Anatomy of digestive sys stomach&si 2012

ANATOMY OF DIGESTIVE SYSTEM: ANATOMY OF DIGESTIVE SYSTEM: STOMACH & SMALL INTESTINESTOMACH & SMALL INTESTINESTOMACH & SMALL INTESTINESTOMACH & SMALL INTESTINE

D R . H E R M I Z I H A P I D I N

S C H O O L O F H E A L T H S C I E N C E S

H E A L T H C A M P U S

U N I V E R S I T I S A I N S M A L A Y S I A

hermizi@kck usm [email protected] February 2012

OBJECTIVES

At the end of this lecture, the students should understand :

1) Introduction to Lower Gastrointestinal (GI) Tract2) Gross Anatomy of Stomach3) Relations Blood Supply Lymphatic Drainage & Nerve3) Relations, Blood Supply, Lymphatic Drainage & Nerve

Supply of Stomach4) Gross Anatomy of Small Intestine

Bl d S l L h i D i & N S l f5) Blood Supply, Lymphatic Drainage & Nerve Supply ofSmall Intestine

INTRODUCTION OF DIGESTIVE SYSTEM

The organs involved in thegbreakdown of food

It has two anatomicalsubdivisions :subdivisions :a) Digestive tractb) Accessory organsb) Accessory organs

DIGESTIVE SYSTEM

Digestive tract Alimentary canal or

gastrointestinal (GI) tract A tube extending fromg

mouth to anus (~ 9 meterslong in cadaver)

It includes ;;i. Upper GIT

oral cavity, pharynx,esophagusesophagus

ii. Lower GITstomach, small intestine,large intestinelarge intestine

(aliment = food)

DIGESTIVE SYSTEM

Accessory organsy g They include ;i. teeth

tii. tongueiii. salivary glandsiv. liveriv. liverv. gall bladdervi. pancreas

* produce variety of secretions to contribute to b kd f f d t ffbreakdown of foodstuffs

STOMACH

Old names = grindingchamber, fermentationvat, cooking pot

Dilated portion of Dilated portion ofalimentary canal betweenesophagus and smalli t ti (d d )intestine (duodenum)

Site – it lies inferior todiaphragm in thediaphragm in theepigastric, umbilical & lefthypochondriac of theabdomenabdomen

Location of Stomach

Midclavicular lines

Midsternal line

Umbilicus

Subscostal line (10th costal cartilages)

Transtubercular line (iliac tubercles)

Anterior view showing location of abdominopelvic regions

Subscostal line



Functions of Stomach

Stomach a) stores the food we ate b) breaks down the food into a liquidly mixture c) mix with enzymes which is chemical that breaks down foodc) mix with enzymes which is chemical that breaks down foodd) slowly empty that liquidly mixture into the small intestine

STOMACH

CapacityE t 50 l f f d Empty = 50 ml of food

After meals = 1.0 to 1.5 L Extremely full = up to 4 L T1y pExtension It extends between the level

f T11 & L1 t b

T1

Cardiac/ esophageal

of T11 & L1 vertebra Upper end continues with

esophagus through cardiac

sphincter

p g gsphincter

Lower end continues withduodenum through pyloric

L1Pyloric sphincterduodenum through pyloric

sphincter

GROSS ANATOMY OF STOMACH

Shape = pear shaped or “J”shaped (upper part is broaderthan lower part)

It has two ends ;

Cardiac end

It has two ends ;i. Cardic endii. Pyloric end Lesser curvature

It has two surfaces ;i. Anteriorii Posteriorii. Posterior

It has two curvatures ;i. Lesser curvature

Pyloric endGreater curvature

ii. Greater curvature


Lesser curvature (LC)f i ht b d f t h forms right border of stomach(concave medial border)

extends from cardiac orifice tolpylorus

it is suspended from liver by lesseromentum

Greater curvature (GC) forms longer convex lateral border

of stomach gastrosplenic omentum extends

from upper part of GC to spleen greater omentum extends fromg

lower part of GC to transverse colon (Omentum = fat skin)


Stomach is covered byperitoneum (intraperitonealorgan) Peritoneum leaves lesser

lcurvature as lesseromentum & greatercurvature as greateromentumomentum Peritoneum = serousmembrane that linesabdominal cavity & coversabdominal cavity & coversviscera within it Omentum = a fold ofperitoneump

Greater omentum is shown in its normal position covering

Lesser omentum attaching liver to

lesser curvature of

Mesentery of small intestine

position covering most of abdominal

viscera

lesser curvature of stomach

Falciform ligament

Greater OmentumFalciform ligament

Liver

GallbladderGallbladder

Spleen

StomachStomach

Ligamentum teres

Greater omentum

Small intestine(anterior to SI)

