. Quain's elements of anatomy . Two other openingsthrough this membrane exist, one on each side, behind the upper roots ofthe glossopharyngeal nerve, in the pouch-hke extension of the membranebeneath the flocculus. A certain quantity of fluid is contained between the arachnoid mem-brane and the dura mater ; but the chief part of the cerebro-spinal fluidis lodged in the subarachnoid space in the meshes of the trabeculartissue. THE ARACHNOID MEMBEANE. 377 The spinal subaraclinoid space (fig. 320, Tc, I) is divided by an imperfectfibrous sej)tuni on eifcher side termed the ligamentum denticulatum
. Quain's elements of anatomy . Two other openingsthrough this membrane exist, one on each side, behind the upper roots ofthe glossopharyngeal nerve, in the pouch-hke extension of the membranebeneath the flocculus. A certain quantity of fluid is contained between the arachnoid mem-brane and the dura mater ; but the chief part of the cerebro-spinal fluidis lodged in the subarachnoid space in the meshes of the trabeculartissue. THE ARACHNOID MEMBEANE. 377 The spinal subaraclinoid space (fig. 320, Tc, I) is divided by an imperfectfibrous sej)tuni on eifcher side termed the ligamentum denticulatum (ff)into anterior and posterior portions. As was pointed out by Magendiethere also exist a sort of septum dividing the subarachnoid space atthe back of the cord {septum posticum (c)), the relations of which havebeen carefully studied by Axel Key and Retzius. It is a thin mem-branous partition, which passes in the median plane from the pia matercovering the j)Osterior median fissm-e of the cord to the opposite part of Fig. Fig. 319.—Section of the postbkioe and lower parts of the brain within the SKULL, to exhibit THE SUBARACHNOID SPACE, AND ITS RELATION TO THE VENTRI-CLES. (After Key and Retzius.) The section was made in the frozen state, the cavities having been previously filledwith injection. 1, 1, atlas vertebra; 2, odontoid process of the axis, 2; 3, third ventricle; 4, fourthventricle; C, C, corpus callosum ? C, gyrus fornicatus; C, cerebellum ; t, tentorum;j>, pituitary body ; c, c, central canal of the cord ; fM, in the cerebello-medullary pai-tof the subarachnoid space, is close to the foramen of Magendie by which that space com-mimicates with the fourth ventricle. the loose portion of the arachnoid membrane. It is most perfect in thecervical region, being incomplete below. It consists of numerous finelamella, enclosing between them small spaces, within which run thelarger blood-vessels. Subarachnoid trabeculse also connect the nerve-roots with the inner sm
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Keywords: ., boo, bookcentury1800, booksubjectanatomy, booksubjecthumananatomy
