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6.Critical illnesses causing metabolic stress:
A. Acute renal failure.
B. Acute severe pancreatitis.
C. Respiratory failure.
D. Abdominal surgery.
E. Multiple traumas.
F. Sepsis.
G. Burns.
x Methods:
1.A nasojejunal or gastrojejunal feeding tube.
2. Jejunal feeding tube (Jejunostomy tube).
x Approaches:
1.Surgically.
2.Endoscopically.
3.Radiologically.
x Level of the feeding tube:
The end of the feeding tube should be beyond the duodenojejunal flexure to prevent reflux of
feed into the duodenum and stomach.
x Advantages: Is superior to parenteral (intravenous) nutrition because:
1.It maintains the integrity of the gut mucosa, therefor reducing bacterial translocation from the
gut lumen.
2. Decreases the incidence of aspiration from gastro-oesophageal reflux.
3. Causes a less stimulus of pancreaticobiliary secretion.
4. Associated with fewer complications.
x Signs of intolerance to a tube feeding:
vomiting, diarrhea, constipation, rashes, retching, frequent burping, gas bloating, or abdominal
pain.
x Complications:
1.Inadvertent removal of the tube (45.1%).
2.Tube leakage (6.4%).
3.Dermatitis of the stoma (stomatitis) (6.4%).
4.Diarrhea (6.4%).
Fig.121: Methods of surgical nutrition. Source [121].
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2.The ileum:
Has a median external diameter of about 3 cm, an internal diameter of about 2.5 cm.
Has a thinner wall than the jejunum.
The plicae circulares become progressively less obvious in the distal ileum; they tend to be single
and flatter.
Vascular supply of the jejunum and the ileum:
The superior mesenteric artery:
Origin: The abdominal aorta 1 cm below the coeliac trunk, in the transpyloric plane (L1).
Course and relations: Descend anterior to the uncinate process of the pancreas and the third part
of the duodenum, and posterior to the splenic vein and the body of the pancreas. The left renal vein
lies behind it and separates it from the aorta.
Branches:
1.Inferior pancreaticoduodenal artery; supplies the head of the pancreas and the inferior and
ascending regions of the duodenum.
2.Middle colic artery; supplies the proximal two thirds of the transverse colon.
3.Right colic artery; supplies the ascending colon.
4.Ileocolic artery; supplies the caecum, appendix and ileum.
5.Jejunal and Ileal branches; They form arterial arcades (longer with less anastomoses for the
jejunum; shorter with more anastomoses in the ileum). The arterial arcades don't supply directly
the small intestine. They give off the so-called straight arteries (arteriae recta) that are longer than
the arcades and they finally supply the small intestine.
6.Marginal artery of Drummond; The terminal branches of the superior mesenteric artery
(middle colic, right colic and ileocolic arteries) and inferior mesenteric artery (left colic and
sigmoid arteries) anastomose to form the marginal artery, that runs along the internal border of the
colon.
Fig.122: Blood supply of the intestine. Source [122].
111
The superior mesenteric vein:
Origin: It is formed in the mesentery of the small bowel by the union of tributaries from the
terminal ileum, caecum and vermiform appendix.
Course and relations: It ascend in the mesentery to the right of the superior mesenteric artery,
passing anterior to the right ureter, inferior vena cava, third part of the duodenum and uncinate
process of the pancreas.
Tributaries: The superior mesenteric vein receives jejunal, ileal, ileocolic, right colic, middle colic,
right gastroepiploic and inferior pancreaticoduodenal veins.
Termination: It joins the splenic vein behind the neck of the pancreas in the transpyloric plane to
form the portal vein.
Fig.123: The superior and inferior mesenteric veins. Source [123].
Lymphatic drainage:
It is organized into two networks;
First, lacteals from the villi drain into a plexus of lymphatics in the submucosa; few, valves.
Second, a coarse plexus of lymphatics runs in the muscularis externa between the two muscle
layers.
Mesenteric nodes drain into superior mesenteric nodes around the root of the superior mesenteric
artery.
