1 A ligand is any molecule that binds to a specific site on a protein or other molecule. In this case, the estrogen hormone 17-beta-estradiol is the ligand, and the estrogen receptor is the protein.  Binding turns on, or activates, a hormone receptor.
A femoral nerve block is a type of regional anesthesia in which the femoral nerve, located in the groin area, is deadened to allow surgery in the leg or knee area.
The femoral nerve is a nerve in the thigh that supplies skin on the upper thigh and inner leg, and the muscles that extend the knee.1  1 Structure. Anterior cutaneous branches: The anterior cutaneous branches comprise the following nerves: intermediate femoral cutaneous nerve and medial femoral cutaneous nerve (Note the lateral femoral cutaneous nerve is a branch from the lumbar plexus.).