. The physiology of the domestic animals; a text-book for veterinary and medical students and practitioners. Physiology, Comparative; Domestic animals. KENAL SECRETION. 649 such circumstances, is a purely reflex action, and may be carried on â without the assistance of the will. The state of contraction of the vesical muscular fibres, as was found to be the case as regards the rectum, is governed by a spinal centre located in the lumbar portion of the spinal cord. When the spinal cord is divided in the dorsal region in a dog, after the shock of the operation has passed off the bladder may fill
. The physiology of the domestic animals; a text-book for veterinary and medical students and practitioners. Physiology, Comparative; Domestic animals. KENAL SECRETION. 649 such circumstances, is a purely reflex action, and may be carried on â without the assistance of the will. The state of contraction of the vesical muscular fibres, as was found to be the case as regards the rectum, is governed by a spinal centre located in the lumbar portion of the spinal cord. When the spinal cord is divided in the dorsal region in a dog, after the shock of the operation has passed off the bladder may fill with urine, and, when distended, empties itself in a perfectljr normal manner. The distention of the bladder starts sensory impulses, which are conducted to the spinal cord through the posterior roots of the third, fourth, and fifth sacral nerves. The centre of micturition, which in dogs is situated opposite the fifth and in rabbits opposite the seventh lumbar. Fig. 270.âDiagram: of the Nervous Mechanism of Micturition. (Yeo.) B, bladder; M, abdominal muscles; C, cerebral centres: R represents impulses which pass from the bladder to the centre in the spinal cord, whence tonic impulses are reflected and pass along T to the sphincter which retains the urine. When the bladder is distended, impulses pass to the brain by 1, and when we will, the tonus of the spina] centre stimulating the sphincter is cheeked, and the abdominal muscles are made by 2 to force some urine into the neck of the bladder, whence impulses pass by 3 to inhibit the sphincter centre and excite the detrusor through i. vertebra, is then called into play, and the muscular fibres of the sphinc- ter of the bladder relax, while contractions of the longitudinal fibres, or the so-called detrusor urinse muscle, are called forth. The contraction of this muscle serves to contract the capacity of the bladder in all directions, its contents are thus forced out through the relaxed sphincter muscle through the urethras, an
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