Shoulder and arm muscles
The arms and shoulders house many major muscles that we use for movements of the upper body. Across the lower arm are the forearm muscles that allow us the grip and lift objects called wrist flexors and extenders. The most well known muscles are in the upper arm, on the front of the upper arm is the bicep which allows our arm to bend. And on the rear of the upper arm are the triceps which straightens the arm. Across the shoulder are the deltoids, front middle and rear, which each work individually to cause movement towards the front, out to the side and to the rear of the body of the arm.