. Anatomy, descriptive and applied. Anatomy. THE ARACHNOID 969 is thin and transparent, and may be easily demonstrated by injecting a stream of air beneath it by means of a blowpipe; it passes over the convolutions without dipping down into the fissures between them, but does pass into the sylvian and intercerebral fissures and is prolonged upon the nerves as a sheath. At the base of the brain the arachnoid is thicker, and slightly opaque toward the central part; it covers the orbital surface of the anterior lobes and extends across between the two temporal lobes so as to leave a considerable
. Anatomy, descriptive and applied. Anatomy. THE ARACHNOID 969 is thin and transparent, and may be easily demonstrated by injecting a stream of air beneath it by means of a blowpipe; it passes over the convolutions without dipping down into the fissures between them, but does pass into the sylvian and intercerebral fissures and is prolonged upon the nerves as a sheath. At the base of the brain the arachnoid is thicker, and slightly opaque toward the central part; it covers the orbital surface of the anterior lobes and extends across between the two temporal lobes so as to leave a considerable interval between it and the brain, the cistema basalis. The subarachnoid space (cavum subarachnoideale) (Fig. 729) is the interval between the arachnoid and pia. It is not only on the surface, but dips between the convolutions. It is not, properly speaking, a space, for it is occupied every- where by a spongy tissue consisting of trabecular of delicate connective tissue covered with endothelium, which pass from the pia to the arachnoid, and in the meshes of which the subarachnoid fluid is contained. This so-called space is small on the surface of the cerebrum; but at the base of the brain the subarachnoid tissue is less abundant and its meshes larger. Emusarp vein Venous lacuna \ Cerebral vein Sup. longitufUnnl sinit^ Pacchionian body. Subdural space Subaraclinoid space Dura mater Arachnoid Cerebral cortex -Diagrammatic representation of a section across the top of the skull, etc. (Modified from Testut.) the membranes of the brain, In certain regions the arachnoid and pia are farther apart than was pre\"iously indicated, and these spaces are called subarachnoid cisternse (cisternae svbarach- noidales). The largest space is the continuation of the posterior part of the sub- arachnoid space of the spinal cord. It is called the postcistema or cistema magna {cisierna cerebellomeduUaris). It is a space formed by the arachnoid passing across the back and under portions of the me
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectanatomy, bookyear1913
