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Development of stomach, Rotations, Abnormal rotations leading to volvulus
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EMBRYOLOGY, BLOOD SUPPLY AND RELATED SURGICAL ANATOMY
OF STOMACH (Ventriculus, Gaster)
Dr. MVR SarmaDept. of Anatomy
GSL Medical CollegeRajahmundry
Stomach – organ of 2nd phase of digestion
The stomach is a muscular, hollow, dilated part of the digestion system, which functions as an important organ of the digestive tract.
It is involved in the second phase of digestion, following mastication (chewing).
The stomach is located between the esophagus and the small intestine.
Stomach – Embryonic foldings
The trilaminar embryonic plate undergoes four foldings to produce the ultimate three dimensional embryo.
Stomach – Formation of primitive gut
During the cephalocaudal and lateral folding of embryo, a portion of the endoderm lined yolk sac is incorporated into the embryo to form the primitive gut.
ForegutMidgut
Hindgut
Subdivisions ofprimitive gut
Foregut Midgut Hindgut
Embryonic extension of GIT
2 – 3 weeks (IUL)
The gastrointestinal tract (GIT) extending from the
Buccopharyngeal membrane to the Cloacal membrane
arises initially from the endoderm of the trilaminar embryo.
It later has contributions from all the germ cell layers.
Stomodeum
Cloacal membrane
Septumtransversum
Foregut
Midgut
Hindgut
Divisions of foregut : Derivatives of foregut
Larygo-tracheal groove
Pre laryngeal (Cephalic part)
Post laryngeal (Caudal part)
Foregut
OesophagusStomach
Duodenal segmentOff shoots – liver
(biliary apparatus) & Pancreas
Development of stomach
The stomach appears as a dilation of the foregut caudal to the esophagus during the fourth week of development.
Stomach
Oesophagus
Intestines
Buccopharyeal membrane
Cloacal membrane
Ventral(Anterior)
Dorsal(Posterior)
RL
Position adjustment of stomach
Descent-Due to rapid elongation of the esophagus,
the cardiac end of the stomach descends from C2 at 4 weeks to T11 at 12 weeks As stomach enlarges, it slowly rotates through 90 degrees,
Axes of stomach
The stomach evolves by two rotations along a 1. Longitudinal and
02. Anteroposterior axis.
Longitudinal axis
Anteroposterioraxis
1st Rotation – on longitudinal axis
The longitudinal rotation of the stomach involves a 90° clockwise rotation resulting in the right side of the stomach becoming posteriorly oriented and the left side of the stomach facing anteriorly.
Change of position of vagii
This explains why the left vagus nerve innervates the anterior wall of the stomach and the right vagus nerve innervates the posterior wall of the stomach in the adult.
2nd Rotation – positioning of fundus & duodenum
The stomach subsequently rocks on its longitudinal axis, causing the pylorus to shift to right and the cardiac orifice to shift to the left.
Positioning of stomach
• Initially the two ends of the stomach lie in the midline.
• During rotation:– the cranial end moves to
the left and slightly downward.
– the caudal end moves to the right and upward.
• After rotation, stomach assumes its final
position with its long axis running from above left to below right.
Formation of curvatures – during Rotation
During this rotation one side of the stomach grows faster than the other forming the greater and lesser curvatures of the stomach
Oesophagus
Intestines
Stomach
Less
er c
urva
ture
Gre
ater
cur
vatu
re
Mesenteries – Development of omentumDevelopment of omentum
• Ventral border of stomach – connected with anterior body wall by ventral mesogastrium
• Dorsal border of stomach - connected with posterior abdominal wall by dorsal mesogastrium.
Dorsal mesogastrium
Ventralmesogastrium
Mesenteries – Development of omentum
Hepatic bud divides ventral mesogastrium into
1) Lesser omentum 2) Falciform & coronary ligament.Developing spleen divides the
dorsal mesogastrium into 1) Gastro-splenic ligament 2) Lieno-renal ligament .
