Gallbladder Anatomy

The gallbladder is a hollow, pear-shaped muscular organ associated with the inferior surface of the liver. Its principal role is to store and concentrate bile produced by the liver and release it into the biliary tree when required for digestion.

The gallbladder lies within the gallbladder fossa on the visceral surface of the liver, between the anatomical right and left lobes. It extends from the region of the inferior hepatic border toward the porta hepatis, where its neck continues into the cystic duct.

Anatomically, the gallbladder is divided into the fundus, body, infundibulum, and neck. Its relationships with the liver, duodenum, transverse colon, cystic duct, hepatic ducts, and hepatic vessels are particularly important in hepatobiliary anatomy and surgery.

Location

The gallbladder is located primarily in the right upper quadrant of the abdomen, closely applied to the visceral surface of the liver.

It occupies a shallow depression called the gallbladder fossa.

Gallbladder Fossa

The gallbladder fossa is a depression on the visceral surface of the liver that accommodates the gallbladder.

It lies between the right lobe of the liver and the quadrate region of the visceral surface.

Surface Projection

The fundus of the gallbladder projects toward the inferior border of the liver and may contact the anterior abdominal wall.

Its surface position is commonly described near the intersection of the right costal margin and the lateral border of the right rectus abdominis muscle.

Shape

The gallbladder is typically described as pear-shaped or flask-shaped.

Its broad distal end forms the fundus, while the narrower proximal end forms the neck and continues into the cystic duct.

Size and Capacity

The size of the gallbladder varies according to its degree of filling and individual anatomy.

It is usually several centimeters long and is capable of storing several tens of milliliters of bile.

Parts of the Gallbladder

The gallbladder can be divided into four principal anatomical regions:

• Fundus
• Body
• Infundibulum
• Neck

Fundus

The fundus is the rounded, expanded distal end of the gallbladder.

It commonly projects beyond the inferior border of the liver and is the portion most closely related to the anterior abdominal wall.

Relations of the Fundus

The fundus may contact the anterior abdominal wall and is also related to adjacent portions of the transverse colon.

Its exact relationships vary according to gallbladder size, body habitus, and the position of surrounding abdominal organs.

Body

The body forms the largest central portion of the gallbladder.

It lies within the gallbladder fossa and extends from the fundus toward the narrower neck.

Relations of the Body

The superior surface of the body is closely attached to the liver.

Its inferior surface may be related to the transverse colon and the superior or descending portions of the duodenum.

Infundibulum

The infundibulum is the tapered region between the body and neck of the gallbladder.

It may form a funnel-shaped transition into the neck.

Hartmann Pouch

A bulging or sacculated region near the gallbladder neck is commonly referred to clinically as Hartmann pouch.

Its size and prominence vary, and it can become particularly apparent in association with gallstone disease or chronic inflammation.

Neck

The neck is the narrow proximal portion of the gallbladder.

It is directed toward the porta hepatis and continues into the cystic duct.

Relationship of the Neck to the Cystic Duct

The neck gradually narrows to become the cystic duct.

This creates the anatomical connection between the gallbladder lumen and the remainder of the biliary tree.

Cystic Duct

The cystic duct carries bile between the gallbladder and the main extrahepatic biliary pathway.

It usually joins the common hepatic duct to form the common bile duct.

Spiral Fold

The mucosa of the gallbladder neck and cystic duct forms spiral folds commonly referred to collectively as the spiral fold or valves of Heister.

These folds help maintain the lumen of the cystic duct but do not function as true one-way valves.

Connection with the Biliary Tree

The gallbladder communicates with the biliary tree through the cystic duct.

Bile can move in either direction through this connection depending on pressure gradients and activity of the distal biliary sphincter apparatus.

Biliary Pathway

A simplified pathway involving the gallbladder is:

Right and left hepatic ducts → Common hepatic duct ↔ Cystic duct ↔ Gallbladder

Below the cystic duct junction, the biliary pathway continues as the common bile duct toward the duodenum.

Relationship to the Liver

The gallbladder is intimately associated with the visceral surface of the liver.

Its hepatic surface is attached to the gallbladder fossa by connective tissue.

Hepatic Surface

The surface of the gallbladder facing the liver is called the hepatic surface.

This surface is generally not completely covered by peritoneum because it is attached directly to the liver.

Free Surface

The surface facing away from the liver is largely covered by visceral peritoneum.

This free surface is related to neighboring abdominal viscera.

Peritoneal Relations

The gallbladder is generally covered by peritoneum on its free surface, while the hepatic surface is attached to the liver.

The exact extent of peritoneal covering can vary.

Relationship to the Duodenum

The gallbladder, particularly its body and neck, is closely related to the duodenum.

