154 THE BRAIN AND ITS MENINGES. 



mic sinuses ; between which from side to side there are two 

 channels of communication running around the corpus 

 albicantium, called the circular sinuses. Continuous with 

 the ophthalmic sinuses are the inferior sinuses ; between the 

 two of which a branch of communication is named the 

 transverse sinus. The inferior sinuses discharge into the 

 lateral, which empty into the jugular vein. 



Besides these there are other sinuses at the base of the 

 brain. A large reddish body lies behind the optic nerves ; 

 which is known as the pituitary gland or corpus albicantium ; 

 and the white substance that connects it to the brain is 

 spoken of as the infundibulum {Plate V. Fig I . d), being 

 nothing more than a hollow portion of the very white 

 matter forming the fornix. At the back of the corpus 

 albicantium is seen a broad white band ; crossing the very 

 commencement of what should be the spinal cord, if it 

 were continued so far, and forming the crus or legs of the 

 cerebellum {Plate V. Fig 1 . e, e). The broad white band 

 is the pons varoli {Plate V. Fig 1 . /) . From this two white 

 streams (the crura cerebri), which seem to flow from the 

 before-mentioned white band, come two strings. These are 

 the third pair of nerves, the motores oculorum {Plate V. Fig 

 1 . 3, 3) ; which go entirely to the eyes for motion. Look now 

 a little higher up, and more backward than the root of the 

 third pair ; there will be seen a white thread, which existing 

 upon either side of the front of the pons varoli, forms 

 the fourth pair, motor nerves ; the pathetic going to the 

 superior oblique of the eye {Plate V. Fig 1 . 4, 4). From 

 the sides of the pons varoli, but not very high up or far 

 backward, are seen a couple of large roots, the par tri- 

 gemini ; the fifth a very mixed nerve {Plate V. Fig 1 . 5, 5). 

 The sixth pair of nerves are situated just behind ; and a little 

 below the fifth pair, and go principally to the abductor 

 muscles of the eye, being hence called the abducens {Plate 

 V. Fig 1 . 6, 6). Upon the posterior part of the brain, 

 behind the pons varoli, is placed a seventh pair of nerves ; 

 consisting of two parts, a portio mollis and a portio dura 

 {Plate V. Fig 1 . 7,7). The portio mollis being a nerve of 

 special sense, and going to the internal ear for hearing ; 

 and the portio dura being a motor nerve ; and as such dis- 

 tributed over the face. The eighth pair arise posterior to 



