Stomach pdf - Abdomen

Basic Anatomy

which is about 1 in. (2.5 cm) long. The circular muscle coat

pyloric canal,

is formed by the

pyloric orifice

The

agus (see page 170).

prevents regurgitation of stomach contents into the esoph

be demonstrated here, a physiologic mechanism exists that

stomach (Fig. 5.21). Although no anatomic sphincter can

is where the esophagus enters the

cardiac orifice

The

transverse colon (Fig. 5.11).

extends from the lower part of the greater curvature to the

greater curvature to the spleen, and the greater omentum

omentum (ligament) extends from the upper part of the

the stomach to the pylorus (Fig. 5.21). The gastrosplenic

over the dome of the fundus, and along the left border of

curvature and extends from the left of the cardiac orifice,

is much longer than the lesser

greater curvature

tum. The

5.21). It is suspended from the liver by the lesser omen

ach and extends from the cardiac orifice to the pylorus (Fig.

forms the right border of the stom

lesser curvature

The

(Fig. 5.21).

pyloric canal

and the cavity of the pylorus is the

ter,

pyloric sphinc

The thick muscular wall is called the

This is the most tubular part of the stomach.

Pylorus:

ris to the pylorus (Fig. 5.21).

This extends from the incisura angula

Pyloric antrum:

in the lower part of the lesser curvature (Fig. 5.21).

a constant notch

incisura angularis,

to the level of the

This extends from the level of the cardiac orifice

Body:

to the left of the cardiac orifice. It is usually full of gas.

This is dome-shaped and projects upward and

Fundus:

(Fig. 5.21):

The stomach is divided into the following parts

position of the body, and the phase of respiration.

same person and depends on the volume of its contents, the

stomach). Its shape undergoes considerable variation in the

and elongated vertically in the tall, thin person (J-shaped

arranged in the short, obese person (steer-horn stomach)

mobile in between. It tends to be high and transversely

The stomach is relatively fixed at both ends but is very

(Fig. 5.21).

posterior surface

anterior

faces, an

and two sur

lesser curvatures;

greater

curvatures, the

two

pyloric orifices;

cardiac

and has two openings, the

ach lies under cover of the lower ribs. It is roughly J-shaped

into the epigastric and umbilical regions. Much of the stom

men, extending from beneath the left costal margin region

The stomach is situated in the upper part of the abdo

so that efficient digestion and absorption can take place.

trols the rate of delivery of the chyme to the small intestine

and it con

chyme,

gastric secretions to form a semifluid

it has a capacity of about 1500 mL), it mixes the food with

and has three main functions: It stores food (in the adult

The stomach is the dilated portion of the alimentary canal

Location and Description

171

Stomach

and

and a

■

fundus

cardiac orifice

lesser curvature

incisura angularis

pylorus

antrum

body

greater

curvature

longitudinal muscle coat

oblique muscle

coat

circular muscle coat

esophagus

duodenum

pyloric orifice

pyloric canal

pyloric sphincter

longitudinal folds of mucous coat

cardiac orifice

FIGURE 5.21

Stomach showing the parts, muscular coats, and mucosal lining. Note the increased thickness of the circular

muscle forming the pyloric sphincter.

172

CHAPTER 5

The

passes down to the pylorus (Fig. 5.24).

branch passes up to the liver, and from this a pyloric branch

supply the anterior surface of the stomach. A large hepatic

may be single or multiple, then divides into branches that

on the anterior surface of the esophagus. The trunk, which

rax mainly from the left vagus nerve, enters the abdomen

which is formed in the tho

anterior vagal trunk,

The

and left vagus nerves (Fig. 5.24).

the celiac plexus and parasympathetic fibers from the right

The nerve supply includes sympathetic fibers derived from

Nerve Supply

abdominal wall.

around the root of the celiac artery on the posterior

the stomach eventually passes to the celiac nodes located

ploic nodes, and the short gastric nodes. All lymph from

left and right gastric nodes, the left and right gastroepi

The lymph vessels (Fig. 5.23) follow the arteries into the

Lymph Drainage

joins the superior mesenteric vein.

right gastroepiploic vein

join the splenic vein. The

veins

left gastroepiploic

and the

short gastric veins

vein. The

drain directly into the portal

right gastric veins

and

left

The veins drain into the portal circulation (Fig. 5.22). The

Veins

greater curvature.