Innervation:
1.Preganglionic sympathetic axons originate from the mid-thoracic spinal segments and travel in
the greater and lesser splanchnic nerves to the coeliac and superior mesenteric ganglia.
2.Postganglionic axons accompany the superior mesenteric artery into the mesentery and are
distributed along branches of the artery.
3.Preganglionic parasympathetic axons travel in the vagus nerves.
4.Visceral afferents from the small bowel, conveying pain and other gut sensations, travel with the
splanchnic and vagus nerves.
Peritoneal coverings:
Completely intraperitoneal.
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Holotopy of the jejunum and the ileum:
1. The loops of the jejunum;
A. Lies mostly to the left and superiorly in the inferior floor of the abdominal cavity.
B. Lies in the umbilical, left lateral and partially in the inguinal regions.
C. Represent about 2/5 of the total length of small intestine.
D. Thicker walls with narrower diameter than those of the ileum.
2. The loops of the ileum;
A. Lies in the right side if the inferior compartment of the abdominal cavity.
B. Lies in the right lateral abdominal region, partially in the umbilical and coeliac region
and lesser pelvic cavity.
C. Represent about 3/5 of the total length of small intestine.
D. Thinner walls with wider diameter than those of the jejunum.
Fig. 124: Jejunum Vs the Ileum. Source [124].
Syntopy of the jejunum and the ileum:
1. Anteriorly and superiorly;
The transverse colon with its mesocolon and the greater omentum.
2. Posteriorly;
Parietal peritoneum of the mesenteric sinuses of the posterior abdominal wall and indirectly the
extraperitoneal organs.
3. Laterally along the flanks;
The cecum and ascending colon to the right side and the descending and the sigmoid colon on
the left side.
Skeletopy of the jejunum and the ileum:
T12- right iliac fossa.
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3.The colon and the vermiform appendix:
The large intestine extends from the ileocaecal junction to the anus. It is formed from the distal
midgut, all of the hindgut, and the proctodeum.
The mean internal diameter of the large intestine is 4.8 cm. Its caliber is greatest near the caecum,
gradually diminishes towards the sigmoid colon, and then increases again in the rectum, where the
lower third is dilated to form the rectal ampulla.
Fig. 125: Parts of the large Intestine. Source [125].
The large intestine differs from the small intestine in several ways:
1. A greater caliber
2. Its course it is more fixed in position
3.The outer longitudinal muscle layer of the colon is concentrated into three longitudinal bands,
taeniae coli; small fatty projections, appendices epiploicae, are scattered over its free surface
4. The colonic wall is puckered into haustrations, visible on plain radiographs as incomplete
septations arising from the bowel wall.
Fig.126: Colonic haustrations. Source [126].
114
The differences between small and large intestine (Table 16):
Feature Small intestine Large intestine
Length (in meters) 6-7. 1.5.
Caliber Narrower Wider
Taeniae coli - +
Sacculations - +
Appendices epiploicae - +
Villi + -
Plicae circularis + -
Payer’s patches Present in ileum Crypts of Lieberkühn Contains absorptive cells and
Paneth cells
Contains numerous goblet
cell, few absorptive cells and
no Paneth cells
The arterial supply of the large intestine:
Is derived from both the superior and the inferior mesenteric arteries.
1.The caecum, appendix, ascending colon and proximal two-thirds of the transverse colon
(derived from the midgut) are supplied from ileocolic, right colic and middle colic branches of the
superior mesenteric artery.
2.The distal third of the transverse colon, descending and sigmoid colon, rectum and upper
anal canal (hindgut derivatives) are supplied the inferior mesenteric artery via the left colic,
sigmoid and superior rectal arteries, with a small contribution from branches of the internal iliac
artery (the middle and inferior rectal arteries).
3.The marginal artery is formed by the main branches and arcades arising from the ileocolic,
right colic, middle colic and left colic arteries. It is most apparent in the ascending, transverse
and descending colons and poorly developed in the sigmoid colon.
