The fascia iliaca is the muscle fascia of the iliacus muscle and is continuous with the fascia of the psoas major muscle. Laterally it is attached to the iliac crest
The femoral as well as the lateral femoral cutaneous nerves are located underneath the fascia iliaca
The idea of the fascia iliaca block is to inject a large volume of local anaesthetic midways between the femoral and lateral femoral cutaneous nerves in order to obtain lateral and medial spread that will cover both nerves
Fascia iliaca (green line), fascia lata (cyan line), femoral nerve (magenta arrow), lateral femoral cutaneous nerve (black arrow), femoral branch of genitofemoral nerve (green arrow), iliacus muscle (red asterix), psoas major muscle (red arrow), spread of local anaesthetic (yellow) under the fascia iliaca, needle (red)