The medial circumflex femoral vein refers to a blood vessel located in the leg. An extension of the major femoral vein, it runs up the thigh. Unlike the accompanying femoral artery, the femoral vein and its branches direct blood flow towards the heart. The medial circumflex femoral vein is identified as one of the components of a segment in the thigh designated as the femoral triangle. The vein is located between the parts of the thigh known as the inguinal ligament, the sartorius muscle, and the abductor longus. It travels within close boundary of the femoral nerve, femoral artery, and the deep inguinal lymph nodes. The medial circumflex extension in conjunction with the femoral triangle plays an important part in maintaining healthy blood flow in the leg and groin. Thrombosis of the medial circumflex femoral vein has been reported. A thrombosis blood clot obstructs blood circulation within the vein and surrounding blood vessels. The patient can experience thigh pain that mimics the pain associated with a hamstring injury.