Cecum

Lesser Omentum

Liver

GallbladderLesser omentumGallbladder

Stomach

(extend from liver to LC)

StomachDuodenum

Transverse colonTransverse colon

Small intestine

Cecum

Urinary bladder

Parts of Stomach

Stomach has four parts :a) Cardiab) Fundusc) Body C di

Fundusc) Bodyd) Pylorus Cardia – surrounds superior

opening of stomach

Cardia

Bodyopening of stomach

Fundus – dilated upper part Body – inferior to fundus,

Pylorus

located between cardiac &pyloric ends

Pylorus – funnel-shapedy pregion of stomach

Parts of Stomach

The pylorus (“gate keeper”)has two parts :has two parts :

i. Pyloric antrumii. Pyloric canal

Pyloric antrum (antrum =cave) – proximal dilatedportion that connects to thebody of stomach

Pyloric canal – narrow portionwhich leads into duodenum Pyloric

canalPyloric

t

Pyloric orifice

Pyloric

Pyloric sphincter - thickeneddistal end of the canal

canal antrumPyloric sphincter

Anterior Surface of Stomach

Esophagus Fundus

Cardia

B d

Longitudinal muscle layer

Circular muscle layer

L

Duodenum

BodyPyloric sphincter

Obli l l

Lesser curvature

Left gastroepiploic

vessels

Pylorus

Oblique muscle layer

Greater curvature

yRugae

Relations of Stomach

AnteriorlyAbd i l ll

PosteriorlyDi h Abdominal wall

Left costal margin Left pleura & lung

Diaphragm Spleen Left suprarenal gland Left pleura & lung

Diaphragm Left lobe of liver

Left suprarenal gland Upper part of left kidney Splenic arterye t obe o e Sp e c a te y Pancreas Transverse mesocolon Transverse colon

Stomach Bed

Structures related to posteroinferior surface of stomach From superior to inferior, it is formed by : Left dome of diaphragm Spleen Spleen Left suprarenal gland Left kidney

Spleen

Left suprarenal & left kidney

Pancreas & Splenic artery

Diaphragm

y Splenic artery Pancreas (head, neck & body)

T l

Splenic arteryTransverse colon

& mesacolon

Transverse mesocolon Transverse colon Spleen separated from stomach by greater sac of peritoneum whileSp ee sepa a ed o s o ac by g ea e sac o pe o eu e

other structures by lesser sac

Stomach

Spleen

Pancreas &

Diaphragm

Pancreas & Splenic artery

Transverse colon & mesacolon

Fig. Posterior relations of stomach

greater sac = main part of peritoneal cavity lesser sac / omental bursa = lies posterior to stomach

Fig. Sagittal section

Stomach

Epiploic foramen/omental foramen/foramen of Winslowforamen/foramen of Winslow

Greater sac or general cavity (red) and lesser sac / omental bursa (blue)Fig. Horizontal sections through abdomen

Greater sac or general cavity (red) and lesser sac / omental bursa (blue) Lesser sac is embryologically formed from an infolding of greater omentum

Histology of Stomach

Stomach wall is composed of four basic layers (inside to Stomach wall is composed of four basic layers (inside tooutside) :a) Mucosa layerb) Submucosac) Muscular layer

ld) Serous layer

Histology of Stomach

Mucosa layer Layer of simple columnar epithelium Contains lamina propria (areolar CT) & muscularis mucosae

(smooth muscle)(s oot usc e) Submucosa layer Lie deep to mucosa layer

Composed of areolar CT Composed of areolar CT Muscularis layer Has 3 layers of smooth muscle ; outer longitudinal layer, middle

i l l & i bli lcircular layer & inner oblique layer Serous layer Composed of simple squamous epithelium (mesothelium) &

areolar CT

Layers of Stomach Wall

Serous layer

Muscularis layer

Mucosa layer

Submucosa layer

RUGAE (Folds in mucosa layer)

Layers of the stomach wall

Surfaceepithelium

Mucosa

Lamina propriaMuscularisMuscularismucosae

Oblique layer

Submucosa(contains submucosalplexus) q y

Circular layer

Longitudinal

Muscularis externa(contains myentericplexus)

plexus)

layerSerosa Stomach wall

plexus)

Enlarged view of gastric pits and gastric glands – Mucosa layer

Gastric pits

Surface epithelium(mucous cells)

Gastric pits

M co s neck cells

( )

Gastric pit Mucous neck cells

Parietal cellChief cell

pit*Gastric pits lead into gastric glands

Gastric gland

Enteroendocrine cell

Gastric Gland

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Cell types Mucous neck cells (secrete thin

