The Posterior Perforated Space (Pons Tarini) corresponds to a whitish-gray Fossa placed between the Corpora Albicantia in front, the Pons Varollii behind, and the Crus Cerebri on either side.
It forms the Posterior part of the floor of the Third Ventricle, and is perforated by numerous small orifices for the passage of the Postero-Median Ganglionic branches of the Posterior Cerebral and Posterior Communicating Arteries.
The Pons Varolii is situated immediately behind the two Crura of the Cerebrum. It consists of a broad band of white fibers, which pass transversely from one Cerebellar Hemisphere to the other; the band becoming narrower as it enters the Cerebellum.
In the Middle Line on its under surface a narrow groove runs from before backward and accomodates the Basilar Artery.
The Medulla Oblongata emerges from the Posterior border of the Pons Varolii; it is Pyramidal in form, and is continuous below with the Cervical portion of the Spinal Cord.
It is marked on its Ventral surface by a median fissure, continuous below with the Anterior median fissure of the Cord, and on either side by secondary fissures and columns, which will be described in the sequel.
The Frontal Lobe's under surface is seen on the Anterior part of the base of the Brain on either side of the Median Line. It is sometines called the Orbital Lobe.
p658
The Fissure Of Sylvius at the base of the Brain separates the Frontal from the Temporal Lobe, and lodges the Middle Cerebral Artery.
The Optic Tracts are well marked, flattened bands of Fibers, which run Obliquely across the Crus Cerebri on either side, and unite Anteriorly to form the Optic Commissure.
The Crura Cerebr (Peduncles of the Cerebrum) are two thick cylindrical bundles of White Matter, which appear in front of the Anterior border of the Pons, and diverge as they pass forward and outward to enter the under surface of each Hemisphere.
Each Crura is about three quarters of an inch in length, and is about the same in breadth Anteriorly, but somewhat less Posteriorly.
They are marked upon their surface with Longitudinal Striae, and each is crossed, just before entering the Hemisphere, by the Fourth Nerve and the Optic Tract, the latter of which is adherent by its upper surface to the Peduncle.
The Temporal Lobe's under surface is visible at the base of the Brain, on either side of the Crura and the structures contained in the InterPeduncular Space.
It is separated Anteriorly from the Frontal Lobe by the Fissure Of Sylvius, and behind is limited by the Anterior border of the Lateral Hemispheres of the Cerebellum.
The Fissures and Lobes on its surface have already been described (p652).
p659
The Hemispheres Of The Cerebellum are situated on either side of the Middle Line, and cover the Occipital Lobes of the Cerebrum, when viewed from the base.
The Cerebellum differs much in appearance from the rest of the EnCephalon, being of a darker color, while its Convolutions are smaller and narrower,and arranged like the leaves of a book, and hence called Folia.
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Continued_In 14-02