Large Intestine & Inferior
Mesenteric Artery
Objectives
• Discuss anatomical structure of large
intestine.
• Enlist the characteristic features of large
intestine.
• What are the different positions of the
Appendix.
• Describe the blood supply of the large
intestine.
• The large bowel may vary considerably in length in
different subjects;the average is approximately 5 feet
(1.5 m).
• The large intestine is subdivided, for descriptive
purposes, into:
• Caecum with the Appendix vermiform
• Colon
ascending colon
hepatic flexure
transverse colon
splenic flexure
descending colon
sigmoid colon
• Rectum & Anal canal .
Large Intestine
• The general characteristics of most of the large
intestine are:
• Its large internal diameter compared to that of the
small intestine;
• the appendices epiploicae (omental appendices)
are fat-filled peritoneal tags
• The taeniae coli: three thickened bands of muscles
• the haustra of colon are sacculations of the colon
between the taeniae
• No taeniae in the appendix or rectum.
• The colon (but not the appendix, caecum or
rectum), bears characteristic fat-filled
peritoneal tags called appendices epiploicae
scattered over its surface.
• These are especially numerous in the sigmoid
colon.
• The transverse colon and sigmoid are
completely peritonealized (the former being
readily identified by its attachment to the
greater omentum).
• The ascending and descending colon
have no mesocolon but adhere directly
to the posterior abdominal wall .
• The caecum is usually completely
peritonealized,
• The appendix has its own mesocolon.
Features of large
intestine:
Taeniae Coli: Three
thickened bands of
muscles
No taeniae in the
appendix or rectum
Haustra:
Sacculations of the
colon between the
taeniae
Omental Appendices:
Small fatty projections
of the omentum
Caliber:
The internal diameter
is much bigger than
small intestine
Cecum and Appendix
Ileocecal
Junction
Taenia Coli
Sacculations
=
Haustra
• The cecum is that part of the large intestine
that lies below the level of the junction of
the ileum with the large intestine . It is a
blind-ended pouch that is situated in the
right iliac fossa. It is about 2.5 in. (6 cm) long
and is completely covered with peritoneum.
• The appendix is attached to the
posteromedial wall of the cecum, just
inferior to the end of the ileum
• The appendix is suspended from the terminal
ileum by the mesoappendix, which contains the
appendicular vessels .
• Its point of attachment to the cecum, the base of
the appendix, is consistent with the highly visible
free taenia leading directly to it.
• But the location of the rest of the appendix varies
considerably .
• The appendix is at the junction of the
lateral and middle one-thirds of a line
from the anterior superior iliac spine to
the umbilicus (McBurney's point).
Variations in position Vermiform Appendix
Variations in position Vermiform Appendix
64%
Inferior mesenteric artery
Branches:
1. Left colic artery
2. Several sigmoid arteries
3. Superior rectal artery
• The inferior mesenteric artery and
arises anterior to the body of vertebra
L3. Its branches include the
• left colic artery,
• several sigmoid arteries,
• superior rectal artery.
• The veins drain into the inferior
mesenteric vein