Mucous neck cell

Parietal cell

Mucous neck cells (secrete thin, acidic mucus)

Parietal cells Chief cells Enteroendocrine or G cells

Chief cell

Gastric gland

G cell

Interior of Stomach

Rugae • numerous gastric folds• mainly in longitudinal direction

f ld fl tt t h t h i di t d d• folds flatten out when stomach is distended

Arterial Supply of Stomach

Arterial supply to stomach is extremely rich & comprises of :a) Left gastric artery - coeliac axisb) Right gastric artery - hepatic arteryc) Right gastroepiploic artery - gastroduodenal branch (hepatic artery)) g g p p y g ( p y)d) Left gastroepiploic artery - splenic arterye) Short gastric arteries - splenic artery

Shorts gastric arteries

Left gastric artery

COELIAC AXIS

Cystic artery

HEPATIC ARTERY

Left gastroepiploic artery

SPLENIC ARTERYHEPATIC ARTERY

Right gastric artery

GASTRODUODENAL ARTERY

Superior pancreatiduodenal artery

Right gastroepiploic arterySuperior pancreatiduodenal artery

Venous Drainage (Stomach)

Gastric veins parallel the arteries in possition and course :a) Left gastric veinb) Right gastric veinc) Right gastroepiploic vein

drain into portal vein

- empties in superior mesenteric vein) g g p pd) Left gatroepiploic veine) Short gastric veins

p p

drain into splenic vein

Lymph Drainage (Stomach)

Lymphatic drainage of stomach accompanies its blood vessels Stomach can be divided into three drainage zones :

a) Area I - drains along right & left gastric vessels to aortic nodes

b) Area II - drains along right epiploic vessels to subpyloric nodes & thence to) g g p p pyaortic nodes

c) Area III - drains via lymphatics along splenic vessels to suprapancreaticnodes & thence to aortic nodes

Lymph drainage of stomach

Nerve Supply of Stomach

Sympathetic nerve supply of thestomach from T5 through T9segments of spinal cord passesto celiac plexus via greater

l h isplanchnic nerve Parasympathetic nerve supply

the stomach is from anteriord t i l t k &and posterior vagal trunk &

their branches• anterior vagal trunk derived

mainl f om left ag s ne emainly from left vagus nerve• posterior vagal trunk derived

mainly from right vagus nerve

Small Intestine

StomachD d

Jejunum

DuodenumDuodenojejunalflexure

Mesentery

Ascendingcolon

Ileocecalj ti

Ileum

CecumAppendix

junction

SMALL INTESTINE

Is the longest part ofli t lalimentary canal

Extends from pylorus ofstomach to ileocecal junctionj

Length = 3 m in a livingperson & 6.5 m in a cadaver(loss of muscle tone)(loss of muscle tone)

Diameter = 4 cm in stomach& 2.5 cm at junction withlarge intestine

Small intestine

large intestine Function = digestion of food

and absorption of nutrients

Location of Small Intestine

Site = it occupies allabdominal regions exceptepigastic and hypochondriacregion

Fixation = it is stabilized bymesentery

Mesentery = peritoneal fold Mesentery = peritoneal foldattaching small intestine toposterior body wall

Sagittal section

Mesentery of Small Intestine

25-37

Greateromentum(retracted)

Transversecolon

Mesentery

Mesocolon

Descendingcolon

Jejunum Mesentery

Sigmoidcolon

Mesentery of small intestines holds many blood vessels

Gross Anatomy of Small Intestine

Anatomical subdivisions :a) Duodenumb) Jejunumc) Ileumc) Ileum

Duodenum = C-shaped tubewhich is attached to thet hstomach

Jejunum = is the coiledmidsection

Ileum = the final section,which leads into the largeintestineintestine

Small Intestine – Duodenum

C-shaped tube about 25 cmlong & width 3 75 cmlong & width 3.75 cm

Joins stomach to jejunum The first & shortest part ofp

small intestine The widest & most fixed part

Curves around the head of Curves around the head ofpancreas

Begins at pylorus on rightside & ends atduodenojejunal junction onleft side

Duodenum

Partially retroperitoneal

Small Intestine - Parts of Duodenum

Duodenum is divided into four parts :a) First (superior) partb) Second (descending) partb) Second (descending) partc) Third (horizontal) partd) Forth (ascending) part

