Anastomosis

n. network of connecting channels (between veins of leaves, rivers, etc.); surgical connection of one organ to another (as in separate parts of the intestine)

Anastomosis (plural anastomoses) refers to a form of network in which streams both branch out and reconnect. The term is used in medicine, biology, and geology.
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n. anastomosis

(n.)
The inosculation of vessels, or intercommunication between two or more vessels or nerves, as the cross communication between arteries or veins.
  

noun
connection made between two vessels or two tubes, either naturally or by surgery