4.The splenic flexure may be supplied by the marginal artery, if absent by an inner arterial arc
(of Riolan), when present, this vessel is usually only prominent when there is occlusion of the
superior or inferior mesenteric artery.
The venous drainage of the large intestine:
1. The superior mesenteric and inferior mesenteric veins to the portal vein.
2. From the rectum:
A. Middle rectal veins into the internal iliac veins.
B. Inferior rectal veins into the internal pudendal veins.
3. Midgut derivatives; caecum, appendix, ascending colon and proximal two-thirds of the
transverse colon drain into colic branches of the superior mesenteric vein.
4. Hindgut derivatives; distal third of the transverse colon, descending and sigmoid colon, rectum
and upper anal canal drain into the inferior mesenteric vein.
Lymph drainage from the large intestine: Follows the course of the arteries.
1.Lymphatic vessels of the caecum, ascending and proximal transverse colon drain ultimately into
lymph nodes related to the superior mesenteric artery.
2.Lymphatic vessels of the distal transvers descending colon, sigmoid colon and rectum drain into
nodes following the course of the inferior mesenteric artery.
3.If the distal transverse colon or splenic flexure is predominantly supplied by vessels from the
middle colic artery, the lymphatic drainage of this area may be predominantly to superior
mesenteric nodes.
115
The innervation of the large intestine:
1)The enteric nervous system: Made from motor neurones, intrinsic sensory neurones, and
interneurons, as well as ganglionated nerve plexuses lying in the submucosa (Meissner’s plexus)
and between the longitudinal and circular smooth muscle layers (Auerbach’s myenteric plexus).
2)The autonomic nervous system:
A) Sympathetic; originate either directly from the sympathetic chain or indirectly via the aortic
plexus.
B) Parasympathetic; from the vagus, via the coeliac and superior mesenteric plexuses, whereas the
hindgut receives its parasympathetic innervation from the pelvic splanchnic nerves.
3) The extrinsic sensory innervation (visceral afferents); Visceral afferent impulses mediating
sensations of distension and spasm from the midgut travel with the vagus nerve while the hindgut
is innervated by afferent neurones with cell bodies in the lumbar (L2 and L3) and sacral dorsal
root ganglia (S1 and S2).
Fig.127: Innervations of the GIT. Source [127].
Peritoneal coverings:
1.The transverse and sigmoid colon are intraperitoneally.
2. The ascending and descending colon are mesoperitonially.
3.The cecum is covered in all sides by peritoneum.
4.The appendix is intraperitoneally.
5.The sigmoid colon is intraperitoneally.
6.The rectum;
A. Upper third, is covered by peritoneum on the anterior and lateral surfaces.
B. Middle third, is covered by peritoneum only on the anterior surface.
C. Lower third, is not covered by peritoneum.
116
The cecum:
Holotopy:
The cecum is projected to the right iliac fossa and is projected upon the inguinal region, where
the floor of the cecum is projected 4-5 cm upwards in the middle of the inguinal ligament.
Syntopy:
1.Anteriorly; The loops of small intestine.
2. On the right; Lateral abdominal wall.
3. Posteriorly and inferiorly; m. Iliacus et m. psoas major
4. Medially; The right ureter (separated by peritoneum) and vasa testicularis (ovaries) were they
become the common iliac vessels.
The vermiform appendix:
Attached to the postero-medial aspect of the Caecum, one inch below the ileo-cecal valve (at the
meeting of 3 taenia coli).
Size: 2-20 cm (average 10 cm) & about 0.5 cm wide
Positions:
1.Retro-cecal (64%-74%)
2.Pelvic (21%-32%)
3.Sub-cecal (2%-3.5%)
4.Pre-ileal (1%)
5.Post-ileal (0.5%)
Fig. 128: Positions of the appendix. Source [128].
Holotopy: The vermiform appendix projects in the right iliac fossa.
Syntopy:
1.If directed medial and downwards;
A. Right iliac vessels.
B. Ureter.
C. vasa testicularis (ovirca).
2. If pelvic;
A. Rectum and urinary bladder in males.
B. Ovary and uterine tubes in females.
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The ascending colon:
Holotopy: the ascending colon projects in the right lateral region of the abdomen.
