It's important to square the hips in yoga when practicing inversions.
The adductors of the hip are part of the inner hip musculature and range from the lower pelvic bone to the femur and knee region. They are in between the extensor and flexor group of the thigh muscles.
The hip adductors shape the surface anatomy of the medial thigh.
The hip adductors are as follows:
Pectineus muscle: runs from the superior pubic ramus to the pectineal line and linea aspera of the femur. It is additionally innervated by the femoral nerve.
Adductor magnus muscle: is one of the biggest muscles of the human body. It originates at the inferior pubic ramus, the ischial ramus and the ischial tuberosity and inserts both at the linea aspera (“fleshy insertion”) and the medial epicondyle (“tendinous insertion”). The superficial part of the adductor magnus is supplied by the tibial nerve.
Adductor longus muscle: has its origin at the superior pubic ramus and the pubic symphysis and insertion at the linea aspera. Distally it forms an aponeurosis extending to the vastus medialis muscle (vastoadductorial membrane).
Adductor brevis muscle: originates at the inferior pubic ramus and inserts at the linea aspera.
Adductor minimus muscle: describes the inconstant cranial separation of the adductor magnus which is found in many people. It extends from the inferior pubic ramus to the linea aspera.
Gracilis muscle: runs from the inferior border of the pubic symphysis to the medial surface of the tibia, where it inserts as the superficial pes anserinus. Its tendon is easy to palpate in the inguinal region – together with the tendon of the adductor longus muscle.
In inversions the adductors job is to hold the thighs firmly together
You can build strength and balance adductors by squeezing a block while standing or laying on your back with legs out straight will keep adductors in place
An adductor strain is most commonly known as a ‘groin strain’. It is a common injury that involves tearing in the adductor muscle(s) found on the inside of the thigh. Adductor magnus, adductor minimus and adductor brevis are skeletal muscles, and they function to pull your leg inwards. This type of movement is often seen in horse riders, and kicking a ball to the side. They also help to balance your body on uneven surfaces, and can stabilize your trunk when moving laterally.