416 COEPORA-STRIATA. 



terior cerebral ganglia are considered as the centres of 

 sensation, and have been observed to bear a proportion in 

 size to the posterior lobes of the cerebrum. Between the 

 thalami a cavity is noticed, called the third ventricle. This 

 cavity has the fornix above and in front the tuber ciner- 

 eum below, and the tubercula quadrigemina behind. At 

 its anterior part it opens into the infundibulum, and in its 

 posterior portion it communicates with the fourth ventri- 

 cle by the aqueduct of Sylvius. 



This cavity is closed by a soft layer of cineritious matter 

 called the commissura mollis, which connects the two inter- 

 nal surfaces of the thalami together. 



In front of this commissure is the foramen commune an- 

 terius, leading to the pituitary gland ; and behind is the 

 foramen commune posterius, leading to the fourth ventricle. 

 The posterior commissure is behind the third ventricle, and 

 connects the thalami at this point. It is a short, white, 

 round cord, extending transversely. There is another 

 white, round cord, called the anterior commissure, which 

 belongs more properly to the next bodies we have to ex- 

 amine. 



Corpora Striata, (Fig. 117.) These bodies, so called from 

 their striated appearance when cut into, are also named 

 anterior or superior ganglia of the cerebrum. Their situa- 

 tion is in front of the thalami ; their shape is pyraform, 

 having their smaller ends looking backward and outward, 

 and enclosing the thalami while their larger extremities 

 converge and touch each other in front. They are about 

 two and a half inches long, and help to form the floor of 

 the lateral ventricles. 



Their structure is soft, vascular, and cineritious on their 

 surface. Internally the gray matter is seen intermixed 

 with the white medullary strias, or fasciculi. These fasci- 

 culi can. be traced from the anterior or motor portion of 

 each crus, and still further back from the anterior rods 

 of the spinal cord ; after passing through the corpora 

 striata, they expand principally into the anterior and 

 middle lobes of the hemispheres, to which they bear a 



