The Liver is a large organ weighing about 1.5 kg and is situated in the upper part of the abdominal cavity mainly in the right and partly in the left hypochondriac region, i.e. under right side of rib cage. The liver performs important functions besides secreting the bile. It stores the glucose in form of animal starch known as glycogen when blood depletes its glucose required by various organs. In case of fat deficiency, the liver magically transforms part of carbohydrates into fats. It also turns certain toxic substances and, therefore, performs a defensive function. The bile secreted by the liver is stored in a balloon-shaped organ called gall bladder, which releases the bile to the duodenum only when the food enters the duodenum.
The liver is one of the largest organs in the body as well as it is by far the largest gland. It is included amongst the accessory organs of the alimentary system because it produces a secretion, the bile, which is poured into the duodenum and assist the digestive system. All the blood circulating through the capillary bed of the abdominal part of the alimentary canal except the lower part of the anal canal, reaches the liver through the portal vain and its tributaries. So all substances absorbed into the blood from the stomach and the intestine are filtered through the liver, where some of them are stored and some toxic bodies may be destroyed. Many other functions essential to the well being for the human body are performed in the liver and so the liver is regarded as one of the vital organs.
The liver situated in the upper part of the abdominal cavity, mainly in the right hypochondrium and the epigastrium, but part of it extends into the left hypochondrium and part of it into the right lateral region. The liver is roughly triangular and appears to have upper, lower and right borders. In the midline the upper border lies at the level of the xiphisternal joint. To the right of the midline the upper border follows the upper convexity of the right dome of the diaphragm reaching to a level just below the right nipple. To the left of the midline the upper border follows the curve of the left nipple. The right border runs vertically, with an outward convexity and ends at the level of the top of the tenth costal cartilage. The lower border runs obliquely upwards to the left. It crosses the midline at the level of transpyloric plane.
The liver has been traditionally divided into right and left lobes using certain features. On the anterior and superior parts of the diaphragmatic surface the line of demarcation is the attachment of the falciform ligament. On the posterior part of the diaphragmatic surface the line of demarcation is the fissure for the ligamentum venosum, and on the visceral surface it is the fissure for the ligamentum teres. According to this plan of division the caudate and quadrate lobes form part of the right lobe. The liver is drained by two hepatic ducts, right and left which join to the to form the common hepatic duct. On the visceral surface the line of demarcation between these territories lies roughly along the fossa for the gall bladder. On the posterior part of the liver it lies alon the groove for the inferior vena cava. Each lobe is divisible into number of sagments based on the branching pattern of the hepatic ducts within the liver. The left lobe is divided into medial and lateral parts. The lateral parts corresponds to the traditional left lobe. The medial part lies to the right of the attachment of the falciform ligament. The right lobe is divided into anterior and posterior parts each of which is subdivided into superior and inferior segments.
From the preceding account of the peritoneal relationships of the liver it will be clear that surrounding the liver there are a number of more or less isolate regions where the peritoneum covering the surface of the liver is separated from the peritoneum lining the diaphragm, or adjoining viscera, only by potential space. The spaces lying between the diaphragm and the liver are referred to as subphrenic spaces and the spaces inferior to the liver are called subhepatic spaces. The liver receives oxygenated blood through the hepatic artery. Blood from the liver is darined by a number of hepatic veins that open directly into the inferior vena cava.