why do my fingers bend so far back
Hypermobility (joints) Hypermobility, also known as double-jointedness, describes joints that stretch farther than normal. For example, some hypermobile people can bend their thumbs backwards to their wrists, bend their knee joints backwards, put their leg behind the head or perform other contortionist "tricks". It can affect one or more joints throughout the body.
Sheet bend The sheet bend (also known as becket bend, weaver's knot and weaver's hitch) is a bend, that is, a knot that joins two ropes together. Doubled, it is effective in binding lines of different diameter or rigidity securely together, although it has a tendency to work loose when not under load.