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Yeditepe University Medical School Department of Anatomy. ANATOMY OF THE DIGESTIVE SYSTEM PART 1. 2.December.2011 Friday. Kaan Yücel M.D.,Ph.D. Oral Region. The oral region includes the oral cavity , teeth , gingivae , tongue , palate , and the region of the palatine tonsils .

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slide1

Yeditepe University

Medical School

Department of Anatomy

ANATOMY OF

THE DIGESTIVE SYSTEM

PART 1

  • 2.December.2011 Friday

Kaan Yücel M.D.,Ph.D.

slide2

Oral Region

The oral regionincludes the oral cavity,teeth, gingivae, tongue, palate, and the region of the palatine tonsils.

The digestion starts here in the oral cavity.

It is the place where the food is ingested and prepared for digestion in the stomach and small intestine.

slide3

Food is chewed by the teeth, and saliva from the salivary glands facilitates the formation of a manageable food bolus(L. lump).

Deglutition (swallowing) is voluntarily initiated in the oral cavity.

The voluntary phase of the process pushes the bolus from the oral cavity into the pharynx, the expanded part of the alimentary (digestive) system, where the involuntary (automatic) phase of swallowing occurs.

slide4

Oral Cavity (Mouth)

Inferiortothenasalcavities .

Extendsfromthelipstothepharynx.

slide5

Oral Cavity (Mouth)

Has a roofandfloor, andlateralwalls.

Opensontothefacethroughthe oral fissure.

Continuouswiththecavity of thepharynx at theoropharyngealisthmus.

slide6

The oral cavity has multiplefunctions:

Inletforthedigestivesysteminvolvedwiththeinitialprocessing of food, which is aidedbysecretionsfromsalivaryglands.

Manipulatessoundsproducedbythelarynx.

Can be usedforbreathingbecause it opensintothepharynx, which is a commonpathwayforfoodandair.

Forthisreason, the oral cavity can be usedbyphysicianstoaccessthelowerairway.

slide7

Oral cavity (mouth) consists of two parts:

Oral vestibule

Oral cavity proper

slide8

Slit-likespacebetweentheteethandgingivae (gums) internallyandthelipsandcheeksexternally.

  • Enclosedbydentalarches.
  • Communicateswiththeexteriorthroughtheoral fissure(opening).

Oral vestibule

slide9

Thelateralwall of thevestibule is formedbythecheek, which is madeupbythebuccinatormuscle.

Thetone of thebuccinatormuscleandthat of themuscles of thelipskeepthewalls of thevestibule in contactwithoneanother.

slide10

Theduct of theparotidsalivarygland (Stensen’sduct) opens on a smallpapillaintothevestibuleoppositetheuppersecondmolartooth.

slide11

Thespacebetweentheupperandthelowerdentalarches.

  • Has a roofand a floor.
  • Theroof of themouth is formedbythe hard palate in frontandthesoftpalatebehind.
  • Oral cavityproper
slide12

Thefloor is formed

  • largelybytheanterior 2/3 of thetongue
  • and
  • bythereflection of themucousmembranefromthesides of thetonguetothegum of themandible.
slide13

Thesubmandibularduct of thesubmandibulargland (Warton’sduct)opensontothefloor of themouth on thesummit of a smallpapilla on eitherside of thefrenulum of thetongue.

slide14

Lips

  • Mobile, musculofibrous folds surrounding the mouth
  • Coveredexternally by skin and internally by mucous membrane.
  • Function as the valves of the oral fissure, containing the sphincter (orbicularis oris) that controls entry and exit from the mouth and upper alimentary and respiratory tracts.
  • .
slide15

Formthe movable walls of the oral cavity.

The prominence of the cheek occurs at the junction of the zygomatic and buccal regions.

  • Cheeks (Buccae)

External aspect- Buccal region

Anteriorly by lips and chin

Superiorly by zygomatic region

Posteriorly parotid region

Inferiorly by inferior border of mandible

slide16

Teeth

  • Thechieffunctions of theteethareto:
  • Incise, reduce, andmixfoodmaterialwithsalivaduringmastication.
  • Helpsustainthemselves in thetoothsocketsbyassistingthedevelopmentandprotection of thetissuesthatsupportthem.
  • Participate in articulation (distinctconnectedspeech).
slide17

The teeth are set in the tooth sockets.

