This sketch shows possible muscle structure and construction. Color codes as follows:

Red = silicone/fiber composite tendon tissue
Yellow = air muscles
Blue = kevlar & carbon fiber composite bones
Green = silicone/fiber composite ligament connective tissue
White = original ostrich bone
Orange = folded position of arm extension

Tech specs: Leg Extensions

We have acquired actual ostrich leg bones which we will either mold and reproduce in fiber composites, or use directly by reinforcing with carbon fiber rod, spectra fiber, and epoxy resin. These bones will have teflon caps (cartilage) interlaced into the bone structure, and will be affixed at each joint with silicone and fiber composite ligaments. Air muscles would be interlaced into this configuration with silicone and fiber composite tendons, and could be activated via computer controlled valves and a source of compressed air. These simple actuators consist of a rubber tube covered in tough plastic netting which shortens in length like a human muscle when inflated with compressed air at low pressure.