The knee helps your leg flex and extend.
extend
your joints help your fingers bend and flex
i done no
fixed joint
Crepitus is the grinding sensation that can be felt if you place your hand over the knee and flex and extend it.
Both
The Biceps flex the elbow The Triceps extend the elbow
The hamstrings flex the knee and extend the hip.
Biceps Brachii flexes the forearm and the Triceps Brachii extends the forearm.
No, this is not possible. Elbows extend by means of the triceps brachii (triceps). You can try to flex your bicep as you extend your arm, but when itès fully extend its not possible.
Pectoralis major