There are 20 deciduous teeth and 32 permanent teeth: four incisors, two canines, four premolars, and six molars in each jaw.

slide18

Gingivae (Gums)

  • Composed of fibroustissuecoveredwithmucousmembrane.
  • The gingiva proper (attached gingiva) is firmly attached to the alveolar processes of the mandible and maxilla and the necks of the teeth.
slide19

Formspart of thefloor of the oral cavityandpart of theanteriorwall of theoropharynx.

  • Tongue

A mass of striatedmusclecoveredthmucousmembrane

slide20

Itsanteriorpart is in the oral cavityand is somewhattriangular in shapewith a bluntapex of tongue.

The apex is directed anteriorly .

Theroot of tongue is attachedtothemandibleandthehyoid bone.

slide21

Papillae

Thesuperiorsurface of the oral part of thetongue is coveredbyhundreds of papillae.

4 types of papillae in thetongue:

slide22

The superior surface of the oral part of the tongue is covered by hundreds of papillae.

4 types of papillae in the tongue.

The papillae in general increase the area of contact between the surface of the tongue and the contents of the oral cavity.

slide23

Muscles of theTongue

IntrinsicandExtrinsicMuscles

Intrinsic muscles: confined to the tongue, are not attached to bone.

Extrinsic muscles: attached to bones and the soft palate.

slide24

Innervation of the tongue is complex and involves a number of nerves.

Trigeminal nerve: sensation from 2/3 anterior tongue

Glossopharyngeal nerve: sensation from 1/3 posterior tongue

Taste from oral part: by the facial nerve

Taste from pharyngeal part: by the glossopharyngeal nerve

slide25

Movements of theTongue

Protrusion:

Retraction:

Depression:

Shape changes:Intrinsic muscles

slide26

Movements of theTongue

Depression:Hyoglossusmuscles on bothsidesactingtogether

Retractionandelevation of theposteriorthird:Styloglossusandpalatoglossusmuscles on bothsidesactingtogether

Shapechanges:Intrinsicmuscles

slide27

Palate

  • Formsthearchedroof of themouthandthefloor of thenasalcavities.
  • Separatesthe oral cavityfromthenasalcavitiesandthenasopharynx, thepart of thepharynxsuperiortothesoftpalate.
  • Consists of 2 regions:
  • Hard palateanteriorly
  • Ssoftpalateposteriorly
slide28

Posteroinferiorly, the soft palate has a curved free margin from which hangs a conical process; uvula.

slide29

Fauces (Thorat)

The space between

the cavity of the mouth and the pharynx.

Bounded

Superiorlyby the soft palate

Inferiorlyby the root of the tongue

slide30

Oropharyngeal isthmus (isthmus of the fauces) is the short constricted space that establishes the connection between the oral cavity proper and the oropharynx. By closing the oropharyngeal isthmus, food or liquid can be held in the oral cavity while breathing.

The palatine tonsils, often referred to as “the tonsils,” are masses of lymphoid tissue, one on each side of the oropharynx.

.

slide32

ParotidGland

Thelargestsalivarygland

Lies in a deephollowbelowtheexternalauditorymeatus, behindtheramus of themandible, and in front of the SCM.

Thefacialnervedividestheglandintosuperficialanddeeplobes.

slide33

Theparotidductpassesforwardoverthelateralsurface of themasseter.

Itentersthevestibule of themouthupon a smallpapillaoppositetheuppersecondmolartooth.

slide34

NerveSupply

Parasympatheticsecretomotorsupplyarisesfromtheglossopharyngealnerve.

Parasympathetic stimulation of the parotid gland produces a thin watery saliva.

slide35

SubmandibularGland

Liesbeneaththelowerborder of the body of themandible

slide36

Submandibular duct runs medially to open at the side of lingual frenulum.

  • Parasympathetic secretomotor supply is from the facial nerve.
slide37

SMG = submandibulargland, ABD = anteriorbelly of digastricmuscle, LN = submandibularlymphnode, FV = facialvein, FA = facialartery, MH = mylohyoidmuscle.

slide38

SublingualGland

Lies beneath the floor of the mouth.

