1. Colon

2. Colon
• Extends superiorly from the cecum.
• Consists of 4 parts:
-ascending colon
-transverse colon
-descending colon
-sigmoid colon
• Ascending and
descending segments
are retroperitoneal and
transverse and sigmoid
segments are intraperitoneal.

3. Ascending Colon
• Lies in the right lower quadrant of trunk.
• It extends from the cecum, upward to the inferior surface
of right lobe of liver.
• At this position, it turns left to form the right colic
flexure and becomes continuous with the
transverse colon.
• The peritoneum covers the front and the sides of
the ascending colon and binds it to the posterior
abdominal wall.

5. Relations of ascending colon:
Anterior relations:
• Coils of small intestine
• Greater omentum
• Anterior abdominal wall
Posterior relations:
• Iliacus muscle
• Iliac crest
• Quadratus lumborum muscle
• Origin of transversus abdominis muscle
• Lower aspect of the right kidney
• Iliohypogastric and ilioinguinal nerves

6. • Blood supply:
Arteries
-ileocolic and
-right colic branches of the superior mesenteric artery
Veins
-The veins correspond to the arteries and eventually drain into
the superior mesenteric vein.
• Lymph drainage:
-The lymph vessels drain into lymph nodes lying along the course
of the blood vessels of the ascending colon. Ultimately the
lymph reaches the superior mesenteric lymph nodes.
• Nerve supply to ascending colon:
- receives sympathetic and parasympathetic nerves from the
superior mesenteric plexus.

7. Transverse Colon
• Passes from right
hypochondriac region into
left hypochondriac region.
• Extends from right colic
flexure to left colic flexure
below the spleen.
• The left colic flexure is
higher and more posterior
than the right colic flexure
,and is attached to the
diaphragm by the phrenicocolic
ligament.
• The transverse colon has its own
mesentery, known as the transverse
mesocolon. It suspends the transverse
colon from the anterior border
of pancreas.

8. Relations of transverse colon:
• Anterior relations:
-Greater omentum
-Umbilical and hypogastric
regions of anterior
abdominal wall
• Posterior relations:
-Descending part of the
duodenum
-Head of the pancreas
-Coils of jejunum and ileum
• superior relations –
– Liver
– Gall-bladder
– Greater curvature of stomach
– Lower end of spleen
• Inferior relations–
– Small intestine

9. • Blood supply:
Arteries
-proximal 2/3 by medial colic artery(branch of superior mesenteric
artery)
-distal 1/3 by left colic artery(branch of inferior mesenteric artery)
Veins
-The veins correspond to the arteries. Those from the proximal 2/3
drain into the superior mesenteric vein and those from the distal 1/3
drain into the inferior mesenteric vein.
• Lymph drainage:
-The lymph from the proximal 2/3 drain into the superior mesenteric
nodes, via the colic nodes.
-the lymph from the distal 1/3 drains into the inferior mesenteric
nodes, via the colic nodes.
• Nerve supply to ascending colon:
-The proximal 2/3 are innervated by sympathetic and parasympathetic
nerves from the superior mesenteric plexus.
-The distal 1/3 innervated by sympathetic and parasympathetic fibers
from the inferior mesenteric plexus.

10. Descending Colon
• lies at the left side of the
abdomen in both the upper
and lower quadrants.
• Begins at the left colic
flexure and ends by
becoming continuous with
the sigmoid colon, at the
pelvic brim.
• is covered from the front
and sides by the peritoneum,
which binds it to the posterior
abdominal wall.

11. Relations of descending colon:
• Anterior relations:
-Coils of small intestine
-Greater omentum
-Anterior abdominal wall
• Posterior relations:
-Lateral border of left
kidney
-Origin of transversus abdominis muscle
-Quadratus lumborum muscle
-Iliac crest
-Iliacus muscle
-Left psoas muscle
-Iliohypogastric and Ilioginuinal nerves
-Lateral cutaneous nerve of thigh
-Femoral nerve

12. • Blood supply:
Arteries
-left colic artery and
-sigmoid artery (branches of inferior mesenteric artery)
Veins
-The veins correspond to the arteries and eventually drain
into the inferior mesenteric vein.
• Lymph drainage:
-The lymph first drains into the colic lymph nodes, from
where it eventually drains to the inferior mesenteric
lymph nodes, which are situated around the root of
inferior mesenteric artery.
• Nerve supply to ascending colon:
- receives sympathetic and parasympathetic pelvic
splanchnic nerves through the inferior mesenteric plexus.

13. Sigmoid Colon
• Begins where descending
colon passes in front of the
pelvic brim. Below, it
becomes continuous with
the rectum at the level of S3.
• Completely surrounded
by peritoneum.
• Sigmoid colon is mobile
up to a certain extent.
• It hangs down into the pelvic
cavity in the form of a loop. It is
attached to the posterior wall of
the pelvis by a fan shaped fold of
peritoneum, known as sigmoid mesocolon. 1-lesser omentum 2-transverse mesocolon
3-small bowel mesentery
4-sigmoid mesentery

14. Relations of sigmoid colon:
• Anterior relations:
-Urinary bladder (in males)
-Posterior surface of uterus and
upper part of vagina (in females)
• Posterior relations:
-Lower coils of terminal
part of ileum
-Rectum
-Sacrum
-external iliac vessels
-left piriformis
-left sacral plexus of nerves

16. • Blood supply:
Arteries
-sigmoid branches of the inferior mesenteric artery.
Veins
-venous drainage through the inferior mesenteric
vein, which eventually drains into the portal venous
system.
• Lymph drainage:
-The nodes that receive lymph from
sigmoid colon lie along the course of the sigmoid
arteries. From these nodes, the lymph eventually
drains into the inferior mesenteric lymph nodes.
• Nerve supply to ascending colon:
-Inferior hypogastric plexus supplies both the
sympathetic and parasympathetic nerves.