What is the function of the structure at Arrow C?

Identify the structure labeled ” C “

Identify muscle “A”.

Identify the insertion of the muscle indicated by “B”.

Identify the type of synovial joint indicated by the arrow

Identify the structure labeled “B  “

  Identify the structure labeled “B” 

Identify the action of the muscle labeled “A”.

Name the structure labeled “D” on the wall mount above.

What is the action of muscle “C”?