Vasculature
The liver has a unique dual blood supply:
- Hepatic artery proper (25%) – supplies the non-parenchymal structures of the liver with arterial blood. It is derived from the coeliac trunk.
- Hepatic portal vein (75%) – supplies the liver with partially deoxygenated blood, carrying nutrients absorbed from the small intestine. This is the dominant blood supply to the liver parenchyma, and allows the liver to perform its gut-related functions, such as detoxification.
Venous drainage of the liver is achieved through hepatic veins. The central veins of the hepatic lobule form collecting veins which then combine to form multiple hepatic veins. These hepatic veins then open into the inferior vena cava.
By TeachMeSeries Ltd (2023)
Fig 6 – An overview of the venous portal system – draining into the hepatic portal vein.
Nerve Supply
The parenchyma of the liver is innervated by the hepatic plexus, which contains sympathetic (coeliac plexus) and parasympathetic (vagus nerve) nerve fibres. These fibres enter the liver at the porta hepatis and follow the course of branches of the hepatic artery and portal vein.
Glisson’s capsule, the fibrous covering of the liver, is innervated by branches of the lower intercostal nerves. Distension of the capsule results in a sharp, well localised pain.
Lymphatic Drainage
The lymphatic vessels of the anterior aspect of the liver drain into hepatic lymph nodes. These lie along the hepatic vessels and ducts in the lesser omentum, and empty in the coeliac lymph nodes which in turn, drain into the cisterna chyli.
Lymphatics from the posterior aspect of the liver drain into phrenic and posterior mediastinal nodes, which join the right lymphatic and thoracic ducts.