The Alimentary System

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The Alimentary System

• ??????? ?????
• ???

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Composition
Digestive tube ???

• Mouth ??
• Pharynx ?
• Esophagus ??
• Stomach ?
• Small intestine??
• Large intestine ??

Superior digestive tube ????
Duodenum ????
Jejunum ??
Inferior digestive tube ????
Ileum ??
Digestive glands ???

• Major salivary glands ????
• Liver ?
• Pancreas ?

Function ingestion, digestion, absorption,
egesting
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The Oral Cavity ??

• Consists of two parts
• Oral vestibule ???? between cheeks and lip and
  teeth
• Oral cavity proper???? within arch of teeth
• Boundaries
• Anterior and lateral gum and teeth
• Posterior isthmus of fauces
• Roof palate
• Floor tongue, muscles and mucous membrane
• Oral vestibule leads, by the space behind the
  molar teeth, into the oral cavity proper

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Palate ?

• Two parts
• Hard palate anterior 2/3, formed by the maxilla
  and palatine bone
• Soft palate posterior 1/3
• Velum palatinum ??
• Uvula ??
• Palatoglossal arch ???
• Palatopharyngeal arch ???
• Isthmus of fauces ?? formed by posterior border
  of velum palatinum, both side of palatoglossal
  arches, and root of tongue.

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Teeth ?

• General features
• Two sets
• Deciduous ??
• Permanent ??
• Classification
• Incisors ??
• Canine ??
• Premolars ???
• Molars ??

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• Deciduous teeth are 20 in number
• Ten teeth in each mandibular and maxillary arch
• Central incisor???, lateral incisor???, canine??,
  first molar???? and second molar???? in each
  quadrant
• Upper jaw ? ? ? ? ?
  total 20
• Lower jaw in. in. can. mol. mol.
• Eruption stars at about 6 mouth of age and
  continues to beginning of 3rd year
• Shedding occurs between 6th and 12th years with
  replacement by permanent teeth

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• Permanent teeth (adult) are 32 in number
• Sixteen in each mandibular and maxillary arch
• Two incisors, one canine, two premolars, and
  three molars in each quadrant
• Upper jaw 1 2 3 4 5 6 7 8
  total 32
• Lower jaw
• First permanent molar- appears at about 6 years
• Third molars (wisdom teeth)-many erupt at any
  time after 12 years of age or not at all
  (impaction).

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• General description
• Each tooth consists of 3 parts
• Crown ??
• Neck ??
• Root ??
• Dental cavity??-contains connective tissue, blood
  vessels and nerves, and is continuous with the
  periodontal tissue through the root canal and
  apical foramen.

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• Calcified tissues ???
• Dentine??- is a yellowish white tissue, that
  forms the bulk of tooth.
• Enamel ??-is a head, brittle white tissue that
  covers the crown of the tooth
• Cement ???-is an unusual form of bone that covers
  the root of the tooth
• Periodontal tissue????
• Periodontal membrane ???
• Alveolar bone ???
• Gum ??

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Tongue ?-muscular organ

• Two parts divided two parts by v-shaped terminal
  sulcus ??
• Body of tongue ??-ant 2/3,
  apex of tongue ??-free rounded tip
• Root of tongue ??- post 1/3
• At the apex of terminal sulcus is a small median
  pit, the foramen cecum of tongue ???

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• Lingual mucous membrane
• Papillae of tongue ???
• Filiform papillae ????
• fungiform papillae ????
• foliate papillae ???? contain taste
  buds
• vallate papillae ????
• Lingual tonsil ????
• -masses of submucosal
  lymphoid tissue on the root of tongue

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• Inferior surface of tongue
• Frenulum of tongue ???-a midline fold of mucous
  membrane connecting tongue to floor of mouth
• Sublingual caruncle ???-small elevation
• Sublingual fold ???

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• Muscles of tongue ??
• Intrinsic muscles of tongue
• Involved in changing shape of tongue
• Include longitudinal, transverse and vertical
  muscles of tongue
• Extrinsic muscles of tongue
• Genioglossus ???
• Arises from mental spine of mandible and inserts
  into either side of midline of tongue
• Action acting together draw tongue forward and
  downward (depresses and protrudes tongue )
  acting along making apex of tongue to opposite
  side
• Hyoglossus ????
• Tyloglossus ????
• Involved in determining shape and position of
  tongue

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Major salivary glands

• Parotid gland ??
• Superficial part triangular in shape, lies below
  and in front of the external acoustic meatus, and
  partially covers the masseter.
• Deep part lies deep to medial pterygoid .
• Parotid duct arises front anterior border of
  gland, runs over the masseter a fingers breadth
  below the zygomatic arch to pierce the buccinator
  and opens into the mouth cavity, opposite the
  upper second molar tooth

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• Submandibular gland ????
• Position lies in submandibular triangle, between
  anterior and posterior bellies of digastric
• Duct opens on to sublingual caruncle
• Sublingual gland ???
• position situated beneath the mucous membrane of
  the floor of mouth
• Ducts
• Major sublingual duct-opens onto the sublingual
  caruncle
• Minor sublingual ducts-open onto the sublingual
  fold

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The Pharyny ?

