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LARGE INTESTINEDr. Zahiri
In the name of God
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
Dr. Maria Zahiri
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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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
Caecum
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Blood supply
Vascular supply for caecum
*Ileocolic artery
Superior branch
Inferior branch
Ascending (colic) artery
Anterior caecal artery
Posterior caecal artery
Appendicular artery
Ileal artery
Ileal artery
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Superior branch
Inferior branch
Appendicular artery Ileal artery
Dr. Maria Zahiri
Dr. Maria Zahiri
Veins:
Superior mesenteric vein
Ileocolic vein
Superior branch
Ascending colic veins
Inferior branch
Appendicular vein
Anterior caecal vein
Posterior caecal vein
Ileal 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 tubearises from the posteromedial caecal wall it varies from 5 to 20 cm in length, 2 cm below the end of the
ileum.
Dr. Maria Zahiri
The vermiform appendixIt may occupy one of several positions:the commonest positionsRetrocaecal (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.
Dr. Maria Zahiri
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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• Ileocolic artery• Inferior branch • Appendicular artery
• accessory arteries are common
VASCULAR SUPPLY
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one or more appendicular veins
posterior caecal ileocolic vein
Superior mesenteric vein
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Lymphatic vesselsare numerous but all end in the inferior and superior nodes of
the ileocolic chain.
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• sympathetic and parasympathetic nerves from the superior mesenteric plexus.
Innervation
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colon
the colon consists of four sections: the ascending colon, the transverse colon, the descending colon,
and the sigmoid colon
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Ascending colon
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
Dr. Maria Zahiri
Dr. Maria Zahiri
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.
Dr. Maria Zahiri
Dr. Maria Zahiri
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.
Dr. Maria Zahiri
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
Superior mesenteric a.
Inf. pancresticodudenal a.
Jejunal and ileal a.Ileocolic a.
Appendicular a.
Right colic a.
Middle colic a. Superior Mesenteric v.
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Inferior mesenteric a.
Left colic a.
Sigmoid a.
Superior rectal a.
Inferior mesenteric v.Dr. Maria Zahiri
Colic marginal arteryDr. 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."
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•RectumDr. Maria Zahiri
• 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
Dr. Maria Zahiri
Dr. Maria Zahiri
: 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
Dr. Maria Zahiri
Dr. Maria Zahiri
Dr. Maria Zahiri
ARTERIES
1.superior rectal artery: upper third2.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
Dr. Maria Zahiriveins
External plexus:• 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
Dr. Maria Zahiri
و سالمت آرزوی با
سعادت
