The stomach is an intraperitoneal digestive organ located between the oesophagus and the duodenum. It has a ‘J’ shape, and features a lesser and greater curvature, with the anterior and posterior surfaces being smoothly rounded with a peritoneal covering.
In this article, we shall look at the anatomy of the stomach – its position, structure and neurovascular supply.
The stomach lies within the superior aspect of the abdomen. It primarily lies in the epigastric and umbilical regions, however, the exact size, shape and position of the stomach can vary from person to person and with position and respiration.
The stomach has four main anatomical divisions; the cardia, fundus, body and pylorus:
The medial and lateral borders of the stomach are curved, forming the lesser and greater curvatures:
The anatomical relations of the stomach are given in the table below:
There are two sphincters of the stomach, located at each orifice. They control the passage of material entering and exiting the stomach.
Emptying of the stomach occurs intermittently when intragastric pressure overcomes the resistance of the pylorus. The pylorus is normally contracted so that the orifice is small and food can stay in the stomach for a suitable period. Gastric peristalsis pushes the chyme through the pyloric canal into the duodenum for further digestion.
Within the abdominal cavity, a double layered membrane called the peritoneum supports most of the abdominal viscera and assists with their attachment to the abdominal wall. The greater and lesser omenta are two structures that consist of peritoneum folded over itself (two layers of peritoneum – four membrane layers). Both omenta attach to the stomach, and are useful anatomical landmarks:
The structures of the abdominal cavity have complex, intricate connections and relationships with one another, making them vital to the digestive process. Understanding the anatomy of the stomach is essential for proper diagnosis and treatment of digestive conditions. With this knowledge, healthcare professionals can identify potential problems and intervene as necessary.
The stomach is an intraperitoneal digestive organ located between the oesophagus and the duodenum, and has been described to have a ‘J’ shape, with both a lesser and greater curvature along its anterior and posterior surfaces, that are covered by a peritoneal lining. This article will explore the anatomy of the stomach, its position, structure and neurovascular supply.
In the abdomen, the stomach primarily lies in the epigastric and umbilical regions, where it is enclosed within the superior aspect of the abdomen. However, its size, shape and position may vary from individual to individual, and can be subject to change due to different body positions and respiration.
The stomach consists mainly of four anatomical divisions; the cardia, fundus, body and pylorus.
Due to its close proximity to several vital organs, the stomach is involved in both the gastrointestinal immunity and is important in minimising the spread of intraperitoneal infections. The stomach is bridged to the liver by the lesser omentum, a smaller peritoneal fold that arises from the lesser curvature of the stomach and extends up to attach to the liver. This allows the stomach and duodenum to be attached to the liver and also divides the abdominal cavity into the greater and lesser sac.
Communication between the two sacs is facilitated by the epiploic foramen, a hole located in the lesser omentum. The arterial supply to the stomach comes from the celiac trunk and its branches, and along the greater and lesser curvatures, anastomoses form by the right and left gastric and the right and left gastro-omental arteries, as follows:
The veins of the stomach run parallel to the arteries. The right and left gastric veins drain into the hepatic portal vein, while the short gastric, left and right gastro-omental veins ultimately drain into the superior mesenteric vein.
The stomach receives innervation from the autonomic nervous system, in the form of parasympathetic and sympathetic nerves from the anterior and posterior vagal trunks, and T6-T9 spinal cord segments, respectively. It also contains pain transmitting fibres.
The gastric lymphatic vessels travel with the arteries along the greater and lesser curvatures of the stomach towards the gastric and gastro-omental lymph nodes. These efferent lymphatic vessels then eventually connect to the coeliac lymph nodes located on the posterior abdominal wall.
Gastro-Oesophageal Reflux Disease (GORD) is a digestive disorder that is known to affect the lower oesophageal sphincter, and refers to the movements of gastric acid and food into the oesophagus. As a common condition, it is estimated to affect 5-7% of the population, and the symptoms can include dyspepsia, dysphagia, and an unpleasant sour taste in the mouth.
The three main causes of reflux disease include dysfunction of the lower oesophageal sphincter, delayed gastric emptying and hiatal hernia. Treatment requires lifestyle changes and the use of medications such as proton pump inhibitors (PPI) to reduce stomach acid. Surgery is necessary as a last resort.
A hiatus hernia occurs when a part of the stomach protrudes into the chest through the oesophageal hiatus in the diaphragm. This is mainly categorised into two types; sliding hiatus hernia and rolling hiatus hernia.
The stomach is an important intraperitoneal digestive organ that has several key roles within the body, and its close proximity to several other vital organs necessitates its detailed understanding. It is important to note, the size, shape and position of the stomach may vary from individual to individual, yet it is neurologically and vascularly supplied as discussed in this article. Furthermore, the anatomy of the stomach allows it to be involved heavily in both gastrointestinal immunity and minimising the spread of intraperitoneal infections.
Knowing the anatomy of the stomach is important for both patient and clinician, as when medical conditions such as GORD and hiatal hernia occur, the patient can be correctly evaluated and treated with lifestyle changes and medications, and surgery may be used as a last resort.
The pyloric sphincter demarcates the transpyloric plane at the level of L1 and is located between the pylorus and the first part of the duodenum. It plays an important role in controlling the passage of food and gastric acid mixture, known as chyme, from the stomach. It is composed of smooth muscle and constricts to limit the discharge of material from the stomach through the orifice. In addition, the pylorus is normally contracted, meaning the orifice is small and food stays in the stomach for an appropriate period. Gastric peristalsis is then used to push the chyme through the pyloric canal into the duodenum for further digestion.
