lateral intermuscular septum of thigh lateral intermuscular septum of thigh the lateral intermuscular septum of thigh is a fold of deep fascia in the thigh. lateral intermuscular septum of thighcross-section through the middle of the thigh.detailsidentifierslatinseptum intermusculare femoris lateraleta98a04.7.03.004ta22691fma58746anatomical terminology it is between the vastus lateralis and biceps femoris. it separates the anterior compartment of the thigh from the posterior compartment of the thigh.