• General features
• A fibromuscular tube, part of digestive and
  respiratory systens
• Extends from base of skull to the inferior border
  of cricoid cartilage (lower border of C6 leavel)
• Three segments

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• Nasopharynx ?? -posterior to nasal
  cavities
• Extends from the base of skull to level of soft
  palate, below
• Features
• Pharyngeal opening of auditory tube ?????Tubal
  torus
• Pharyngeal recess ???
• Tubal tonsil ??????
• Pharyngeal tonsil ????
• Oropharynx ?? -posterior to oral
  cavity
• Lies below soft palate, extends to upper border
  of epiglottis

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• Oropharynx ??
• Features
• Median glossoepiglottic fold ??????
• Epiglottic vallecula ???
• Palatine tonsil ????-lies within tonsillar fossa
• Lymphatic ring-consists of pharyngeal tonsil,
  tubal tonsil, and lingual tonsil, forming a
  circular band of lumphoid tissue at oropharyngeal
  isthmus

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• Laryngopharynx ??-posterior to larynx
• Extends from upper border of epiglottis to the
  level of lower border of C6
• Piriform recess????-a deep depression on each
  side of aperture of larynx, common side for
  lodgement of foreign bodies (for example, fish
  bones)

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The Esophagus ??

• General features - a muscular tuber about
  25cm long, connecting the pharynx at level of C6
  vertebra, passes through the diaphragm at level
  of T10 vertebra and after 12 cm enters the
  stomach
• Division
• Cervical part
• Thoracic part
• Abdominal part

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• Three constrictions
• At its beginning, 15cm from incisors, lies at
  level of C6, is the narrowest part of the
  esophagus
• Where it is crossed by left main bronchus, 25cm
  from incisors, lies at level of intervertebral
  disc between T4 and T5.
• Where it passes through the esophageal hiatus of
  diaphragm, 40cm from incisors, at level of T10

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The Stomach ?

• Shape
• Two surface anterior and posterior
• Two curvatures
• Lesser curvature ??? short, concave and
  directed to the right and upward, near its lower
  part is angular incisure ???
• Greater curvature ??? long, convex and directed
  to the left and downward, at the junction of left
  margin of esophagus and greater curvature is
  cardiac incisure ????
• Two openings
• Cardia ??
• Pylorus ??

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• Four parts
• Cardiac part ???
• Fundus of stomach ??
• Body of stomach ??
• Pyloric part ???
• Pyloric antrum ???
• Pyloric canal ???

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• Structure of stomach wall -consists of four usual
  layers
• Mucous membrane
• Submucous ( loose areolar tissue connecting the
  mucous and muscular layer)
• Muscular layer contains
• The most superficial longitudinal frbres
• Inner circular fibres
• Sphincter of pylorus ?????
• Pyloric valve ???
• Innermost oblique fibres
• Serous (visceral peritoneum)

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• Position
• -Mainly parts is situated in the left
  hypochondriac region, small in the epigastric
  region the cardia is situated to the left of
  T11, the pylorus lies to the right of L1

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The Small Intestine??

• About 5-7m long,
• Divided into
• Duodenum
• Jejunum
• Ilium

Duodenum
Jejunum
Ilium
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Duodenum

• Four parts
• Superior part ??
• Duodenal cap ?????
• Superior duodednal flexure ??????
• Descending part ??
• Longitudinal fold of duodenum ??????
• Major duodenal papilla ???????
• Minor duodenal papilla ???????
• Inferior duodenal flexure ??????
• Horizontal part ???
• Ascending part ??
• duodenojejunal flexure ???????

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• Suspensory muscle of duodenum?????? (ligament of
  Treitz), a surgical landmark, descends from the
  right crus of diaphragm to duodenal termination.

