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
Anterior view showing location of abdominopelvic regions
Anterior view showing location of abdominopelvic regions
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
GROSS ANATOMY OF STOMACH
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)
GROSS ANATOMY OF STOMACH
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
Longitudinal muscle layer
Ci l
Barium radiograph of jejunum
Circular muscle layer
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)
Longitudinal muscle layer
Ci lBarium radiograph of ileum
Circular muscle layer
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)
Histology of Small Intestine
Villi (tufts of hair) = fingerlike projections of mucosa (0.5 – 1mm long)
Layers of small intestine
Histology 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.
Histology of Small Intestine
Villi (Small, finger-like projections of mucosa)
Histology of Small Intestine
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.
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