VertPhys20 - Lecture 20 Mechanosensory neurons...

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Lecture 20 Mechanosensory neurons: adaptations -slowly adapting vs rapidly adapting Muscle Stretch Receptor: -muscle spindles convey info on muscle stretched. Innervated by motor neurons Somatosensory Lemniscal Channel: -long and ribbon-like -afferent fibers of the dorsal root ganglion cells synapse in the spinal cord in the segment of the cord in which they enter to control spinal reflexes -send an axon up the spinal cord to synapse in a nucleus In the medulla. Neurons in teis nucleus send axons to the thalamus and thalamic neurons send axons to the somatosensory cortex Dermatomes: region of skin innervated by each spinal nerve Neurons in the medullary somatosensory nuclei (gracilis and cuneate) send axons to the thalamus via the medial lemniscus. Pain and temperature information run in a different pathway. These axons also run into the spinal cord via dorsal root ganglion axons. They synapse immediately in the cord in the segment in which they enter. The postsynaptic neurons send an axon that crosses over to the other side of the cord, and travels up to the brain in the spino-thalamic tract. Spinothalamic pathways cross in the spinal cord but the lemniscalar pathways do not
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This note was uploaded on 07/31/2009 for the course BIO 365R taught by Professor Draper during the Spring '08 term at University of Texas.

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VertPhys20 - Lecture 20 Mechanosensory neurons...

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