1st part

First part of duodenum It is 5 cm long

Lies anterolateral to the

2nd part

3rd part

4th part

Lies anterolateral to the body of L1 vertebra

3 part

Small Intestine - Parts of Duodenum

Second part of duodenumIt i 7 t 10 l It is 7 to 10 cm long

Descends along right sides ofL1 through L3 vertebrae

Third part of duodenum It is 6 to 8 cm long Crosses L3 vertebra

1st part

Crosses L3 vertebra Forth part of duodenum It is 5 cm long

2nd part

3rd part

4th part

J j Begins at left of L3 vertebra &

rises superiorly as far assuperior border of L2 vertebra

3 part Jejunum

and continues with jejunum

Interior of Duodenum

Superior duodenal flexure

(flexure at junction of first and second parts of duodenum)

1st part (superior) – ampulla (no circular folds)

2nd part (descending)

Minor duodenal papilla

Valves of Kerckring (circular folds)

Jejunum

Duodenojejunal flexure

4th part (ascending)

Major duodenal palilla (of Vater)

Longitudinal fold

Head of pancreas

3rd part (horizontal) Superior mesenteric artery and vein

Interior of Duodenum

2nd part ofPlicae circulares

2nd part of duodenum

Major duodenal papilla

Note smooth muscle lining of 1st part of duodenum, plicae circularis(circular folds) of 2nd part of duodenum Major duodenal papilla is a small rounded elevation at site where bileMajor duodenal papilla is a small rounded elevation at site where bileduct & main pancreatic duct pierce medial wall of 2nd part of duodenum

Small Intestine – Jejunum & Ileum

Jejunum begins atd d j j l fl (L2) &duodenojejunal flexure (L2) &ileum ends at ileocecaljunction

Pylorus of stomachDuodenum

Ascending colon

Jejunum & ileum = 6 to 7 mlong (jejunum 2/5, ileum 3/5)

Coils of jejunum & ileum are

Mesentery

Jejunum

Coils of jejunum & ileum aresuspended by mesenteryfrom posterior abdominal wall& freely movable J jIl l& freely movable

Most jejunum lies in leftupper quadrant & most ileumli i i ht l d t

JejunumIleocecal junction

IleumCecum

lies in right lower quadrant

Differences between Jejunum & Ileum

Characteristic Jejunum IleumCharacteristic Jejunum Ileum

Color Deeper red Paler pink

Wall Thick & heavy Thin & light

Vascularity Greater Less

Arcades A few large loops Many short loops

V t / L Sh tVasa recta / arteriae rectae

Long Short

Fat in mesentery Less More

Circular folds (plicae circularis)

Large, tall & closely packed (valves of Kerkring)

Low & sparse; absent in distal part

Lymphoid nodules Few Manyy p o d odu es (Peyer’s patches)

ew a y

JEJUNUM

Mesentery

JEJUNUM

Arcade of jejunal arteries

Straight arteries (arteriae rectae)

Serosa


Ci l

Barium radiograph of jejunum


Submucosa

Mucosa

Circular folds (valves of Kerckring)

Solitary lymphoid nodulenodule

ILEUM

ILEUMILEUM

Mesentery

Arcade of ileal arteries

Straight arteries (arteriae rectae)

Serosa (visceral Se osa ( sce aperitoneum)


Ci lBarium radiograph of ileum


Submucosa

MucosaMucosa

Circular folds

Solitary lymphoid nodulesAggregate lymphoidAggregate lymphoid

nodules (Peyer’s patches)

The main distinguishing feature of the jejunum is the presence

of prominent Valves of Kerckring (plicae circulares)

Barium radiograph of jejunum

Kerckring (plicae circulares) -numerous folds of the mucous

membrane of the small intestine.

The ileum is almost devoid of Valves of Kerckring, but

Barium radiograph of ileum

glarge accumulations of

lymphatic tissue or Peyer's Patches.

Peyer’s patches

External and internal differences between jejunum and ileum

Thick wall

Jejunum

Jejunum

Jejunum

Plicae circularis (valves of Kerckring)

Fat

Arterial arcadesIleum

Thin wall

Ileum

Superior mesenteric artery

Peyer’s patch

Fat

Smooth mucous membrane

Superior mesenteric arteryArterial arcades Superior mesenteric artery

Ileocecal Junction

Point where small intestine (ileum) ends ( )as it opens into large intestine (cecum) ;

occurs usually within the iliac fossa (right ( g

lower quadrant of abdomen)

Iliac fossa

Histology of Small Intestine

Wall of small intestine is made of the following layers :a) Serosa coatb) Muscular coatc) Submucosa coat)

d) Mucosa coat Serosa – made of peritoneum Muscular made of smooth muscle fibers arranged in outer Muscular – made of smooth muscle fibers arranged in outer

longitudinal & inner circular layers Submucosa – contains loose CT & large venous plexuses (submucosa

duodenum contains duodenal or Brunner’s glands)duodenum contains duodenal or Brunner s glands) Mucosa – composed of a layer of epithelium, lamina propria &

muscularis mucosa (Plicae circulares numerous in jejunum, Peyer’spatches present in ileum)patches present in ileum)


Villi (tufts of hair) = fingerlike projections of mucosa (0.5 – 1mm long)

Layers of small intestine


* One mucous tubule is outlined in the image above.

