ANATOMY. 



under the fbrnix, and 



< ailed tin: v e 



lat'-ral ventricle contains certain 

 eminences, which form its sides ; tin- cor- 

 pus striutiiin is the anterior and superior 

 eminence, grey on > ts external surface, 

 int< rnally. Tlii 1 posterioremi- 

 nenre in each ventricle is called the thala- 

 HIIIS nervi optici ; it is hemispherical, and 

 white, and joined to its opposite one by 

 HII union of substance, culled the softcom- 

 The hippocampus major is a 

 large elongated eminence, lying in the de- 

 scending portion of the later.il ventricle: 

 and the hippoeampus minor is a smaller 

 one, in the digital cavity. 



The pineal gland, orconarium, is found 

 behind the opt if thalanii. Its si/e is about 

 that of a small horse-bean ; its colour 

 irn-y. and ligure conical. Two small me- 

 dullary chords connect it to the optic tha- 

 lanii. In the substance oi' this body is 

 found a small quantity of a gritty mutter, 

 :i- -arl\ resembling sand. It consists of a 

 number of semi-transparent and light \vl- 

 lo\v grains. Soeinmcrring, \vho first dis- 

 covered that this belonged to the healthy 

 structure of the brain, calls it thear.ervulus 

 of the pineal gland. This little body has 

 hceii more intended to and noticed than 

 it would otherwise ha\ e been, inconse- 

 quence of the chimerical dream of Des- 

 cartes, who represented it as the seat of 

 the soul. 



Bcluw the pineal gland is a square por- 

 tion of the brain, divided into four super- 

 ficial eminences called corpora quadrige- 

 mina, and from these a thin production 

 extends to the cerebellum, under the 

 name of valvula cerebri. 



Hy drawing asunder the optic thalami, 

 and separating their soft commissure, we 

 expose the third ventricle of the brain. 

 This appears as an oblong cavity, about 

 an inch and a quarter in length. A round 

 medullary rope is seen in front of it, and 

 a similar one behind; the.v -are i. tiled the 

 anterior and posterior commissures. A 

 round aperture is observed under the an- 

 terior commissure, beyond which tin ven- 

 tricle terminates by a pointed and conical 

 extremity, from which a short pn 

 continued to the pituitary gland, under 

 the name of infundibulum. Tin- foramen 

 commune anterius is an opcningo" 



n the optic thalarni before they are 

 disturbed, and leading from the aperture 

 of communication, which connects the 

 two lateral ventricles under the fornix, into 



the third ventricle. Just be! 

 terior commissure a round opening is 

 found, leading through a short canal, in 

 front of the tubcrcula quadrigemina, to the 



fourth ventricle. It is named canalis mr- 

 dius, iter ad quartum ventriciilum, or 

 aqujeductus Sylvii. Thus the for 

 ventricles of the brain have afree commu- 

 nication with each other. 



Under the posterior lobes of the cere- 

 brum there is found a transverse produc- 

 tion of dura mater, failed te HI ori um, which 

 is attached tothe internal tran-.. 

 of the occiput behind, and to the petrous 

 portions of the temporal bone in front . 

 Under this membrane lie the two lobes >(' 

 the cerebellum, separated by a small per- 

 pendicular production, called the falx ce- 

 rehclli. 



The fourth ventricle is a cavity, leftbe- 

 t\\ een the upper and posterior surface of 

 the medulla oblongata, and the fi-ont of the 

 cerebellum. It extends laterally to a con- 

 siderable distance in the cruva cerebelli: 

 a groove nms along the middle of the me- 

 dulla oblongata, which constitutes tho 

 front of the ventricle, and terminates at 

 the end of the cavity in a point. From 

 the lateral productions, and the pointed 

 termination of the cavity, it has been 

 named the calamus scriptorius. 



The pituitary gland is a firm substance, 

 differing in texture from the brain, and 

 lodged in the sella turcica. Its name is 

 derived from a supposition that it se 

 the mucus of the nose, which in ancient 

 times was supposed to flow from the head. 

 It is connected by the infundibulum to the 

 basis of the brain. Behind the last men- 

 tioned part, at the basis cei-'-bri. are seen 

 two small rounded eminences, called cor- 

 pora subrotunda. The crura cerebri are 

 two large medullary processes going from 

 the cerebrum to the medulla oblongata. 



The cerebellum is situated in the lower 

 fossae of the occipital bone, under i 

 torium. It consists of an int. 

 cortical and medullary substance, arrang- 

 ed differently from the order 

 the cerebrum. A perpendicular section of 

 this part discovers a very dlcgant structure 

 in this respect. A thick tnnk of medul- 

 lary matter sends off ;> .every 

 direction; from thesv oilier branches pro- 

 ceed, all of which art' surrounded ! 

 te.V This is called the arbor vita.-. The 

 arbor \. ites the crus cerebelli 

 on each side, and these processes join the 

 medulla ii 



The medulla oblongata is a large me- 

 dullary protubera onthebasi- 

 lar process of the occiput. Its connection 

 with the crura cerchri and ci re'.u-Ili have 

 hecnahvaih \ medullary chord 

 is continued from > rend, under 

 the name of medni 



.'/ ' -Ha ftfiinati*. This is a roundish 