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Jejunum and ileum
Characteristic Jejunum Ileum
Position Upper 2/5 Lower 3/5
Diameter Greater Less
Wall Thicker Thin
Circular folds Larger, numerous and large villi Fewer,smaller and less abundant villi
Vascularity Greater Less
Vasa recta Long Short
Colour Deeper red Paler pink
Lymphatic follicles Solitary Aggregated
Fat in mesentery Less More
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Jejunum and ileum
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• Meckels diverticulum
• Persistence of proximal portion of yolk
  sac(vitelline duct, omphalomesenteric duct)
• Common malformation of digestive tract (2-4) -
  more prevalent in males
• About 2-5cm long and located 30-100cm from
  ileocecal valve
• Usually asymptomatic but
• May become inflamed (mimicking appendcitis) or
  bleed
• May be attached to umbilicus by a fibrous cord
  (distal end of yolk stalk) and cause intestinal
  obstruction by compressing adjacent intestinal
  loops

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Large Intestine

• Approximately 1.5m long,
• Five parts
• Cecum ??
• Vermiform appendix ??
• Colon ??
• Rectum ??
• Canal ??

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Large Intestine ??

• Features
• Colic bands ???
• Haustra of colon ???
• Epiploic appendices ???

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Cecum ??

• Blind sac, first part of large intestine, with
  largest diameter and thinnest wall
• Lies in right iliac fossa
• The ilium enters the cecum obliquely, and
  partially invaginates into it, forming the
  ileocecal valve-consists of two folds, probably
  delays flow of ileal contents into large intestine

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Vermiform appendix ??

• Blind worm-like tube, 6-8cm long, about 0.5cm in
  diameter
• Opens into posteromedial aspect of cecum,about 2
  cm below ileoceal orifice
• The base at the appendix lies at the point of
  convergence of three colic bands (used as a
  guide to find the appendix during operation)

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• Surface marking of the base is at the so-called
  McBurneys point which is at junction of lateral
  and middle thirds of line joining right anterior
  superior iliac spine and umbilicus

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• Tip variable in position
• Preileal -28
• Pelvic-26
• Retrocecal -24
• Retroileal-8
• Subcecal-6
• Mesentery of vermiform appendix ????
• Triangular mesentery-extends from terminal part
  of ileum to appendix
• Appendicular a. runs in free margin of the
  meseoappendix then along wall of appendix

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Colon ??

• Ascending colon ???
• right colic flexure ????
• Transverse colon ???
• left colic flexure
• Descending colon ???descends almost vertically
  from left colic flexure to sigmoid colon at left
  iliac crest.
• Sigmoid colon????-extends from descending colon
  to rectum at level of S3.

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Rectum ??

• Position within pelvic cavity, extends from S3
  to pelvic diaphragm.
• Curves
• Sagittal plane
• Sacral flexure ???? convex backward
• Perineal flexure ????? convex forward.
• Coronal plane
• Upper and lower part-convex to the right.
• Middle part-convex to the left.
• Lower part of rectum dilated, to from ampulla of
  rectum ????
• Three transverse folds of rectum ????

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Anal canal ??

• Anal columns ??-6-11 in number,
• Anal valves ??
• Anal sinuses ??
• Anorectal line????
• Dentate line???
• Above line, of endodermal origin
• Below line, of ectodermal origin
• Anal pecten ??
• White line ??(Hiltons line)
• Anus ??
• Anal sphincters ?????
• Sphincter ani internus??????
• Sphincter ani externus ??????

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The Liver ?

• Shape
• Two surfaces
• Diaphragmatic surface??
• Convex and smooth
• Divided into right and left lobes by falciform
  lig. of liver ????
• Visceral surface ??

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• Visceral surface -has a H-shaped
  fissures and grooves
• Left limb of H
• Anteriorly fissure for ligamentum teres
  hepatis?????
• Posteriorly fissure for ligamentum venosum
  ?????
• Right limb of H
• Anteriorly fossa for gallbladder ???
• Posteriorly sulcus for vena cava ?????

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• Cross-bar of H is the porta hepatic?? traversed
  by right and left hepatic ducts, left and right
  branches of proper hepatic artery and hepatic
  portal vein, nerves and lymphatic vessels. These
  structures which are surrounded by connective
  tissue called hepatic pedicle ??
• Four lobes left, right, quadrate and caudate
  lobes

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• Inferior border thin and sharp
• Notch for ligamentum teres hepatis ??????
• Nothch for gallbladder ????

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• Position Most of liver lies in the right
  hypochondriac region and epigastric region, less
  part extending into the left hypochondriac region
• Surface projection
• Upper border on the right midclavicular line it
  extends the level of 5th rib
• Lower border Normally, the right lobe extends
  just beneath the costal margin, it doesnt down
  beyond the costal margin on the anterior median
  line its lower border crosses a point about 35cm
  below the xiphoid process. In children, the liver
  being larger in proportion to the body than in
  the adult stage, it extends below the costal arch
  within in 2cm.

