. Text-book of anatomy and physiology for nurses. rebellum,medulla oblongata, and pons Varolii. The cerebrum is the largest division and occupies nearly thewhole cranial vault. It is divided into two hemispheres, right andleft, by a longitudinal fissure. At the bottom of this fissure whitefibers are seen to pass from one side to the other, thus forming a THE BRAIN. 251 transverse commissure, connecting the hemispheres, and called thecorpus callosum (Fig. 179). Each hemisphere is marked off byspecially deep fissures, into lobes, the principal ones being thefrontal, parietal, occipital, and temp
. Text-book of anatomy and physiology for nurses. rebellum,medulla oblongata, and pons Varolii. The cerebrum is the largest division and occupies nearly thewhole cranial vault. It is divided into two hemispheres, right andleft, by a longitudinal fissure. At the bottom of this fissure whitefibers are seen to pass from one side to the other, thus forming a THE BRAIN. 251 transverse commissure, connecting the hemispheres, and called thecorpus callosum (Fig. 179). Each hemisphere is marked off byspecially deep fissures, into lobes, the principal ones being thefrontal, parietal, occipital, and temporal. The principal fissuresbetween the lobes are: the fissure of Rolando between the frontaland parietal; the parieto-occipital, between the parietal and occipital;and iYvQ fissure of Sylvius, between the temporal lobe below and thefrontal and parietal above it. Important note.—The fissure of Rolando is often called the central fissure, andthe convolutions in front of and behind it, are called the central convolutions(anterior and posterior).. Fig. 179.—Median Surface of a Hemisphere, sii<j\vi.\(; Third and Fourth\entricles; also the Corpus Callosum Divided, and the Structltre of theCerebellum with the Pons in Front of It. The Pituitary Body is Suspendedfrom the Floor of the Third Ventricle (Deaver). Within the white substance of the hemispheres are the largestganglia in the brain, and since they are situated near the base,they are called basal ganglia. They are the optic thalamus, thelentiform nucleus, and the caudate nucleus (Fig. 181). The whitematter between the optic thalamus and the other two, constitutesthe internal capsule. Here are the fibers which connect centers inthe cortex with those in the spinal cord; hence the great importanceof the internal capsule. The hemispheres are not solid, but each encloses a cavitycalled the lateral ventricle, shaped like the italic letter / with aprojecting arm (laterally and downward). The extremities of the 252 ANATOMY AND PH
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