On the dorsal side, two long extrinsic extensor muscles are superficial to the intrinsic muscles, and their tendons form the dorsal aponeurosis of the toes.
It runs through the fourth tendon compartment together with the extensor digitorum, from where it projects into the dorsal aponeurosis of the index finger.
L oose connective tissue between the periostium and the aponeurosis makes these two rigid structures easily slide over each other and contributes to skin movement.