454 



EXTENT OF THE SCHNEIDERIAN MEMBRANE. 



only of the double membrane. This fold generally continues 

 backwards as far as the spheno-maxillary foramen, which it 

 closes ; the periosteum, exterior to the foramen, passing through 

 H, and blending itself with the fibrous surface of the Schneide- 



l\\. - -a 



^^-'h 



C 



* Fi?. 118 — is a vertical section, exhibiting a profile vievp from the inside of 

 the cavities of the nostrils, mouth, and pharynx, a, The nose. J, Upper lip, 

 situated in front of the palatine arch, which runs horizontally backwards, and 

 divides the cavity of the mouth from the nasal fossse. c, The tongue, the base 

 of which is attached to the os hyoides d. e, The larynx, suspended from the os 

 hyoides, by the thyreo-hoid ligaments which are seen intervening ; it opens 

 backwards towards the pharynx. /, Trachea, g, Cuneiform process of the 

 occipital bone, united to the body of the sphenoid, and to which is chiefly 

 suspended the pharynx h, which is laid open (in order to show its shape and 

 position) by the removal of its right half, and is seen terminating below opposite 

 the cricoid cartilage in the cesophagus. i, Commencement of the cEsophagus. 

 k, Section of the velum pendulum palatee, the lower point of which constitutes 

 the uvula; above this is seen the opening of the posterior nares, 7, into the 

 top part of the cavity of the pharynx ; below this are seen the two half arches 

 of the palate, o, Posterior half arch, r, Anterior half arch, the space or 

 cavity between these occupied by the tonsil gland or amygdala p. I, Sublingual 



