Karugtong stems from "dugtong" which means "connection / addition / extension".
E.g. "<em>Ang tricycle ay isang sasakyan na motorsiklong may karugtong na sidecar."</em> (A tricycle is a vehicle which is a motorcycle that has a sidecar attached to it).
Hope this helps.
PS:
<em style="background-color: rgb(251, 250, 250); color: rgb(112, 112, 112);">Yung karugtong ng bituka ng manok </em>--> "The thing that's attached/connected to the chicken's intestines".