Shira is a term used collectively for blood vessels (the arteries, the veins and the capillaries). In simple language, dhamani denotes the artery; which carries pure or oxygenated blood. This is also referred to as the arterial system and forms integral part of the circulatory system. Preliminary knowledge of dhamani is very important for physicians as well as surgeons.
The cardiovascular system comprises of the heart and blood-vessels with their contained fluid, blood. The heart is basically a muscular organ pumping blood to all parts of the body by its contraction.
Sushruta calculated that there were about seven hundred, siras (veins), two hundred, dhamanis (arteries). The number of the minute sira and dhamani was equal to same as the number of the hair-follicles. Sushruta Samhita had used the word dhamanis (artery) to some of the mula sthanas of srotas (origin of the channels of the circulations), but he had not used any siras as the mula sthana of a srotas (channels of the circulations).
A structure which has originated in the hollow organs or the vacant are found widespread throughout the human body. These structures are better understood as srotas (channels of circulation) and are distinct from dhamani (artery) and sira (vein).
According to Charaka Samhita, srotas (channels of circulation), sira (vein), dhamani (artery), rasavahini (capillaries), rasayani (lymphatic channels), marga (track), nadi (duct), pantha (passage), sariracchidra (spaces inside the body), samvritasamvrita (duct closed at one end and open at the other), sthana, ashaya and niketa (visible and invisible spaces inside the human body) are constant part of the human anatomy.
According to Charaka Samhita, some of the above described structures having pulsation, and are known as dhamani. Pulsation is described as 'dhmanaddhamanyah' (pulsating process) in Ayurvedic system of medicine. Some have hollow space and allow translocation of nutriments, liquid and blood and are known as srotas (channels of circulation). Some perform simple duty of simply carrying a substance from one place to another, are known as sira (veins).
According to Sushruta Samhita, the concept that there is no difference among sira (vein), dhamini (artery) and srotas (channels of circulations), as dhamini and srotas are only sira vikara (by-products) is wrong. Sushruta categorically says that shamini and srotas are different entities than sira. Sushruta describes following reasons for differentiation among sira (vein), dhamini (artery) and srotas (channels of circulations).
From above discussion, it can be concluded that the arteries can only act as moola sthana (point of origin) but not the veins because they carry impure blood. Further, veins are situated after the channels of circulation, hence veins cannot be considered as mula sthana (point of origin) of any channels of circulation.