TEXTURE AND ORGANIZATION OF THE TEETH. 477 



sides of the tooth, but receives, through the opening in the root, 

 an artery, a vein, and a nerve. The surface of the pulp is 

 moistened by a slight exhalation, and its principal bulk seems 

 to be formed by the nerve, on which the vessels ramify; the 

 latter in youth are much more abundant than in old age.* The 

 base of each projection on the grinding surface of a tooth is hol- 

 lowed out for receiving a process from the pulp. The latter is 

 supposed, by M. Serres, to be a ganglion; it must, however, 

 be a point of much difficulty to fix this character upon it, as the 

 fine cellular substance which holds its constituents together may 

 be readily mistaken for soft nervous fibres. 



The arteries of the teeth of the upper jaw are derived from 

 the alveolar and the infra-orbitar, and the nerves from the se- 

 cond branch of the fifth pair. The arteries of the teeth of the 

 tower jaw come from a single branch of the internal maxillary, 

 and the nerves from the third branch of the fifth pair. The in- 

 ferior maxillary, or dental artery, and nerve, go through the 

 canal in the centre of the spongy structure of the lower jaw, 

 and send off branches successively to the roots of the teeth. 

 The residue of the artery and nerve issues through the ante- 

 rior mental foramen. 



The teeth have been, till lately, very generally ranged among 

 the bones belonging to the skeleton ; the continental anatomistsf 

 are, however, now more disposed to view them as the produc- 

 tion of the dermoid tissue, like the nails and the hair; and to 

 withdraw them from the class of bones for the following rea- 

 sons. The rudiments of the bones are always in a cartilagi- 

 nous state, and they are gradually changed from that condition 

 to^the perfect bone; the teeth are never so, for the secretion 

 which forms them is from the beginning deposited in the state 

 in which it ever afterwards remains. The bones are all fur- 

 nished with a periosteum; the teeth are not, but have the sur- 

 faces of their bodies exposed to the air. The general soften- 

 ing of the skeleton which occurs in some cases of rickets, never 

 is manifested in the teeth.J The texture of the bones is pene- 

 trated in every direction with blood vessels, but only the cen- 



* Serres, Essai sur 1'Anat. et Physiol. des Dents, Paris, 1817. 

 t J. F. Meckel, Hipp. Cloquet, Breschet, Serres, &c. 



t There is, however, a species of brittleness of the teeth, in which their strength 

 becomes about that of pipe clay. 



