The liver is a large essential organ found in the upper right quadrant of the abdomen. It is a multifunctional accessory to the gastrointestinal tract and performs such duties as detoxification, protein synthesis, biochemical production and nutrient storage to name but a few. It is the largest gland in the human body, weighing in at approximately 1.5 kilograms. It works synchronously with many other organs and contributes to the maintenance of the basic homeostatic mechanisms.
|Function||Over 500; Main: xenobiotic biotransformation, protein synthesis, nutrient storage, bile production|
Lobes: right, left, caudate, quadrate
Surfaces: diaphragmatic, visceral
Ligaments: coronary, left triangular, falciform, round ligament, venous
Fissures and recesses: porta hepatis (central fissure - contains portal vein, hepatic artery, hepatic nervous plexus, hepatic ducts, lymphatic vessels), subphrenic recess (division between the liver and the diaphragm), hepatorenal recess (separates the liver and the right kidney and suprarenal gland)
Hepatic nodes → celiac nodes -> cisterna chyli -> thoracic duct
Via bare area of liver: right lumbar nodes -> right posterior mediastinal nodes -> right lymphatic duct or thoracic duct
Inferior/anterior/superior surfaces → hilar hepatic nodes
Right superior surface → celiac nodes (via path of inferior phrenic artery)
Surface of coronary and right triangular ligaments → thoracic duct (direct)
Posterior surface → right lumbar nodes → right posterior mediastinal lymph node chain (bypasses thoracic duct)
Functional: portal vein (metabolic processing of the matters absorbed in intestines)
Nutritive: hepatic artery (supplying the tissue of the liver with oxygen and nutrients)
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 main anatomical knowledge that is generally required plus a few notes about the clinical pathology of the liver.
- Porta hepatis and recesses of the liver
- Lymphatic drainage
- Blood supply
- Clinical aspects
There are four anatomical lobes to the liver, which are further divided into even smaller segments in accordance with the blood supply. The right lobe is the largest of the four lobes and the left lobe is a flattened smaller one.
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. If we would divide the liver into the left and right halves by a line that lies in the sagittal plane and passes through the falciform ligament, then the all the lobes but the right one lie from the left side of the sagittal plane.
The two major aspects or surfaces of the liver are the diaphragmatic surface and the visceral surface. The latter is shrouded by the peritoneum except at the porta hepatis and the bed of the gallbladder. It is directly related to several anatomical structures which include the:
The diaphragmatic surface is also covered by the peritoneum except in the bare area.
There are five ligaments that are directly related to the liver and they are called:
Coronary ligament -
formed by the peritoneal reflection from the diaphragm to the liver which has two layers that meet on the right.
- Left triangular ligament - is a mix of the falciform ligament and the lesser omentum.
- Falciform ligament - is not of embryological origin, but a peritoneal reflection of the upper abdominal wall from the umbilicus to the liver and has the round ligament of the liver on its free edge.
- Ligamentum teres hepatis - is also known as the round ligament of the liver. It is a fibrous remnant of the umbilical vein which still extends from the internal aspect of the umbilicus up to the liver.
- Ligamentum venosum - is also an embryonic remnant of the ductus venosus. In utero it extended between the umbilical vein and the inferior vena cava.
Porta hepatis and recesses of the liver
The porta hepatis is the central intraperitoneal fissure of the liver that separates the caudate and the quadrate lobes. It is the entrance and the exit for several important vessels including the portal vein, the hepatic artery, the hepatic nervous plexus, the hepatic ducts and the lymphatic vessels.
The subphrenic recess which is split by the falciform ligament of the liver, is the division between the liver and the diaphragm.
The hepatorenal recess is on the inferior right aspect of the liver and separates it from the kidney anterior inferiorly and the suprarenal gland posterior inferiorly.
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 inferior diaphragmatic/phrenic nodes (or uppermost members of the the right lumbar lymph nodes) which drain to the right posterior mediastinal 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. The inferior, anterior and superior surfaces drain to hepatic nodes at the liver hilum. The right superior surface will often drain to lymph vessels following the inferior phrenic artery and connect with the celiac nodes. The posterior surface of the liver is conducted towards the bare area of the liver and into the inferior diaphragmatic nodes/right lumbar nodes, which drain as described above.
The liver is a special organ in the sense that it receives more venous blood than arterial blood and this is due to the fact that the liver helps clean the blood via detoxification. The majority of the vascular supply is brought into the organ by the portal vein which carries the blood filled with metabolytes absorbed in the intestines, whereas the rest of the blood comes from the common hepatic artery which originates from the celiac trunk and carries the oxygenated blood to the liver.
The hepatic veins drain the blood supply to the liver and they are formed by the union of the central veins which drain 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 characteristic clinical signs of severe hepatic dysfunction include:
- jaundice and cholestasis
- palmar erythema
- spider angiomas
- weight loss
- muscle wasting
If one or more of the previously mentioned symptoms is present, a blood test is performed to test the liver’s hepatocyte integrity, biliary excretory function and hepatocyte function. The most common hepatic disorders include hepatic failure, cirrhosis, portal hypertension and cholestasis.