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• The segments of the liver
• The segmentation of the liver, bases upon the
  principal divisions of the proper hepatic artery
  and accompanying hepatic ducts and hepatic portal
  vein-Glisson system.
• The hepatic veins, however do not follow the same
  pattern and vary their main tributaries tend to
  run rather intersegmental.

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Extrahepatic Biliary Apparatus

• Consists of
• Gallbladder ??
• Left and right hepatic ducts ?????
• Common hepatic duct???
• Common bile duct ???

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Gallbladder ??

• Position lies in fossa for gallbladder on
  visceral surface of liver
• Four parts
• Fundus of gallbladder ???
• Surface projection at the junction of right
  midclavicular line and right costal arch
• Body of gallbladder ???
• Neck of gallbladder ???
• Cystic duct ???
• Function stores and concentrate bile

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Biliary duct system

• Right and left hepatic ducts unite outside of
  liver to form the common hepatic duct
• Cystic duct joins common hepatic duct to form
  common bile duct

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• Common bile duct and pancreatic duct run
  obliquely through the wall of the descending part
  of duodenum where the two ducts usually unite to
  form the hepatopancreatic ampulla ????(ampulla of
  Vater), which rounded by sphincter of
  hepatopancreatic ampulla???????(sphincter of
  Oddi), each has an independent sphincteric
  mechanism for regulating flow, and opens at the
  major duodenal papilla

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Divisions and relations of common bile duct

• Supraduodenal segment
• Descends along the right margin of hepatoduodenal
  lig.
• To the right of proper hepatic a.
• Anterior to hepatic portal v.
• Retroduodenal segment
• Behind the superior part of duodenum
• Anterior to the vena cava
• To the right of the hepatic portal v.

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• Pancreatic segment
• Lies in a groove between posterior surface of
  head of pancreas and duodenum
• Intraduodenal segment
• Enters the wall of descending part of duodenum
  obliquely where jions the pancreatic duct to form
  the hepatopancreatic ampulla
• opens at the major duodenal papilla

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Biliary ductuli
Bile is secreted by the liver cells
Right and left hepatic ducts
Gallbladder (store, concentrate)
Common hepatic duct
Cystic duct
when the fat enters the small intestine, the
gallbladder contracts, the sphincter of
hepatopancreatic ampulla relax
Common bile duct
Major duodenal papilla
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• Triangle of Calot
• Boundaries the common hepatic duct on the left,
  the cystic duct on the right, the liver,
  superiorily
• Content cystic artery

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The Pancreas ?

• Shape and Position
• A soft yellowish lobulated gland
• Lies behind the peritoneum on the posterior
  abdominal wall, roughly at the level of of L1L2

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• Three parts
• Head
• Flattened and located in C-shaped curvatune of
  duodenum
• Uncinate process
• Neck-constricted part
• Body
• Tail-runs in base of lienorenal ligament to reach
  hilum of spleen

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• Pancreatic duct
• Main Pancreatic duct
• Begins at tail and throughout gland
• Joins common bile duct before entering descending
  part of duodenum at major duodenal papilla
• Accessory pancreatic duct
• Opens 2cm above main duct at lesser duodenal
  papilla

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Divisions and relations of pancreas

• Head of pancreas
• Located in C-shapes curvature of doudenum
• Anteriorly
• Transverse mesocolon
• Posteriorly
• Inferior vena cava
• Right renal vessels
• Common bile duct
• Neck of pancreas
• Anteriorly-pylorus
• Posteriorly-commencement pf hepatic portal v.
  (formed by union of splenic and superior
  mesenteric veins

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• Body of pancreas
• Anteriorly
• Separated from stomach by omental bursa
• Posteriorly
• Abdominal aorta
• Left suprarenal gland
• Left kidney
• Left renal vessels
• Spleen vein
• Superiorly
• Celiac trunk
• Celiac plexus
• Splenic a.

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• Tail of pancreeas
• Runs in spleicorenal ligament to reach hilum of
  spleen
• Accompanies with splenic vessels

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• Function
• The pancreas is both an exocrine and an
  endocrine gland. The exocrine portion of the
  gland produces a secretion that contains enzymes
  that are capable of hydrolyzing proteins, fats,
  and carbohydrates. The endocrine portion of the
  gland, the pancreatic islet, produces the
  hormones insulin and glucagons that play a key
  role in carbohydrate metabolism.