Vascular family and vascular order

What is a vascular family?
The term "vascular family" refers to a group of vessels that arises from a single vessel originating from aorta. For example right iliac artery and all its branches and subbranches comprise a vascular family called right iliac family.


What is a vascular  order?
Within a vascular family, the branch that arises from the aorta is called first order vessel. The branches that arises from first order vessel are termed as second order vessels. The branches that arises from second order vessels are termed as third order vessels. In other terms, order increases each times a vessel bifurcates or splits. For example common iliac are first order vessels because they arise directly from aorta. The internal and external iliac are second order because they arise from first order vessel "iliac."

Some of the first order vessels are Iliac artery, left common carotid, brachiocephalic, renal artery, etc.