Lienorenal Ligament
GastrosplenicLigament
Lesseromentum
FalciformLigament
Omental bursa – Lesser sac
Begins as small isolated clefts in the dorsal mesogastrium, that soon join to form a single cavity
Rotation of stomach pulls the dorsal mesogastrium to the left thus enlarging the cavity
The bursa expands transversely and cranially and lies between the stomach and the posterior abdominal wall
Omental bursa – Lesser sac
The superior part of the bursa is cut off as the diaphragm develops. Inferiorly it persists as the superior recess of the omental bursa
The inferior part grows Within the 4-layered greater omentum forming the inferior recess of the omental bursa.
The inferior recess later on closes down because of fusion of the layers of the greater omentum.
Stomach - Arterial supply
Factors demanding rich vascularity:
1. Highly distensible & mobile area in GI Tract (Frequent changes in volume)2. Five types of cells – High metabolic activity3. 2nd phase of digestion – Brisk peristalsis4. Three layers of sheets of muscles.5. Propulsive pressures against pyloric sphincter and physiological oesophageal sphincter.
Coeliac trunk : Direct anterior branch from aorta is main source of arterial supply.
Stomach - Blood supply
Arterial arcade
Subserosal plexus
Intramuscular plexus
Sub mucosal plexus
Mucosal plexus
Mucosal capillaries
Along the lesser and the greater curvature of stomach
Patch of mucosa is prone to vascular
obstruction
They do not anastomose with each other
Stomach – Venous drainage
Parts of stomach
Anterior relation of Stomach
Stomach bed
Structures & factors maintaining Intra abdominal position of stomach
1.Oesophagus2.Duodenum3.Lesser omentum4.Phrenico colic lig.5.Gastro splenic lig.6.Blood vessels – Coeliac trunk7.Veins, Lymphatics & Nerves8.Structures forming stomach bed9.Liver, spleen and diaphragm 10.anterior and lateral abd. Wall11.Intra abdominal pressure.
Omenta & ligaments of stomach
Anomalies of Stomach
01. Malrotation of stomach
02. Changes in shapes of stomach
03. Variation of origin of blood vessels
04. Congenital hypertrophic pyloric stenosis
Some of the recorded variations Gastroduodenal artery
Some of the recorded variationsCoeliac trunk
Malrotation of Stomach - Volvulus
Gastric volvulus or volvulus of stomach a twisting of all or part of the stomach by more than 180 degrees with obstruction of the flow of material through the stomach, variable loss of blood supply and possible tissue death.
The twisting can occur around the long axis of the stomach
- organoaxial or
around the axis perpendicular to this
- mesentericoaxial.
About one third of volvulus cases are associated with hiatus hernia.
Malrotation of Stomach - Volvulus
Gastric volvulus is a rare but potentially life-threatening clinical entity due to possible gastric necrosis.
A wandering spleen may also be associated with gastric volvulus.
Clinical features - Volvulus
Borchardts triad: 1. Severe epigastric pain
02. Vomiting followed by violent retching with inability to vomit
03. Inability to pass NGT
Volvulus - Organoaxial
The stomach rotates around an axis that connects the Gastro-esophageal junction and the pylorus.
Antrum rotates in opposite direction to the fundus of stomach
Comprises 59% of cases of gastric volvulus.
Obstruction is common in organoaxial volvulus
Short axis
Antrum
Volvulus - Mesentericoaxial
The axis bisects the lesser and greater curvatures.
The antrum rotates anteriorly and superiorly so that the posterior surface of the stomach lies anteriorly
Comprises 29% of cases of gastric volvulus.
Ischaemia is common in mesentericoaxial volvulus.
Greatercurvature
Long axisLessercurvature
Volvulus – Combined rotation
A
A
AB
B
B
Department of AnatomyGSL Medical College
Rajahmundry