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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_627_Библиотеки_им_академика_М_И_Перельмана
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part, is retroperitoneal. It is C-shaped and formed around the head of the
pancreas (Fig. 1-3).
FIGURE 1-2 The small intestine is shown with its location relative to the large intestine.
FIGURE 1-3 The duodenum is located in close proximity to the pancreas, hepatobiliary
system, vena cava, portal vein, vertebral column, aorta, superior mesenteric vessels, urinary
system, and the colon.
The duodenum is divided into four parts (Fig. 1-4) as follows.
FIGURE 1-4 The duodenum and its relationship to the biliary system, vena cava, portal
vein, and superior mesenteric artery/vein. The pancreas has been removed.
The superior or first part begins at the pyloric sphincter and ends in the
area of the neck of the gallbladder. It lies anterior to the bile duct,
gastroduodenal artery, portal vein, and inferior vena cava.
The descending or second part passes from the neck of the gallbladder to
the inferior edge of vertebra L3. It is anterior to the medial portion of the
right kidney and just lateral to the head of the pancreas. Associated with
this part are the major duodenal papilla and minor duodenal papilla.
The inferior or third part passes anterior to the inferior vena cava,
abdominal aorta, and vertebral column, and its anterior surface is crossed
by the superior mesenteric artery and vein.
The ascending or fourth part is to the left of the abdominal aorta and
passes upward, ending at the duodenojejunal junction. The ligament of
Treitz (suspensory muscle/ligament of the duodenum) is associated with
this junction.
The arterial supply to the duodenum is from the gastroduodenal artery, the
supraduodenal artery, duodenal branches from the anterior and posterior
superior pancreaticoduodenal arteries, duodenal branches from the anterior
and posterior inferior pancreaticoduodenal arteries, and the first jejunal
branch from the superior mesenteric artery (Fig. 1-5).
FIGURE 1-5 Details of the arterial supply to the duodenum.
Jejunum and Ileum
The jejunum and the ileum are completely covered by peritoneum and
connected to the posterior abdominal wall by a mesentery. They travel from
the left upper quadrant to the right lower quadrant.
Jejunum
The word “jejunum” is derived from the Latin ieiunum or “empty” because it
is often found empty on dissections. The jejunum follows the duodenum and
represents about two-fifths of the small intestine. The arterial supply to this
portion of the small intestine consists of jejunal arteries that are branches of
the superior mesenteric artery (Fig. 1-6). Venous drainage is via the superior
mesenteric vein.
FIGURE 1-6 The jejunum and ileum are intraperitoneal structures that travel from the left
upper quadrant to the right lower quadrant and suspended on a mesentery. The vascular
supply is from the superior mesenteric artery and vein.
Ileum
The word “ileum” is derived from the Latin ilia for “groin” or “flank.” The
ileum is the final portion of the small intestine and represents about threefifths of this structure (Fig. 1-6). The ileum joins the large intestine at the
junction of the cecum and the ascending colon. The arterial supply to this
portion of the small intestine consists of ileal arteries from the superior
mesenteric artery and an ileal branch from the ileocolic artery.
Large Intestine
The large intestine begins as the cecum in the lower right quadrant and
continues superiorly as the ascending colon with the right colic flexure
(hepatic flexure) inferior to the liver. Continuing to the left, the transverse
colon turns inferiorly at the left colic flexure (splenic flexure). It continues
inferiorly as the descending colon and enters the lower abdomen as the
sigmoid colon. It continues into the pelvic cavity as the rectum and anal canal
(Fig. 1-7). The colon has three taeniae coli and haustra (taenia means ribbon
or tape; haustrum means pouch). The taeniae coli are three longitudinal bands
of smooth muscle that are on the outside of the colon and are part of the
longitudinal muscles. The appendices epiploicae are small pouches of
peritoneum filled with fat and along the colon and upper part of the rectum.
There are three taeniae: the mesocolic, the free, and the omental. When the
taenia contracts, haustra, or bulges, form. The taenia converge at the
appendiceal orifice in the cecum. At the rectosigmoid colon, they spread out
to become the longitudinal muscle layer of the rectum. The ascending and
transverse colons are perfused by the superior mesenteric artery. The left
colon, sigmoid colon, and rectum are perfused by the inferior mesenteric
artery (Fig. 1-8). Venous drainage is from the inferior mesenteric veins, the
splenic vein, and the portal vein (Fig. 1-9). The lymphatic drainage follows
the vascular supply. The large intestine and its relationships to neighboring
structures are shown in Figure 1-10.
FIGURE 1-7 The colon and its relation to the terminal ileum and the anorectum.
FIGURE 1-8 The terminal ileum, right colon, and transverse colon receive their blood
supply from the superior mesenteric artery. The left colon and sigmoid colon are perfused by
the inferior mesenteric artery. The watershed region between the superior and inferior
mesenteric circulations is at the splenic flexure. The marginal artery at the splenic flexure (of
Drummond)18 connects the superior and inferior circulations.
FIGURE 1-9 The venous drainage of the colon is via the superior and inferior mesenteric
veins. The inferior mesenteric vein merges with the splenic vein. The splenic vein merges with
the superior mesenteric vein to form the portal vein.
FIGURE 1-10 The colon and its relations to the pelvis, liver, spleen, diaphragm, and rib
cage.
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