large intestine-1.pdf. for medical students

presentation of large Intestine

3. Large Intestine
Last part of gastrointestinal track.
1.5 m long
It extend from ileocolic junction to
anus
Parts
Cecum Appendix
Colon
Ascending colon
Transverse colon
Descending colon
Sigmoid Colon
R
Rectum Anal canal

4. Structure
Greater part of large intestine is fixed except appendix,
transverse colon, and sigmoid colon
LAYERS:

5. 1.CAECUM
First part Of large intestine
Length 6cm Width 7.5 cm
•Location
Large blind sac situated in right illiac fossa , above lateral
half of inguinal ligament. It communicates superiorly with
ascending Colon , medially at level of caecocolic junction
with ileum and posteriorly with appendix.

6. RELATIONSOf Caecum
ANTERIOR
Coil of Intestine and anterior abdominal wall
POSTERIOR
Muscle : Right psoas muscle
and iliacus
Nerve: Genetofemoral ,
femoral and lateral
cutaneous nerves of thigh.
Vessels : testicular or ovarian
Appendix in retrocaecal recess

7. •BLOOD SUPPLY
ARTRIES
Anterior and posterior cecal artries from ileocolic artery
which is branch of superior mesenteric artry..
VEIN
The vein drain into superior mesenteric vein.
LYMPH DRAINAGE
The Lymph drain into mesenteric and superior
mesenteric nodes.
NERVE SUPPLY
Sympathetic and vagus nerve , via superior
mesenteric plexus supply cecum.

8. ILEOCOLIC VALVE
Lower end of iluem open on posteromedial aspect of
caecocolic junction . The ileocaecal opening is
guarded by ileocaecal valve.
The valve has two lips and two frenula.
Upper lip is horizontal and lies at ileocolic junction .
The lower lip is longer and concave and lies at
ileocaecal junction.
Two frenula are formed by fusion of lips at end of
aperture.
Left or anterior aperture is rounded . Right or
posterior aperture is narrow and pointed

10. •2.APPENDIX
A narrow finger like tubular projection arise from
ceacum.
It arises from posteromedial wall of Caecum about
2cm below ileocaecal junction.
Dimensions:
Length is 2 to 20cm but average is
9cm.
Diameter : 5mm
It has complete peritoneal covering, which is attached
to mesentry of small intestine by short mesentry of its
own called mesoappendix.

11. POSITION
The appendix lies in
right illiac fossa. The
base of appendix is fix,
the tip can point in any
direction.

12. BLOOD SUPPLY
ARTRIES
Appendicular artery is a branch of posteriocecal artry.
VEIN
The vein drain into posterior cecal vein.
LYMPH DRAINAGE
Lymph drain into nodes in the mesoappendix and
eventually into superior mesenteric lymph nodes.
Nerve supply
The appendix is supplied by sympathetic and
vagus nerves from superior mesenteric plexus.

13. CLINICAL IMPORTANCE
Inflammation of appendix is called
Appendicitis.
Operation for removal of appendix
is called " appendictomy"
The pain caused by Appendicitis is
first felt in reigon of umblicus . Both
umblicus and appendix are
innervated by segment T10 of spinal
cord..
With increasing inflammation pain is
felt in right illiac fossa...

14. Mcburney's point

15. 3.A SCENDING COLON
Ascending colon is about 12.5 cm long and extends from
Caecum to inferior surface of right lobe of liver. Here it
bends to form right colic flexture.
Right colic flexture
Lies at junction of ascending
colon and transverse colon.
The flexture lies on lower part of
right kidney.
Anterosuperiorly it related to
colic impression on inferior
surface of right lobe of liver.

16. Posterior : iliacus and quadrantus lumborum ,
ilioinguinal and iliohypogastric nerves and right
kidney.
Relations
Anterior : coils of small intestine,right
edge of greater omentum and anterior
abdominal wall.

17. Blood supply
ARTRIES
ileocolic and right colic branches of superior
mesanteric Arty.
VEIN
The vein drain into superior mesenteric vein.
LYMPH DRAINAGE
Colic lymph node and superior mesanteric node.
Nerve supply
Sympathetic and vagus nerve from superior
mesenteric plexus.

18. 4. TRANSVERSE COLON
Transverse colon is 15 inch (38cm )in length
passes across the abdomen , occupying umblical
and hypogastric reigon.
It extend across the abdomen from
right colic flexture to the left colic
flexture.

19. left colic flexture )splenic flexture
It lies at the junction of
transverse colon and descending
colon..
The flexture lies on lower part of
left kidney and diaphragm
behind the stomach below
anterior end of spleen...
It attach with 11th rib by
horizontal fold of peritonium
called phrenicocolic ligament.

20. Blood supply
ARTRIES
Proximal 2/3rd : of transverse colon is supplied
by middle colic artry ,which is branch of superior
mesenteric artry...
Distal 1/3rd: supply by the left coloic artry
which is branch of inferior mesenteric artry..
Vein
It is drain into superior and inferior mesentric vein...
LYMPH DRAINAGE
Proximal 2/3rd drain into colic nodes and into
superior mesenteric nodes
Distal 1/3rd drain into colic nodes and then
inferior mesenteric nodes.

