stomach anatomy and histology gastric

1. By
Dr Mohanad
Stomach

2. The stomach

 The stomach is a dilated
part of the alimentary
canal between the
esophagus and the small
intestine.
 It is a muscular sac.
 It is a J-shaped.

3. The stomach

 It occupies the left upper
quadrant, epigastric, and
umbilical regions, and
much of it lies under cover
of the ribs.
 Stomach located at level
of T10 and L3 vertebral.
 Position of the stomach
varies with body
habitués.

4. 
The stomach is divided into four
regions:
1. The cardia, which surrounds the
opening of the esophagus into the
stomach.
2. The fundus of stomach, which is
the area above the level of the
cardial orifice.
3. The body of stomach, which is the
largest region of the stomach.
4. The pyloric part, which is divided
into the pyloric antrum and pyloric
canal and is the distal end of the
stomach.
The stomach

5. The Stomach

6. The stomach

 Openings:
Gastroesophageal:
To esophagus
Pyloric: To
duodenum

7. The stomach

Sphincters
 The cardiac sphincter
(lower esophagus
sphincter) closes off the
top end of the stomach.
 The pyloric sphincter
closes off the bottom.

8. The stomach

Other features of the
stomach include:
 The greater curvature,
which is a point of
attachment for the
gastrosplenic ligament and
the greater omentum
 The lesser curvature,
which is a point of
attachment for the lesser
omentum.

9. 
The stomach
Read about:
 Lesser omentum
 Greater omentum
 Layers of peritoneum
attached to the
stomach:
 Lesser omentum:
attaches the liver to
the lesser curvature.
 Greater omentum:
attaches the greater
curvature to the
posterior body wall.

12. 
Arterial blood supply:
3 Branches
Left Gastric Artery
Supplies the cardia of the stomach and distal esophagus
Splenic Artery
Gives rise to 2 branches which help supply the greater curvature of
the stomach
Left Gastroepiploic
Short GastricArteries
Common Hepatic or Proper Hepatic Artery
2 major branches
Right Gastric- supples a portion of the lesser curvature
Gastroduodenal artery
-helps supply greater curvature in conjunction with Left
Gastroepiploic Artery
Stomach Blood Supply

13. 
Stomach Blood Supply

14. 
Stomach Venous Drainage

15. 
Stomach Lymphatic Drainage

16. The main innervations are Left and Right Vagus Nerves.
Stomach Innervations


17. Stomach Innervations
 Parasympathetic innervation of
Stomach- Vagus Nerve
 90% of fiber in vagal trunk
is afferent (info transmitting
from stomach to CNS).
 Sympathetic innervation of
Stomach- Splanchnic Nerve
 Derived from spinal
segement T5-T10

18. Stomach Microscopic Anatomy
Four layers of stomach
wall
 Mucosa
 Submucos
 Muscle
 Serosa

19. 
Stomach Microscopic Anatomy

20. Stomach Microscopic Anatomy

Mucosa:
 The first main layer.
 It consists of an epithelium.
 Lined by simple columnar
epithelium
 The lamina propria
composed of loose
connective tissue
 It has gastric glands in it
underneath, and a thin layer of
smooth muscle called the
muscularis mucosae.

21. Stomach Microscopic Anatomy
Mucosa:
 This luminal surface is
interrupted at intervals by
gastric pits.
 Gastric pits formed by
folded mucosa.
 Opening into these gastric
pits are one or more gastric
glands that have functional
significance.


22. 
Stomach Microscopic Anatomy
Mucosa:
 Four major types of secretory
epithelial cells cover the surface
of the stomach and extend down
into gastric pits and glands:
 Mucous cells: secrete an alkaline
mucus that protects the
epithelium against shear stress
and acid
 Parietal cells: secrete hydrochloric
acid
 Chief cells: secrete
pepsinogen, a proteolytic
enzyme
 G cells: secrete the hormone
gastrin

23. Stomach Microscopic Anatomy

Mucosa:
 Mucous cells
 Parietal cells
 Chief cells
 G cells

24. Stomach Microscopic Anatomy

Submucosa:
o This layer lies over
the mucosa.
o It consists of fibrous
connective tissue,
separating the
mucosa from the next
layer.
o The Meissner's
plexus is in this layer.

25. Stomach Microscopic Anatomy
 Muscularis Externa:
 The muscularis externa
in the stomach differs
from that of other GI
organs in that it has
three layers of smooth
muscle instead of two

26. Stomach Microscopic Anatomy

Muscularis Externa:
 Inner Oblique Layer
 Middle Circular
Layer
 Outer Longitudinal
Layer

27. Stomach Microscopic Anatomy
 Serosa:
 This layer is over the muscularis
externa, consisting of layers of
connective tissue continuous with
the peritoneum.

28. 
Stomach Microscopic Anatomy

29. THE MUCOSAL BARRIER
 The mucosa of the stomach is exposed to the highly corrosive acidity of
gastric juice. Gastric enzymes that can digest protein can also digest the
stomach itself. The stomach is protected from self-digestion by
the mucosal barrier.
 This barrier has several components. First, the stomach wall is covered
by a thick coating of bicarbonate-rich mucus.
 This mucus forms a physical barrier, and its bicarbonate ions neutralize
acid. Second, the epithelial cells of the stomach’s mucosa meet at tight
junctions, which block gastric juice from penetrating the underlying
tissue layers.
 Finally, stem cells located where gastric glands join the gastric pits
quickly replace damaged epithelial mucosal cells, when the epithelial
cells are shed. In fact, the surface epithelium of the stomach is
completely replaced every 3 to 6 days.