stomach part 1||Everything of abdomen series||radiology notes

Definition
The stomach is a muscularbagforming the widest and
most distensible part of the digestive tube. It is
connected above to the lower end of the oesophagus,
and below to the duodenum. It acts as a reservoir of
food and helps in digestion of carbohydrates, proteins
and fats.
Locotion
The stomach lies obliquely in the upper and left part of
the abdomen, occupying the epigastric, umbilical and
left hypochondriac regions. Most of it lies under cover
of the left costal margin and the ribs .
Shape ond Position
The shape of the stomach depends upon the degree of
its distension and that of the surrounding viscera, e .g.
the colon. When empty, the stomach is somewhat
J-shaped (vertical) ; when partially distended,
it becomes pyriform in shape. In obese persons, it is
more horizontal. The shape of the stomach can be
studied in the living by radiographic examination after
giving a barium meal .
Size and Capacity
The stomach is a very distensible organ. It is about
25 cm long, and the mean capacity is one ounce (30 ml)
at birth, one litre (1000 ml) at puberty, andlVzto 2 liters
or more in adults.

The stomach has two orifices or openings, two
curvatures or borders, and two surfaces
Two Orifices
The cardiac orifice is joined by the lower end of the
oesophagus. It lies behind the left 7th costal cartilage
2.5 cm from its junction with the sternum, at the level
of vertebra T11. There is physiological evidence of
sphincteric action at this site, but a sphincter cannot be
demonstrated anatomically.
The pyloric orifice opens into the duodenum. In an
empty stomach and in the supine position, it lies 1.2 cm
to the right of median plane, at the level of lower border
of vertebra L1 or transpyloric plane. Its position is
indicated on the surface of the stomach:
a. By a circular groove (pyloric constriction, i.e. sthenic.
Sometime it may be hyposthenic (thin and long)
hypersthenic pylorus) produced by the underlying
pyloric sphincter or pylorus (pylorus = gate guard)
which feels like a large firm nodule
b. By the prepyloric vein which lies in front of the
constriction

Two Curvatures
The lesser curvature is concave and forms the right
border of the stomach. It provides attachment to the
lesser omentum. The most dependent part of the
curvature is marked by the angular notch or incisura
angularis
The greater curvature is convex and forms the left
border of the stomach (see Figs 18.9 and 18.18). It
provides attachment to the greater omentum, the
gastrosplenic ligament and the gastrophrenic ligament.
At its upper end the greater curvature presents the
cardiac notch which separates it from the oesophagus.


Sufaces
The anterior or anterosuperior surface faces forwards and
upwards.
The posterior or posteroinferior surface faces backwards
and downwards.
Parts Subdivided into Four
The stomach is divided into two parts. (i) Cardiac and
(ii) Pyloric, by a line drawn downwards and to the left
from the incisura angularis. The larger, cardiac part is
further subdivided into the fundus and body, and the
smaller, pyloric part is subdivided into the pyloric
antrum and pyloric canal .


Cardiac part
I Thefundus of the stomach is the upper convex dome-
shaped part situated above a horizontal line drawn
at the level of the cardiac orifice. It is commonly
distended with gas which is seen clearly in
radiographic examination under the left dome of the
diaphragm

2 The body of the stomach lies between the fundus and
the pyloric antrum. It can be distended enormously
along the greater curvature. The gastric glands
distributed in the fundus and body of stomach,
contain all three types of secretory cells, namely:
a. The mucous cells.
b. The chief, peptic or zymogenic cells which secrete
the digestive enzymes.
c. The parietal or oxyntic cells which secrete HCl.
Pyloric part
I Thepyloric antrum is separated from the pyloric canal
by an inconstant sulcus, sulcus intermedius present
on the greater curvature. It is about 7.5 cmlong. The
pyloric glands are richest in mucous cells.
2 The pyloric canal is about 2.5 cm long. It is narrow
and tubular. At its right end it terminates at the
pylorus.

Relations of Stomach
Peritonieal relations
The stomach is lined by peritoneum on both its surfaces.
At the lesser curvature the layers of peritoneum lining
the anterior and posterior surfaces meet and become