Rectum anus Anatomy complete

1. Colon

2. Colon
A tubular organ and largest part of large
intestine is considered as colon.
OR
The cecum merges with a long tube called
the colon (= food passage

4. Sub-divisions of Colon
Colon is divided into 4 sub-parts,
1. Ascending colon (Right Colon)
2. Transverse Colon (Middle Colon)
3. Descending Colon (Left Colon)
4. Sigmoid Colon

6. Retroperitoneal and Intraperitoneal
Both the ascending and descending colon
are retroperitoneal
The transverse and sigmoid colon are
intraperitoneal.

8. Ascending Colon length and location
The ascending colon by length is
about 5inches long (13cm).

10. Ascending Colon Location
 It lies in the right lower quadrant of abdomen
or (in the right iliac fossa and right lumbar
regions).
 It is retroperitoneal and is attached to
posterior abdominal wall.

13. Course of Ascending Colon
 It begins from cecum and ascends upwards till
inferior surface of right lobe of liver.
 Here it turns to left forming a bend called as right
colic flexure.
 It becomes continuous with transverse colon.

17. Blood Supply
Ileocolic arteries and
Right colic artery , branches of
superior mesenteric artery supplies
this area.

20. Venous Drainage
The veinous drainage occurs by ileocolic
veins which empties into superior
mesenteric vein.

22. Transverse Colon
It is about 15inches long.
extends across the abdomen,
occupying the umbilical region.
It is intraperitoneal.

24. Suspension of Transverse Colon
 It is suspended from the diaphragm by the phrenicocolic
ligament
 The transverse mesocolon, or mesentery of the
transverse colon, suspends the transverse colon from the anterior
border of the pancreas.
 The mesentery is attached to the superior border of the transverse
colon,
 Posterior layers of the greater Omentum are
attached to the inferior border.

26. Course of Transverse Colon
It begins at the right colic flexure below the
right lobe of liver.
It then ascends to the left colic flexure till the
spleen.
The left colic flexure is higher than right colic
flexure.

31. Blood Supply of Transverse Colon
Middle Colic Artery supplies proximal
2/3rd. (branch of superior mesenteric
artery).
Left Colic artery supplies distal 1/3rd of
transverse colon (branch of inferior
mesenteric artery).

33. Venous Drainage
Venous drainage happens by means of
superior and inferior mesenteric veins by
means of similar veins as of arteries i.e.
Middle and left colic veins.

35. Descending Colon
It is about 10 inches in length.
It lies in left upper and lower
quadrants of abdomen
In left lumbar and left iliac fossa of
abdominal cavity.

38. Course
It extends from left colic flexure.
It descends downwards till the pelvic
brim.
In pelvic brim it becomes continuous
with sigmoid colon.

41. Blood supply
 Left Colic artery and sigmoid branches of
inferior mesenteric artery supplies this part of
colon.
 The veins follow the arteries and empties into
inferior mesenteric vein.

43. Sigmoid Colon
IT IS ABOUT 10-15INCHES LONG.
IT IS MOBILE PART OF COLON AND
HANGS DOWN INTO PELVIC CAVITY
IN THE FORM OF A LOOP.

46. Sigmoid Colon
The sigmoid colon is attached to
posterior pelvis by sigmoid mesocolon.

48. Course
It begins as a continuation of
descending colon in front of pelvic
brim.
Below it becomes continuous with
rectum in front of 3rd sacral vertebrae.

52. Blood Supply
Sigmoidal Arteries of Inferior
Mesenteric Artery supply blood to
sigmoid colon.
Venous drainage happens by means of
sigmoidal veins which drains into
inferior mesenteric vein.

54. Rectum
It is about 5 inches long.
The lower end of rectum is
dilated and forms rectal
ampulla.

57. Course
 It begins at the level of 3rd sacral vertebrae.
 It is continuation of sigmoid colon.
 It descends following the curve of sacrum and
coccyx.
 It ends at the level of tip of coccyx.
 Where it becomes continuous with anal canal.

61. Coverings of Rectum and Muscle Coat
 Peritoneum covers anterior and lateral surface
of first part of rectum.
 It covers anterior surface of middle third.
 Lower third is devoid of peritoneum.
 Muscle coat is of outer longitudinal and inner
circular layer.

62. Transverse Folds of Rectum
The mucous membrane of rectum
with circular muscle layer forms two
or three semicircular permanent
folds called as transverse folds of
rectum.

64. Blood Supply of Rectum
Superior Rectal Artery (branch of inferior
mesenteric artery)
Middle Rectal Artery (branch of internal
iliac artery)
Inferior Rectal Artery (branch of internal
pudental artery)

66. Veinous Drainage
 Superior Rectal vein drains into inferior
mesenteric vein and follow portal circulation.
 Middle rectal veins drains into internal iliac vein.
 Inferior rectal vein drains into internal pudental
vein.