Stomach: surgical anatomy

1. Location

• Left upper quadrant → epigastrium, left hypochondrium and umbilical region
• Cardia (gastro-oesophageal junction) → left of T11
• Pylorus → transpyloric plane, lower border of L1
• Abdominal oesophagus → 0.5–2.5 cm long
• Two surgical units:
  • Proximal gastric unit → proximal stomach, distal oesophagus, oesophageal hiatus
  • Distal gastric unit → antrum, pylorus, first 2.5 cm of the duodenum

2. Course and relations

Abdominal oesophagus

• Anterior → posterior surface of the left lobe of the liver
• Posterior → right crus of the diaphragm and aorta
• Right → caudate lobe (segment 1)
• Left → fundus of the stomach

Stomach bed (posterior)

• Lesser sac (omental bursa)
• Left crus of the diaphragm
• Spleen
• Left kidney and left adrenal gland
• Body and tail of the pancreas, with the splenic artery on its upper border
• Transverse mesocolon and splenic flexure

Distal gastric unit

• Posterior:
  • Floor of the lesser sac and transverse mesocolon
  • Head and neck of the pancreas
  • Aorta, coeliac trunk and coeliac plexus
  • Hepatic triad
  • Gastroduodenal artery (GDA)
• Anterior:
  • Anterior abdominal wall
  • Liver segments 4, 5 and 8
  • Neck of the gallbladder, when the stomach is empty

Peritoneal attachments

• Hepatogastric ligament (proximal lesser omentum) → porta hepatis to lesser curvature:
  • Left gastric artery and vein
  • Hepatic division of the anterior vagal trunk
  • Anterior and posterior nerves of Latarjet
  • Lymph nodes
  • Aberrant left hepatic artery → in 23%
• Hepatoduodenal ligament (distal lesser omentum) → liver to first 2.5 cm of the duodenum:
  • Free edge → proper hepatic artery, portal vein, common bile duct (CBD)
  • Anterior boundary of the epiploic foramen (foramen of Winslow)
• Gastrocolic ligament → greater curvature and first part of the duodenum to the transverse colon
• Gastrosplenic ligament → short gastric and left gastroepiploic vessels
• Gastrophrenic ligament:
  • Upper part avascular → finger or Penrose drain passed around the cardia
  • Lower part → short gastric vessels and lymph nodes

3. Parts

1. Cardia → around the gastro-oesophageal junction
2. Fundus → above a horizontal line from the angle of His; contains gas when erect
3. Body → between fundus and antrum; parietal (acid, intrinsic factor) and chief (pepsinogen) cells
4. Pyloric antrum → 7.5 cm; flat mucosa without rugae; G cells (gastrin) and D cells (somatostatin)
5. Pyloric canal → 2.5 cm
6. Pylorus → thickened circular muscle (pyloric sphincter)

Antral boundary

• Externally ill-defined
• Lesser curvature → incisura angularis, inconstant at operation
• Lesser curvature landmark → 3–4 cm proximal to the crow's foot, 8–10 cm from the pylorus
• Line → from 2/5 of the lesser curve to 1/8 of the greater curve (measured from the pylorus)

Pyloroduodenal junction

• Submucosal annular septum → divides pyloric sphincter from the thin duodenal circular muscle
• Prepyloric vein of Mayo → marks the junction on the surface; drains to the right gastric vein
• Brunner's glands → start at the junction, may extend a few cm into the pylorus

Wall

1. Serosa
2. Muscularis → outer longitudinal, middle circular, inner oblique
3. Submucosa → strongest, collagen-rich layer
4. Mucosa

4. Blood supply, venous and lymphatic drainage

• Arteries → all from the coeliac trunk (T12), plus the left inferior phrenic artery
  • Lesser curvature → left and right gastric arteries
  • Greater curvature → left and right gastroepiploic arteries
  • Fundus → short gastric and posterior gastric arteries
• Veins → follow the arteries into the portal system
• Lymph → follows the arteries to the coeliac nodes

5. Clinical significance

• Stomach survives on any single one of its primary arteries
• Extragastric artery ligation → does not control bleeding from a gastric ulcer
• Bare area 1–2 cm wide on the lesser curvature between anterior and posterior left gastric branches
• Aberrant left hepatic artery in the lesser omentum → check before dividing it; may be the only supply to the left lobe
• Antrectomy → resection line set by the antral boundary, not the incisura
• Highly selective vagotomy → crow's foot preserved to keep the antral pump