Fundus of the Stomach

The fundus of the stomach is the rounded, dome-shaped superior portion of the stomach that lies above the level of the cardiac orifice. Despite its name, the fundus is not the lowest part of the stomach. In anatomical terminology, a fundus is a part of a hollow organ situated opposite or away from its opening, and the gastric fundus occupies the superior left portion of the organ.

The fundus lies predominantly beneath the left dome of the diaphragm and forms part of the proximal stomach together with the cardia and upper body. It has important relationships with the diaphragm, spleen, and left upper abdominal structures and is connected to the spleen through the gastrosplenic ligament.

Functionally, the fundus contributes to the reservoir function of the stomach. Its wall can relax during swallowing and gastric filling, allowing ingested material to enter the stomach without producing a large increase in intragastric pressure. Histologically, the fundus contains characteristic fundic or oxyntic glands rich in acid-secreting parietal cells and pepsinogen-secreting chief cells.

Location

The gastric fundus occupies the left upper part of the abdominal cavity, immediately inferior to the left dome of the diaphragm.

It is positioned superior to the cardiac orifice and generally extends upward and to the left from the gastroesophageal junction.

Position Relative to the Cardia

The cardia surrounds the opening of the esophagus into the stomach. The fundus is the portion of the stomach that projects superiorly above a horizontal plane passing through this opening.

This relationship provides a useful anatomical definition of the fundus.

Shape

The fundus has a characteristic rounded or dome-shaped contour.

Its superior convex surface conforms partly to the inferior surface of the left diaphragmatic dome.

Orientation

The exact position and shape of the fundus vary with gastric filling, body position, respiratory movement, and individual anatomy.

When the stomach is distended, the fundus becomes more prominent and can extend farther superiorly beneath the diaphragm.

Relationship to Other Regions of the Stomach

The stomach is commonly divided anatomically into the cardia, fundus, body, and pyloric part.

Region	General Location
Cardia	Surrounds the esophageal opening
Fundus	Dome-shaped region above the cardiac orifice
Body	Large central portion below the fundus
Pyloric part	Distal portion leading toward the duodenum

Fundus and Body

There is no sharp external anatomical boundary separating the fundus from the body of the stomach.

The fundus merges inferiorly with the gastric body, and both regions contain similar fundic or oxyntic mucosa.

Cardiac Notch

The cardiac notch, also called the incisura cardiaca, is the acute angle formed between the left side of the abdominal esophagus and the fundus of the stomach.

It is an important external landmark near the gastroesophageal junction.

Angle of His

The angle formed between the esophagus and the fundus is commonly referred to clinically as the angle of His.

This region contributes to the geometry of the gastroesophageal junction and is relevant to mechanisms that help limit gastroesophageal reflux.

Superior Surface

The superior surface of the fundus lies directly beneath the diaphragm.

The close relationship between these structures means that movement of the diaphragm during respiration can alter the position of the fundus.

Anterior Relations

Anteriorly, the fundus is related primarily to the diaphragm and, depending on the degree of gastric filling and individual anatomy, the anterior abdominal and lower thoracic relationships of the upper stomach.

Posterior Relations

The posterior aspect of the fundus contributes to the posterior surface of the stomach and is related through the lesser sac and peritoneal folds to structures of the left upper abdomen.

Relationship to the Diaphragm

The left dome of the diaphragm is one of the most important anatomical relations of the fundus.

The superior fundus lies immediately inferior to the diaphragm, separated from thoracic structures by the diaphragmatic muscle and associated tissues.

Relationship to the Spleen

The fundus is closely related to the spleen, which lies posterolateral to the upper stomach.

The two organs are connected by the gastrosplenic ligament.

Gastrosplenic Ligament

The gastrosplenic ligament is a double layer of peritoneum extending between the stomach and spleen.

It is associated particularly with the upper greater curvature and fundic region.

Contents of the Gastrosplenic Ligament

The gastrosplenic ligament transmits important vessels between the splenic vascular territory and the stomach.

These include:

• Short gastric vessels
• Left gastro-omental vessels

Short Gastric Vessels

The short gastric arteries and veins are particularly important to the fundus.

They pass between the spleen and upper stomach through the gastrosplenic ligament.

Greater Curvature

The lateral contour of the fundus contributes to the superior portion of the greater curvature of the stomach.

The greater curvature continues inferiorly and to the right along the body and pyloric region.

