1. Anatomy of stomach and its relations
By Praveen Panicker

2. STOMACH(ventriculus/gaster)
Most dilated part of GIT
Occupies in the epigastric, umbilical &left hypochondral areas
Occupying a recess bounded by upper abdominal viscera, completed above& anterolateraly by anterior abd wall &diaphragm

3. Parts of stomach

5. Stomach Roughly J Shaped at rest Size and Shape varies with
a) Volume of food or fluid it contains
b) Position of body
c) Phase of respiration
High and transverse in obese and short persons
Elongated in thin persons

6. Mean capacity 30ml at birth 1000ml at puberty 1500ml at adult
2 OPENINGS
2SURFACES
2BORDERS

7. Gastric orifices Cardiac orifices
Situated to the left of midline behind 7th costal cartilage 2.5cm from its sternal junction at the level of T11
10 cm from ant abd wall
40 cm from incisor teeth

8. Pyloric orifice
Can be identified by prepyloric vein crossing its anterior surface vertically
1.2cm to right of midline in trans pyloric plane provided the body is supine & stomach is empty

9. Gastric curvatures Lesser curvature
Extends b/w cardiac & pyloric orifice forming right border
Incisura angularis is a notch in the most dependent part ,its position varies with gastric distension
Gives attachment to lesser omentum

10. Greater curvature 4 to 5 times longer than lesser curvature
Starts at cardiac incisure
Arches upwards & postero laterally & to Lt
Highest convexity is fundus Lt 5th ICS
Finally turns right to end at the pylorus Attachments
Lt of fundus & adjoining body - gastrosplenic lig.
Beyond this - greater omentum

11. Gastric surfaces Antero superior Postero inferior
Antero superior surface
Lt part of this surface is posterior to Lt costal margin & in contact with diaphragm.
It is related to costal attachments of upper fibers of transverse abdominis which separate it from7th to 9th costal margin

12. Whole of the surface is covered by peritoneum.
Upper &Left part of this surface becomes postero lateral & is in contact with spleen’s gastric surface
Rt half of this surface is related to Lt & quadrate lobe of liver & ant abd wall
Whole of the surface is covered by peritoneum.
part of greater sac separate it from above structures

14. Postero inferior surface
Related to STOMACH BED
diaphragm Lt suprarenal gland
upper part of front of left kidney splenic artery
anterior pancreatic surface
colic flexure together with transverse mesocolon

15. This surface is also covered by peritoneum except near the cardiac orifice where a small triangular area contacts diaphragmatic crus

16. INTERIOR OF STOMACH
A large globular Lt part & a narrow tubular Rt part

17. Gastric micro structure
Mucosa
Sub mucosa
Muscularis externa
Serosa
Thick, smooth surface, velvetty
Reddish brown to pink in colour

18. In contracted state mucosa is folded to form RUGAE.
They are Longitudinal & more marked towards pyloric & greater curvature
Actually they are large folds in sub mucosal connective tissue
Obliterated when stomach is distended

19. MUCOSA
Epithelium
Lamina propia
Muscularis mucosa

20. Epithelium
Appears as honey combed due to small gastric pits (foveola). Base of gastric pits (foveola) receives gastric glands which
extend deep into lam propria
Epithelium simple columnar mucous cells

21. Gastric glands cardiac Principal pyloric
Found In body & fundus
Cardiac glands
Situated near the cardia
Pyloric glands
numerous mucous & entero endocrine cells predominate

22. Principal Are made of different types of cells Parietal Mucous Stem
Highly differentiated
Found In body & fundus
Are made of different types of cells
Chief
Parietal
Mucous
Stem
Entero endocrine

23. these cells undergo constant replacement (3 to 7 days)

25. Cardiac glands Situated near the cardia
Mucous secreting cells predominate
Pyloric glands
numerous mucous & entero endocrine cells predominate

26. Lamina propria Found in b/w the glands
Contain gastric follicles which are aggregations of lymphoid tissue
A periglandular
vascular plexus is also present

27. Muscularis mucosa Sub mucosa Inner circular Outer longitudinal
Ext circular in some places
Sub mucosa
Loose connective tissue
Collagen, elastin,sub mucosal plexus of stomach

28. Muscularis externa From within outwards layers are
Oblique fibres
Circular
longitudinal

29. Oblique fibres Circular fibres Limited to gastric body
Most developed near the cardiac orifice
Circular fibres
Form a uniform layer external to oblique fibres
At the pylorus form annular pyloric sphincter

30. Longitudinal fibres Arranged in 2 groups
1st set radiates from cardiac orifice, best developed along the curvatures
2nd set commence in the body, passes to right, some fibres pass to duodenum, deeper fibres interlace with pyloric sphincter
Muscle action upper region of stomach forms an area of storage, lower region has a pump like axn mixing & delivering the contents to duodenum

31. Gastric vessels Left gastric artery Rt gastric artery
Lt & Rt gastro epiploic artery
Short gastric artery

32. These form anastomosis in all layers, forming sub serosal, intramuscular & sub mucosal plexus ;from these anterior & posterior branches arise
Mucosal arteries usually arise from sub mucosal plexus. But along the curvatures they arise directly from sub serosal arteries without anastomosing with other plexus. So that these are more vulnerable to ischemic injury

