Basketball is a game of speed, quickness, agility and jumping power. You also have to make quick decisions, and make them while you are dribbling and weaving around defenders. When you find an opening and it comes time to plant your feet and shoot the basketball, numerous muscles are being used.
The triceps are the large muscles located on the backs of your upper arms. Their anatomical function is to extend the elbow. This action would be seen when your arm goes from a bent to straight position during your shot.
Every time your upper arm gets elevated, your shoulder muscles are being used. While shooting a basketball, the shoulder muscles on your shooting arm are being more heavily recruited than the muscles on your non-shooting arm. This is because the humerus--the large bone in your upper arm--is being elevated higher. The trapezius and deltoids are the anatomical names for the muscles being used. The trapezius is located on the top of the collar bone, and the deltoids are found at the very top of the arm around the shoulder joint.
The forearms contain two groupings of muscles on the inner and back sides. The wrist extensors open the fingers and cause the hand to go back toward your upper arm. These muscles are being activated when you ave the ball up in front of your body. Once you follow through with your shot and your hand goes downward, your wrist flexors are being used.
The biceps brachii are the muscles on the front of your upper arms. They cause the elbow to flex, which is a motion you would see when your lower arm is coming back toward your upper arm. When shooting a basketball, your biceps promote the movement of the ball from a position in front of your body to the shooting position. Notice how both elbows are bent right before you shoot.
The pectoralis major and minor are the muscles in your chest. The pec minor is located under the pec major, and it is being activated when your shoulder shrugs in a forward direction. This is the movement you would see when your shooting arm is going forward.