y///: CENTRAL .f.v/N or Tin: \/-;/;i , /:v. 



(This ligament, or membra mi tit nlutn. serves to maintain the position of 

 the spinal cord in its hydrostatic bed, and to prevent the nerves proceeding 

 from it being dragged during flexion of the spine.) 



CRANIAL, OH ENCEPHALIC PIA MATER. The vascular clement pre- 

 dominates in this portion of the internal meningo. 



This membrane sends scarcely any prolongations to the dura muter, 

 except at the medulla oblongata, though it projects remarkably large >n<-s 

 into the cerebral mass and the sides of the cerebellum. The description of 

 the velum interpositnin, and the cerebral and cerebettar ftextu diornlib-n, belongs 

 to the encephalon. 



(The pia mater is extremely vascular on the surface of the cerebrum, and 

 forms remarkable anastomosing loops in the intermediate spares of the 

 convolutions, which chiefly supply the grey substance. It is the nutrient. 

 membrane of the brain and spinal cord. Its nerves accompany its arterial 

 branches, and are minute filaments from the sympathetic.) 



DIFFEBENTIAL CHARACTERS IN THE ENVELOPING AND PROTECTIVE PARTS OF THE CKRKUK'i- 

 SPINAL AXIS IN OTHER THAN SOUPED ANIMALS. 



The bony canal that protects the spinal cord and brnin docs not present any note- 

 worthy differences in the domesticated animals, and the subject has been already 

 sufficiently studied in the osteology of the head and vertebral column. 



With regard to the meuinges, their number and general disposition are the same in 

 all the species. 



COMPARISON OF THE ENVELOPING AND PROTECTIVE PARTS OF THE CEREBRO-SPINAL 

 AXIS OF MAN WITH THOSE OF ANIMALS. 



There is nothing particular to be said resorting the cranial cavity and spinal can:il, 

 nor yet the arachnoid and pia mater. The dura mnter offers the folds described in 

 SilijKtds, and, in addition, afalx cerebellum, that extends from the tcnlorinm of flu- *ame 

 name to near the foramen magnum. The mcningeal granulations, or I'acehioninn glands, 

 are nearly constant in aged individuals, and their volume is sometimes SO considerable, 

 that by compression they thin uway, and even perforate, the cranium at corresponding 

 points. 





CHAPTER II. 



THE SPINAL CORD. 



. Isolate the cranium and vertebral column from all the oilier purls of the 

 l>dy; open the spinal caiial and the cranial cavity by thtir superior surface, a* in 

 figure 316, by raising with a chisel (or wjne-;// </, the farrier's "toe-knife") and hammer. 

 the roof of the skulfand annular portion of all the vertebra-. The organ may tin n !>, 

 .4m lied / *itu in its bony case, and surrounded by its membranes; afterwards extra'-t 

 tlie whole cerebro-spinal axis inclosed in the dura mater, and open up tho latt.-r along 

 the course of the cord, so as to completely expose that portion of the nervous sy.-tem. 



(The saw and farrier's pincers, or spine ratchet, will be found n.-efnl auxiliaries in tbc 

 tedious and delicate operation of exposing the brnin and cord; and particularly in lay- 

 ing open the cranial cavity. An easy mode of obtaining aecess to the spinal canal and 

 its contents, is to saw through the lamina 1 of the veid lira 1 on each ,-ide. at the loots of 

 the transverse processes, and raise the arches with the chisel or to. -knife.) 



KXTKKNAL CONFORMATION OF THE SPINAL CORD. 



General view. Tho spinal card is that portion of the nervous centres u liieli 

 occupies the spinal canal. It is a thick, \vliile,.und irregularly cylindrical 

 cord, commencing at tho occipital foramen, where it continues the medulla 

 oldoiigata, terminating in -a point at tho upper third of the sacral canal, or a 



