SECTION YIII 



THE ORGANS OF DIGESTION 



THE ORGANS ABOVE THE DIAPHRAGM 



Bv ARTHUR HENSMAX, F.R.C.S. 



RKVI?:KI) FOK second KDITION 1(Y ARTHUR ROBINSON, M.D., M.R.C.S., LECTURER ON ANATOMY IN THE MIDDF-ESEX 

 IIOSPITAI, MEDICAL SCHOOL; EXAMINER IN ANATOMY FOR THE CONJOINT BOARD OF ENGLAND 



T' 



THE MOUTH 



iHE mouth is the cavity at the commencement of the alimentary canal ■svhich 

 j contains the organs of taste and mastication and the greater part of those of 

 speech. It comnmnicates with the exterior through a transverse orifice (the 

 buccal orifice) and with the pharynx through the fauces. 



It is bounded anteriorly and laterally by the teeth and alveolar arches; external 

 to which is a second cavity, often described as the vestibule of the mouth, which 

 is enclosed by the lips and cheeks. Its roof is formed by the hard palate, its floor 

 by the tongue, with the nuicous membrane re-flected from it to the inner surface of 

 the gums over the sublingual glands and the A^'hartonian ducts; and posteriorly it 

 opens into the fauces. It is lined by mucous membrane, which is continuous with 

 that of the pharynx, and at the outer margin of the lips it is continuous with the skin. 



The buccal orifice is a horizontal slit, the extremities or " angles " of which are 

 ojiposite the first bicusj^id teeth. The orifice is bounded by the upper and lower 

 lips, of Avhich the former is distinguished by a median tubercle, the remains of the 

 free extremity of the fronto-nasal process. The lips are covered b}' a dry mucous 

 membrane, bright red in color, and extremely sensitive, containing large numbers 

 of vascular papillae, in many of which are nerve-terminations resembling touch- 

 corpuscles. Near to the junction of the skin and mucous membrane are numerous 

 sebaceous follicles, but these are devoid of haii'-bulbs. 



The substance of the lips consists of the orbicularis oris and a quantity of 

 areolar tissue in which are eml^edded the coronary vessels, lymphatics, and small 

 l»ranclH's of the infraorbital and mental nerves. Around the orifice of the mouth 

 on its inner aspect, and })laced beneath the mucous membrane, are a number of 

 small lobulated glands known as the "labial glands." 



The cheeks consist of the buccinator muscle, covered externally, first by a 

 stratum of sul)cutaneous fat, then by the dermal muscles, zygomatici and risorius, 

 and lastly by the skin. They are lined with mucous membrane, which contains 

 numerous buccal glands similar to, but smaller than, the labial glands. Between 

 the integument and the buccinator, in each cheek, besides vessels and nerves there 

 are several glands, the molar glands, whose ducts pierce the Ijuccinator and open 

 in the vestibule opposite tlie last molar teeth, and a large quantity of fat, which 

 gives rotundity to the features, and constitutes what is sometimes spoken of as the 

 sucking cushion of the cheek. Opposite the second upper molar tootli is a papilla 

 which marks the opening of the duct of the parotid gland. 



The gums are formed by a layer of tough areolar tissue covering the alveolar 

 processes, and firmly attached to their periosteum. 



They are covered on l)oth aspects l)y the mucous membrane of the mouth, the 

 iimer surfaces receiving reflexions from the sides and anterior extremity of the 

 tongue, a median fold forming the frffiuum of that organ; and the outer surfaces 

 receiving reflexions from'tlie cheeks and lips. In the median line alcove and below 

 the orifice of tlie mouth are folds of mucous membrane, forming the fraena laljiorum, 

 of whicli the upper is the more marked. 



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