Lobus caudatus

The liver is grossly divided into two portions – a right and a left lobe, as viewed from the front (diaphragmatic) surface; but the underside (the visceral surface) shows it to be divided into four lobes and includes the caudate and quadrate lobes. The liver is grossly divided into two portions – a right and a left lobe, as viewed from the front (diaphragmatic) surface; but the underside (the visceral surface) shows it to be divided into four lobes and includes the caudate and quadrate lobes. The falciform ligament, visible on the front of the liver, divides the liver into a left and a much larger right lobe. From the underside, the two additional lobes are located between the right and left lobes. A line can be imagined running from the left of the vena cava and all the way forward to divide the liver and gallbladder into two halves. This line is called 'Cantlie's line'. Other anatomical landmarks exist, such as the ligamentum venosum and the round ligament of the liver (ligamentum teres), which further divide the left side of the liver in two sections. An important anatomical landmark, the porta hepatis, also known as the transverse fissure of the liver, divides this left portion into four segments, which can be numbered starting at the caudate lobe as I in an anticlockwise manner. From this parietal view, seven segments can be seen, because the eighth segment is only visible in the visceral view. The left lobe is smaller and more flattened than the right. It is situated in the epigastric and left hypochondriac regions. Its upper surface is slightly convex and is moulded on to the diaphragm; its under surface presents the gastric impression and omental tuberosity. The right lobe is much larger than the left; the proportion between them being as six to one. It occupies the right hypochondrium; on its posterior surface by the ligamentum venosum for the cranial (upper) half, and by the ligamentum teres hepatis (k.a.k.a. Round ligament of liver) for the caudal (under) half. The ligamentum teres hepatis turns around the inferior marging of the liver to come out ventral in the falciform ligament. The right lobe is functionally separated from the left lobe by the middle hepatic vein. A common misconception is that the falciform ligament separates the two lobes. However, from a functional perspective (one that takes the arterial, portal venous, and systemic venous anatomy into account) the falciform ligament separates the medial and lateral segments of the left hepatic lobe. The right lobe is of a somewhat quadrilateral form. Its under and posterior surfaces being marked by three fossæ: the fossa for the portal vein, the fossa for the gall-bladder and the fossae for the inferior vena cava. These separate the right lobe in two smaller lobes on its left posterior part: the quadrate lobe and the caudate lobe. The quadrate lobe is an area of the liver situated on the under surface of the medial segment left lobe (Couinaud segment IVb), bounded in front by the anterior margin of the liver; behind by the porta hepatis; on the right, by the fossa for the gall-bladder; and on the left, by the fossa for the umbilical vein.