LARGE INTESTINE
- is about l,5 m long
- its caliber is greatest in the caecum,
gradually diminishes to the rectum
the large intestine differs from the small intestine:
l. has greater caliber
2. is more fixed in position
3. its longitudinal muscle is concentrated into the three
longitudinal taeniae coli
4. colonic wall is puckered into the sacculations –
the haustrations
5. small adipose projections - appendices epiploicae are
found on its external surface (except vermiform appendix
and rectum)
The parts of the large intestine:
• caecum
• ascending colon
• right colic flexure
• transverse colon
• left colic flexure
• descending colon
• sigmoid colon
• rectum
• anal canal
Caecum
- is a commencement of the large intestine
- lies in the right iliac fossa
- is about 6 cm long, 7 cm wide
- is continuous with the ascending colon
- ileum opens into the caecum in
the ileocaecal orifice - closed by
the ileocaecal valve
- vermiform appendix arises from the caecum (below the ileocaecal orifice)
- relations:
behind - lateral cutaneous femoral nerve
in front - anterior abdominal wall, greater omentum
- commonly caecum is completely covered by peritoneum
Vermiform appendix
- is a narrow tube
- arises from the caecum
- is various in the position (retrocaecal, pelvic)
- has small mesentery - mesoappendix
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Ascending colon
- ascends from the right iliac fossa to the liver
- is retroperitoneal in position
- relations:
behind - iliohypogastric, ilioinguinal and
lateral cutaneous femoral nerves
in front - ileum and greater omentum
Right colic flexure
- joins ascending and transverse colons
- lies in the right hypochondriac region
relations: behind - right kidney
above and in front – the liver and gallblader
Transverse colon
- lies in the umbilical region
- extends from the right colic flexure to the left colic flexure
(from right hypochondriac to the left hypochondriac region)
- is intraperitoneal – attached to the dorsal abdominal wall by
the transverse mesocolon
relations: behind - descending duodenum and pancreas
in front - greater omentum and ventral abdominal wall
above - liver and gallbladder (on right side)
- stomach - great gastric curvature
below - jejunum
Left colic flexure
- lies in the left hypochondriac region
- relations: above - pancreatic tail
laterally and behind - spleen
medially - left kidney
Descending colon
- descends from the left colic flexure to the left iliac fossa
- is retroperitoneal
relations: behind - iliohypogastric, ilioinguinal and
lateral cunateous femoral nerves
in front - coils of jejunum
Sigmoid colon
- descends from the left iliac fossa into the lesser pelvis
- is intraperitoneal - attached to the dorsal wall by sigmoid
mesocolon
the root of sigmoid mesocolon crosses:
- left iliac vessels
- left gonadal vessels
- left ureter
relations: below - urinary bladder in male
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- uterus, lelft ovary and left uterine tube in female
above - ileum
BLOOD SUPPLY: superior mesenteric a. – caecum, ascending, right flexure, transverse colon
inferior mesenteric a. - left colic flexure, descending, sigmoid colon
NERVE SUPPLY: superior and inferior mesenteric plexuses
(vagus and splanchnic nerves)
Lymph drainage: superior and inferior mesenteric lymph nodes
Rectum
- is about 12 cm long
- begins at the level of 2nd - 3rd sacral vertebra
- descends in front of the sacrum and coccyx so that it has
- sacral flexure and perineal flexure
- it also deviates in lateral curves - right - left - right
- is dilated in the ampulla
the characteristics of the rectum:
- has no sacculation, no appendices epiploicae
- taeniae coli blend to form wide muscular bands
- mucosa presents transverse folds - commonly 3 in number
- superior, middle, inferior - middle is the largest
the relation to the peritoneum:
peritoneum covers anterior surface of the upper part
it is retrioperitoneal in position
relations:
behind: - sacrum, coccyx
in front: IN MALE
• urinary bladder – partly separated from the
rectum by rectovesical pouch
• PROSTATE
lower part of rectum is connected with lower part of the urinary bladder and with the prostate
by rectovesical septum containing • deferent ducts
• seminal vesicles
in front: IN FEMALE
• uterus
• vagina
rectum is separated from the uterus by rectouterine pouch
and connected with the vagina by rectovaginal septum
Anal canal (about 4 cm long)
- mucosa is folded into 6 – 10 vertical folds - anal columns
separated by vertical grooves - anal sinuses
sinuses are closed inferiorly by anal valves
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- reach venous plexus lies in the anal mucosa - internal
rectal venous plexus
- anal wall contains involuntary sphincter ani internus muscle
- externally anal canal is surrounded by voluntary
sphincter ani externus muscle
Blood supply of the rectum and anal canal:
superior rectal vessels (drained into the portal v.)
