The liver is a solid glandular organ that produces bile and processes substances carried in the blood. It lies mainly in the upper right abdomen, immediately beneath the diaphragm, the muscular partition between the chest and abdomen, and extends across the midline into the upper left abdomen.
Where is the liver, and what lies next to it?
Most of the liver lies deep to the lower right ribs. Its central portion occupies the epigastrium, the upper middle region of the abdomen. Its position changes with breathing as the diaphragm moves.
The diaphragm separates the liver from the right lung and the heart. Below and behind the liver are the stomach, duodenum, right kidney, right suprarenal gland and right colic flexure. The duodenum is the first part of the small intestine; the right colic flexure is the bend between the ascending and transverse colon.
The gallbladder rests in a shallow depression on the liver's inferior surface. The inferior vena cava, the large vein returning blood from the lower body to the heart, occupies a groove on its posterior aspect.
What are the liver's surfaces and attachments?
The capsule of the liver is a fibrous connective-tissue covering. Most of the organ also has a covering of peritoneum, the membrane lining the abdominal cavity and covering many abdominal organs.
| Surface or area | Position and main relation |
|---|---|
| Diaphragmatic surface of liver | Smooth, convex surface facing the diaphragm, mainly above and in front. |
| Visceral surface | Mainly inferior and posterior surface related to abdominal organs. |
| Bare area of liver | Posterior region without a peritoneal covering, in contact with the diaphragm through connective tissue. |
The visceral surface bears shallow impressions, or indentations, from neighbouring structures. These include the gastric impression of liver, duodenal impression of liver, colic impression of liver, renal impression of liver and suprarenal impression of liver.
The falciform ligament is a fold of peritoneum connecting the liver to the anterior abdominal wall and diaphragm. The coronary ligament of liver consists of peritoneal reflections bordering the bare area; these folds meet laterally to form triangular attachments.
The round ligament of liver lies in the free lower edge of the falciform ligament and is the remnant of the fetal umbilical vein. The ligamentum venosum is the remnant of a fetal channel that allowed blood to bypass much of the liver.
What are the liver's lobes and functional divisions?
The right lobe of liver and left lobe of liver are the main anatomical lobes. On the anterior surface, the falciform ligament marks their boundary.
The quadrate lobe of liver lies on the inferior surface between the gallbladder fossa, its shallow bed, and the fissure containing the round ligament. The caudate lobe of liver lies posteriorly, between the inferior vena cava and the fissure containing the ligamentum venosum.
Functional divisions follow the distribution of blood vessels and bile ducts rather than the external lobe boundaries. The right hemiliver and left hemiliver are separated by a plane running approximately from the gallbladder fossa to the inferior vena cava. The caudate lobe has relatively independent vascular connections and direct venous drainage into the inferior vena cava.
What passes through the porta hepatis?
The porta hepatis is a transverse gateway on the visceral surface. Branches of the hepatic portal vein and hepatic artery enter here, while hepatic ducts leave; lymphatic vessels and nerves also pass through it.
The hepatoduodenal ligament connects this region to the duodenum. It contains the hepatic portal vein, hepatic artery proper and common bile duct, together with lymphatic vessels and nerves. These three main structures are commonly called the portal triad.
The intrahepatic biliary tree is the branching network of bile ducts within the liver. Its channels converge into right and left hepatic ducts, which unite outside the liver to form the common hepatic duct. This joins the cystic duct from the gallbladder to form the common bile duct, which carries bile towards the duodenum.
How does blood enter and leave the liver?
The hepatic portal vein brings nutrient-rich blood from the digestive organs and blood from the spleen. The hepatic artery proper supplies oxygenated arterial blood and divides into branches serving the liver.
Both supplies enter sinusoids, specialised small vascular channels where blood passes close to liver cells. The blood then collects into progressively larger veins. Each hepatic vein drains towards the inferior vena cava; this outflow does not pass through the porta hepatis.
What supplies the liver's nerves and lymph drainage?
Nerves reach the liver through the hepatic plexus, a network surrounding its vessels. Sympathetic fibres, belonging to the involuntary nervous system, arrive through pathways associated with the celiac ganglia, clusters of nerve-cell bodies in the upper abdomen. Parasympathetic fibres, another division of this system, arrive through the vagus nerve (X).
Lymph, fluid collected from tissues, drains chiefly to hepatic lymph nodes near the porta hepatis and then towards celiac lymph nodes. Some lymphatic vessels also pass towards nodes associated with the diaphragm and posterior chest.
What does the liver do?
The liver's main functions include:
- Producing bile, a fluid that helps the intestine handle dietary fats.
- Processing absorbed nutrients and storing glucose as glycogen, a carbohydrate reserve.
- Making blood proteins, including albumin and proteins involved in clotting.
- Converting ammonia from amino-acid breakdown into urea for excretion by the kidneys.
- Processing substances carried in the blood, including hormones and products of blood-cell breakdown.
How can I orient the liver in the 3D model?
In the 3D model beside this article, select the liver, rotate it and zoom to compare its superior, inferior and posterior aspects. Hide or fade surrounding structures to examine its position beneath the diaphragm, or isolate it to study its overall shape. Switch between layers as needed, or cut a section along a sagittal, coronal or transverse plane; you can also pull selected parts apart.