Quick Jump to Sections
Section A
Location & Position
Exact Location
- Position: Intraperitoneal organ, in the epigastric, umbilical, and left hypochondriac regions
- Vertebral level: Extends from T10 (cardiac orifice) to L1 (pyloric orifice)
- Cardiac orifice (inlet): Left of T10 vertebra, behind 7th costal cartilage
- Pyloric orifice (outlet): Transpyloric plane (L1), right of midline
- Shape: J-shaped when upright; varies with posture, respiration and content
- Size: ~25–30 cm long; 10–15 cm wide when full
Relations
Anterior Relations
- Left lobe of liver (upper part)
- Anterior abdominal wall (lower part)
- Diaphragm (upper left area)
Posterior Relations (Stomach Bed)
- Diaphragm (left crus)
- Spleen (left)
- Left suprarenal gland
- Upper left kidney
- Splenic artery & body of pancreas
- Transverse mesocolon
Peritoneal Folds
- Lesser omentum: connects lesser curvature to liver
- Greater omentum: hangs from greater curvature
- Gastrosplenic ligament: connects to spleen
- Gastrophrenic ligament: connects to diaphragm
Section B
Parts of the Stomach
Cardia
Inlet Zone- Surrounds the cardiac orifice (gastroesophageal junction)
- At level of T10 vertebra
- Lower oesophageal sphincter (LES) prevents reflux
- Mucosa transitions from stratified squamous to columnar epithelium
- No true anatomical sphincter — physiological only
Fundus
Superior Dome- Dome-shaped, lies above and left of cardia
- Contains swallowed air (gas bubble visible on X-ray)
- Related to left dome of diaphragm and spleen
- Rich in parietal (oxyntic) cells — produces HCl
- Gastric rugae most prominent here
Body (Corpus)
Main Region- Largest part of the stomach
- Between fundus and pyloric antrum
- Contains parietal cells (HCl, intrinsic factor)
- Contains chief cells (pepsinogen)
- Main site of mechanical churning and mixing
- G cells secrete gastrin in pyloric region
Pyloric Part
Outlet- Divided into pyloric antrum and pyloric canal
- Pyloric canal: ~2.5 cm long, leads to pyloric orifice
- Pyloric sphincter: smooth muscle ring, controls gastric emptying
- Transpyloric plane (L1) — important landmark
- G cells produce gastrin in antrum
- Congenital hypertrophic pyloric stenosis occurs here
Stomach Characteristics
Length
25–30 cm
When moderately full
Capacity
1–1.5 L
Adults (up to 4L max)
Gastric pH
1.5–3.5
Highly acidic
Emptying
4–5 hrs
Mixed meal
Weight
~150 g
Empty stomach
Muscle Layers
3 Layers
Unique to stomach
Section C
Curvatures & Orifices
Lesser Curvature
- Length: ~10 cm — shorter, concave right border
- Angular notch (incisura angularis): Marks junction of body and pyloric antrum — important landmark
- Attached: Lesser omentum (hepatogastric ligament)
- Blood supply: Right and left gastric arteries run along it
- Gastric canal (Magenstrasse): Longitudinal mucosal fold along lesser curvature — channels fluids quickly to pylorus
NEET Alert: Incisura angularis is the site most commonly affected by peptic ulcers on the lesser curvature.
Greater Curvature
- Length: ~40 cm — longer, convex left border
- Attachments: Greater omentum, gastrosplenic ligament, gastrophrenic ligament
- Blood supply: Right and left gastroepiploic arteries
- Short gastric arteries: Supply the fundus along greater curvature
Orifices
Cardiac Orifice (Inlet)
- Gastroesophageal junction
- Level: T10 vertebra
- No true anatomical sphincter
- Angle of His prevents reflux
- LES is physiological mechanism
Pyloric Orifice (Outlet)
- Opens into 1st part of duodenum
- Level: L1 (transpyloric plane)
- True anatomical sphincter present
- Thickened circular muscle
- Palpable as firm mass in pyloric stenosis
Section D
Wall Layers & Histology
Gastric Wall — 4 Coats
The stomach wall has the standard GIT structure PLUS an additional oblique muscle layer — unique to stomach.
1
Mucosa
Simple columnar epithelium. Contains gastric pits, glands (fundic, pyloric, cardiac). Has rugae (folds) when empty.
2
Submucosa
Dense connective tissue. Contains Meissner's plexus, blood vessels, lymphatics. No glands (unlike duodenum).