21. NERVE SUPPLY
Proximal 2/3rd by the sympathetic and the
vagal nerve through superior mesenteric
plexus..
The distal 1/3rd is innervated by sympathetic
and parasympathetic pelvic splanchnic nerve
through inferior mesentric plexus..

22. DESCENDING COLON:
•The part of large intestine that passes downwards on
the left side of abdomen towards the rectum.
•The descending colon is approximately 25cm long and
extends from the splenic flexure down to the pelvic
brim. From the lateral border of left kidney, it descends
vertically and slightly toward the midline in the groove
between the psoas and the quadratus lumborum to the
iliac crest.
•The descending colon lead to inverted v-shaped sigmoid
colon.
•The descending colon is narrower than the ascending
colon.

23. RELATIONS:
ANTERIORLY:
•Coils of small intestine, the greater omentum,
and the anterior abdominal wall.
POSTERIORLY:
•The lateral border of the left kidney, the origin of
the transversus abdominis muscle,the quadratus
lumborum, the iliac crest, the iliacus, and the left
psoas. The iliohypogastric and the illioinguinal
nerves, the lateral cutaneous nerve of the thigh,
and the femoral nerve also lie posteriorly.

24. BLOOD SUPPLY:
•The left colicand the sigmoid branches of the
inferior mesenteric artery supply this area.
•The veins correspond to the arteries and drain into
the inferior mesenteric vein.
LYMPH DRAINAGE:
•Lymph drains into the colic lymph nodes and the
inferior mesenteric nodes around the origin of the
inferior mesenteric artery.
NERVE SUPPLY:
•The nerve supply is the sympathetic and
parasympathetic pelvic splanchnic nerves through the
inferior mesenteric plexus.

25. SIGMOID COLON:
•The sigmoid colon is the last section of bowl-the part
that attaches to the rectum.
•The sigmoid colon is 10 to 15(25 to 38cm)long and
begins continuous of the descending colon in front of
pelvic brim.
•It is shaped like the letter "S".
•The sigmoid colon contains a lot of muscle tissue.
•It contains four layers of tissue.
•The inside layer is a mucous membrane. Next to mucous
membrane is a layer of connective tissue.
•Third layer is made of muscle to propel feces along the
sigmoid tube.

26. •And fourth layer of smooth epithelial tissue called
the serosa protects the outside of colon by
secreting a liquid.
RELATIONS:
•ANTERIORLY:
In the male, the urinary bladder. In the female, the
posterior surface of thr uterus and the upper part of
the vagina.
•POSTERIORLY:
The rectum and the sacrum. The sigmoid colon is also
related to thelower coils of the terminal part of the
ileum.l

27. BLOOD SUPPLY:
•Sigmoid branches of the inferior mesenteric
artery supply the sigmoid colon.
•The accompanying veins drain into the inferior
mesenteric vein.
LYMPH DRAINAGE:
The lymph drains into nodes along the course of
the sigmoid arteries. From these nodes, the
lymph travels to the inferior mesenteric nodes.
NERVE SUPPLY:
The sympathetic and parasympathetic nerves from the
inferior hypogastric plexuses.

28. RECTUM:
•Rectum is about five inch(13cm) long and began in
front of the third sacral vertebra as a continuation of
the sigmoid colon.
•It passes downward following the curve of sacrum and
coccyx and end in front of the tip of the coccyx by
piercing the pelvic diaphragm and becoming
continuous with the anal canal.
•The lower part of the rectum is dilated to form the
rectal ampulla.
•Rectum deviates to the left but quickly return to the
median plane.
•On lateral view rectum follow the interior concavity of
the sacrum before bending downward and backward at
its junctions with the anal canal.

30. RELATIONS:
POSTERIORLY:
The rectum is in contact with the sacrum and coccyx; the
piriformis coccygeus and levatores ani muscles; the sacral
plexus and the sympathetic trunks.
ANTERIORLY:
•In the male, the upper two thirds of the rectum wich
is covered by peritoneum. The lower third of the
rectum which is devoid of peritoneum, is related to
the posterior surface of the bladder, to the
termination of the vas deferens and the seminal
vesicles on each side and to the prostr ate.

31. •In the female, the upper two third of rectum,
which is covered by peritoneum. The lower third
of rectum which is devoid of peritoneum is
related to the posterior surface of the vagina.
ARTERIES:
The superior, middle and inferior rectal arteries supply
the rectum.
•The superior rectal arteryia a direct continuation of
the inferior mesenteric artery and is the chief artery
supplying the mucous membrane.It enters the pelvis
by descending in the root of sigmoid mesocolon and
divides into right and left branches, which pierce the
muscular coat and supply the mucous membrane.

