314- ANATOMY OF 



bellura. 24. Median line of the cerebellum. 25. Middle of the nervous 

 mass of the fundamental part of the cerebellum. 26. Ganglion or corpus 

 rhomboideum of the cerebellum. 27, 27. Mesolobe. 28, 28. Valve of Vieus- 

 sens or mass of connection of the primitive part of the cerebellum with the 

 corpora quadrigemina. 29,29. Pathetic nerves. 30. Commissure of the corpora 

 quadrigemina. 31. Pineal gland. 32,32. Superior band of connection of the 

 pineal gland with the great inferior cerebral ganglion. 33. Soft or middle com- 

 missure of the inferior cerebral ganglion. 34, 34. Mammillary bodies. 35, 35. 

 Transverse interlacement of the great cerebral bundle. 36, 36. Transverse in- 

 terlacement below the optic nerve. 37, 37. Optic thalamus or great inferior 

 cerebral ganglion. 38, 38. Transverse interlacement of the nervous bands of 

 the middle lobes. 39, 39. Transverse interlacements of the great superior cere- 

 bral ganglion. 40, 4O. Fold of the corpus callosum or mass of union of the 

 inferior convolutions of the anterior lobe. (GalL) 



and two of the cerebellum, called crura cerebelli, appear to run 

 to it. The corpora quadrigemina are a part of its superior, or, 

 as it lies obliquely, posterior, portion ; and it, with its continuation 

 the chorda oblongata, furnishes the anterior wall of the fourth 

 ventricle. This cavity is irregularly quadrilateral, and runs ob- 

 liquely from the aquaeductus Sylvii or iter a tertio ad quartum 

 ventriculum, under the valve of Vieussens and processus ad 

 testes, downwards upon the back of the chorda oblongata, and 

 before the vermiform process of the cerebellum. On the floor of 

 it, or, as from the oblique position of the parts we might say, the 

 back of the chorda oblongata, is a groove which ends in a tri- 

 angular depression called calamus scriptorius. 



The mesocephalon, thus appearing formed of prolongations 

 two from the cerebrum, and two from the cerebellum is itself 

 apparently prolonged into a short bulbous chord, termed chorda 

 oblongata, which lies upon the basilar process of the occipital 

 bone. (Cut, p. 304.) On its anterior or lower surface (for it, like 

 the mesocephalon, lies obliquely) are seen four elevations ; the two 

 outer called corpora olivaria, the two inner corpora pyramidalia, 

 or c.p. anteriora, or anterior pyramids. (Cut, p. 311.) On its lateral 

 parts are two oblong prominences, called corpora restiformia : 

 and on its posterior portion two others, called corpora pyramid- 

 alia posterior a or posterior pyramids. (Cut, p. 313.) This chord 

 apparently prolonged becomes the chorda spinalis, which runs in 

 the vertebral canal, from the foramen occipitale to the first or 

 second lumbar vertebra, larger and smaller in various parts of 

 its course : smaller at first than the bulbous chorda oblongata, it 

 swells in the middle of the cervical region, diminishes at the 

 end of this, swells again at the upper part of the loins, and 

 diminishes through the rest of its course, till it ends in an oval 