Lesser Curvature

The fundus does not form a major portion of the lesser curvature. The lesser curvature begins near the cardia and extends along the right border of the stomach toward the pylorus.

Peritoneal Covering

The fundus is covered by visceral peritoneum over its external surface.

This serosal covering permits movement of the stomach relative to adjacent structures and becomes continuous with peritoneal ligaments at the gastric curvatures.

Gastric Wall of the Fundus

The wall of the fundus has the same general organization as the rest of the stomach.

From the lumen outward, it consists of:

1. Mucosa
2. Submucosa
3. Muscularis externa
4. Serosa

Fundic Mucosa

The mucosa of the fundus is characterized by numerous fundic glands, also called oxyntic glands.

This glandular pattern extends through the body of the stomach and accounts for much of the acid and enzyme-producing capacity of the gastric mucosa.

Surface Epithelium

The fundic mucosa is lined by simple columnar epithelium composed predominantly of surface mucous cells.

These cells produce mucus and bicarbonate that contribute to protection of the mucosa from acidic gastric contents.

Gastric Pits

The surface epithelium invaginates into the lamina propria to form gastric pits.

In the fundus and body, these pits are relatively shallow compared with those of the pyloric region.

Fundic Glands

Fundic glands are long tubular glands extending from the bases of the gastric pits toward the muscularis mucosae.

They contain several specialized epithelial cell populations involved in gastric secretion.

Cells of the Fundic Glands

Major cell types include:

• Parietal cells
• Chief cells
• Mucous neck cells
• Enteroendocrine cells
• Stem and progenitor cells

Parietal Cells

Parietal cells, also called oxyntic cells, are particularly prominent in the upper and middle regions of fundic glands.

They are large eosinophilic cells specialized for secretion of hydrochloric acid and intrinsic factor.

Hydrochloric Acid

Hydrochloric acid secreted by parietal cells creates the strongly acidic environment of the stomach.

This acidity assists protein digestion, promotes conversion of pepsinogen to pepsin, and contributes to defense against many ingested microorganisms.

Intrinsic Factor

Parietal cells also secrete intrinsic factor, a glycoprotein required for efficient absorption of vitamin B12 in the terminal ileum.

Chief Cells

Chief cells are concentrated particularly within the deeper portions of the fundic glands.

They contain abundant rough endoplasmic reticulum and secretory granules reflecting their protein-secreting function.

Pepsinogen

Chief cells secrete pepsinogen, the inactive precursor of pepsin.

Within the acidic gastric lumen, pepsinogen is converted into pepsin, which participates in protein digestion.

Gastric Lipase

Chief cells also produce gastric lipase, an enzyme involved in the digestion of dietary triglycerides.

Mucous Neck Cells

Mucous neck cells are located within the necks of fundic glands.

The mucus they produce differs from the thick protective mucus secreted by surface mucous cells.

Enteroendocrine Cells

Enteroendocrine cells are scattered throughout the fundic glands and release signaling molecules involved in regulation of gastric function.

Enterochromaffin-Like Cells

Enterochromaffin-like cells, or ECL cells, are prominent within oxyntic mucosa.

They release histamine, which acts locally on parietal cells to promote gastric acid secretion.

Fundic Gland Cell Functions

Cell Type	Major Product or Function
Surface mucous cells	Protective mucus and bicarbonate-associated barrier
Mucous neck cells	Mucus secretion
Parietal cells	Hydrochloric acid and intrinsic factor
Chief cells	Pepsinogen and gastric lipase
ECL cells	Histamine
Stem cells	Epithelial renewal

Muscularis Externa

The fundic wall contains the characteristic gastric muscularis externa composed of smooth muscle arranged in inner oblique, middle circular, and outer longitudinal layers.

The organization of these layers contributes to gastric tone and movement.

Fundic Muscle Function

The proximal stomach performs a different mechanical role from the strongly contractile distal antrum.

The fundus is particularly adapted to receive and store ingested material while maintaining relatively low intragastric pressure.

Reservoir Function

The fundus and adjacent proximal body act as an important gastric reservoir.

After swallowing, the proximal stomach can accommodate a substantial increase in volume without a proportional increase in pressure.

Receptive Relaxation

Receptive relaxation refers to relaxation of the proximal stomach associated with swallowing and the arrival of food.

This response allows the fundus to expand and receive gastric contents efficiently.

Gastric Accommodation

Gastric accommodation is the adaptive relaxation of the proximal stomach during filling.

