Download Small intestine

The intestine :
It is a tube extend from the stomach to the anus, it is divided into two groups (small intestine
and large intestine).
Small intestine:
It is tube which connects the stomach with large intestine, it begins at the pylorus and terminates
at the junction of colon and cecum is suspended by the mesentery and includes:
A-Duodenum B-Jejunum
C-Ileum
The long of intestine: 1-In the horse about: 70 feet.
2-In the cattle about: 130 f
3-In the sheep about: 8o feet.
4-In the dog about: 5 times the body length of the
animals.
The duodenum:
1-It is first part of small intestine; it has shape like a horse shoe (in the horse). The convexity being
directed towards the right. It contacts with the quadrate and right lobes of the liver and has two
ampullae’s with constriction between them.
2-It consists of 3 parts and 3 flexures:
1-The parts:
A-cranial part: begin at the pylorus and passes on right side above the visceral surface of the liver
forms V-shape and ended by the cranial flexure, in horse and ruminants and pigs is sigmoid shape,
it receive bile duct from the liver and pancreas.
B-Descending part: begins at the cranial flexure, directed caudally towards the lateral border of
right kidney, than curved caudally to right kidney to make the caudal flexure (opposite the last rib).
C-Ascending part: passes from right to the left caudal to the attachment of the base of the cecum
cross the median plane caudal to the root of the mesentery and turn cranially to become continuous
with mesenteric part (jejunum and ileum). Under the left kidney by the doudojejunal flexure.
2-The flexures:
A-cranial duodenal flexure they are where the cranial part turns to course.
B-caudal duodenal flexure after descending part.
C-doudenojejunal flexure the portion which turns caudally to be continuous by the jejunum.
3-doudenum in the cranial part attached with the liver by hepatoduoddenal ligament.
4-in the horse there is hepatopancreatic ampulla, in which the pancreatic and hepatic ducts open on
small papillae.
5-the cranial part of duodenum has sigmoid loop which is found in horse, ruminants and pigs.
6-the ascending duodenum connect with the descending colon near the jejunoduodenal flexure by
the duodenocolic fold.
Mesenteric part: consist of two parts (jejunum and ileum), suspended to the roof of the abdomen
by mesentery.
Jejunum:
It is the longest part of small intestine; it begins at the duodenojejunum flexure. Located in
dorsal part of the left half of the abdominal cavity from the visceral surface of the stomach to the
pelvic inlet. In some cases coils of it lie against the right flank when the cecum contains little
material.
In horse related with liver, spleen, pancreas and cranial part of colon.
In ruminants form numerous close coils arranged in festoon around the border of mesentery.
Caudally just before it joins the ileum, it is prolonged by a-u-shaped series of loops on an extension
of the mesentery. The jejunum lies in supraomental recess on right side of the rumen therefore,
related with pancreas, omasum, abomasums, liver and rumen.
Ileum:
It is the terminal part of the small intestine extends from the free edge of ileocecal fold to the
ileocecal orifice, it is smaller in all animals. It connect with the cecum by ileocecal fold, the
ileocecal orifice guarded by sphincter muscle in all animals, except in horse there is venous plexus
instead the sphincter muscle which acts the valve when full with blood.
Mesenteric part:
Connected with dorsal abdominal wall by the mesentery, this is a wide fan shaped fold consisting
of two layers of peritoneum, between which the vessels and nerves reach the bowel; it also contains
the mesenteric lymph nodes and some fats.
The visceral parts of the mesentery contains the intestine, while the parietal border or root of
mesentery, is attached to small area around the cranial mesenteric artery under the first and second
lumber vertebrae.
The large Intestine
Extends from the termination of the ileum to the anus. It is divided into cecum, colon and rectum.
The cecum: is the first part of the large intestine, is the blind sac extend from ileocecal opening to
the beginning of the colon at the cecocolic orifice found at the right side of abdominal cavity in all,
domestic animals except pigs found in the left side.
In horse:
1-it is great cul-de-sac intercalated between the small intestine and the colon.
2-it is curved like a comma shape.
3-it is situated chiefly to the right side of the median plane, extend from the right side iliac and sub
lumber regions to abdominal floor.
4-both extremities are blind.
5-it have two openings are placed at the concave curvature are ileocecal orifice and cecocolic
orifice.
6-it has base, body and apex:
Base:-cranial on right side.
Apex:-on abdominal floor.
Body:-ventrally and cranially.
7-it has greater curvature begin dorsal, the lesser curvature ventral, connected with the lateral are
the termination of ileum and origin of the colon.
8-it has four surfaces which are:
A-dorsal and ventral surface.
B-right or parietal surface: related to the right abdominal wall, diaphragm and liver.
C-the left or visceral surface: related to the terminal part of colon, the root of mesentery and small
intestine.