The sublingual ducts (8 to 20 in number) open into the mouth.

slide39

PHARYNX

Musculofascialhalf-cylinder

Links oral and nasal cavities in the head to the larynx & esophagus in the neck.

Superiorexpanded part of the alimentary system posterior to the nasal and oral cavities, extending inferiorly past the larynx.

Extendsfrom the cranial base to and is continuous with the top of the esophagus.

slide40

Based on these anterior relationships the pharynx is subdivided into 3 regions:

  • Posteriorapertures (choanae) of the nasal cavities open into the Nasopharynx
  • Posterioropening of the oral cavity opens into
  • Oropharynx
  • 3) Apertureof the larynx (laryngeal inlet) opens into the
  • Laryngopharynx
slide41

Nasopharynx has a respiratory function; posterior extension of the nasal cavities.

Oropharynxis posterior to the oral cavity, inferior to the level of the soft palate, and superior to the upper margin of the epiglottis. It opens anteriorly, through the isthmus faucium, into the mouth.

Laryngopharynxlies posterior to the larynx and anterior to the vertebral column.

slide42

Waldeyer's Ring of Lymphoid Tissue

1- Pharyngeal tonsil-Adenoid

2- Tubal tonsil

3- Palatine tonsil

4- Lingual tonsil

slide44

OESOPHAGUS

Musculartube about 10 in. (25 cm) long

Extendsfrom the pharynx to the stomach.

Beginsin the neck where it is continuous with the laryngopharynx .

Consistsof striated (voluntary) muscle in its upper 1/3, smooth (involuntary) muscle in its lower 1/3, and a mixture of striated and smooth muscle in between.

slide45

STOMACH

Expandedpart of the digestive tract between the esophagus and small intestine.

Specializedfor the accumulation of ingested food, chemically and mechanically prepares for digestion and passage into the duodenum.

Actsas a food blender and reservoir; its chief function is enzymatic digestion.

slide46

The size, shape, and position of the stomach can vary markedly in persons of different body types (bodily habitus)

May change even in the same individual as a result of

Diaphragmaticmovements during respiration

Stomach'scontents (empty vs. after a heavy meal)

Positionof the person.

slide47

The stomach has four parts:

Cardia: part surrounding the cardial orifice (opening), the superior opening or inlet of the stomach.

Fundus:dilated superior part related to the left dome of the diaphragm and is limited inferiorly by the horizontal plane of the cardial orifice.

Body:major part of the stomach between the fundus and pyloric part.

Pyloric part: funnel-shaped outflow region of the stomach.

slide48

SMALL INTESTINE

Primarysite for absorption of nutrients from ingested materials.

Extendsfrom the pylorus to the ileocecal junction

where the ileum joins the cecum (the first part of the large intestine).

slide49

Duodenumfirst part of the small intestine

Shortest, widest and most fixed part.

Jejunumbegins at the duodenojejunal flexure where the digestive tract resumes an intraperitoneal course.

Ileumends at ileocecaljunction, union of the terminal ileum & cecum.

Together, jejunum and ileum are 6-7 m long.

Jejunum2/5 , Ileum 3/5

intraperitonealsection of the small intestine.

slide50

Most of the jejunum lies in the left upper quadrant (LUQ), whereas most of the ileum lies in the right lower quadrant (RLQ).

The terminal ileum usually lies in the pelvis from which it ascends, ending in the medial aspect of the cecum.

slide52

LARGE INTESTINE

Where water is absorbed from the indigestible residues of the liquid chyme, converting it into semi-solid stool or feces that is stored temporarily and allowed to accumulate until defecation occurs.

Cecum

Appendix

Ascending colon

Transverse colon

Descending colon

Sigmoid colon

Rectum

Anal canal

slide53

The large intestine can be distinguished from the small intestine by:

Omental appendices: small, fatty, omentum-like projections.

Teniae coli: three distinct longitudinal bands.

Haustra: sacculations of the wall of the colon between the teniae

A much greater caliber (internal diameter).