It depends on coordinated neural and muscular mechanisms, particularly vagovagal reflex pathways.

Fundic Tone

The fundus maintains a degree of smooth muscle tone that contributes to pressure within the proximal stomach.

Changes in this tone help move gastric contents gradually toward the distal stomach for further mixing and grinding.

Fundus Versus Antrum

Feature	Fundus	Antrum
Major mechanical role	Storage and accommodation	Mixing and grinding
Typical contractions	Predominantly tonic activity	Strong phasic contractions
Mucosal pattern	Fundic or oxyntic glands	Pyloric glands
Prominent secretory cells	Parietal and chief cells	Mucous and endocrine cells, including G cells

Gastric Air Bubble

Swallowed air commonly accumulates in the fundus because of its superior position when a person is upright.

This produces the characteristic gastric air bubble that may be visible beneath the left hemidiaphragm on an upright radiograph.

Fundic Gas on Radiographs

On an upright chest or abdominal radiograph, gas within the fundus can appear as a radiolucent area immediately inferior to the left hemidiaphragm.

Its appearance depends on body position, gastric contents, and the amount of intragastric gas.

Effect of Body Position

Gas rises to the nondependent portion of the stomach, while fluid moves toward dependent regions.

Consequently, the distribution of gas and fluid within the fundus changes when the patient changes position.

Arterial Supply

The fundus receives arterial blood from branches of the celiac arterial system.

The short gastric arteries are particularly important, with additional contributions from nearby gastric arterial branches.

Short Gastric Arteries

The short gastric arteries usually arise from the splenic artery or its branches.

They pass through the gastrosplenic ligament to reach the fundus and upper greater curvature.

Left Gastro-Omental Artery

The left gastro-omental artery, also called the left gastroepiploic artery, arises from the splenic artery and travels along the greater curvature.

Its branches contribute to the vascular supply of the adjacent upper gastric wall.

Left Gastric Artery

The left gastric artery supplies the region around the cardia and upper lesser curvature and can contribute branches to adjacent proximal gastric tissue.

Arterial Anastomoses

The gastric arterial supply contains extensive anastomoses between neighboring arterial territories.

These connections provide overlapping vascular supply to much of the stomach.

Major Arterial Sources

Artery	Relationship to Fundus
Short gastric arteries	Major direct supply to fundus
Left gastro-omental artery	Supplies upper greater curvature and adjacent wall
Left gastric artery	Contributes to proximal stomach near cardia and lesser curvature

Venous Drainage

Venous drainage generally parallels the arterial supply.

Veins draining the fundus ultimately enter the hepatic portal venous system.

Short Gastric Veins

The short gastric veins drain blood from the fundus and pass through the gastrosplenic ligament.

They typically empty into the splenic vein or its tributaries.

Left Gastro-Omental Vein

The left gastro-omental vein drains the upper greater curvature and typically empties into the splenic venous system.

Portal Venous Pathway

Blood entering the splenic vein subsequently reaches the portal vein, carrying venous blood from the fundic region toward the liver.

Lymphatic Drainage

Lymphatic vessels from the fundus generally follow the arterial pathways toward regional lymph nodes.

The upper greater curvature and fundic region have particularly important drainage toward nodes associated with the splenic vascular territory.

Pancreaticosplenic Nodes

Lymph from portions of the fundus can drain toward pancreaticosplenic lymph nodes located along the splenic artery.

Efferent lymphatic vessels from these nodes ultimately contribute to drainage toward the celiac nodal group.

Gastric Lymph Nodes

Some lymphatic drainage from the proximal stomach also communicates with gastric nodal pathways associated with the left gastric vessels.

The precise drainage pattern depends on the region of the fundus and neighboring gastric wall.

Celiac Nodes

The celiac lymph nodes form a major central nodal group for lymphatic drainage from the stomach and other foregut structures.

Lymph from regional gastric and pancreaticosplenic nodes ultimately reaches this central territory.

Innervation

The fundus receives parasympathetic, sympathetic, and enteric innervation as part of the general neural supply of the stomach.

These systems regulate fundic tone, accommodation, secretion, vascular activity, and sensory signaling.

Parasympathetic Innervation

Parasympathetic fibers reach the fundus primarily through branches of the anterior and posterior vagal trunks.

These fibers interact with enteric neurons within the gastric wall.

Vagal Control of Accommodation

Vagovagal reflex pathways are particularly important for relaxation of the proximal stomach during gastric filling.