left and supplies the stomach along the lower part of the

troduodenal branch of the hepatic artery. It passes to the

arises from the gas

right gastroepiploic artery

The

along the upper part of the greater curvature.

gastrosplenic omentum (ligament) to supply the stomach

artery at the hilum of the spleen and passes forward in the

arises from the splenic

left gastroepiploic artery

The

plenic omentum (ligament) to supply the fundus.

at the hilum of the spleen and pass forward in the gastros

arise from the splenic artery

short gastric arteries

The

stomach.

the lesser curvature. It supplies the lower right part of the

the upper border of the pylorus and runs to the left along

arises from the hepatic artery at

right gastric artery

The

right part of the stomach.

It supplies the lower third of the esophagus and the upper

then descends along the lesser curvature of the stomach.

passes upward and to the left to reach the esophagus and

arises from the celiac artery. It

left gastric artery

The

artery (Fig. 5.20).

The arteries are derived from the branches of the celiac

Arteries

mesocolon, and the transverse colon (Figs. 5.4, 5.6,

kidney, the splenic artery, the pancreas, the transverse

the left suprarenal gland, the upper part of the left

The lesser sac, the diaphragm, the spleen,

Posteriorly:

left lobe of the liver (Figs. 5.2 and 5.6)

margin, the left pleura and lung, the diaphragm, and the

The anterior abdominal wall, the left costal

Anteriorly:

Relations

plenic omentum and the greater omentum.

lesser omentum and the greater curvature as the gastros

rounds the stomach. It leaves the lesser curvature as the

(visceral peritoneum) completely sur

peritoneum

The

nal fibers, circular fibers, and oblique fibers (Fig. 5.21).

contains longitudi

muscular wall of the stomach

The

ten out when the stomach is distended.

mainly longitudinal in direction (Fig. 5.21). The folds flat

that are

rugae,

cular and is thrown into numerous folds, or

of the stomach is thick and vas

mucous membrane

The

sphincter.

nerve plexus in its wall and reflexly cause relaxation of the

the stomach due to filling will stimulate the myenteric

ach and duodenal walls. For example, the stretching of

local nervous and hormonal influences from the stom

from the vagi. In addition, the pylorus is controlled by

fibers from the sympathetic system and inhibitory fibers

tents into the duodenum. The sphincter receives motor

The pyloric sphincter controls the outflow of gastric con

Function of the Pyloric Sphincter

stomach.

be recognized by a slight constriction on the surface of the

pylorus lies on the transpyloric plane, and its position can

(Fig. 5.21). The

pyloric sphincter

tomic and physiologic

of the stomach is much thicker here and forms the ana

The Abdomen: Part II—The Abdominal Cavity

■

and 5.11)

Blood Supply

with peritoneum and has the lesser omentum attached to

in that it is covered on its anterior and posterior surfaces

first inch (2.5 cm) of the duodenum resembles the stomach

curves around the head of the pancreas (Fig. 5.26). The

openings of the bile and pancreatic ducts. The duodenum

long, which joins the stomach to the jejunum. It receives the

The duodenum is a C-shaped tube, about 10 in. (25 cm)

Location and Description

the ileum.

divided into three parts: the duodenum, the jejunum, and

and food absorption takes place in the small intestine. It is

ileocecal junction (Fig. 5.1). The greater part of digestion

canal and extends from the pylorus of the stomach to the

The small intestine is the longest part of the alimentary

the vagi.

from the sympathetic system and inhibitory fibers from

stomach. The pyloric sphincter receives motor fibers

gastric glands and motor to the muscular wall of the

the parasympathetic vagal fibers are secretomotor to the

a proportion of pain-transmitting nerve fibers, whereas

The sympathetic innervation of the stomach carries

(Fig. 5.24).

intestine as far as the splenic flexure and to the pancreas

and superior mesenteric plexuses and is distributed to the

surface of the stomach. A large branch passes to the celiac

then divides into branches that supply mainly the posterior

men on the posterior surface of the esophagus. The trunk

rax mainly from the right vagus nerve, enters the abdo

which is formed in the tho

posterior vagal trunk,

-
-

Small Intestine

Duodenum