Brunner's glands are compound, tubular, mucous glands in the submucosa of the duodenum.


Villi (Small, finger-like projections of mucosa)


Ileum

Mucosa

Submucosa

Payer’s patch in ileum mucosaPlicae circulares - jejunum

Microvilli

Intestinal crypt = crypt of LieberkuhnMicrovilli(brush border)

Absorptive cells

LactealGoblet cellBlood Vilus

Mucosaassociated

Bloodcapillaries

Vilus

Intestinal cryptlymphoid tissue

Muscularis

EnteroendocrinecellsVenule

mucosaeDuodenal gland Submucosa

Lymphatic vessel

Intestinal Crypts

i l i h li Intestinal crypt epithelium Secretory cells that produce intestinal juice Enteroendocrine cells Enteroendocrine cells Intraepithelial lymphocytes (IELs)

Release cytokines that kill infected cellsRelease cytokines that kill infected cells Paneth cells

Secrete antimicrobial agents (defensins and lysozyme) Stem cells

Blood Supply of Small Intestine

Duodenumi l lArterial supply

Upper half is supplied bysuperior pancreaticoduodenal

Portal vein

Superior mesenteric vein

artery (gastroduodenal artery) Lower half is supplied by

inferior pancreaticoduodenal

Superior panncreaticoduodenal

artery

partery (superior mesentericartery)

Venous drainage

Inferior panncreaticoduodenal

artery

Venous drainage Superior pancreaticoduodenal

vein drains into portal vein(inferior vein joins superior(inferior vein joins superiormesenteric vein)

Arterial Supply of Duodenum

Superior pancreaticoduodenal artery

Gastroduodenal artery

Superior pancreaticoduodenal artery

Posterior superior pancreaticoduodenal artery

Anterior superior pancreaticoduodenal artery

Posterior inferior pancreaticoduodenal artery

Anterior inferior pancreaticoduodenal artery

SUPERIOR MESENTERIC ARTERY

Inferior pancreaticoduodenal artery

Blood Supply of Small Intestine

Ileum and Jejunum Arterial supply From branches of superior mesenteric artery

Intestinal branches arise from left side of the artery & run in Intestinal branches arise from left side of the artery & run inmesentery to reach the gut (gastrointestinal tract)

They anastomose with one another to form as series of arcadesL t t f il i li d b il li t Lowest part of ileum is supplied by ileocolic artery

Venous drainage Veins correspond to branches of superior mesenteric artery & drainVeins correspond to branches of superior mesenteric artery & drain

into superior mesentery vein

Arterial Supply & Venous Drainage of Small Intestine

Superior mesenteric artery and its branches

Lymphatic Drainage of Small Intestine

Duodenum Lymph vessels follows arteries & drain ; upward via pancreaticoduodenal nodes to gastroduodenal nodes &

then to celiac nodesthen to celiac nodes downward via pancreaticoduodenal nodes to superior mesenteric

nodes around origin of superior mesentery artery

Jejunum & Ileum Lymph vessels pass through many intermediate mesenteric Lymph vessels pass through many intermediate mesenteric

nodes & finally reach superior mesenteric nodes (situated around origin of mesenteric artery)

Celiac nodes

Superior mesenteric nodesSuperior mesenteric nodes (central superior group)

S i t iSuperior mesenteric nodes (juxtaintestinal

group)

mesenteric lymph nodes located in immediatelocated in immediate proximity to the jejunum or ileum

Nerve Supply of Small Intestine

Duodenum Nerves are derived from sympathetic & parasympathetic

(vagus) nerves from celiac & superior mesenteric plexuses

Jejunum & Ileum Nerves are derived from sympathetic & parasympathetic Nerves are derived from sympathetic & parasympathetic

(vagus) nerves from superior mesenteric plexus

Practical Session 0n 05/03/2012Practical Session 0n 05/03/2012 (MONDAY): Digestive system II

TIME GROUPTIME GROUP

2 00 to 3 30 p mA

2.00 to 3.30 p.m.

3 30 t 5 00B

3.30 to 5.00 p.m.

Education

Anatomy of digestive sys stomach&si 2012