The posterior femoral cutaneous nerve (PFCN) runs underneath the fascia lata most of its trajectory from the gluteal crease to the popliteal fossa with its branches piercing the fascia lata in order to innervate the skin of the posterior thigh, the gluteal crease and the perineum
The PFCN runs across the long head of the biceps femoris in an infero-medial direction between the fascia lata and the muscle fascia
PFCN (yellow) and its inferior cluneal branches (green), long head of biceps femoris (blue asterix), semitendinosus (red asterix), semimembranosus (cyan arrows), gracilis (green arrow), gluteus maximus (cyan asterix)