This muscle group is part of the upper back area located and attached medially to your scapula. It is also located between the teres major and teres minor muscle ground, also part of the back. The primary function of this muscle is to aid with movement of the shoulder joint.
All muscles of your back are significant to exercise and strengthen for complete back development. Many of the muscles, such as this one interact and effect other groups such as the shoulder muscles so it is important to keep them strong, flexible and healthy. Your rotator cuff is a delicate area and improving you Infraspinatus is beneficial to protecting it.