A sketch of the central nervous system and its origins G E Schneider 2009 Part 4 Development and differentiation spinal level MIT 9 14 Class 8 CNS structure at the spinal level autonomic and enteric nervous systems Survey of adult human spinal cord Different levels illustrated The sensory channels reflex spinocerebellar and spinothalamic tracts origin of dorsal column axons Major descending pathways cortico rubro reticulo and vestibulo spinal Propriospinal fibers INTERNAL STRUCTURE OF THE SPINAL CORD Left Internal structure of spinal cord Dorsal Root Fibers Nuc cornucommissuralis Posterior Fasc Substantia Gelatinosa Gracilis Nuc Posteromarginalis Spinal Cord Segment C1 Zone of Lissauer Lat Corticospinal Tr Nuc Proprius Cornu Dorsalis Nuc Reticularis Nuc Dorsalis of Clarke Ant Spinocerebellar Tr Lat Spinothalamic Tr Nuc Motorii Lateralis Fasc Proprius Ant Spinothalamic Tr Vestibulospinal Tr Ventral Root Fibers Nuc Motorii Medialis Segment C5 Segment C8 Segment T2 II I Segment T10 III IV Right Levels rostral to caudal Internal Structure V Segment L1 VI X M VII VIII IX Segment L4 IX IX IX Figure by MIT OpenCourseWare Segment S4 Different levels illustrated Note the following things Gray vs white matter Gray matter dorsal and ventral horns Changes in amount of white matter rostral to caudal More and more descending axons leave the white matter More and more ascending axons join the white matter Cervical and lumbar enlargements See Striedter p 222 for Brontosaurus cord Presence of lateral horn in thoracic and upper lumbar cord Comparisons speculations Myelin A crucial vertebrate innovation Allman p 78 Why Not found in any invertebrate or in the jawless vertebrates hagfish lampreys How does spinal cord of humans differ from spinal cords of other mammals Spinal cord cross section Lumbar level Zona Terminalis I Substantia Gelatinosa II III IV V VI VII IX Note the laminae of Rexed VIII Drawing based on cell body stain Figure by MIT OpenCourseWare Note the laminae of Rexed See Per Brodal p 80f Survey of adult human spinal cord Different levels illustrated The sensory channels reflex spinoreticular spinothalamic and spinocerebellar tracts origin of dorsal column axons Major descending pathways reticulo vestibulo rubro and corticospinal Propriospinal fibers Termination of Dorsal Root Fibers Again note the laminae of Rexed Adult spinal cord schematic frontal section reflex and lemniscal channels Dorsal columns Dorsal root fibers of various sizes Spinothalamic tract Adult spinal cord schematic frontal section reflex and lemniscal channels Dorsal columns Dorsal root fibers of various sizes Spinothalamic tract Spinoreticular axons Superior colliculus Ascending reticular projections to intralaminar thalamic nuclei and hypothalamus Red nucleus Midbrain interior colliculus Medial lemniscus Remaining from very early chordates Spinoreticular fibers on right in blue Pontine reticular formation nucleus reticuloris pontis oralis Trigeminal nerve Pons Pontine reticular formation nucleus reticularis pontis caudalis Medullory reticular formation nucleus reticularis gigantocellularis Medulla Ascending reticular fiber system Tegmentum of midbrain Collateral endings in reticular formation Ascending collateral fibers Collateral endings in reticular formation Facial nerve Abducens nerve Ascending collateral fibers Descending nucleus and tract of trigeminal nerve Lateral reticular nucleus Pontine reticulospinal fibers Medullary reticulospinal fibers Hypoglossal nerve Ascending spinoreticular fibers Figure by MIT OpenCourseWare Spinoreticular axons include a few spinothalamic axons Superior colliculus Red nucleus Ascending reticular projections to intralaminar thalamic nuclei and hypothalamus Midbrain interior colliculus Medial lemniscus Pontine reticular formation nucleus reticuloris pontis oralis Trigeminal nerve Ascending reticular fiber system Tegmentum of midbrain Collateral endings in reticular formation Ascending collateral fibers Pons Figure by MIT OpenCourseWare At the rostral end of the spinal cord The dorsal column nuclei namely the gracile and cuneate nuclei nuc gracilis and nuc cuneatus What sensory cell group is found just lateral to these nuclei in the caudal hindbrain and upper cervical spinal cord With these cells there is a representation of the entire body surface at this level around the junction of spinal cord and hindbrain The body surface represented at the hindbrain cord boundary Cerebellar thchannel Clarke s Column illustrated at 5 thoracic segment Nauta Feirtag Fig 64 Info on complex joint movements from lower limbs trunk Figure by MIT OpenCourseWare Survey of adult human spinal cord Different levels illustrated The sensory channels reflex spinocerebellar and spinothalamic tracts origin of dorsal column axons Major descending pathways cortico rubro reticulo and vestibulospinal Propriospinal fibers Adult spinal cord some descending and intrinsic axons Proprio spinal axons Corticospinal axons after their decussation Rubrospinal axons Reticulospinal Vestibulospinal Fastigiospinal from Cb Tectospinal Corticospinal axons uncrossed variable in quantity Ascending and descending long axons of primate spinal cord Propriospinal axons Ascending and descending axons Ascending axons Corticospinal axons after their decussation Rubrospinal axons Reticulospinal Vestibulospinal Fastigiospinal from Cb Tectospinal Corticospinal axons uncrossed variable in quantity Intermission The ventricular system the meninges and glia Remember the origins of the ventricle in the formation of the neural tube The importance of the cerebrospinal fluid in the mature CNS Nutrients Fluid balance regulation via specific cell regions Also a communication medium because of chemical secretions into it and diffusion from it Where the fluid is made and how it flows Ventricular system The foramena of Luschka lateral apertures and the foramen of Magendie median aperture Interventricular Foramen Choroid Plexus of Lateral Ventricle Choroid Plexus of Third Ventricle Aq Lateral Aperture Choroid Plexus of Fourth Ventricle Median Aperture Central Canal Choroid plexus specialized ependymal cells which make cerebrospinal fluid Figure by MIT OpenCourseWare The Meninges 1 Define dura mater and pia mater meaning of the Latin terms and basic anatomy 2 Define arachnoid membrane and subarachnoid space See Nauta Feirtag ch 10 also P Brodal ch 1 and other texts Meninges Glia P Brodal 98 p 19 Figure by MIT OpenCourseWare Picture taken with