Syntopy:
1. On the right; joins the right parabolic gutter.
2. On the left; sinus mesentrica dexter.
3. Anteriorly; Loops of intestine and greater omentum separating it from the ALAW.
4. Posteriorly; Rt. Kidney, its capsule and the muscles of the posterior abdominal wall.
The hepatic flexure:
Holotopy & Skeletopy;
The hepatic flexure projects on the right hypochoruim at the level of the X costal cartilage.
Syntopy;
1.Anteriorly and superiorly; inferior surface of the rt. Hepatic lobe and the fundus of the GB.
2.Poster-medially; descending part of the duodenum.
3.Posteriorly; inferior pole of the rt. Kidney.
The transvers colon:
Holotopy:
The transvers colon projects on the Rt. hypochondrium., epigastric, umbilical and Lt.
hypochondrium regions.
Syntopy:
1. Superiorly; the liver, GB, the greater curvature of the stomach and the spleen.
2. Inferiorly; loops of small intestine.
3. Anteriorly; ALAW.
4. Posteriorly; The duodenum, the pancreas and the left kidney.
The splenic flexure:
Holotopy & Skeletopy;
The splenic flexure projects to the Lt. hypochondrium at the level of the IX costal cartilage and
th
8
intercostal space.
Syntopy:
Superiorly; The tail of the pancreas.
Posteriorly; Spleen and lt. kidney.
The descending colon:
Holotopy:
The descending colon projects in the Left lateral region of the abdomen.
Syntopy:
1. Externally; The lt. paracolic gutter separate from the ALAW.
2. Interiorly; sinus mesentrica sinister.
3. Anteriorly; loops of small intestine and greater omentum separate from the ALAW.
The sigmoid colon:
Holotopy:
The sigmoid colon projects in the Lt. iliac fossa and projects to the ALAW on the lt. inguinal and
pubic region.
Syntopy;
Crosses over left iliac and testicular vessels.
118
The lower floor of the abdominal cavity contains also lateral channels, mesenteric sinuses.4
divisions – 2 external and 2 internal.
External divisions – lateral channels – fixed spaces between the fixed parts of the large intestine
(colon ascendens and colon descendens) and the side walls of the abdomen.
Superiorly, each of the channels communicates with the upper floor of the abdominal cavity.
Inferiorly, each channel passes into the iliac fossa, from there – into the small pelvis.
On the left, there is a lig. Phrenicocolicum stretched between the diaphragm and the spleen
curvature of the colon. If the fingers inserted into the left side channel are moved up, they will
meet an obstacle from this ligament, but there is no obstacle on the right.
CLINICAL NOTE: If the spleen is damaged, the phernicocoloic ligament may delay blood flow
to the left lateral canal. Therefore, when checking the abdominal cavity to identify the source of
bleeding, it is necessary to examine the space above the phernicocoloic ligament.
Fig.129: The splenic ligaments. Source [129].
Canals (channels) of the abdominal cavity:
1- The right-side channel (Canalis lateralis dexter):
Borders:
Superiorly, it communicates with the liver bag
Inferiorly, it communicates with the right iliac fossa and with the peritoneal cavity of the pelvis
To the right – side wall of the abdomen
To the left – the ascending colon
Surgical importance of canalis lateralis dexter:
1.If a purulent process occurs in the upper floor of the abdominal cavity e.g. perforation of the
stomach wall or gall bladder, the spread of the purulent process or the contents of the hollow viscus
will propagate along the right-side channel to the organs of the lower floor with the possibility of
developing a secondary inflammatory process.
2.In case of the contents of a perforated duodenal ulcer are spilled into the abdominal cavity, they
will propagate through the right-side channel to the right iliac fossa and to the pelvic cavity.
3.In the upright position, the fluid from the canal can spread to the lesser pelvis, therefore during
the postoperative period of surgery in the lower floor of the abdominal cavity, it is recommended
to put the patient in a semi-setting position in order to prevent the upward spread of the
inflammatory process.
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