Alimentary SystemChapter 2the digestive glands.The alimentary system (or digestive system)Thealimentarycanal isatubeabout9mlong,adapted(Fig. II-2-1) is composed of the alimentary canal andNasalcavityNasopharynxPalateOral cavityOropharynxTongueLaryngopharynx③LarynxOIEsophagusCardia(CardiacorificeEStomachSnPancreasGallbladderPancreatic ductDuodenojejunal flexureDuodenumLeft colic flexureRight colicflexureTransverse colonJejunumAscendingcolonDescending colonAuCecumVermiformappendixlleumSigmoid colonRectumAnusFig. II-2-1 A diagram of the alimentary system120.DK扫描全能王创建DK
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Chapter2AlimentarySystem121.palate,inferiorlybythe oral base.It communicatesto theingestion,mastication transports,digestionandforward with the exteriorthrough the oral fissure andabsorption of the residues. In sequence from begin-backward with the pharynx through the isthmus ofningto ending, it includes themouth,pharynx,esophfauces (oropharyngeal isthmus).With the gums andagus, stomach, small intestine (subdivided into theteeth, the oral cavity can be divided into two parts,duodenum,jejunum,and ileum)and largeintestinethe oral vestibule and the oral cavity proper.(subdivided intothe cecum,appendix,colon,rectumThe oral vestibule is a slit-like space located beandanalcanal)In clinic,alimentarycanal isdividedtween the lip,cheek and the gums,teeth.When theinto two parts:one part is named the superior di-jaws are closed, atube in it canbe inserted into thegestive tube that contains the mouth, pharynx, esoph-proper oral cavitybyan aperturebehind the3rdmolaragus, stomach and duodenum; another part is calledtooth on either side.the inferior digestive tube that involves the jejunum,The portion between the teeth and the isthmus ofileum and all parts of thelarge intestinefauces is the oral cavity proper.This portion is boundThe digestive glands contain the salivary glands,ed laterally and ventrallyby the alveolararches withliver and pancreas,which are called the large diges-their contained teeth and roofed by the palate, whiletive glands. In addition to that, there are numerousits floorisformedbythetongue,mucousmembrane,minute glands in the walls of the alimentary canal.musclesand skin(Fig.II-2-2).These glands can secret various digestive enzymes toassist in theprocess of digestion.I . LipsSection 1Oral CavityThe lips are two fleshy folds that surround theTheoral cavity,or the mouth,is bounded anterior-lybythelip,laterallybythecheeks,superiorlybythe8169.UpperlipHard palateSoftpalateUvulaPalatopharyngealarchPalatinetonsilPalatoglossal archmedian glossoepiglottic foldRoot of tongueLingual tongsilForamen cecumoftongueVallate papillaeDorsumoftoongueFoliate papillaeFungifom papillacFiliformpapillaeApexoftongueFig. II-2-2The oral cavity and isthmus offaucesborder) of the lips is seen where the skin meets theoral orifice.They are mainly made of the orbicularismucous membrane.oris covered by the skin externally and by the mu-On the external surface of the upper lip there arecous membrane internally.The red margin (vermilion口2DK扫描全能王创建尚
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·122·PARTII SPLANCHNOLOGYpassage from the mouth to the pharynx, named thethree shallow grooves:one named the philtrum inisthmus of fauces, surrounded by the uvula, palato-the middle and two termed the nasolabial sulcus onglossal arches and the root of tongue. The tonsillarlateral.The former is vertical and only found in hu-fossa, a triangular recess in which the palatine tonsilman being, while the latter look like the eight in Chi-is lodged, situates between the palatoglossal arch andnese and are the boundary between the upper lip andthe palatopharyngeal arch.cheek.In the median plane of the inner surface of eachlip,a fold of mucous membrane termed the labialIV.Teeth (Dentes)frenulum connects the lip with the correspondingTwo sets of teeth appear at different periods of lifegum.in human being:the deciduous teeth (milk teeth)II.Cheeksappeared in infancy and the permanent teeth eruptedin childhood. But every one of them can be dividedThe cheeks are continuous with the lips in frontinto three parts:a crown projecting above the gum,and have a structure similar to the lips.Opposite thea root (or roots) embedded in the alveolar bone andsecond molar tooth of the maxilla, there is a smalla constricted neck covered by the gum. The cavitypapilla (papilla of parotid duct) on the mucous mem-in the inner of a tooth is named the cavum dentisbrane, on the summit of which is the opening of the(dental cavity),consisted of thecavity ofthecrownparotid duct.In chewing,blowing,suckingand speak-and the root canal, and is filled with the dental pulp.ing, the buccinator in the cheeks contract so that theA small opening at the apex of theroot is called thecheeks are pressed closelyto the teeth for preventingapical foramen through which vessels andnerves passthe food or saliva from dropping out.and form the dental pulp.Because the dental pulp isentirely surrounded by the hard dental substance, theII.Palateman would feel severe pain if his dental pulp is in-fected.The forming substance of the tooth includes theThe palate is the roof of the oral cavity anddentine, enamel and cement.The dentine forms theseparates it from the nasal cavity.It consists of twobulk of the tooth and is distributed with the nerveparts:the hard palate,an anterior two-thirds, and theThe enamel is the hardest substance in the body andsoft palate,a posterior one-third (Fig.II-2-1,2)The hard palate has a bony support, formed bycovers on the surface of the dentine of the crown.Thethe palatine process of the maxilla and the horizontalcement is a thin bone-like tissue that covers the sur-plate of the palatine bone. A dense structure, com-face of the dentine of the neck and the root. Both theposed of the periosteum and mucosa, is closely stuckenamel and cement have no innervation (Fig.II-2-3)on the bone.According to the characteristics and function ofThe soft palate is suspended from the