9-the base attached dorsally by peritoneum with pancreas and right kidney, medially with
transverse colon, ventrally to the origin of great colon.
10-the body is attached dorsolaterally to the 1st part of colon by the cecocolic fold.
11-the apex is free end.
12-the cecum has 4 longitudinal bands situated on the dorsal, ventral, right, left surface; these cause
4 rows of sacculation.
In ruminants: it has S-shaped.
1-it has an average length of 12cm in ox, 8cm in sheep and goats.
2-the cecum extends caudodorsally along the right flank. It is blind end lies at the right side of the
pelvic inlet. The apex on left side on inlet and the base cranially.
3-dorsally it is attached by short cecocolic fold to the proximal loop of the colon.
4-ventrally by the ileocecal fold to the ileum.
5-it opens at the region between joins the ileum with colon by opening called ileocolic opening.
6-it doesn’t have longitudinal bands and sacculations except of the free end.
The colon: begins at the cecocolic orifice and terminates at the rectum at the pelvic inlet (there is
no demarcations between the colon and rectum).
According to its position in man it divided into:
1-ascending colon: directed cranially on the right side.
2-transverse colon: directed from right to left side cranially to cranial mesenteric artery.
3-descending colon: directed caudally on left side.
1-Ascending colon:
A-in horse: called great colon, begins at the cecocolic orifice and terminates in the transverse
colon, it consists of two parallel parts which connected by peritoneum, it is folded as u-shaped
loops, so that it consist of four parts which are named according to their position or numerically.
The three parts are termed the flexures:
1-the right ventral colon: begins at the lesser curvature of the base of the cecum directed cranially.
It forms initial curve and this part is in contact with the flank. It has four bands and sacculation it
ends at the sternal flexure.
2-the left ventral colon: passes caudal on the abdominal floor to the left part of the cecum and
reaching the pelvic inlet, bends sharply and dorsally and cranially forming the pelvic inlet flexure, it
has 4 bands and sacculation.
3-the left dorsal colon: This passes cranial and dorsal to the left ventral colon and on reaching the
diaphragm and the left lobe of liver, turns to the right to the right and caudal forming the
diaphragmatic flexure, it have one bands and sacculations.
4-the right dorsal colon and on reaching, the medial surface of the base of the cecum, it turns to the
left and dorsally caudal to the left sac of stomach where it becomes the short and narrow transverse
colon, it has 3 bands and 3 rows of sacculations.
B-In ruminants (ascending colon):
1-located on the right side of the mesentery connecting the cecum to the transverse colon, it is
longer than other parts of colon. This elongation forms a loop and coils up in conical spiral on the
left side of the mesentery, this loops include:
A-proximal loop: begins as the direct continuation of the cecum at ileocecal orifice.
B-spiral loop:
1-centripetal turns: coil toward central and form central flexure, it has two coils.
2-centrifugal turns: coming back out from the central flexure.
C-distal loop: proceeds from the last centrifugal loop, on the right side medial to the proximal loop,
it is continuous with the transverse colon.
2-it doesn’t has band and sacculation and don’t have sub division.
Transverse colon: is the constricted portion between the large and small colons, which passes from
right to left around the cranial surface of the cranial surface of the cranial mesenteric artery and
continuous caudally as descending colon. In horse have 2 bands and 2 sacculations but in ruminant
doesn’t has bands.
Descending colon:
In horse: located in left side of abdominal cavity known as small colon, begins at the termination
of the transverse colon and is continued by the rectum at the pelvic inlet, there are 2 bands and 2
sacculations.
In ruminant: has sigmoid flexure near the pelvic inlet and joins the rectum. It help to rectal
palpation, it is attached to the sub lumber region by the colic mesentery and to the duodenum by
duodenocolic fold.
The rectum: found on the pelvic cavity on the left side of median plane. It is the terminal part of
the bowel, it extend from the pelvic inlet to the anus. In horse, dog and ox it details terminal to form
the rectal ampullae. The major clinical value of the rectum is its use in palpation, rectal prolapsed
occur in several species. It has two parts: parietal part and retro peritoneal part, which form flaskshaped dilation called the ampulla’s recti (develop in horse and do not found in cat, sheep and
goats).
Anal canal:
It is the terminal part of the alimentary canal; it is situated below the roof of the tail. It is separated
from rectum by line called Anorectal line and separated from skin (which covered the anus by line
called Anocutaneous line. In dog and cat, the cutaneous zone of it has two openings lead to two
sacs, which considered the storage of the secretions which have hate odor, which secreted from the
gland surrounded the anal sacs.
Muscles of the anus:
1-muscle sphincter ani internus (involuntary muscles)
2-muscle sphincter ani externus (voluntary muscles)
3-retractor ani muscle (elevator ani muscle) which is retract partial prolapsed the anus undergoes
during defecation.