There could be several reasons why a horse is biting at it's hindquarters.
First it could be a simple itch, caused by either a bug bite or dry skin etc.
Secondly and more importantly, it could be a sign of colic. Horses will bite at their stomachs and flanks when they are experiencing a bout of colic. You should immediately go examine the horse for further signs of colic if you see them doing this just to be on the safe side.
Lastly and rarely it could be a 'vice' some horses will self mutilate in an attempt to relieve boredom. If this is the cause, you will need to make lifestyle changes for the horse.
The hind quarters are upper back leg (thigh) or rump (butt).
It's the backside or hind quarters. That's where the brand goes
They do not have strong hind-quarters and a horse for barrel racing needs them to be able to do fast turns.
Stay a little more then the length of the horses leg behind the horses hind quarters
all dogs have HIND quarters
A horses barrel is it's middle piece, the portion of the body between the shoulders and hind quarters so they only have one.
Horses are built to run, with powerful muscles in the fore- and hind-quarters, long spindly legs, large lungs and a stout heart.
It is called a haunch.
It's a tendon found on the hind quarters that controls the muscle movements of that hind quarter.
This a cross between a zebra and another equine such as horse or donkey. They look like a donkey but with zebra stripes on the legs and sometimes on the hind quarters as well.
the hind quarters or hip area
Yes, the drive comes from the horse's hind legs, which is why when he is not using them properly, his pace is off. You may hear of the horse's hind end "not engaging", which means it is not in sync with is front legs.