Stomach
The stomach lies between the esophagus and duodenum and it&#39;s one of the most important parts of the digestive system. Learn the stomach anatomy at Kenhub!
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Location

The stomach is the most dilated part of the digestive system, lying between the esophagus and duodenum. More precisely, the stomach spans the region between the cardiac and pyloric orifices of the gastrointestinal tract. It is covered and connected to other organs by peritoneum. The lesser omentum connects the stomach to the liver and then extends around the stomach. The greater omentum then continues inferiorly from the stomach, hanging from it like a curtain.The peritoneum has a convoluted course that requires visualization for a complete understanding, so study the following resources to avoid taking a wrong turn. They trace the trajectory of the peritoneum and provide you with an overview of the entire digestive system, including labeling worksheets and a study unit:

The stomach is located inside the abdominal cavity in a small area called the bed of the stomach, onto which the stomach lies when the body is in a supine position, or lying face up. It spans several regions of the abdomen, including the epigastric, umbilical, left hypochondriac, and left flank regions. The stomach also has some precise anatomical relations and comes in contact with several neighboring structures.

Anatomical relations of the stomach Anteriorly Diaphragm, liver (left lobe), and anterior abdominal wall Posteriorly Omental bursa (lesser sac), pancreas, left kidney and adrenal gland, spleen, and splenic artery Superiorly Esophagus and diaphragm Inferiorly and laterally Transverse mesocolon

Parts

The stomach consists of several important anatomical parts. The four main sections of the stomach are the cardia, fundus, body, and pyloric part. As the name implies, the cardia surrounds the cardiac orifice, which is the opening between the esophagus and the stomach. It is the first section that ingested food passes through, representing the inflow part. The fundus is the superior dilation of the stomach, which is located superiorly relative to the horizontal plane of the cardiac orifice.

Next, we have the corpus, or gastric body, which is the largest part of the organ. Finally, the pyloric part represents the outflow section of the stomach, passing stomach contents into the duodenum. The pylorus is further divided into two distinct areas – the pyloric antrum connected to the stomach and the pyloric canal connected to the duodenum. The contents of the pyloric canal enter into the duodenum via the pyloric orifice, the opening and closing of which are controlled by the pyloric sphincter (pylorus), a circular layer of smooth muscle.

As you might notice in the stomach diagram illustrated above, the organ has a characteristic J-shape created by two unequal curvatures. The longer and convex curvature located on the left of the stomach is called the greater curvature, this starts from the cardiac notch that is formed between the esophageal border and fundus. In contrast, the shorter concave curvature found to the right is the lesser curvature. The latter contains a small notch called the angular incisure which marks the line of intersection between the body and pyloric part of the stomach.

Mnemonic

You might be wondering if there's an easy way to remember the parts of the stomach. Of course there is and we're about to tell you! Just remember the phrase ' Cows Find Bulls Passionate', which stands for:

Cardium

Fundus

Body

Pylorus

Now to cement your newly acquired knowledge about the parts of the stomach take a look at the following study quiz!

Function

The main function of the stomach involves mechanical and chemical digestion of ingested food. Ingested food enters the stomach from the esophagus via the cardiac orifice, falling into gastric juice produced by the stomach. Repetitive muscle contractions physically churn food particles, breaking them into smaller fragments which are mixed with the gastric juice. The various enzymes and hydrochloric acid (pH 1-2) in the gastric juice break food down even more, forming a semi-liquid substance called chyme. This ultimately passes into the duodenum through the pyloric orifice by a process called gastric peristalsis. Being a muscular organ, the stomach can distend quite a lot, accumulating anywhere between 2 and 3 liters of food.

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In addition to digestion, this organ is also involved in a small degree of absorption. Specifically, it can absorb water, caffeine, and a small proportion of ingested ethanol. The stomach also plays a role in controlling secretion and motility within the digestive tract by releasing several hormones such as gastrin, cholecystokinin, secretin, and gastric inhibitory peptide.

Hiatal hernia

A hiatal hernia is a protrusion of part of the stomach into the mediastinum through the esophageal hiatus of the diaphragm. Any gastric part can be involved, but the most common situation is a protrusion of the gastroesophageal junction (sliding hiatal hernia), accounting for 95% of cases. The fundus of the stomach (paraesophageal hiatal hernia), multiple parts, or even the entire organ can herniate into the mediastinum, making the pathology quite varied.

There are several causes of hiatal hernias, such as trauma, congenital malformations, and previous surgery. Perhaps the most common, however, is advanced age which results in weakening of the diaphragm and widening of the esophageal hiatus, facilitating protrusions.

Patients suffering from hiatal hernias are mostly asymptomatic but can complain of non-specific symptoms like heartburn (pyrosis), regurgitation, dysphagia, epigastric discomfort, postprandial fullness, and nausea. Due to their asymptomatic nature, hiatal hernias are mostly diagnosed incidentally during upper endoscopy or imaging performed for other specific reasons.

Asymptomatic hiatal hernias are treated conservatively, managing the symptoms of gastroesophageal reflux disease for instance. Symptomatic hernias, however, require surgical intervention.