The liver is a large organ found in the upper right quadrant of the abdomen. It is a multifunctional accessory organ of the gastrointestinal tract and performs several essential functions such as detoxification, protein synthesis, bile production and nutrient storage to name only a few. It is the largest gland in the human body, weighing approximately 1.5 kilograms. It works synchronously with many other organs and contributes to the maintenance of basic homeostatic mechanisms.
|Function||Xenobiotic biotransformation, protein synthesis, nutrient storage, bile production, bilirubin metabolism|
Lobes: right, left, caudate, quadrate
Surfaces: diaphragmatic, visceral
Ligaments: coronary, left triangular, falciform, round ligament, venous
Fissures and recesses: porta hepatis (central fissure), subphrenic recess, hepatorenal recess
Superficial system (lymphatic vessels of subserosal areolar tissue)
Deep system (lymphatic vessels within the substance of the liver)
Functional: portal vein
Nutritive: hepatic artery
Drainage: hepatic vein -> inferior vena cava -> right atrium
|Innervation||Hepatic plexus, cervical plexus|
|Clinical relations||Hepatic failure, cirrhosis, portal hypertension, cholestasis, hepatocellular carcinoma|
This article will highlight the anatomy and functions of the liver.
- Lobes of the liver
- Porta hepatis and recesses of the liver
- Lymphatic drainage
- Blood supply
- Clinical aspects
Lobes of the liver
There are four anatomical lobes, which are further divided into even smaller segments in accordance with the blood supply of the liver.
The right lobe is the largest of the four lobes and the left lobe is a flattened smaller one. These two lobes are separated by the fossae for the gallbladder and the inferior vena cava.
The caudate lobe sits between the fissure for the ligamentum venosum and the inferior vena cava, while the quadrate lobe is located between the gallbladder and the fissure for the ligamentum teres hepatis.
The two main surfaces of the liver are the diaphragmatic surface and the visceral surface. The latter is covered by visceral peritoneum except at the porta hepatis and the bed of the gallbladder. This surface is directly related to several anatomical structures which include the:
The diaphragmatic surface lies against the inferior surface of the diaphragm and is also covered by the visceral peritoneum except in the bare area.
This integrated quiz will test you on the surfaces of the liver.
There are five types of ligaments that are directly related to the liver:
Coronary ligament - formed by folds of peritoneum reflect form the inferior surface of the diaphragm, connecting this structure to the liver; has two layers: (anterior and posterior).
- Left and right triangular ligament - are the lateral extensions of the coronary ligaments and also connect the diaphragm to the left and right lobes of the liver, respectively.
- Falciform ligament - it is a peritoneal reflection that connects the liver to the upper anterior abdominal wall; has the round ligament of the liver on its free edge.
- Ligamentum teres hepatis - also known as the round ligament of the liver, is a fibrous remnant of the umbilical vein, and extends from the internal aspect of the umbilicus up to the liver.
- Ligamentum venosum - is also an embryonic remnant, in this case of the ductus venosus of the fetal circulation. In utero, the ductus venosus shunts blood from the umbilical vein to the inferior vena cava.
Porta hepatis and recesses of the liver
The porta hepatis is the central intraperitoneal fissure of the liver (in the visceral surface) that separates the caudate and the quadrate lobes. It is the entrance and exit point for several important structures including the portal vein, the hepatic arteries, the hepatic ducts, the hepatic nervous plexus and the lymphatic vessels.
The subphrenic recess is a space between the diaphragmatic surface of the liver from the inferior surface of the diaphragm; it is split by the falciform ligament of the liver into right and left areas.
The hepatorenal recess is a space located on the inferior right aspect of the liver, between this organ and the right kidney and suprarenal gland.
The lymphatic drainage of the liver is split into deep and superficial drainage systems.
The deep system consists of hepatic lymph vessels which follow the hepatic portal veins, therefore most of the lymph will flow towards the hepatic nodes at the hilum of the liver, which drain to the celiac nodes. These drain to the cisterna chyli (if present) and on into the thoracic duct. Additional lymphatic vessels exit via the bare area following the hepatic veins as they join the inferior vena cava. Therefore, some the hepatic lymph vessels drain to the posterior mediastinal/right lumbar nodes. From there lymph flows up the right mediastinal lymphatic chain and flows into the right lymphatic duct or thoracic duct.
The superficial system transports lymphatic fluid through channels in the subserosal areolar tissue (Glisson’s capsule) which envelopes the liver. Lymphatics from the anterior, superior and inferior surfaces of the liver drain into the hepatic lymph nodes located at the porta hepatis. Additionally, lymphatics from inferior surface can drain directly to lumbar lymph nodes, whereas lymphatics from the superior surface also drain into parasternal/pericardiac nodes. Lymphatics from the posterior surface of the liver drain into celiac/superior mesenteric or posterior mediastinal lymph nodes. Ultimately, lymph reaches the right lymphatic and thoracic duct.
The liver is a special organ in the sense that it receives more venous blood than arterial blood because it helps clean the blood via detoxification. The majority of the vascular supply is brought into this organ by the portal vein which carries blood from the gastrointestinal tract filled with metabolites absorbed in the intestines. The rest of the blood supply to this organ comes from the common hepatic artery which originates from the celiac trunk and carries oxygenated blood to the liver.
The hepatic veins are formed by the union of the central veins. They drain blood from the liver directly into the inferior vena cava just before it passes through the diaphragm.
The nervous supply of the liver comes from the hepatic plexus which travels along with the hepatic artery and the portal vein. The liver also receives sympathetic fibers from the celiac plexus and parasympathetic fibers from the anterior and posterior vagal trunks.
The liver is an essential organ that is responsible for several life-sustaining functions such as metabolism, immunity, digestion, detoxification, and vitamin storage. It is responsible for producing bile which helps in the digestion and absorption of lipids (or fats), while also storing and metabolising fat-soluble vitamins. This organ is crucial in the metabolism or detoxification of several chemical substances such as drugs. It is responsible for the metabolism of bilirubin which results from the breakdown of heme of red blood cells. The liver also participates in the metabolism of thyroid hormones. Finally, it is the place of synthesis of fundamental plasma proteins like albumin and clotting factors.
The characteristic clinical signs of severe hepatic dysfunction include:
- jaundice and cholestasis
- palmar erythema
- spider angiomas
- weight loss
- muscle wasting
Blood tests are performed to evaluate the liver's hepatocyte function and biliary excretion if one or more of these signs are present. The most common hepatic disorders include hepatic failure, cirrhosis, portal hypertension, and cholestasis.
Liver anatomy: want to learn more about it?
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