These fibers eventually end In the hypogastric ganglia Hypogastric ganglia are therefore

intermediate horns of 1st and 2nd lumbar segments ofthespnal cord. These fibers eventually end In the hypogastric ganglia Hypogastric ganglia are therefore the relay station of both tie sympathetic and parasympathetic nerves The postganglicnic fibers of the sympathetic end in the detrusor and the internal sphincter Stimulation of the sympathetic efferent leads to relaxation ofthedetrusor and contraction of the internal sphincter and, as a result, the urine is retained in the bladder The afferent fibres belonging to the sympathetic system arise from the bladderproceed to the spinal cord lying side by side with the sympathetic efferents enter the dorsal horns or L1 and L.2 segments of the spinal cords. The sympathetic afferent fibres carry the pain sensation Sensation of the bladder 1 Mucous membrane of the bladder is normally insensitive to the light touch When inflamed (as n cystitis) it becomes sensitive. 2 The sense of stretching, that is. the degree of distension of the bladder (witch Is caused by accumulation of urine), arses from tie detrusor muscles and carried up by the afferent nerves. When distenson is only mild or moderate a 'desire to pass urine' develops, but when the distension cs severe, actual plam t felt and a tremendous desire to pass the urine arises In short, sense of distension is carried in parasympathetic. whereas pain sensation from bladder is earned by the sympathetic Cortical control The S2, S3 and L1 , L2 are spinal centers for bladder. A higher center, which may be called 'cortical center', also axists, one on either side, on the medial aspect of the cerebral hemisphere, in the motor homcnculus, close to the perinea! area (fig. 10C 1.1). Sense of distension from the spinal center (that Is, 52 & S3) reach the cortical center via the dorsal column, whereas pain sensation (from L1 & L2) reach the corlicaE center via the spinothalamlc tract Efferent fibers from this higher center descend down, remaining lateral to the pyramidal fibers and ultimatety reach the spinal centers Through these paths the higher center controls the spiral (or Iower) center, in transection of the spinal cord, these (i e. cortical) controls are. therefore,