32. •The middle rectal artery is a small branch of internal iliac
artery and is distributed mainly to the muscular coat.
•The inferior rectal artery is a branch of internal pudendal
artery in the perineum. It anastomosis with the middle
rectal artery at the anorectal junction.
VEINS:
•The veins of the rectum correspond to the arteries.
•The superior rectal vein is a tributary of the portal
circulation and drain into the inferior mesenteri vein.
•The middle and inferior rectal vein drain into the
internal iliac and internal pudendal vein,respectively.

33. LYMPH DRAINAGE:
The lymph vessel of the upper rectum drain first
into the pararectal nodes and then into inferior
mesenteric nodes. Lymph vessel from the lower
part of the rectum follow the middle rectal artery to
the internal iliac nodes.
NERVE SUPPLY:
The nerve supply is from the sympathetic and
parasympathetic nerves from the inferior
hypogastric plexuses. The rectum is sensitive only
to stretch.

34. ANAL CANAL:
•The anal canal is about
1.5 in (4cm) and passes
downward and
backward from the
rectal ampulla to the
anus.
•The levatores ani
muscles and the anal
sphincters keep its
lateral walls in
appositions except
during defecation.

35. RELATIONS:
POSTERIORLY:
The anococcygeal body, which is a mass of fibrous tissu
e lying between theanal canal and the coccyx.
LATERALLY:
The fat-filled ischiorectal fossae.
ANTERIORLY:
In the male, the perineal body, the urogenital
diaphragm, the membranous part of the urethra, and
the bulb of the penis. In the female, the perineal body,
the urogenital diaphragm, and the lower part of the
vagina.

36. STRUCTURE:
UPPER HALF OF ANAL CANAL:
The mucous membrane of the upper half of the anal
canalis derived from hindgut entoderm.
FEATURES:
•It is lined by columnar epithelium.
•It has vertical folds called anal columns,which are
joined together by small semilunar folds called anal
valves.
•The nerve supply is derived from the autonomic
hypogastric plexuses.
•The arterial supply is the superior rectal artery, a
branch of the inferior mesenteric artery.

37. •The venous drainage is mainly by the superior rectal
vein, atributary of the inferior mesentericvein, and the
portal vein.
•The lymphatic drainage is mainly to the pararectal
nodes and then to the inferior mesenteric nodes.
LOWER HALF OF THE ANAL CANAL:
The mucous membrane of the lower half of the anal
canal is derived from ectoderm of theproctodeum.
FEATURES:
•It is lined by stratified squamous epithelium.
•There are no anal columns.

38. •The nerve supply is from the somatic inferior rectal
nerve.
•The arterial supply is the inferior rectal artery,a
branch of the internal pudendal artery.
•The venous drainage is by the inferior rectal vein,a
tributary of the internal pudendal vein, which
drains into the internal iliac vein.
The pectinate line indicates the level where the
upper half of the anal canal joins the lower half.
MUSCLE COAT:
As in the upper parts of the intestinal tract, it is
divided into an outer longitudinal and an inner
circular layer of smooth muscle.

39. ANAL SPHINCTERS:
The anal canal has an involuntary internal sphincter and
a voluntary external sphincter.
INTERNAL SPHINCTER:
•The internal sphincter is formed from a thickening of
the smooth muscle of the circular coat at the upper
end of the anal canal.
•A sheath of skeletal muscle that forms the voluntary
external sphincter encloses the internal sphincter.

40. EXTERNAL SPHINCTER:
The external sphincter has three parts:
subcutaneus, superficial,and deep.
SUBCUTANEOUS PART:
It encircles anal canal.
SUPERFICIAL PART:
It originates from the perineal body and insert in
the coccyx.
DEEP PART:
It encircles anal canal, no bony attachments.

42. BLOOD SUPPLY OF ANAL CANAL:
•The superior rectal artery supplies the upper half,
and the inferior rectal artery supplies the lower
half.
•The superior rectal vein drains the upper half into
the inferior mesenteric vein. The inferior rectal vein
drains the lower half into the internal pudendal
vein.
LYMPH DRAINAGE OF ANAL CANAL:
•The upper half of the anal canal drains into the
pararectal nodes and then the inferior mesenteric
nodes

43. •The lower half drains into the medial group of
superficial inguinal nodes.
NERVE SUPPLY OF ANAL CANAL:
•The hypogastric plexusesinnervate the mucous
membrane of the upper half, which is sensitive to
stretch.
•The inferior rectal nerves supply the lower half, which is
sensitive to pain, temperature, touch and pressure.
•Sympathetic fibers from the inferior hypogastric
plexuses innervate the involuntary internal sphincter.
•The inferior rectal nerve, a branch of pudendal nerve,
supply the voluntary external sphincter.

44. COLON CANCER:
•Colon cancer occurs when abnormal cells develop
inside the colon, usually in polyps.
•The cancerous cells can spread from the inner layers of
the colon through the walls of the organ and eventually
into the blood vessels and lymph system, if left
untreated.
TREATMENT:
•Cancer of colon is a high treatable and often curable
disease when localized to the bowel.
•Surgery is the primary form of treatment and results
in cure in approximately 50% of the patients.
•Recurrence following surgery is amajor problem and is
often the ultimate cause of death.