The stomach

Where is the stomach?

The stomach is a J-shaped organ in the upper left side of your abdomen, just under your ribs. The top lies behind your left ribs, and the bottom sits above your belly button. When empty, it’s about the size of your fist, but it stretches to hold up to two litres of food and liquid.

The stomach joins the oesophagus (food pipe) at the top and the duodenum, the first part of the small intestine, at the bottom. It’s the widest part of your digestive tract, the tube that runs from your mouth to your anus.

The peritoneum surrounds the stomach. It is a thin, protective sac that holds many other organs, including the liver, spleen, pancreas, and intestines.

Areas of the stomach

If you’re diagnosed with stomach cancer, it helps to know the names of the stomach’s areas. These terms often appear in scan results or operation notes, and the cancer’s location can sometimes influence treatment decisions.

There are five regions of the stomach, plus the gastro-oesophageal junction (GOJ).

Gastro-Oesophageal Junction (GOJ)

The gastro-oesophageal junction (GOJ), also called the lower oesophageal sphincter, is the ring of muscle where the oesophagus (food pipe) meets the stomach. It opens to let food in and closes to stop it from flowing back upwards. Cancers here were managed like oesophageal cancers. Recent evidence (such as the ESOPEC trial) means many specialist centres now consider whether a stomach cancer pathway is more appropriate for some people.

Cardia

The cardia is a small area, just a few centimetres below the GOJ. It helps stop food and acid from moving back up into the oesophagus, reducing reflux. The cardia is within the actual stomach, but tumours here are sometimes classified as gastro-oesophageal junction cancer.

Fundus

The fundus is the dome-shaped top of the stomach, tucked under the diaphragm. It holds small amounts of swallowed air and gas released during digestion and provides extra space after meals. Cells here make ghrelin, the hormone that triggers hunger.

Body (Corpus)

The body, or corpus, is the largest area of the stomach. Its folded inner lining expands as the stomach fills. Specialised cells here make stomach acid, digestive enzymes, and Intrinsic Factor, which helps absorb vitamin B12. Muscular contractions in this area churn food into chyme before it moves to the antrum.

Antrum

The antrum is the funnel-shaped lower part of the stomach. It holds food and churns it into chyme until it is ready to pass into the intestines. Cancers can develop in any part of the stomach, but the antrum is one of the more common sites. In scan or surgery reports, it may be described as the distal or antral region.

Pylorus

The pylorus is the narrow lower end of the stomach. At the bottom of the pylorus is a ring of strong muscles, the pyloric sphincter, which lets chyme out of the stomach into the intestines. The pylorus is very narrow, so even minor swelling or a tumour here can make it harder for food to pass through. Reports may refer to this area as the gastric outlet.

The stomach wall

The stomach wall has five main layers. Knowing the layers can help you understand your T stage, which describes how deep the tumour has grown through the layers of the stomach.

• The mucosa is the inner lining that makes acid, enzymes, and protective mucus. Most stomach cancers start here.
• The submucosa lies underneath and contains blood vessels, nerves, and connective tissue.
• The muscularis propria is the thick muscle layer that contracts to churn food.
• The subserosa is a thin layer of supportive tissue just before the outer lining of the stomach.
• The serosa is the tough outer covering that anchors the stomach to the peritoneum.

The lymph nodes nearest the stomach sit just outside the serosa. They are often the first place cancer cells spreads. The number of affected nodes found determines the N stage of stomach cancer.