The shoulder make up a very large and powerful muscle group that assists in almost all upper body movements. The deltoid and rhomboid muscles that make up the build of the shoulder area are powerful, dense muscles seldom injured in baseball. However if the smaller muscle groups in the rotator cuff area that are more susceptible to injury.
Four small but very important muscles that make up the rotator cuff also with their tendons are the subscapular, supraspinous, infraspinous, and teres minor. This group is located on the rear of the scapula or shoulder blade. Neglecting these small muscle groups in strength training program would be detrimental to a baseball player.