middle and inferior rectal vessels (drained into the inf. v. cava)
Nerve supply: inf. mesenteric and pelvic autonomic plexuses
LIVER
- is an accessory organ (gland) of digestive system
- it is situated in right hypochondriac and epigastric regions
extends into the left hypochondriac region
- it lies below the diaphragm
The liver consists of right and left lobes
has
diaphragmatic surface
visceral surface
inferior (anterior) border - anteriorly follows costal margin,
in the epigastric region inf. border extends below the infrasternal angle
The liver is covered by peritoneum and connected to
the anterior abdominal wall, diaphragm, stomach and duodenum by peritoneal folds:
diaphragmatic surface is connected :
- to the anterior abdominal wall by the falciform ligament
containg round ligament of the liver = ligamentum teres
(which is a remaining of umbilical vein)
- to the diaphragm by falciform and coronary ligaments extending into
the right and left triangular ligaments
coronary ligament borders "bare area"– here the liver is not covered with
peritoneum and is firmly attached to the diaphragm
- visceral surface is connected with the stomach and duodenum
by the lesser omentum consisting of
hepatogastric ligament and
hepatoduodenal ligament - contains bile duct, portal vein and hepatic artery
RELATIONS OF THE LIVER
- diaphragmatic surface - is related to the diaphragm, which separates it from the pleural
cavities (including the costodiaphragmatic recesses), lungs and heart
- visceral surface is related to some abdominal organs
- oesophagus - oesophageal impression
- stomach - gastric impression
- duodenum - duodenal impression
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- right colic flexure - colic impression
- right ren - renal impression
- right supraren - suprarenal impression
visceral surface is marked by
- fissure for the ligamentum venosum and - fissure for the ligamentum teres (on left)
- groove for the inferior vena cava and - fossa of gallbladder (on right)
the fissure for the lig.venosum and groove for v. cava border caudate lobe
the fissure for the round lig. and fossa of gallbladder- border quadrate lobe
caudate and quadrate lobes are separated by
the porta hepatis which contains:
• portal vein
• hepatic artery and nervous plexus
• hepatic ducts - right and left
• lymph vessels
EXCRETORY APPARATUS OF THE LIVER
consists of:
∗ right and left hepatic ducts
∗ common hepatic duct
∗ gall bladder and cystic duct
∗ bile duct
right and left hepatic ducts - issue from the porta hepatis and unite to form
common hepatic duct - this descends in the hepatoduodenal ligament nd joins with the cystic
duct into
the bile duct
- this is about 7 cm long tube
- descends in the hepatoduodenal ligament
- then descends behind the superior part of duodenum and behind the head of pancreas
unites with the pancreatic duct to form
hepatopancreatic ampulla – surrounded by sphincter (Oddi)
hepatopancreatic ampulla opens into the descending part of duodenum
on the major duodenal papilla (Vater)
relations of bile duct in the hepatoduodenal ligament:
- proper hepatic a. - on its left
- portal vein - behind
Gall bladder
- is a pear-shaped sac, 7 - 10 cm long
- extends from the porta hepatis to the inferior border of the liver
- it is attached to the inferior surface of the liver
- its free surface is covered with the peritoneum
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gall bladder has:
♦ fundus
♦ body
♦ neck
fundus - lower expanded part - projects beyond the inf. margin of liver
neck – upper constricted part - its mucosa is folded to form spiral valve
- is continuous with the cystic duct
relations: fundus - is in contact with the ant. abdominal wall
body – is related to the transverse colon and to
the descending duodenum
Cystic duct – arises in the bladder, joins with the common hepatic duct to form
bile duct - this opens into the duodenum (bile duct sphincter)
PANCREAS
- is about 12 - 15 cm long
- it is situated in the epigastric and left hypochondriac region
- it is retroperitoneal, placed behind the stomach
- extends from the duodenum to the spleen
- consists of head
body
tail
head
- is flattened antero-posteriorly
- lies within duodenal curve
- anterior surface is crossed by transverse mesocolon
- posterior surface is related to: the inferior vena cava
abdominal aorta
renal vessels
bile duct
body
- is prism-like in section
- has anterior and posterior surfaces
relations:
- above: - lienal (splenic) vessels
- behind: - abdominal aorta
- superior mesenteric vessels
- left kidney and renal vessels
- in front: - it is covered by peritoneum
- related to the stomach (separated from it by the omental bursa)
- below: - transverse mesocolon
tail
- reaches the spleen
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Pancreatic ducts:
Main pancreatic duct - traverses gland from left to right
- opens on the major duodenal papilla
together with the bile duct
Accessory pancreatic duct - drains head of thepancreas
- opens on minor duodenal papilla
Blood supply: Superior and inferior pancreaticoduodenal vessels, blood is drained into the
portal vein
Nerve supply: PS fibres from vagus nerve
S fibres from splanchnic nerves
PERITONEUM