3
Muscularis Externa
3 layers — outer longitudinal, middle circular (thickened at pylorus), inner oblique (unique to stomach). Auerbach's plexus between layers.
4
Serosa (Peritoneum)
Visceral peritoneum covering entire stomach. Continuous with lesser and greater omentum.
Key Fact: Stomach is the only GIT organ with 3 muscular layers — outer longitudinal, middle circular, inner oblique. This enables churning (peristalsis + retropulsion).
Gastric Cells & Secretions
| Cell Type | Location | Secretion | Function |
|---|---|---|---|
| Parietal (Oxyntic) | Fundus & body | HCl, Intrinsic factor | Acid digestion; B12 absorption |
| Chief (Zymogenic) | Fundus & body | Pepsinogen, Gastric lipase | Protein & fat digestion |
| G cells | Pyloric antrum | Gastrin | Stimulates HCl secretion |
| Mucous neck cells | Gland necks | Mucus, HCO₃⁻ | Protects gastric mucosa |
| D cells | Antrum | Somatostatin | Inhibits gastrin & HCl |
| ECL cells | Fundus | Histamine | Stimulates parietal cells |
Section E
Blood Supply
Arterial Supply — Coeliac Trunk Branches
The stomach has the richest blood supply of any abdominal organ — from all 3 branches of the coeliac trunk.
| Artery | Origin | Supply Area |
|---|---|---|
| Left gastric a. | Coeliac trunk (directly) | Lesser curvature (left part), lower oesophagus |
| Right gastric a. | Hepatic artery proper | Lesser curvature (right part) |
| Left gastroepiploic a. | Splenic artery | Greater curvature (left part) |
| Right gastroepiploic a. | Gastroduodenal artery | Greater curvature (right part) |
| Short gastric aa. (5–7) | Splenic artery | Fundus of stomach |
Mnemonic: "Left Right Left Right Short" — along lesser curvature: Left gastric + Right gastric; along greater curvature: Left gastroepiploic + Right gastroepiploic; fundus: Short gastric.
Venous Drainage
- Left gastric vein (coronary vein): Drains to portal vein — important in portal hypertension (oesophageal varices)
- Right gastric vein: Drains to portal vein
- Left gastroepiploic vein: Drains to splenic vein
- Right gastroepiploic vein: Drains to superior mesenteric vein
- Short gastric veins: Drain to splenic vein
- All ultimately drain to portal vein → liver
Lymphatic Drainage
- Lesser curvature: → Left gastric nodes → coeliac nodes
- Upper right (pyloric area): → Hepatic nodes → coeliac nodes
- Greater curvature (left): → Pancreaticosplenic nodes → coeliac nodes
- Greater curvature (right): → Subpyloric/right gastroepiploic nodes → coeliac nodes
- All ultimately drain to coeliac lymph nodes then thoracic duct
- Virchow's node (Troisier's sign): Left supraclavicular node — enlarges in gastric carcinoma
Section F
Nerve Supply
Autonomic Innervation
Parasympathetic (Vagus — CN X)
- Left vagus → anterior gastric nerve (cephalic phase of gastric secretion)
- Right vagus → posterior gastric nerve
- Stimulates: HCl secretion, gastric motility, gastrin release
- Auerbach's & Meissner's plexuses relay signals
- Vagotomy → reduces acid secretion (treatment for PUD)
Sympathetic
- T6–T9 spinal segments
- Via coeliac plexus and coeliac ganglia
- Reduces gastric motility and secretion
- Vasoconstriction of gastric vessels
- Pain sensation via sympathetic afferents (referred to epigastrium)
Section G
Functions of the Stomach
Major Functions
Storage
- Accommodates 1–1.5L of food
- Receptive relaxation (vagal reflex)
- Slows entry into duodenum
- Allows enzymatic digestion time
Mechanical Digestion
- Churning via 3 muscle layers
- Mixes food with gastric juice → chyme
- Peristaltic waves: 3/minute
- Retropulsion back through body
Chemical Digestion
- HCl: denatures proteins, kills bacteria, activates pepsin
- Pepsin: begins protein digestion
- Gastric lipase: limited fat digestion
- Intrinsic factor: essential for B12 absorption (ileum)
Hormonal
- Gastrin (G cells): stimulates HCl, motility
- Somatostatin (D cells): inhibits gastrin
- Ghrelin: hunger hormone (fundus)
- Histamine: stimulates parietal cells
Phases of Gastric Secretion
| Phase | Stimulus | Mechanism | % of Total HCl |
|---|---|---|---|
| Cephalic | Sight, smell, thought of food | Vagus nerve → ACh → parietal cells | ~30% |
| Gastric | Food in stomach (distension, peptides) | Local reflexes + gastrin → HCl | ~60% |
| Intestinal | Chyme in duodenum | Secretin, CCK inhibit; initial gastrin stimulates | ~10% |
Section H
Clinical Anatomy
Important Clinical Conditions
- Peptic Ulcer Disease (PUD): Most common at lesser curvature (incisura angularis) and posterior wall of duodenum. H. pylori infection + NSAIDs are main causes. Posterior gastric ulcer may erode gastroduodenal artery → massive haemorrhage; or pancreas → referred back pain.
