Sinew is the term used to describe tendon or ligament in more formal English. It is the cord that connects muscle to bone or bone to bone in skeletal animals. Like rope, it is made up of bundles of bundles of bundles as shown in this anatomical illustration.
For our purposes, sinew is a true gift to the primitive technologist, survivalist, or low-tech hunter as it provides us with so many possibilities. Sinew is the fiber stripped from animal tendons and used as a strong thread or it can be braided or plied together to make a stronger cord or rope. It can be used to make bow strings, tie objects together permanently, backing and strengthening a bow, or lashing spear or arrow points onto their shafts. It binds well with hide glue, having almost identical chemistry (collagen). This causes it to act a lot like duct tape, binding and sticking to most surfaces.
It is also important to know that every human on Earth had access to and likely utilized sinew in the pre-modern world. It is a gift of nature that aided our ancestors in the making of compound and composite tools.
Here are two recently hafted spear points points. If you haven’t worked with sinew, its difficult to convey just how amazing and useful this material is. It has been called the “duct tape” of prehistory but it is even better than that. It not only holds well and is remarkably strong, but shrinks and strengthens as it cures. The points above were hafted (tied on) with sinew dipped in hide glue to create a solid and tight hold on points. This method holds up very well for throwing darts or spears and is nearly impossible to break.
If you hunt (or know someone who does), you can acquire this from the legs and back straps (the strap covering the tenderloins) of nearly any animal of size. Elk, bison, and deer are obvious candidates for long pieces and are readily available in North America. Smaller animals such as rabbit can be used, but as in so may things, longer can really be better. The main issue I have with the shorter sinews is that it is more difficult to work wet as it must be continually added while binding.
The more you know…