Colon Flashcards
Parts of the colon
Ascending
Transverse
Descending
Sigmoid
Length of the colon
150cm
Course of the ascending colon
Ascends from the caecum to the right lobe of the liver and turns 90 degrees to move horizontally at the right colic flexure
Where is the right colic flexure
Deep to ribs 9-10 and inferior part of the liver
What kind of peritoneal structures are the ascending and descending colon
Secondary retroperitoneal
What percentage of people have a short mesentery of the ascending colon
25%
Where is the right paracolic gutter
Between the lateral aspect of the ascending colon and the posterolateral abdominal wall
What’s the longest part of the colon
Transverse colon
What’s the most mobile part of the colon
Transverse colon
Where does the transverse colon run from and to
Right colic flexure to the left colic flexure
Differences between the left (splenic) and right (hepatic) colic flexures
Left colic flexure is more superior, more acute and less mobile than the right colic flexure
What does the phrenicocolic ligament attach
Diaphragm to the left colic flexure
Where is the left colic flexure
Anterior to the left kidney
Vertebral level of the transverse colon
L3 (level of the umbilicus) but in tall thin people it may extend into the pelvis
Where does the sigmoid colon run from and to
From the left iliac fossa to the S3 vertebra
Shape of the sigmoid colon
S-shaped
What signals the rectosigmoid junction
Termination of the teniae coli
Length of the sigmoid colon
Variable but roughly 40cm
Describe the sigmoid mesocolon and the consequence of this
Very long therefore the sigmoid colon is very mobile which can lead to volvulus of the sigmoid colon
What kind of peritoneal structure is the transverse colon
Intraperitoneal
Where is the transverse mesocolon
Fused with the posterior wall of the lesser sac and loops down inferior to the level of the iliac crests
Where is the root of transverse mesocolon
What is it continuous with
Inferior border of the pancreas
Continuous with the posterior parietal peritoneum
What percentage of people have a short mesentery of the descending colon
33%
Where does the descending colon run from and to
From the left colic flexure to the left iliac fossa
What does the descending colon cross
Lateral border of the left kidney
Where is the left paracolic gutter
Between the lateral aspect of the descending colon and the posterolateral abdominal wall
Describe the root of the sigmoid mesocolon
Inverted V-shaped attachment
Arterial supply of the ascending colon and right colic flexure
Abdominal aorta -> SMA -> ileocolic artery
Abdominal aorta -> SMA -> right colic artery
What do the ileocolic and right colic arteries anastomose with and what does this form
They anastomose with the right branch of the middle colic artery to form a series of arcades that forms the marginal artery (continuous arterial channel round the large intestine)
Venous drainage of the ascending colon and right colic flexure
Ileocolic and right colic veins which drain into the SMV and subsequently the hepatic portal vein
Link the embryological origin of the transverse colon to its blood supply
Derived from midgut and hindgut so is supplied by the superior and inferior mesenteric vessels
Arterial supply of the transverse colon
Abdominal aorta -> SMA -> middle colic artery
Abdominal aorta -> SMA -> right colic artery
Abdominal aorta -> IMA -> left colic artery
Venous drainage of the transverse colon
Middle colic vein which drains into the SMV and subsequently the hepatic portal vein
Arterial supply of the descending colon
Abdominal aorta -> IMA -> left colic artery
Arterial supply of the sigmoid colon
Abdominal aorta -> IMA -> sigmoid arteries
Venous drainage of the descending colon
Left colic vein which drains into the IMV
Venous drainage of the sigmoid colon
Sigmoid veins which drain into the IMV
Where do vasa recta arise from
The marginal artery (of Drummond)
Innervation of ascending colon and proximal 2/3 transverse colon
Superior mesenteric plexus
Innervation of distal 1/3 transverse colon, descending colon and sigmoid colon
Inferior mesenteric plexus
Sympathetic - lumbar splanchnic nerves
Parasympathetic - pelvic splanchnic nerves
What does lymph from the ascending and transverse colon drain into
Superior mesenteric nodes
What does lymph from the descending and sigmoid colon drain into
Inferior mesenteric nodes
What do the superior and inferior mesenteric nodes drain into
Intestinal lymph trunks and subsequently the cisterna chyli where it ultimately empties into the thoracic duct
