If you are an active person, you likely rely on your thigh muscles to move the leg forward, backward and to the side. Two muscles, the Sartorius and gracilis are integral to these movements. When injury occurs, this can sideline you from activity and cause pain. Understanding how and why injuries to these muscles occur can help you engage in preventive measures.
The gracilis muscle lies on the inner thigh, connecting from the lower portion of your pubic bone to the upper inner surface of your knee bone. The Sartorius muscle connects from the upper portion of your pubic bone and wraps around the thigh and connecting to the inner portion of the knee. Although the muscles end at similar points, they work in opposition to each other. The gracilis lifts the thigh up, then the Sartorius brings it down. However, both muscles work to flex the knee, allowing the lower leg to come up and foot to touch the buttocks. These muscles can be prone to dysfunction, both due to injury and overuse.
The Sartorius, gracilis and semitendinosus muscles -- which also attaches to the top of the thigh -- and their tendons, which attach the muscles to bone, comprise the pes anserinus, according to Running Times. Underneath this muscle lies a bursa sac, which works to provide a smooth, gliding motion against the hipbone when the muscles are in use. Over time, however, these muscles and tendons can wear against the bursa sac, causing pes anserinus bursitis, which signals inflammation in the bursa sac. This causes pain in the hip and thigh area. If you experience this pain with activities, such as running, see your physician for diagnosis.
Although they act in opposition to move the thigh, the Sartorius and gracilis muscles are used frequently in activity. Any athletic activity that requires running or fast changes of weight will affect these muscles, making them prone to injury. A fast change of weight or a fall can be significant enough to cause injury. Because the thigh area consists of a complex working of muscles, injuries to the Sartorius and gracilis muscles can be mistaken for groin pulls and tibia fractures, according to Sports Injury Bulletin and Running Times, respectively. A physician can evaluate your thigh muscle and target the injury's source.
A good stretching routine prior to activity can help you to reduce gracilis and Sartorius muscle injury. Crossing one leg over the other and leaning forward can stretch the muscles, as can pulling the foot in toward the buttocks and holding for 10 to 15 seconds. Wearing supportive shoes can help as well. If you do experience injury, rest the muscles and ice the affected area to reduce inflammation, according to Running Times. Avoid re-introducing activity too quickly because this can lead to muscle tears and strains.