The stomach is curved in shape, with the medial and lateral sides forming the lesser and greater curvatures, respectively. The greater curvature starts at the cardiac notch before arching backwards and turning slightly to the left as it continues inferiorly. It eventually curves to the right and forms the long, convex lateral border of the stomach. Meanwhile, the lesser curvature forms the shorter, concave medial surface of the stomach and gives attachment to the hepatogastric ligament. The most inferior part of this curvature, the angular notch, indicates the junction of the body and pyloric region.
The greater curvature is supplied by the short gastric arteries and the right and left gastro-omental arteries. The lesser curvature is supplied by the left gastric artery and the right gastric branch of the hepatic artery.
The anatomical relations of the stomach are diverse and depend on the structure's surronding environment. The superior structures include the oesophagus and left dome of the diaphragm, while the anterior structures consist of the diaphragm, greater omentum, anterior abdominal wall, left lobe of the liver, and gallbladder. The posterior structures include the lesser sac, pancreas, left kidney, left adrenal gland, spleen, splenic artery, and transverse mesocolon.
There are two sphincters located at each orifice of the stomach which are responsible for controlling the passage of material entering and exiting the stomach. The inferior oesophageal sphincter is found at the T11 level and marks the transition point from the oesophagus to the stomach. It allows food to pass through the cardiac orifice and into the stomach and is not under voluntary control. The pyloric sphincter, as already discussed, lies between the pylorus and first part of the duodenum and is an anatomical sphincter.
The arterial supply to the stomach comes from the celiac trunk and its branches. Anastomoses form along the lesser curvature by the right and left gastric arteries and along the greater curvature by the right and left gastro-omental arteries. Meanwhile, the veins of the stomach run parallel to the arteries and the right and left gastric veins drain into the hepatic portal vein. The short gastric vein, left and right gastro-omental veins ultimately drain into the superior mesenteric vein.
In terms of innervation, the stomach receives nerve supply from the autonomic nervous system. Parasympathetic nerve supply arises from the anterior and posterior vagal trunks, derived from the vagus nerve. Sympathetic nerve supply arises from the T6-T9 spinal cord segments and passes to the coeliac plexus via the greater splanchnic nerve. It also carries some pain transmitting fibres. The gastric lymphatic vessels travel with the arteries along the greater and lesser curvatures of the stomach. Lymph fluid drains into the gastric and gastro-omental lymph nodes found at the curvatures. Efferent lymphatic vessels from these nodes then connect to the coeliac lymph nodes, located on the posterior abdominal wall.
Gastro-Oesophageal Reflux Disease (GORD) is a common digestive disorder which affects the lower oesophageal sphincter. It occurs when gastric acid and food move into the oesophagus and affects 5-7% of the population. Other stomach disorders include Gastroenteritis and Stomach Cancer.
Hiatus hernia is a condition where the stomach protrudes into the thoracic cavity, through a weakness in the diaphragm, which is the muscle between the abdomen and chest. The anatomy of the stomach, as well as its anatomical position, structure, divisions, greater and lesser curvatures, relations, neurovascular supply, sphincters, omenta, lymphatics and gastro-oesophageal reflux disease are all integral when diagnosing hiatus hernia. It is classified into three types, sliding, rolling, and mixed type, with mixed type hernia being the most complex.
Hiatus hernia is characterised by symptoms such as heartburn, discomfort, gas, bloating and chest pain. In adults these hernias are more common after the age of 50 and occur in about 10–20% of the adult population.
There are two main types of hiatus hernia: sliding and rolling. Sliding hiatus hernia occurs when the lower oesophageal sphincter (LES) slides superiorly, and reflux is a common complication, as the diaphragm is no longer reinforcing the sphincter. Rolling hiatus hernia is when the lower oesophageal sphincter remains in place, but a part of the stomach herniates into the chest next to it.
Hiatus hernias can be characterised radiologically and endoscopically and the two main types are paraesophageal and sliding. Sliding hernias have a protrusion of the fundus of the stomach into the thoracic cavity, but the gastro-oesophageal junction remains intra-abdominal, while for a paraesophageal hernia, the gastro-oesophageal junction migrates into the thoracic cavity.
There are three main causes of reflux disease, Dysfunction of the lower oesophageal sphincter, Delayed gastric emptying, and Hiatal hernia.
Symptoms of reflux disease include dyspepsia, dysphagia, and an unpleasant sour taste in the mouth.
Treatment of reflux disease involves lifestyle changes, medication such as a PPI (Proton Pump Inhibitor) to reduce stomach acid, and as a last resort, surgery.
Medications used to treat reflux disease include antacids, H2-blockers, and PPIs. Antacids work by neutralizing stomach acid, while H2-blockers reduce acid production. PPIs are the most effective medications used to treat reflux disease as they reduce both acid production and the amount of time the acid remains in the stomach. All of these medications have side effects, so it is important to speak to a doctor about the risks and benefits before starting any of them.
Surgery may be necessary in cases where lifestyle changes, medications, and other treatments are not effective. There are several types of surgery used to treat reflux disease. Laparoscopic Nissen Fundoplication is one of the most commonly used surgeries, and it involves wrapping the top of the stomach around the lower end of the oesophagus to create a valve that prevents acid reflux. Endoscopic treatments are also available and may be recommended by your doctor.
Hiatus hernia is a condition where the stomach protrudes into the thoracic cavity, through a weakness in the diaphragm. It is characterised by symptoms such as heartburn, discomfort, gas, bloating and chest pain. Treatment for reflux disease involves lifestyle changes, medications, and as a last resort, surgery. It is important to discuss the risks and benefits of any medication with your doctor before starting any treatment for reflux disease.
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