Inflammation of the gallbladder can therefore affect adjacent duodenal structures.

Relationship to the Transverse Colon

The fundus and body may lie adjacent to the transverse colon.

This relationship is clinically important because chronic inflammation can occasionally produce adhesions between the gallbladder and colon.

Relationship to the Porta Hepatis

The neck of the gallbladder is directed toward the porta hepatis, where it connects with the cystic duct and the extrahepatic biliary system.

This places the proximal gallbladder close to major hepatic vessels and bile ducts.

Hepatocystic Triangle

The hepatocystic triangle is an important anatomical space adjacent to the gallbladder neck.

Its boundaries are formed by the cystic duct, common hepatic duct, and inferior surface of the liver.

Contents of the Hepatocystic Triangle

The hepatocystic triangle commonly contains the cystic artery, cystic lymph node, lymphatic vessels, connective tissue, and autonomic nerve fibers.

Variable arteries and bile ducts may also pass through this region.

Calot Triangle

The term Calot triangle was originally used for a triangle bounded by the cystic duct, common hepatic duct, and cystic artery.

In modern surgical usage, the larger hepatocystic triangle is frequently discussed when describing gallbladder surgery.

Wall of the Gallbladder

The wall of the gallbladder is adapted for absorption, concentration of bile, and contraction.

It consists of a mucosa, irregular smooth muscle layer, perimuscular connective tissue, and an outer serosal or adventitial covering depending on the surface.

Mucosa

The gallbladder mucosa forms numerous folds when the organ is not fully distended.

These folds flatten as the gallbladder fills.

Gallbladder Epithelium

The mucosal surface is lined by simple columnar epithelium.

The epithelial cells possess apical microvilli that increase the surface area available for absorption.

Lamina Propria

Beneath the epithelium lies a connective tissue lamina propria containing blood vessels, lymphatics, and immune cells.

The gallbladder lacks a muscularis mucosae and a distinct submucosa.

Muscular Layer

The muscular wall consists of irregularly arranged bundles of smooth muscle rather than the clearly organized layers characteristic of much of the gastrointestinal tract.

Contraction of these smooth muscle fibers helps expel bile from the gallbladder.

Perimuscular Connective Tissue

Outside the smooth muscle is a layer of connective tissue containing larger blood vessels, lymphatics, nerves, and variable adipose tissue.

Serosa

Where the gallbladder is covered by peritoneum, its outermost surface forms a serosa.

This consists of connective tissue covered by mesothelium.

Adventitia

On the hepatic surface, the gallbladder is attached to the liver by connective tissue rather than a free serosal surface.

This connective tissue attachment can be described as an adventitial layer.

Layers of the Gallbladder Wall

Layer	Key Feature
Mucosa	Folded lining with simple columnar epithelium
Lamina propria	Connective tissue supporting the epithelium
Muscular layer	Irregular smooth muscle bundles
Perimuscular connective tissue	Contains vessels, nerves, lymphatics and connective tissue
Serosa or adventitia	Depends on relationship to peritoneum and liver

Rokitansky-Aschoff Sinuses

Rokitansky-Aschoff sinuses are invaginations of gallbladder mucosa that extend into or through the muscular wall.

They may become prominent in chronic gallbladder disease.

Function

The gallbladder has two major functions: storage of bile and concentration of bile.

It also contracts to deliver stored bile into the extrahepatic biliary system during digestion.

Bile Storage

Bile produced continuously by the liver can be diverted into the gallbladder between meals.

The gallbladder provides a reservoir that allows bile to accumulate until it is required in the intestine.

Bile Concentration

The gallbladder epithelium absorbs water and electrolytes from stored bile.

This process concentrates bile constituents within the gallbladder lumen.

Gallbladder Contraction

Following a meal, particularly one containing fat, hormonal and neural signals stimulate contraction of the gallbladder.

This increases pressure within the gallbladder and moves bile through the cystic duct toward the common bile duct.

Cholecystokinin

Cholecystokinin is released from enteroendocrine cells in the small intestine in response to nutrients, particularly fats and amino acids.

It promotes gallbladder contraction and coordinates biliary emptying with digestion.

Arterial Supply

The principal arterial supply of the gallbladder is the cystic artery.

The cystic artery most commonly arises from the right hepatic artery.

Cystic Artery

The cystic artery usually passes through the hepatocystic triangle toward the gallbladder.

It commonly divides into superficial and deep branches that supply different surfaces of the organ.

Superficial Branch

The superficial branch of the cystic artery primarily supplies the free or peritoneal surface of the gallbladder.

Deep Branch

The deep branch passes between the gallbladder and liver and supplies the hepatic surface of the gallbladder.