This allows the fundus to function effectively as a reservoir.

Sympathetic Innervation

Sympathetic fibers reach the fundus through pathways associated with the celiac plexus and periarterial nerve networks.

They influence gastric vascular tone and modify enteric motor and secretory activity.

Enteric Innervation

The fundic wall contains the myenteric and submucosal plexuses of the enteric nervous system.

These intrinsic neural networks coordinate local motility, secretion, and mucosal functions.

Myenteric Plexus

The myenteric plexus is located within the muscularis externa and participates in regulation of gastric smooth muscle activity.

Submucosal Plexus

The submucosal plexus lies within the submucosal region and contributes to regulation of mucosal secretion and local blood flow.

Fundus and Gastric Secretion

Because the fundic mucosa contains numerous parietal and chief cells, it is an important secretory region of the stomach.

Its glands produce major components of gastric juice involved in digestion and nutrient absorption.

Acid Secretion

Parietal cells within the fundus secrete hydrochloric acid through specialized membrane transport mechanisms.

Acid secretion is regulated by neural, endocrine, and paracrine signals.

Regulation of Parietal Cells

Important stimulatory influences on parietal cells include acetylcholine, gastrin, and histamine.

These pathways interact to regulate the amount of hydrochloric acid released into the gastric lumen.

Pepsin Secretion

Chief cells release pepsinogen into the gastric lumen.

The acidic environment promotes its conversion into active pepsin, which begins the digestion of proteins.

Fundus and Vitamin B12 Absorption

Although vitamin B12 is ultimately absorbed in the terminal ileum, the fundic mucosa contributes critically to this process by producing intrinsic factor.

Loss or dysfunction of parietal cells can therefore interfere with normal vitamin B12 absorption.

Fundus on Endoscopy

During upper gastrointestinal endoscopy, the fundus can be examined by directing or retroflexing the endoscope within the stomach.

This allows visualization of the proximal gastric mucosa and the region surrounding the gastroesophageal junction.

Retroflexed Endoscopic View

A retroflexed endoscopic view can demonstrate the cardia, fundus, and gastroesophageal junction from within the stomach.

This perspective is useful for examining regions that may be difficult to visualize directly during forward viewing.

Fundus on CT

CT demonstrates the fundus as the superior portion of the stomach beneath the left hemidiaphragm.

Its appearance varies with gastric distension and the relative amounts of gas, fluid, and food within the lumen.

Fundus on MRI

MRI can demonstrate the wall and surrounding soft-tissue relationships of the fundus.

The spleen, diaphragm, gastroesophageal junction, and adjacent upper abdominal structures provide useful anatomical landmarks.

Fundus on Contrast Studies

Contrast examinations can demonstrate the contour and mucosal pattern of the fundus.

The distribution of contrast and gas changes with patient positioning because of gravity.

Fundic Gastritis

Inflammatory processes can involve the fundic mucosa and alter its glandular architecture.

Damage to parietal cells may affect both gastric acid production and intrinsic factor secretion.

Autoimmune Gastritis

Autoimmune gastritis characteristically affects the oxyntic mucosa of the gastric body and fundus.

Progressive loss of parietal cells can produce reduced acid secretion and impaired intrinsic factor production.

Parietal Cell Loss

Loss of parietal cells reduces hydrochloric acid secretion and may decrease intrinsic factor availability.

Severe intrinsic factor deficiency can interfere with vitamin B12 absorption.

Fundic Gland Polyps

Fundic gland polyps are mucosal polyps arising predominantly in the fundus and body of the stomach.

They involve cystically altered fundic glands and can occur in several clinical settings.

Gastric Varices

Dilated submucosal veins can occur within the stomach in association with abnormalities of portal venous circulation.

Varices involving the fundus are clinically important because they may produce significant gastrointestinal bleeding.

Fundal Varices

Fundal gastric varices are dilated venous channels within the proximal stomach, particularly the fundus.

Their anatomy is closely related to venous drainage through the short gastric and splenic venous systems.

Splenic Vein Obstruction

Obstruction of the splenic vein can increase pressure within tributaries such as the short gastric veins.

This altered venous drainage can contribute to formation of isolated gastric varices, particularly in the fundic region.

Hiatal Hernia

In a hiatal hernia, portions of the stomach may move superiorly through the esophageal hiatus into the thorax.

