Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
CHAPTER 12 CENTRAL NERVOUS SYSTEM – SPINAL CORD spinal cord • • • • CNS below foramen magnum within vertebral canal ends at L2 vertebra functions : – – – superhighway between brain and periphery source of spinal nerves integration center for reflexes gross structures • • • • • conus medullaris end of spinal cord filum terminale pia beyond conus medullaris attaches to coccyx cauda equina nerve roots inferior to sp cord cervical enlargement thickened for nerves to UE lumbar enlargement thickened for nerves to LE spinal meninges • • • • continuous from cranial meninges dura mater – – epidural space outer between dura and vertebra attach to foramen magnum and coccygeal ligament arachnoid mater – middle subarachnoid space contains CSF pia mater – inner on spinal cord cross section • • • gray matter – – – inner area (H pattern) cell bodies interneurons synapses white matter – – outer area myelinated axons up and down spinal cord central canal continuation of 4th ventricle cross section • dorsal sensory • ventral motor organization • • • gray matter – – ventral motor cell bodies dorsal sensory ; interneurons white matter – – ventral motor tracts dorsal sensory tracts nerve roots – – ventral root peripheral motor neuron dorsal root peripheral sensory neuron – axon gray matter • integration center - connect sensory and motor neurons connect brain and periphery • anterior horns cell bodies of motor neurons • posterior horns interneurons terminal axon – sensory neurons • lateral horns cell bodies – ANS neurons T1 – L2 only • gray commissure connection R & L white matter • • • • 3 white columns = funiculi posterior funiculus = ascending sensory lateral funiculus ascending and descending anterior funiculus descending motor (mostly) spinal tracts • • • • tract = bundles of neurons (axons) in CNS spinal tracts are organized by : – – – – sensory vs motor neuron type pain, touch, motor direction ascending ; descending body location hand, heart, brain center decussation crossover to other side of body spinal tracts 2 • ascending tracts sensory neurons to brain (from peripheral nerve) • descending tracts motor neurons from brain (to peripheral nerve) commissural tracts cross spinal cord organized by motor or sensory origin and destination • • ascending tracts • dorsal (posterior) white column – – – – – – touch, pressure, vibration, proprioception to what cerebral lobe ? fasciculus cuneatus fasciculus gracilis synapse at medulla and thalamus • spinothalamic spine to thalamus pain, temp, touch, pressure • spinocerebellar spine to cerebellum proprioception • corticospinal = pyramidal descending tracts • – – – – – – motor cortex to spine motor to muscles motor cortex cerebral peduncles pyramids decussation corticospinal tract anterior horn - synapse with peripheral motor neuron extrapyramidal : – – – rubrospinal red nucleus to spine (muscle tone) vestibulospinal vestibular nuclei (balance) reticulospinal spinal nerve roots • • • within vertebral foramen dorsal root – – – – cell bodies - dorsal root ganglion connects to posterior horn of gray matter synapse with ascending (sensory) tracts ventral root – – – sensory from periphery sensory neurons motor to periphery axon of motor neurons cell bodies - anterior horn post-synaptic neuron from descending (motor) tracts Neural Pathways • pathway between periphery and brain - 2 or 3 neurons • peripheral nerve • spinal tract • neuron above thalamus (sensory) • brain center sensory pathway • • • • • • 3 neurons peripheral sensory neuron – – 1st order neuron receptor, axon dorsal root • dorsal root ganglion posterior horn ascending spinal tract • 2nd order neuron synapse at thalamus neuron above thalamus 3rd order neuron brain center motor pathway • • • • • • 2 (skeletal) or 3 (autonomic) neuerons brain center motor cortex ANS descending tract UMN anterior horn of gray matter synapse peripheral motor neuron LMN – – cell body anterior horn ventral root effector muscle