Transcript LARGE INTESTINE

In the name of God
LARGE INTESTINE
Dr. Zahiri
Dr. Maria Zahiri
The large intestine (or colon)
• the last part of the digestive system
• Absorb water, sodium and some fat soluble vitamins.
• The large intestine consists of :
the cecum, appendix, colon, rectum, and anal canal.
• is about 4.9 feet (1.5 m) long
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Dr. Maria Zahiri
Characteristics of large intestine
• Taeniae coli: three bands of smooth muscle
• Haustra : bulges caused by contraction of taeniae coli
• Epiploic appendages (omental appendices ):
are small pouches of the peritoneum filled with fat and situated
along the colon.
• their function is unknown.
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Taeniae coli
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Epiploic appendages
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Caecum
Position:
Lie in the right iliac fossa below
the ileocaecal valve.
Is a intraperitoneal organ (?)
Posteriorly lies the retrocaecal
recess which frequently
contains the vermiform
appendix.
Size: Average 6-7 cm
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Blood supply
Superior
branch
Anterior caecal
artery
*Ileocolic
Vascular
supply for
caecum
Ascending
(colic) artery
artery
Inferior
branch
Ileal artery
Posterior caecal
artery
Appendicular
artery
Ileal artery
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Superior branch
Inferior branch
Appendicular
artery
Ileal artery
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Dr. Maria Zahiri
Veins:
Ascending
colic veins
Superior
branch
Appendicular
vein
Anterior
caecal vein
Posterior
caecal vein
Ileal vein
Ileocolic vein
Inferior
branch
Superior
mesenteric
vein
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Lymphatic drainage
Anterior lymphatic vessels drain to:
• Anterior ileocolic nodes
Posterior lymphatic vessels drains to:
• Posterior ileocolic nodes
• Inferior ileocolic nodes
• To: Superior mesenteric nodes
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Innervation:
sympathetic and parasympathetic nerves via the superior
mesenteric plexus.
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Vermiform appendix
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The vermiform appendix
is a narrow, vermian tube
arises from the posteromedial caecal wall
 it varies from 5 to 20 cm in length, 2 cm below the end of the
ileum.
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The vermiform appendix
It may occupy one of several positions:
the commonest positions
Retrocaecal (12 o’clock), retrocolic , pelvic or descending (4
o’clock)
Other positions are occasionally seen especially when there is a
long appendix mesentery allowing greater mobilit:
subcaecal(6 o’clock) ; preilial(2 o’clock) ; postileal(2 o’clock) .
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McBurney’s point
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The three taeniae coli on the ascending colon and caecum
converge on the base of the appendix, and merge into its
longitudinal muscle.
The anterior caecal taenia is usually distinct and can be traced
to the appendix.
It is connected by a short mesoappendix to the lower part of the
ileal mesentery.
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The lumen of the appendix is small and opens into the caecum
by an orifice lying below and slightly posterior to the
ileocaecal opening.
The orifice is sometimes guarded by a semi lunar mucosal fold
forming a valve.
The appendix usually contains numerous patches of lymphoid
tissue although these tend to decrease in size from early
adulthood.
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VASCULAR SUPPLY
• Ileocolic artery
• Inferior branch
• Appendicular artery
• accessory arteries are common
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one or more
appendicular
veins
posterior
caecal
Superior
mesenteric
vein
ileocolic vein
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Lymphatic vessels
are numerous but all end in the inferior and superior nodes of
the ileocolic chain.
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Innervation
• sympathetic and parasympathetic nerves from the superior
mesenteric plexus.
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colon
the colon consists of four sections:
the ascending colon, the transverse colon, the descending colon,
and the sigmoid colon
Ascending colon
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narrower than the caecum- 15cm
It ascends to the inferior surface of the right lobe of the liver,
on which it makes a shallow depression, and then turns
abruptly forwards and to the left, at the hepatic flexure.
It is a retroperitoneal
Told fascia
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TRANSVERS COLON
 The transverse colon is 50 cm long
 extends from the hepatic flexure in the right lumbar region
across into the splenic flexure.
The transverse colon is suspended from the anterior border of
the body of the pancreas by the transverse mesocolon.
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SPLENIC FLEXURE
forms the junction of the transverse and descending colon
lies in the left hypochondriac region anteroinferior to the lower
part of the spleen
 The left kidney lies behind to it
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 It lies more superiorly and posteriorly than the right hepatic
flexure
 is attached to the diaphragm at the level of the tenth and
eleventh ribs by the phrenicocolic ligament which lies below
the anterolateral pole of the spleen.
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DESCENDING COLON
25 cm
It descends through the left hypochondriac and lumbar regions
curves inferomedially to become the sigmoid colon at the inlet
of the lesser pelvis.
It is a retroperitoneal structure covered anteriorly and on both
sides by peritoneum.
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SIGMOID COLON
begins at the pelvic inlet and ends at the rectum(S3)
It is completely invested in peritoneum and is attached to the
posterior pelvic wall and lower posterior abdominal walls by the
fan-shaped mesosigmoid.
The root of the sigmoid mesocolon has an inverted 'V‘ shape.
The position and shape of the sigmoid colon vary greatly
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Left paracolic
gutter
Left ureter
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Middle colic a.
Inf. pancresticodudenal a.
Right colic a.
Ileocolic a.
Appendicular a.
Superior
Mesenteric v.
Superior
mesenteric a.
Jejunal and ileal a.
Inferior
mesenteric v.
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Inferior mesenteric a.
Left colic a.
Sigmoid a.
Superior rectal a.
Colic marginal artery
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Dr. Maria Zahiri
• The Sudeck's point (or Sudeck's critical point):
• refers to a specific location in the arterial supply of the
rectosigmoid junction, namely the origin of the last sigmoid
arterial branch from the inferior mesenteric artery (IMA) .
• This arterial branch usually forms an anstomosis with a
branch of the superior rectal artery.
• The anastomosis is small and often only singular.
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• The "critical point" of Sudeck is marked with an "X."
• Rectum
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• Rectum continuous with the sigmoid colon(S3)
• To upper end of the anal canal.
Flexure:
• the sacral flexure & the perineal flexure
• three lateral curves :
• upper is convex to the right, the middle (the most prominent) bulges
to the left, and the lower is convex to the right
• Both ends of the rectum are in the median plane
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:2/3anterior and 1/3lateral covered by peritoneum.
the rectovesical pouch :
The peritoneum is reflected superiorly onto the urinary
bladder in males
recto-uterine pouch (pouch of Douglas):
• onto the posterior vaginal wall in females
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Dr. Maria Zahiri
ARTERIES
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1.superior rectal artery: upper third
2.middle rectal artery: middle third (from Int. Iliac)
3.inferior rectal artery: distal third ( from Int. pudendal)
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veins
• 1.internal part: below the rectal and anal epithelium
• 2.external part: outside the muscular wall
veins
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External plexus:
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1.inferior portion of the external plexus :
is drained by the inferior rectal vein into the internal pudendal vein
2.middle portion :
by a middle rectal vein into the internal iliac vein,
3.superior part :
By a superior rectal vein, which is the start of the inferior mesenteric
vein. Communication between portal and systemic venous systems is
thus established in the rectal plexus.
Internal plexus& External plexus:
Lymph
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