posteriorthe teeth, the permanent teeth can be divided into fourborder of the hard palate and extended backwardskinds:the incisors, canine teeth, premolars and mobetween the mouth and the oropharynx.It consistslars.But in the deciduous teeth, there are only threemainly of the mucosa, muscles and aponeurosis.Thekinds:the incisors, canine teeth and molars.Theposterior portion of the soft palate goes downwardsmethod of recording theteeth is asfollows:fromand is termed the palatine velum. The uvula, a smallthe midline in front passing laterally and backwards,conical process,hangs from the middleof thefreethe arrangement of the permanent teeth are two in-posterior border of the palatine velum.Two curveds,one canine, two premolars and three molars inmucous folds are extended laterally and downwardseach quadrant, a total of thirty two; @ the milk teethfrom each side of the base of the uvula. The anteriorare two deciduous incisors, one deciduous caninefold is named the palatoglossal arch,running down-and two deciduous molars in each quadrant, a total ofward to the side of the root of the tongue.The pos-twenty(FigII-2-4).In clinic, the permanent teethteriorfold is called the palatopharyngeal arch,goingare recorded with the Arabic number but the milkdownward to the side of the pharynx.A littlenarrowteethwiththeRoman number.话扫描全能王创建DK
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Chapter2AlimentarySystem123.Grown oftoothEnamelDentineGumNeckoftoothDental pulpRoot oftoothBoneCementPeriodontiumNerveFig.II-2-3The section through a typical toothSometimes the third molars do not erupt.Everykind of the teeth has its characteristicsEach incisor has a crown with a horizontal sharp cut-ting edge and a single root. The crown of the caninesis conical and the root is single too,but stronger andlonger than the root of the incisors.Two cusps aresurmounted on the crown of each premolar, so theteeth are named the bicuspids too. The premolarsgenerally have a single root except the upper first pre-molar which usually has a double roots.The crown ofeach molar teeth is surmounted by four or five cusps.Hence the molars are sometimes called the multicus-pids. As a rule, each upper molar has three roots butCanineIncisorsPremolarsMolarsteetheachlowermolar has two.In general, the incisors andcanine are adapted for biting but the premolars andFig.-2-4Theright permanent teethmolars for grinding and crushing.The first tooth of the deciduous teeth, usually theThe structures surrounding the teeth are usuallylower deciduous central incisor, erupts at about thecalled the periodontal structures that consist of thesixth month. All twenty teeth usually present by thesockets, gums and periodontal membrane.The sock-end of the second year. The first of the permanentets of the alveolar processes of the mandible and max-teeth to erupt at about the sixth year is the first mo-illae are used for holding the roots of the teeth. Thelar and appears behind the second deciduous molar.periosteum lining the sockets is called theperiodontalThe rest of the permanent teeth appear between themembrane and continues with the gums. The gumsseventh and thirteenth years except the third molars,(gingivae)are the tissue surrounding the neck of thewhich appear between the seventeenth and twen-teeth and the alveolar processes, and extends slightlyty-fifth years and are known as the wisdom teeth.into each socket. The periodontal structures play an口扫描全能王创建D
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·124.PART II SPLANCHNOLOGYthe tongue is linked with the hyoid bone, the mandimportantroleinfixing,nourishing and protecting theble,thestyloidprocesses,thesofpalate andthe wallteeth.of thepharynx.In shape the tongue has a root, an apex, a body,adorsum (or superior surface)and an inferior surface.V.Tongue (Lingua)A V-shaped groove called the terminal sulcuson theThe tongue is a flat muscular organ associateddorsum divides the tongue into two parts:the oralwith thefunctions of deglutition, taste and speech.Itpart (or anterior 2/3) and the pharyngeal part (or pos-is situated partly in the floor of the mouth and partlyterior 1/3) (Fig. II-2-2, 5) .in the pharynx.By the muscles and the mucous folds,Epiglotis Median glossoepiglttic foldEpiglottic valleculaRootof tongueLingual tonsilVallate papillaeForamencecumoftonguPalatoglossal archFoliate papillaeTerminalsulcusMedian sulcus of tongueBodyof tonguFungiformpapillaeFiliform papillaeApexoftongueFig. II-2-5 The tongue (dorsal view)Themucousmembrane of theanterior2/3of thenear the terminal sulcus. Above three kinds of papil-dorsum is thicker,rough and covered by the stratifiedlae are studded with taste buds which can feel thesquamous epithelium.The epithelium forms a lot ofstimulation of acid, sweet, bitter and salt substance.small projections called the papillae of the tongue.The fliform papillae are conical in shape and can beThe papillae have four types:the vallate papillae,found nearly everywhere on the anterior two-thirdfungiform papillae,foliate papillaeand filiform papilof dorsum of the tongue. These papillae have a colorlae (Fig.1I-2-2,5).The vallate papillae arelarge andof white and no taste buds. The fur of tongue in Tra-vary in number from 8-12, which form a row on eachditional Chinese Medicine is formed by the filiformside just infront ofand parallelto theterminal sulcus.papillae and the debris of the food remained betweenEach papilla is 1-2mm wide and has a shape of flatthe papillae.topped and circle elevationi that is surrounded by aThe mucous membrane of the posterior one thirddeep groove.The fungiform papillae,arefound chiefofthe dorsum ofthe tongue is smoother and containsly on the sides and tip of the tongue and appeared asa numerous lymphfollicles (lingual tonsil).red round eminences.The foliate papillae are redIn the midline of the inferior surface, the tongueleaf-like projections found at the sides ofthe tongueis connected with the oral foorby a vertical mucous口福扫描全能王创建合
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