Cystic Artery Variations

The cystic artery shows substantial anatomical variation in its origin, number, and course.

It may arise from vessels other than the right hepatic artery, and more than one cystic artery may be present.

Venous Drainage

Venous drainage of the gallbladder occurs through small cystic veins.

Some drain directly into the liver, while others communicate with branches of the portal venous system.

Cystic Veins

Small veins from the hepatic surface can pass directly into hepatic sinusoids or portal venous branches within the liver.

Other venous channels accompany the cystic artery toward the portal venous circulation.

Lymphatic Drainage

Lymph from the gallbladder initially drains toward lymphatic vessels near the neck of the organ.

A major early drainage site is the cystic lymph node.

Cystic Lymph Node

The cystic lymph node is commonly located near the neck of the gallbladder and cystic duct.

It is also known as the node of Lund.

Hepatic Lymph Nodes

From the cystic region, lymph generally passes toward hepatic lymph nodes along the hepatic vessels.

It subsequently reaches lymph nodes associated with the celiac arterial system.

Innervation

The gallbladder receives autonomic innervation through nerve plexuses associated with the celiac and hepatic arterial systems.

Both sympathetic and parasympathetic fibers reach the organ.

Parasympathetic Innervation

Parasympathetic fibers reach the biliary system primarily through the vagus nerves.

They participate in regulation of biliary motility together with gastrointestinal hormones.

Sympathetic Innervation

Sympathetic fibers reach the gallbladder through the celiac plexus and associated periarterial pathways.

They participate in vascular regulation and visceral sensory pathways.

Visceral Sensory Fibers

Visceral afferent fibers convey sensory information from the gallbladder and biliary tract.

Distension, inflammation, and obstruction can activate these pathways and produce visceral pain.

Referred Pain

Pain arising from the gallbladder is commonly perceived in the right upper abdomen or epigastric region.

Irritation of diaphragmatic peritoneum associated with inflammation may produce referred pain toward the right shoulder region through pathways associated with the phrenic nerve.

Gallstones

Gallstones, or cholelithiasis, are solid deposits that form within the gallbladder or biliary tract.

They vary in composition, size, and number.

Sites of Gallstone Impaction

A stone leaving the gallbladder can become lodged in the neck, cystic duct, common bile duct, or near the distal biliary opening.

The anatomical consequences depend on the site of obstruction.

Cystic Duct Obstruction

A stone obstructing the cystic duct can prevent normal emptying of the gallbladder.

Persistent obstruction can contribute to gallbladder distension and inflammation.

Acute Cholecystitis

Acute cholecystitis is acute inflammation of the gallbladder, commonly associated with obstruction of the cystic duct by a gallstone.

Inflammation can involve the gallbladder wall and adjacent peritoneum.

Chronic Cholecystitis

Repeated or persistent inflammation can produce fibrosis and structural changes in the gallbladder wall.

Chronic inflammation may also be associated with prominent Rokitansky-Aschoff sinuses.

Gallbladder Distension

Obstruction of bile outflow can cause enlargement of the gallbladder as bile and secretions accumulate within its lumen.

The degree of distension depends on the location and duration of obstruction and the condition of the gallbladder wall.

Mirizzi Syndrome

A stone impacted near the gallbladder neck or cystic duct can compress the adjacent common hepatic duct.

This anatomical relationship provides the basis for Mirizzi syndrome.

Gallstone Ileus

Chronic inflammation can rarely produce an abnormal communication between the gallbladder and adjacent gastrointestinal tract.

A large gallstone may pass through such a fistula into the intestine and subsequently cause mechanical obstruction.

Gallbladder Perforation

Severe inflammation or ischemic injury can compromise the gallbladder wall and result in perforation.

The anatomical consequences depend on whether leakage is contained by surrounding structures or enters the peritoneal cavity.

Cholecystectomy

Cholecystectomy is surgical removal of the gallbladder.

Safe surgery requires identification of the cystic duct and cystic artery while preserving the common hepatic duct, common bile duct, hepatic arteries, and other nearby structures.

Critical View of Safety

The critical view of safety is an anatomical identification technique used during cholecystectomy.

Its purpose is to establish that only the cystic duct and cystic artery enter the gallbladder before these structures are divided.

Gallbladder Bed

During cholecystectomy, the gallbladder is separated from its attachment to the liver within the gallbladder fossa.

Small vessels and bile ducts can be encountered in this region.

Subvesical Bile Ducts

Small bile ducts may occur in or near the gallbladder fossa and are commonly described as subvesical bile ducts.

These ducts are anatomically variable and can be a source of bile leakage if injured.

Gallbladder Variations

The gallbladder varies in shape, position, size, and peritoneal attachment.

