In the common imagination, the thoracic and abdominal organs occupy certain positions: the heart is slightly to the left; the lung with three lobes is the right one while the lung with two lobes is the left one; the liver is on the right abdominal side, with the minor lobe oriented towards the inside and with the greater one towards the outside; the stomach is slightly to the left; the first part of the colon (ascending colon) is to the right of the small intestine while the last part of the colon (descending colon) is to the left of the small bowel etc.
In reality, however, there is the possibility that this arrangement is completely reversed, as if it were a mirror image of what has just been described.
In other words, some people have the heart slightly shifted to the right and with the cavities (atria and ventricles) reversed, the lung having three lobes on the left instead of the one with two lobes (which is on the right), the liver on the left but always oriented with the minor lobe towards the inside and the major lobe towards the outside, the stomach to the right, the ascending colon to the left, the descending colon to the right, etc.
This curious condition - called situs inversus totalis or situs viscerum inversus totalis - is of a congenital type and concerns, according to some US estimates, one person per 10, 000. So it's a very rare anomaly.
A VARIANT WITH SITUS INVERSUS TOTALIS
A variant of the situs inversus totalis is the situs inversus with levocardia : the latter is characterized by the inversion of all thoracic and abdominal organs except the heart. The term levocardia, in fact, indicates that the heart is located in the traditional position.
