Looking over the unified MMA rules.. not a whole lot that is specific...
The Unified Rules are the de facto rules for mixed martial arts in the United States, and have been adopted by other promotions and jurisdictions worldwide.
The Unified Rules used to allow all elbow strikes except those hitting downwards with the point of the elbow.
Recent amendments and clarifications to the unified rules now allow all elbow strikes (except those to illegal striking areas of the body, for example, the groin)
The following are fouls, as set out by the Nevada State Athletic Commission:
* Putting a finger into any orifice or into any cut or laceration on an opponent. (see Gouging)
* Clawing, pinching or twisting the flesh.
* Grabbing the clavicle.
* Kicking the head of a grounded opponent.
* Kneeing the head of a grounded opponent.
* Stomping a grounded opponent.
* Spiking an opponent to the canvas on his head or neck. (see piledriver)
* Holding the shorts or gloves of an opponent.
* Spitting at an opponent.
* Engaging in an unsportsmanlike conduct that causes an injury to an opponent.
* Using abusive language in the ring or fenced area.
* Attacking an opponent on or during the break.
* Attacking an opponent who is under the care of the referee.
* Attacking an opponent after the bell has sounded the end of the period of unarmed combat.
* Flagrantly disregarding the instructions of the referee.
* Timidity, including, without limitation, avoiding contact with an opponent, intentionally or consistently dropping the mouthpiece or faking an injury.
* Interference by the corner.
* Throwing in the towel during competition. (forfeit)
* Fighters are tested for steroids and other illegal substances.
It is because you chose to get on the mat that makes you the winner. Think about how many people are not on that mat right now. - Luis Sucuri Togno