Depending on the type of hernia, the proximal stomach and fundus can have important relationships to the herniated segment.

Paraesophageal Hernia

In a paraesophageal hernia, part of the stomach can herniate through the esophageal hiatus alongside the esophagus while the gastroesophageal junction may remain relatively near its usual position.

The fundus commonly forms part of the herniated stomach.

Gastric Volvulus

Gastric volvulus involves abnormal rotation of the stomach that can produce obstruction and compromise vascular supply.

The position of the fundus and the ligamentous attachments of the stomach are important in understanding patterns of gastric rotation.

Fundoplication

Fundoplication is a surgical procedure in which part of the gastric fundus is wrapped around the distal esophagus.

The procedure modifies the anatomy of the gastroesophageal junction to reinforce the antireflux barrier.

Nissen Fundoplication

In a Nissen fundoplication, the fundus is used to create a complete wrap around the distal esophagus.

This procedure demonstrates the close anatomical relationship between the gastric fundus and gastroesophageal junction.

Fundus and Bariatric Surgery

The fundus is an important anatomical landmark in several bariatric operations.

Procedures that alter or remove portions of the fundus can change gastric volume, mechanical function, and gastrointestinal signaling.

Sleeve Gastrectomy

During sleeve gastrectomy, a large portion of the greater-curvature side of the stomach, including much of the fundus, is removed to create a narrow gastric tube.

Recognition of the fundus and its vascular attachments is therefore important during the procedure.

Short Gastric Vessels in Surgery

Mobilization of the fundus may require division of the short gastric vessels within the gastrosplenic ligament.

Their close relationship to the spleen makes careful dissection important to avoid splenic injury or hemorrhage.

Fundus and the Spleen

The anatomical proximity of the fundus to the spleen has important surgical implications.

Procedures involving the proximal greater curvature or gastrosplenic ligament can place splenic vessels and splenic tissue at risk.

Fundus Versus Cardia

Feature	Fundus	Cardia
Location	Above the level of the cardiac orifice	Immediately surrounding esophageal opening
Shape	Rounded and dome-shaped	Relatively small transition region
Predominant glands	Fundic glands	Cardiac glands
Major mechanical role	Reservoir and accommodation	Gastroesophageal transition

Fundus Versus Body

Feature	Fundus	Body
Position	Superior to cardiac orifice	Central major portion of stomach
Mucosal type	Fundic or oxyntic mucosa	Fundic or oxyntic mucosa
Major function	Storage, accommodation and secretion	Storage, secretion and movement of contents
Boundary	Merges gradually with body	Continues inferiorly toward pyloric part

Key Anatomical Relations

Structure	Relationship to Fundus
Diaphragm	Immediately superior
Esophagus	Medial relationship near cardia and cardiac notch
Spleen	Posterolateral relationship
Gastrosplenic ligament	Connects upper stomach to spleen
Greater curvature	Fundus contributes to its superior portion

Key Features of the Gastric Fundus

Feature	Key Point
Definition	Part of stomach above the level of the cardiac orifice
Shape	Dome-shaped
Location	Left upper abdomen beneath left diaphragm
Adjacent organ	Spleen
Peritoneal connection	Gastrosplenic ligament
Major arterial supply	Short gastric arteries
Major venous pathway	Short gastric veins toward splenic vein
Mucosal type	Fundic or oxyntic mucosa
Important gland cells	Parietal and chief cells
Major mechanical function	Gastric reservoir and accommodation
Common radiographic feature	Gastric air bubble

Anatomical and Clinical Importance

The gastric fundus is the superior dome-shaped portion of the stomach situated above the cardiac orifice and beneath the left hemidiaphragm. Its close relationships with the gastroesophageal junction, diaphragm, spleen, and gastrosplenic ligament make it an important landmark in upper abdominal anatomy and surgery.

The fundus performs both mechanical and secretory functions. As part of the proximal stomach, it can undergo receptive relaxation and accommodation, allowing it to serve as a reservoir for ingested material. Its fundic glands contain abundant parietal and chief cells responsible for producing hydrochloric acid, intrinsic factor, pepsinogen, and gastric lipase.

The vascular anatomy of the fundus is also clinically important. Short gastric vessels connect the fundic region with the splenic vascular territory through the gastrosplenic ligament, while venous abnormalities can contribute to fundal gastric varices. The fundus is additionally important in procedures such as fundoplication, sleeve gastrectomy, and surgical mobilization of the proximal stomach.