Anatomy of liver,eight lobes of liver,grooves and fissures|blood and nerve supplies to liver

Liver:

The largest organ in the body and is the accessory organ of the gastrointestinal system. I t is completely covered by by a fibrous capsule but is only partially covered by peritoneum.

Location: 

The liver is predominantly located in the right hypochondrium and epigastric areas, and extends into the left hypochondrium.

It occupies the upper part of abdominal cavity just beneath the diaphragm.It is usually 15 to 17 cm in length with its upper border usually at the level of nipples and lower border at the level of costal cartilage of the 8-9th rib.

The  liver may be divided into a large right lobe and the small left lobe by the attachment of the peritoneum of the falciform ligament.
The right lobe is further divided into:
Quadrate lobe and caudate lobe.

Couinaud's Anatomy:

It is becoming the universal nomenclature for hepatic lesion localisation.It is based on portal segments.The liver has eight segments and each segment has its own blood supply and these are of both functional and pathological importance.

Segment 1 is the caudate lobe,2 and 3 are the  left superior and inferior lateral segments respectively.Segment 4 is the medial segment of the left lobe and further divided into the 4(a) and 4(b). The right lobe consists of four segments.

Segment 5 and 6 are the inferior anterior and posterior segments respectively.Segment 7 is the posterior superior segment and segment 8 is the superior anterior one.

Fissures:

The two fissures, fissure for the ligamentum teres and fissure for ligamentum vesnosum are present in the liver.

Fissure for the ligamentum teres:

The fissure that contains the ligamentum teres(the fibrous remains of the umbilicak vein) lies between the left lobe and the quadrate lobe.

Fissure for ligamentum venosum:

The fissure that contains the ligamentum venosum(fibrous remains of ductus venosus) lies between the left lobe and caudate lobe.

Groove:

The liver contains a groove for the inferior vena cava which lies between the right lobe  and caudate lobe. Here the hepatic vein joins the inferior vena cava.

Ligaments of liver:

There are various ligaments that attaches the liver to near structures, these are:

• Falciform ligament :

The falciform ligement is a two layered fold of peritoneum that attaches the liver to the diaphragm above and to the anterior abdominal wall below.It has a sickle shaped free margin that contains the ligamentum teres.

• Coronary ligament (anterior and posterior folds):

  It attaches the superior surface of the liver to the inferior surface of the diaphragm and demarcates the bare area of the liver The anterior and posterior folds unite to form the triangular ligaments on the right and left lobes of the liver.

• Triangular ligaments (left and right):
  • The left triangular ligament is formed by the union of the anterior and posterior layers of the coronary ligament at the apex of the liver and attaches the left lobe of the liver to the diaphragm.
  • The right triangular ligament is formed in a similar fashion adjacent to the bare area and attaches the right lobe of the liver to the diaphragm.

• Lesser omentum – Attaches the liver to the lesser curvature of the stomach and first part of the duodenum. It consists of the hepatoduodenal ligament (extends from the duodenum to the liver) and the hepatogastric ligament (extends from the stomach to the liver). The hepatoduodenal ligament surrounds the portal triad.

Blood supply of liver:

Arterial supply

• The celiac artery branches into hepatic artery.
• Hepatic artery divides into left and right terminal branches that supplies the porta hepatis.

Venous supply

• Portal vein divides inro right and left terminal branches that enter the porta hepatis.
• Three or more hepatic veins drain into inferior vena cava emerge from the posterior surface of liver.

Lymphatic drainage:

• celiac nodes
• posterior mediastinal nodes 

The above nodes receives the lymph drainage that passes from porta hepatis and diaphragm respectively to enter the nodes.

Nerve supply

The liver is supplied by both sympathetic and parasympathetic fibers from celiac plexus.

The 10th cranial nerve(vagus nerve)gives off a large hepatic branch that travels to liver.