- Gastric Carcinoma: Most common in pyloric antrum. Spreads to Virchow's node (left supraclavicular). Krukenberg tumour = ovarian metastasis. Blumer's shelf = rectal metastasis. Linitis plastica = diffuse infiltration → "leather bottle" stomach.
- Congenital Hypertrophic Pyloric Stenosis: Hypertrophy of pyloric circular muscle → projectile non-bilious vomiting at 3–6 weeks of age. Palpable "olive-shaped" mass in RUQ. Treated by Ramstedt's pyloromyotomy.
- Hiatus Hernia: Stomach herniates through oesophageal hiatus. Sliding type (90%) — gastroesophageal junction moves up; Rolling/paraesophageal type (10%) — fundus herniates alongside oesophagus. Presents with GORD, dysphagia.
- GORD (Gastro-Oesophageal Reflux Disease): Failure of lower oesophageal sphincter mechanism. Leads to Barrett's oesophagus (columnar metaplasia) → risk of oesophageal adenocarcinoma.
- Zollinger-Ellison Syndrome: Gastrin-secreting tumour (gastrinoma) of pancreas/duodenum. Causes severe peptic ulcers, diarrhoea. Elevated fasting gastrin levels confirm diagnosis.
- Volvulus of Stomach: Rotation along long or short axis. Organoaxial (common) — along pylorus-cardia axis. Presents with Borchardt's triad: epigastric pain, retching without vomit, NGT cannot be passed.
Surgical Anatomy Points
- Highly Selective Vagotomy (HSV): Preserves nerve of Latarjet (to pylorus) — no drainage procedure needed
- Truncal Vagotomy: Requires drainage procedure (pyloroplasty/gastrojejunostomy) as it causes pyloric spasm
- Billroth I (Gastroduodenostomy): Partial gastrectomy + anastomosis to duodenum
- Billroth II (Gastrojejunostomy): Duodenal stump closed; anastomosis to jejunum
- Gastrectomy lymph node levels: D1 (perigastric nodes), D2 (coeliac axis nodes) — D2 is gold standard for gastric cancer
Section I
NEET High-Yield Points
Must-Know for Exams
- Stomach bed structures: Diaphragm, spleen, left kidney, left suprarenal, splenic artery, pancreas, transverse mesocolon — 7 structures
- Only GIT organ with 3 muscle layers — outer longitudinal, middle circular, inner oblique
- Intrinsic factor is produced by parietal cells — deficiency → pernicious anaemia (B12 deficiency)
- Pyloric stenosis → projectile non-bilious vomiting (bile enters distal to pylorus)
- Virchow's node = left supraclavicular node, enlarged in gastric carcinoma (Troisier's sign)
- Left gastric artery is the most common origin of replaced/accessory left hepatic artery
- Angle of His (~45°) between oesophagus and fundus — acts as flutter valve against reflux
- Gastric canal (Magenstrasse) along lesser curvature — channels fluids rapidly to duodenum
- Incisura angularis = most common site of gastric ulcer on lesser curvature
- Ghrelin (hunger hormone) produced mainly by fundus of stomach
- Blood supply memory: Stomach is supplied by ALL branches of coeliac trunk (direct/indirect)
- Portal hypertension: Left gastric (coronary) vein connects portal to systemic → oesophageal varices
Memory Tricks
Stomach Bed — "DeSKLiSPaT"
- Diaphragm
- Spleen
- Kidney (left)
- Left suprarenal
- Splenic artery
- Pancreas
- Transverse mesocolon
Pyloric Stenosis Triad
3 Ps: Projectile non-bilious vomiting + Palpable olive mass + Peristaltic visible waves. Age: 3–6 weeks. Boys > Girls (4:1).
Gastric Cell Secretions
Parietal = HCl + IF (both "P"rocesses for digestion and B12); Chief = pepsinogen (C for Churning protein); G cell = Gastrin (G-G).