98 



ANATOMY AND PHYSIOLOGY OF 



inferior parts consist of the excavations in 

 the superior maxillary bone ; snpcn-iorly, the 

 sinus is open, being there continuous with 

 the frontal : the boundary line between 

 these cavities is marked by the suture 

 uniting the lachrymal to the frontal and 

 nasal bones on the outer side, and by the 

 prominent crest formed by the junction of 

 the superior turbinated with the ethmoid 

 bone on the inner ; underneath which part, 

 through a curved (and in the recent subject 

 sort of valvular) fissure, the sinus opens 

 into the middle meatus, between the bases 

 of the turbinated bones. The cavity is but 

 small, and still more irregular, in the young 

 subject, in consequence of the intrusion of 

 the yet uncut molar teeth. 



The frontal sinus, then, terminates in the 

 nasal, but both discharge themselves into the 

 maxillary ; the maxillary has also a blind 

 termination, but empties itself into the pos- 

 terior part of the middle nasal meatus. 



The sphenoidal sinus is situated within 

 the palatine portion of the body of the 

 sphenoid bone. It has no existence in the 

 young subject, the bone being solid through- 

 out ; but in process of growth a cavernous 

 hollow is formed, which, from the seces- 

 sion and attenuation of the lamina? of the 

 bone, continues to enlarge. It communi- 

 cates, by two ovoid openings, with the eth- 

 moidal sinuses. 



The ethmoidal sinuses are two cavities, 

 separated by the perpendicular plate, situa- 

 ted beneath the ethmoidal cells. They 

 have openings in front, communicating with 

 the lowermost and largest grooves of the 

 same bone, and with the palatine sinuses. 



The palatine sinuses are formed between 

 the superior maxillary and palate bones ; 

 are situated below and in front of the for- 

 mer ; are separated from each other by the 

 vomer; and open into the maxillary sinuses: 

 they are irregular in form and cavernous 

 interiorly. They are not to be found in the 

 young subject. Some might be inclined to 

 treat them as parts of the maxillary sinuses ; 

 they are, however, as perfectly distinct from 

 the latter as the frontal are. 



IV. THE MOUTH. 



The mouth is the cavity included be- 

 tween the superior and inferior maxillse, 

 making (in the skeleton) one common va- 

 cuity with the inter-maxillary space. Its 

 antero-posterior dimensions can be but 

 little varied; but its supero-inferior diame- 

 ter will be increased in the ratio of the dis- 

 tance to which the inferior maxilla recedes 

 from the superior; the cavity during the 

 distraction of the jaws assuming the figure 

 of a misplaced t> , the angle of which is 

 turned backward. 



The mouth is formed — superiorly, by 

 the palatine and superior and anterior max- 

 illary bones ; inferiorly, by the inferior 

 maxilla ; laterally, by the molar teeth ; an- 

 teriorly, by the incisive teeth. Behind, 

 through the posterior opening of the nose, 

 it communicates with the nasal fossae. 



PERITONEUM.* 



The whole of the viscera contained 

 within the abdomen proper, including the 

 anterior part of the rectum, bladder, and 

 vasa deferentia, are either entirely or par- 

 tially covered by or in contact with perito- 

 neum. This is a serous membrane reflected 

 also over the parietes of the abdomen, so 

 that a parietal and visceral or reflected por- 

 tion require notice. Like other membranes 

 of the same nature, it forms a closed sac, 

 which, however, is not the case in the 

 female, as its cavity communicates with 

 that of the uterus, owing to the open state 

 of the FaUopian tubes at their fimbriated 

 edges. 



It is loosely connected with the abdominal 

 parietes by subserous cellular tissue, and 

 the same obtains with regard to its connec- 

 tion with the viscera. But we find some 

 parts more adherent than others, such as 

 along the linea alba and cordiform portion 

 of the diaphragm. Also on the organs it 

 is but loosely connected with them at their 

 attached border, where it forms generally a 

 triangular space, occupied simply by vessels, 

 nerves, and cellular tissue, and allowing of 



* Prize Essay by Mr. Gamgec. 



