Which muscle is responsible for pulling the hand inward?

The adductor muscle is primarily responsible for pulling the hand inward. In the context of arm and hand movement, adductor muscles function to bring body parts closer to the body's midline. This contraction helps in various movements, such as gripping or drawing the hand towards the torso.

Understanding the role of different muscle groups is crucial in a nail technician's practice, as it aids in providing effective hand and arm care for clients. The biceps, while significant for flexion of the elbow, does not specialize in pulling the hand inward. The extensor muscles work to extend the fingers and the wrist, and the flexor muscles help in bending the fingers and wrist. All of these serve specific functions that are different from the action of adduction, which is why the adductor is the correct choice for this question regarding inward hand movement.