When your tricep contracts when you extend your arm at the same time your bicep relaxes. Your bicep contracts when you bend your arm and your tricep relaxes. It happens the same way in the chicken arm. In this video you can see the tricep and the bicep relaxing and contracting when moving. IMG_0054-2mhnxix
The surface of the cartilage (elbow joint) feels smooth.
The human arm and the chicken wing both have hinge joints in the elbow and ball and socket in the shoulder. Chicken wings and human arms have a lot in common but both of the structures get modified so that they can get used for what they need to be used for.
The chicken wing has a tendon that extends between the shoulder, radius and ulna. This tendon helps the chicken catch wind and therefor fly. The human arm has hands to grip on to things that help us to pick up things.