - ascend one to two segments before crossing somatotopically arranged Arrangement of the Major Ascending Tracts marginal layer & substantia gelatinosa spinothalamic trac

13、t uncleus propris fasciculi gracilis & cuneatus nucleus thoracicus spinocerebellar tract spinocerebellar tract - ant. spinocerebellar tract sup. cerebellar peduncle - post. spinocerebellar tract inf. cerebellar peduncleSubconscious Ascending Long Tracts convey subconscious proprioceptive sensation s

14、pinoreticular tractprovides an afferent pathway for the reticular formation spinotectal tract provides afferent information for spinovisual reflexes and brings about movements of the eyes and head toward the source of the stimulation. spino-olivary tractconveys information to the cerebellum from cut

15、aneous and proprioceptive organs Subconscious Descending Long Tracts tectospinal tractconcerned with reflex postural movements in response to visual stimuli. rubrospinal tract facilitates the activity of the flexor muscles vestibulospinal tractfacilitates the activity of the extensor muscles reticulospinal tractprovides a pathway by which the hypothalamus can control the sympathetic outflow and the sacral parasympathetic outflow The Principal Tracts of the Spinal CordShort Ascending & Desending Tracts surrounding the grey matter of the spinal cord conn