30 



ANATOMY. 



Fig. 12. 





Fig. 12. A vertical median section through 

 the cavity of fhe skull, and the spinal canal, 

 to show the way in which the brain and its 

 prolongation, the spinal cord, are lodged 

 within the bony axis of the body, a is the 

 cerebrum, or brain proper ; b the cerebellum, 

 or little brain; < the spinal canal; <' the 

 lower end of the spinal cord ; e the roots of the 

 lumbar or sacral nerves, forming the cauda 

 equina, or so-called horse's-tail ; s the sacral 

 plexus of nerves, and n the great sciatic 

 nerve. This cut also shows sections of the 

 bodies and rings of all the vertebrae; and of 

 the nose, mouth, throat, gullet, tongue, lar- 

 ynx, and windpipe. The brain and spinal 

 cord are protected from the bones by the dura 

 mater, by two layers of the arachnoid, and by 

 the inner membrane or pia mater. (After 

 Bourgery.) 



lary bone, 5, a single strong bone, 

 shaped like a horseshoe with its ends 

 turned up, which finishes the face 

 below, and gives form to the chin. 

 Other bones, such as two palate bones, 

 which complete the hard palate, the 

 vomer or ploughshare bone, the edge 

 of which is seen in Fig. 9, and which 

 helps to part off the right from the 

 left cavity of the nose, two twisted or 

 turbinated bones within the nose, and 

 the two little lacrymal bones in the 

 orbits, also enter into the formation 

 of the face. Like the cranial bones, 

 those of the face, of course excepting 

 the lower jaw, are joined by sutures, 

 but the lines of suture are more even 

 than in the cranium. 



The cavities of the face are these : 

 first, the two eye-sockets or orbits, for 

 the lodgment of the eyeballs, their 

 muscles, vessels, and nerves, and of 

 two little bodies called glands, which 

 secrete or form the tears, the lacry- 

 mal glands (lacrymce, the tears) ; sec- 

 ondly, the nasal cavities, right and 

 left, separated one from the other by 

 a median partition, partly bony and 

 partly cartilaginous, and from the 

 mouth by the palate, but opening back- 

 wards (as shown in the perfect state 

 of the parts in Fig. 9, in which n in- 

 dicates the right nasal cavity) into 

 the upper part of the throat-cavity 

 or pharynx, p, as well as forwards 

 through the nostrils ; thirdly, the cav- 

 ity of the mouth, which also commu- 

 nicates with the pharynx, p, through 

 the arched opening named the fauces, 

 where the tonsils are seen at either 

 side and the uvula in the middle ; it 

 contains, besides the tongue and teeth, 

 two of the glands, named sublingual 

 (sub, under, and lingua, the tongue), 

 which secrete or form the saliva ; 

 lastly, there are certain small cham- 

 bers, situated within the temporal 

 bones, and communicating, at least in 

 the dried state, with the exterior of 

 the sides of the head, in which the 

 apparatus of the internal ears is con- 