Most variations are asymptomatic but can become important during imaging or surgery.

Folded Gallbladder

The fundus may fold back upon the body, producing a configuration often called a Phrygian cap.

This is generally an anatomical variation rather than a pathological abnormality.

Intrahepatic Gallbladder

An unusually large portion of the gallbladder may be embedded within hepatic tissue.

This position can alter imaging appearances and surgical access.

Floating Gallbladder

In some individuals, the gallbladder has an unusually extensive peritoneal covering and may be attached to the liver by a mesentery.

This increased mobility can predispose the organ to torsion.

Gallbladder Torsion

A highly mobile gallbladder can rarely rotate around its vascular and ductal attachments.

Such torsion can compromise cystic arterial blood flow and biliary drainage.

Gallbladder Agenesis

Rarely, the gallbladder fails to develop.

Recognition of this congenital variation is important because apparent absence on imaging does not necessarily indicate a contracted or diseased gallbladder.

Duplicated Gallbladder

Duplication of the gallbladder is a rare developmental variation.

Associated cystic duct anatomy can vary and is particularly important during surgical procedures.

Ultrasound

Ultrasound is commonly used to evaluate gallbladder anatomy.

It can demonstrate the lumen, wall, gallstones, distension, surrounding fluid, and portions of the biliary tree.

Gallbladder Wall on Ultrasound

The gallbladder wall is normally thin when adequately distended.

Wall thickening can occur in inflammatory conditions but is not specific to gallbladder disease.

CT Imaging

CT demonstrates the gallbladder in relation to the liver, duodenum, colon, pancreas, and surrounding tissues.

It can also demonstrate complications of inflammation, perforation, masses, and some gallstones.

MRCP

Magnetic resonance cholangiopancreatography provides detailed noninvasive visualization of the fluid-filled biliary system.

It can demonstrate the gallbladder, cystic duct, hepatic ducts, common bile duct, and many anatomical variations.

HIDA Scan

Hepatobiliary scintigraphy can evaluate the movement of radiotracer from the liver through the biliary system.

Visualization or nonvisualization of the gallbladder can provide functional information about cystic duct patency.

Embryological Development

The gallbladder develops from the cystic diverticulum associated with the embryonic hepatic diverticulum.

The connecting stalk contributes to development of the cystic duct.

Hepatic Diverticulum

The hepatic diverticulum arises from the ventral aspect of the embryonic foregut.

Its derivatives contribute to development of the liver and biliary apparatus.

Development of the Gallbladder Lumen

The developing gallbladder and bile ducts undergo epithelial proliferation and subsequent remodeling to establish patent lumina.

Variations in development can contribute to congenital abnormalities of the gallbladder and biliary tree.

Gallbladder Anatomy Summary

Feature	Anatomy
Location	Visceral surface of liver within gallbladder fossa
Main parts	Fundus, body, infundibulum and neck
Continuation	Neck continues into cystic duct
Main arterial supply	Cystic artery
Common arterial origin	Right hepatic artery
Initial lymphatic drainage	Cystic lymph node
Epithelium	Simple columnar
Main functions	Storage and concentration of bile

Gallbladder Relations

Structure	Relationship
Liver	Gallbladder lies in a fossa on its visceral surface
Anterior abdominal wall	Related particularly to the fundus
Duodenum	Related to body and neck
Transverse colon	May contact fundus and body
Common hepatic duct	Located near neck and cystic duct
Cystic artery	Usually approaches through hepatocystic triangle

Key Features of the Gallbladder

Feature	Key Point
Shape	Pear-shaped muscular sac
Position	Inferior visceral surface of liver
Fundus	Rounded distal end
Body	Largest central portion
Neck	Narrows into cystic duct
Wall	Lacks muscularis mucosae and distinct submucosa
Blood supply	Primarily cystic artery
Biliary connection	Cystic duct
Primary functions	Stores, concentrates and releases bile

Anatomical and Clinical Importance

The gallbladder is anatomically positioned between the liver and the extrahepatic biliary tree, allowing it to function as a reservoir for bile. Its fundus, body, infundibulum, and neck form a continuous sac that communicates with the biliary system through the cystic duct.

Its close relationships with the liver, duodenum, colon, common hepatic duct, hepatic arteries, and other structures of the porta hepatis explain much of its clinical importance. The hepatocystic triangle is especially significant because it contains the cystic artery and lies immediately adjacent to the major biliary pathways.

Understanding gallbladder anatomy, including its wall structure, vascular supply, lymphatic drainage, innervation, and common anatomical variations, is essential for interpreting biliary imaging and understanding gallstone disease, cholecystitis, biliary obstruction, and the anatomical principles of cholecystectomy.