33. pyloric region is supplied by pyloric arteries (br of rt gastric & gastroepiploic) where they form a submucosal plexus. They also anstomose with Duodenal & gastric arteries
Arterioles from Submucosal arterial plexus penetrate the mucosa & branch to form capillary beds which drain to sub mucosal venous plexus

34. This rich lumen directed blood flow enablesHCO3- generated basally by the parietal cells as a counterpart of their secretion of acid to be carried into apical part in order to protect the cells from acid damage
Fenestrated capillaries also facilitate delivery of HCO3-
In antrum where HCO3- secreting parietal cells are few blood supply is increased in order to facilitate removal of acid

35. Gastric nerves Parasympathetic sympathetic [ vagus]
Anterior br Posterior br
(frm rt vagus) ( frm Lt vagus)

36. Gastric
Anterior nerve
Pyloric
Gastric nerve radiates on anterior surface of body &fundus
One br which is larger near lesser curvature is called greater anterior gastric N (anterior nerve of latarjet)

37. Pyloric br
2 in no: one which traverses the lesser omentum almost horizontally to Rt, then turns down on the left side of hepatic artery to reach pylorus
Other arises from greater anterior gastric nerve & passes obliqly to pylorus

39. Posterior
Gastric coeliac
Gastric
Radiate over the posterior surface of body & fundus upto pyloric antrum
Largest pass along lesser curvature Greater posterior gastric nerve
Coeliac
Pass to coelic plexus

40. Sympathetic supply From Coeliac plexus Hepatic plexus
Lt phrenic plexus
Inconstant brs Lt thorasic nerve, thorasic &
lumbar trunks
Form Sub mucosal plexus of Meissner
Myentric plexus of Auerbach

41. Lymphatics are continous with that of oesophagus & duodenum
Arranged in 4 groups
1st gp accompany Lt gastric artery. Receives a large area on both gastric surface. They end in Lt gastric nodes
2nd gp short gastric & Lt gastro epiploic arteries. Drains Left of the vertical from oesophagus. End in pancreaticosplenicnode

42. 3rd gp drains Rt half of grtr curvature as far as pylorus.
End in Rt gastro epiploic nodes which drain to pyloric nodes
4th gp Pylorus
Drains to hepatic, pyloric & Lt gastric nodes

44. LYMPH NODES ON POTERIOR SURFACE

45. Although these vessels communicate, their valves direct lymph from
Rt part of stomach towards lesser curvature From Lt side to greater curvature

46. Important Lymph node stations-(Japanese)

48. PHYSIOLOGY Parietal cells HCL & IF Chief cells pepsinogen
ECL histamine

49. Gastric secretions Contents 2500 ml/day cations Na,K,Mg,H+
anions Cl,HPO2,so4
pepsin
lipase
Mucus IF

50. MUCOSAL BARRIER Formed by mucous & HCO3-
Mucous made of glycoprotein forms a flexible gel coat
They also protect duodenal mucosa
Their stimulation is augmented by prostaglandin
Trefoid peptides also provide protection

51. HCL SECRETION
H+ -K+ ATPase in the apical membrane of parietal cells pumps H+ against concentration gradient.
When stimulated tubulo vesicular structures inside the parietal cell move to apical membrane & fuse with it thus inserting more H+ -K+ ATPase (which are present in the walls of tubulo vesicular structures )

52. Regulation of acid secretion
H+ -K+ ATPase is activated by
Histamine
Ach secretogouges
Gastrin which act through
their receptors
Histamine play the dominant role
Ach & Gastrin act partly directly & partly indirectly by releasing histamine

54. Regulation of gastric secretion
Cephalic influence
Gastric influence
Intestinal influence

55. Gastric motility & emptying
The pacemaker of gastric muscle action is called gastric pacemaker cells of Cajal situated in the FUNDUS of the stomach
They are located in the outer circular muscle layer near the myentric plexus
They initiate the basic electrical rhythm

56. Gastric motility & emptying
When food enters the stomach fundus & upper part of body relax & accommodate the food called receptive relaxation
This is vagally mediated & triggered by movement of pharynx & oesophagus
Soon after, peristaltic waves settle in distal stomach, mixing & grinding the food permitting semi liquid portion to enter the duodenum

57. The contraction of distal stomach caused by each peristaltic waves is called antral systole & can last upto 10 seconds.
In regulation of gastric emptying antrum, pylorus & upper duodenum act as a single unit.
In antrum partial contraction ahead of advancing gastric contents prevent solid masses from entering duodenum

58. Regurgitation from duodenum will not occur because contraction of pyloric segment tends to persist longer than that of duodenum
Hunger contractions
Gastric contractions in b/w meals sometimes be felt, sometimes mildly painful

59. Rate at which stomach empties into duodenum depends on
Type of food
Oncotic pressure of food
food rich in carbohydrate leaves the stomach in few hrs, protien rich food leaves more slowly, slowest for fat.
Hyperosmolarity of duodenal contents
gastric emptying

60. Thank you