Latin: hepar – liver
The anatomy of the liver describes the anatomic structure of the liver.
The anatomy of the liver can be described according to the morphological or functional aspects. The functional anatomy is primarily used in the clinic. The following information describes the morphological anatomy of the liver and the functional anatomy is depicted in the last paragraph.
The liver is the largest digestive gland of the human body. Its average weight in men is between 1,400 and 1,600 g, in women it is between 1,200 and 1,400 g. Its outer shape can be best compared with that of a broad wedge, with its base directed to the diaphragm and its lower edge is sharply positioned on the ventral or caudal side.
In a transverse direction, the largest expansion of the liver is approx. 20-23 cm, in the vertical direction near the right lateral edge it is 15-18 cm. At the height of the upper right pole of the kidney, there is a sagittal diameter between 10 and 13 cm, which is reduced to approx. 7-8 cm at the height of the spinal column and it continues to decrease laterally in the area of the left lobe of the liver.
The consistency of the liver is soft and elastic. It is dark auburn with a slightly reflective surface. The external coarse adventitia of the liver, which surrounds the actual liver tissue, is known as the liver capsule (Capsula fibrosa renis).
The liver has 3 surfaces, the superior, inferior and posterior. The inferior surface is divided from the superior surface by a sharp, well-defined margin, the sharp liver margin (margo inferior). The other liver margins are rounded.
The facies superior is attached to the diaphragm and the anterior abdominal wall by a falciform ligament, the ligamentum falciforme hepatis. The round ligament of the liver, ligamentum teres hepatis, is located in the free margin of this ligament, which contains the rest of the obliterated umbilical vein. The line of attachment of the falciform ligament divides the liver into 2 parts, a significantly larger right lobe (lobus hepatis dexter) at a left lobe (lobus hepatic sinister).
The facies inferior and posterior are divided into four lobes by five fossae. These fossae are arranged in the form of the letter H, which includes the lobus caudatus to the top and the lobus quadratus to the bottom. The left limb of the “H” is known as the left sagittalis fossa or even the sagittal fissure of liver. It marks the division of the liver into the right and left lobes and is composed of 2 parts, a fossa for the umbilical vein in front (fissura ligamenti teretis) and one to the back for the obliterated Ductus venosus hepatis (fissura ligamenti venosi) for the Ligamentum venosum. The right limb of the “H” is formed in front by the fossa for the gall bladder, the glass bladder fossa (Fossa vesicae felleae), and behind by the fossa for the inferior vena cava, the (fossa venae cavae). These two fossae are separated from one another by a band of liver tissue, termed the caudate process processus caudatus. The bar connecting the two limbs of the “H” is the porta (porta hepatis). This is where the arteria hepatica propria and the vena portae enter the liver, and the ductus hepaticus exit out of the liver.
In addition to these fossae, other impressions of the surface of the liver can be seen on the lower surface of the liver, which are created by the neighbouring organs. These include:
The right lobe is much larger than the left. The proportion between them is approximately 6:1. It occupies the right upper abdomen and is separated from the left lobe on its upper surface by the falciform ligament; on is under or posterior surface by the left sagittal fossa. It is somewhat of a quadrilateral form.
The quadrate lobe is situated on the under surface of the right lobe, bounded ventrally by the inferior border of liver; dorsally by the porta hepatis, on the right by the gall bladder, and on the left, by the left sagittal fissure of liver.
The caudate lobe is situated upon the posterior surface of the right lobe of the liver, opposite the 10th and 11th thoracic vertebrae. It is bounded caudally by the porta hepatis, on the right by the fossa vena cava and on the left by the left sagittal fissure of liver. It is nearly in a vertical position and has a somewhat concave form in the transverse direction. The caudate process is a small elevation of liver tissue from the under surface of the right lobe.
The left lobe is smaller and flatter than the right. It is situated in the epigastrium and in the left upper abdomen. Its superior surface is convex and appears to be moulded on to the diaphragm. There, the inferior surface shows a depression, where the stomach borders the liver.
In young embryos (approx. 28 days), the liver can already be recognised as an epithelial thickening of the endoderm at the transition of the intra to extra-embryonic part of the yolk sac (vesicula umbilicalis). It comprises of an epithelial bud of the embryonic foregut, which proliferates and differentiates to a mature organ.
In addition to the afore-mentioned morphological anatomy – particularly, in surgery – a division of the liver is used according to functional aspects. In doing so, the liver is divided into 8 liver segments. The left lobe is assigned the segments 2-4 and the right lobe, the segments 5-8. Segment 1 corresponds to the lobus caudatus. It is functionally independent because it has an independent vascular supply. According to this division, the margin of the right lobe is at the fossa sagittalis dextra (cava/gall-bladder line).
Important visceral surgical regions of orientation close to the liver during a [[cholecystectomy] are:
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