Patagium

[3][4] Various species have styliform bones to support the membranes, either on the elbow (colugos, anomalures, greater glider, Eomys) or on the wrist (flying squirrels).

[citation needed] In birds, the propatagium is the elastic fold of skin extending from the shoulder to the carpal joint, making up the leading edge of the inner wing.

Many authors use the term to describe the fold of skin between the body (behind the shoulder) and the elbow that houses the outer segments of the latissimus dorsi caudalis and triceps scapularis muscles.

[5] Similarly the fleshy pad that houses the follicles of the remiges (primary and secondary feathers) caudal to the hand and the ulna is also often referred to as a patagium.

[6] The interremigial ligament that connects the bases all the primary and secondary feathers as it passes from the tip of the hand to the elbow is thought to represent the caudal edge of the ancestral form of this patagium.