294 HUMAN ANATOMY. 



The inner or median surface of the hemispheres presents five 

 fissures, as follows : 



1. Colloso-marginal. 



2. Parieto-occipital. 



3. Calcarine. 



4. Occipito-temporal or collateral. 



5. Dentate fissure, or sulcus hippocampi. 



The lobes on the internal surface are six in number., as 

 follows : 



1. Gyms fornicatus, or convolution of the corpus callosum, de- 

 scends as the gyrus hippocampi and terminates as the uncinate gyrus. 



2. Marginal, or first frontal convolutions. 



3. Quadrate, or praecuneus. 



4. Cuneus, or occipital lobule. 



5. Uncinate gyrus. 



6. Temporo-sphenoidal lobe. 



The inferior surface of each hemisphere is divided into three 

 lobes the anterior, middle, and posterior. The two former 

 occupy the anterior and middle fossa of the skull and the poste- 

 rior rests upon the cerebellum, separated from it by the tento- 

 rium. This surface presents for study from before backward 

 the following points: 



The longitudinal fissure, separates the two hemispheres; 



Corpus callosum, the great transverse commissure of the cerebrum, 

 extending by means of its peduncles to near the Sylvian fissure; 



Lamina cinerea, is a thin, gray layer, forming the anterior part of 

 the inferior boundary of the third ventricle; 



Olfactory nerve, with its bulb; 



Fissure of Sylvius, between the anterior and middle lobes of the 

 cerebrum, and lodges the middle cerebral artery; 



Anterior perforated space, transmits vessels to the corpus striatum ; 



Optic commissure, is formed by the junction of the optic tracts; 



Tuber cinereum, is a gray eminence between the corpora albicantia 

 and optic tracts, and forms part of the floor of the third ventricle; 



Infundibulum , is a tube of gray matter connecting the pituitary 

 body with the third ventricle; 



Pituitary body, is a small, vascular, bilobed body, connected by 

 the infundibulum and occupying the sella Tursica (for histology vide 

 "Ductless Glands"); 



Corpora albicantia, or mammillaria, are two white, rounded 

 masses, formed by the folding of the anterior crura of the fornix, and 

 are sometimes called the bulbs of the fornix; 



Posterior perforated space, allows the passage of blood-vessels to 

 the optic thalami; 



Crura cerebri, or cerebral peduncles, connect the cerebrum with the 

 medulla, cerebellum, and spinal cord; it consists of the anterior portion, 



