The |extensor digitorum| is a wide, lateral muscle group. It has a flat, fusiform belly that extends from the |humerus| (upper arm bone) and towards the lower half of the forearm and develops into four ~tendons~ that insert into the middle and |distal phalanges| of the fingers. It does not insert into the thumb. This muscle works to extend all the joints of the fingers. It also extends the wrist.
