Sunday, August 2, 2009

system However, the lernniscal system gives collate rats to SGR for gate controlling in pain.

) The anterolaleral system gives collateral;, during its upward journey to the (a] penaqueductal gray (thus controlling the pain sensation) and (b) RAS (thus influencing the state of alertness), whereas no such thing happens wtlh the lemniscal system However, the lernniscal system gives collate rats to SGR for gate controlling in pain. (5) Localization of the sense is much better in the lerrmiscal system than that in the anterolateral system SPINO CEREBELLAR TRACTS (fig 10B1 3.3) These tracts, as staled earlier, do not reach Ihe level of consciousness There are two such well recognized tracts, (i) antenor or ventral, and (ii) posterior or dorsal spino cerebeliar tracts In addition, some fibers of the dorsal column, after reaching the medulla, enter the cerebellum Dorsal spinocerebellar tract (fig. IDA 1 3) The first order neuron arises from the muscle spindle, joints and The skin enters the spinal cord via the DRG -+ makes a short ascent in The dorsal fuinculus of The same side then terminate in the Clarke's column (also called, nucleus dorsahs) situated al Ihe base of the dorsal horn The second neuron arises from the Clarke's column proceeds up through The dorsal spinocerebellar tract of Ihe same side reaches medulla turns posteriorly to enter cerebellum through the inferior cerebellar peduncle Fig in Spino cerebeliar tracts Ventral spino cerebellar tract First order neuron anses from the muscle spindle, joint and shin enters the spinal cord via Ihe DRG relays in the dorsal horn The second order neurons anse from the Rexed lamina V to VII (fig IDA 1 6) Most of (he second order neurons cross to Ihe opposite side proceed up via the vantral spinocerebellar tract [tig 10A1.3) medulla pens mid brain In The mid brain the fibers turn posteriorly via superior c e rebellar peduncle enters the cerebellum The spinocerebellar tracts carry impulses arising from the muscles and joints (= non conscious propnocepfive senses), and [ii) impulses from the skin (non conscious cutaneous senses) Bolh these are sensory input to The cerebellum; on the basis of these (and other inputs from Ihe brain), Ihe cerebellum acts properly Nerve fibers from The neck and supenor extremity muscles enter The dorsal column (instead of The spnoc erebell at tracts) and

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