peritoneum is a serous membrane (smoot, shining)
covers
- the walls of abdominal and pelvic cavities - this part is named
parietal peritoneum
- the organs contained - this is named
visceral peritoneum
Peritoneal cavity - under the normal conditions it is a narrow space among the organs
contained in the abdominal and pelvic cavities
- free surface of peritoneum is smooth layer of mesothelium lubricated by small amount of
serous fluid allowing the viscera to glide against the abdominal wall and upon each other
- peritoneum is connected to the abdominal and pelvic walls by areolar tissue - subserous
fascia (loose areolar tissue) and fused with the surface of the organs
1. certain abdominal organs are completely surrounded by peritoneum and are connected
to the abdominal or pelvic walls by peritoneal duplication (carrying blood vessels)
- such organs are named
intraperitoneal organs
liver, stomach, spleen, jejunum, ileum, transverse colon, sigmoid colon, uterus, uterine
tubes (ovaries)
2. the other organs are attached to the abdominal or pelvic walls and partly covered with the
peritoneum - such organs are named
retroperitoneal organs - these are placed in front of the posterior abdominal or pelvic wall
- kidneys, ureters, suprarens
- duodenum, pancreas
- ascending and descending colon, rectum
- abdominal aorta, inferior vena cava
preperitoneal organs - urinary bladder - placed behind the anterior pelvic and abdominal
walls
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PELVIS
Parietal peritoneum of the anterior abdominal wall continues into the lesser pelvis and
coveres:
- in male: - upper part of urinary bladder
- upper part of seminal vesicles
from which it is reflected to the rectum –
lining a space named RECTOVESICAL POUCH – this is
the lowest part of the peritoneal cavity in male
- in female:
peritoneum covering upper part of - urinary bladder is reflected on the uterus lining
vesicouterine pouch
peritoneum covering the uterus and upper part of vagina is reflected to the rectum lining the
space
RECTOUTERINE POUCH (of Douglas) - which is
the lowest part of peritoneal cavity in female
ANTERIOR ABDOMINAL WALL
Parietal peritoneum of the anterior abdominal wall between the umbilicus and pubic bone is
folded by some embryonic vestiges:
- middle umbilica fold - caused by middle umbilical ligament
(remnant of urachus)
- medial umbilical fold - elevated by medial umbilical ligament
(remains of umbilical artery)
- lateral umbilical fold - elevated by inferior epigastric vessels
middle and medial umbilical folds flank supravesical fossae
medial and lateral umbilical folds border medial inguinal fossae
on sides of the lateral umbilical folds lateral inguinal fossae are found
A peritoneal fold falciform ligament of the liver extends from the umbilicus to the liver
Falciform ligament contains fibrous cord - round ligament of the liver - ligamentum teres
(remnant of umbilical vein) – this runs on the inferior surface of the liver
Falciform ligament continues on the diaphragmatic surface of the liver into the
ligaments (right ane left) – these attach the liver to the diaphragm
coronary
Peritoneum covering the inferior surface of the liver is continuous on the stomach and
duodenum to form peritoneal duplicature lesser omentum subdivided into the hepatogastric
and hepatoduodenal ligaments
The peritoneum covering the stomach continues down from the greater gastric curvature to
form
greater omentum - descends in front of the intestines separating them from the anterior
abdominal wall.
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POSTERIOR ABDOMINAL WALL
On the posterior abdominal wall we can find
attachment of some parts of digestive tube:
- attachment of transverse mesocolon – crosses descending part of duodenum and pancreas divides the peritoneal cavity into the supramesocolic and inframesocolic parts
The organs contained in the supramesocolic part are supplied by coeliac a., the organs
contained in the inframesocolic part are supplied by sup. and inf. mesenteric arteries
- attachment of the sigmoid mesocolon (the root of sigmoid mesocolon) - extends from the
left iliac fossa to the lesser pelvis
- attachment of the mesentery (the root of mesentery) - extends from the duodenojejunal
flecture to the ileocaecal orifice - crossing the abdominal aorta, inferior vena cava and right
ureter
Peritoneal cavity is divided into
• the lesser sac - omental bursa - is a narrow cavity
behind the stomach and below the liver
• greater sac is a rest of the peritoneal cavity
Lesser sac – omental bursa
boundaries
- superiorly - the liver
- anteriorly - lesser omentum
- stomach
- origin of the greater omentum
- inferiorly - transverse colon
- posteriorly - pancreas
- left kidney - upper part
- left supraren
- transverse mesocolon
- laterally bursa extends
- from the epiploic foramen (on right)
- to the hilum of spleen (on left)
omental bursa communicates with the greater sac through
the epiploic foramen (foramen of Winslow)
- borders of the epilploic foramen:
- the liver - superiorly
- hepatoduodenal ligament - anteriorly
- superior part of duodenum - inferiorly
- inf. v.cava (covered with the peritoneum) - posteriorly
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