Made up body part found in some Pharmacology books. Often associated with "Tennis Elbow".
"Usu" has not been found in any other text book as a real connective tissue.
"Tennis Elbow affects the lateral epicondyle of the humerus and the usu."
"I have never heard of an usu muscle or bone."
A suggestion that pops up when you type a single dot(.) into the Youtube search bar. Videos under this search term are known to be extremely disturbing.
A sunburn or suntan focused on the left arm. It is caused by the left side of the body being the only half that gets exposed to sunlight while driving. Presumably, it would be located on the right side of the body in countries where they drive on the left side of the road.