Bennie,
Typically, injuries can be divided into three main catagories: blunt trauma, penetrating trauma and acceleration/deceleration injuries.
"Blunt trauma" essentially envolves a sudden and violent force that does not pierce or penetrate, the injury can "appear" to be minor, however the underlying injury to bloodvessels, nerves, bones and organs can be significant.
"penetrating injuries" are excatly that, something penetrates into the body, anything from a small splinter to your profile tube through your chest wall, once again the injury can appear failry insignificant as the entrance site may be small, however when major body cavities or blood vessels are are envolved these are usually very seriousrequiring promt attention.
Acceleration/ deceleration injuries happen when a body is suddenly throw foward/ or stopped. Structures within the body are damaged as they are moved beyond their usual range of motion. typical examples usually envolve the neck eg someone drive up your rear while you are stopped (rapid accelaration, head thrown backwards), or you drive into something stationary (rapid decelaration, head thrown foward). Another structure that is at risk of injury with this type of injury is a section of the main artery that leaves the heart (the aorta). a high speed impact in your trike could cause this type of injury.
Pilots can be exposed to any combination of the above mechanism of injuries with all of the associated problems. When encapsulated in a "blik", the occupants are typically surounded by a "crumple zone" ie the body of the A/C absorbs and disipates the intial forces of the impact, aswell as a physical barrier from debris thrown up eg broken props, however once the dust has settled, this very same "protective" barrier may become a prison, many crash victims have survived the crash only to be overcome by the secondary smoke, fumes and fire, with no way out.
A trike pilot is not protected by surrounding structures at all. The trike pilots body is exceptionally exposed to the forces of the impact, followed by the rest of the wing, motor, the prop and pax from above and behind so unfortunately the probability of severe injury is significant, the risk to pax is marginally lower as he/she has you, the pilot, to use as a "airbag".
It would be near impossible to draw up stats on the injury types as there are so many variable factors envolved with a/c crashes, just like car crashes, each and every one is unique. There are just so many factors and foces at play.
It would be howver fair to suggest that the risk (based on the mechanism) of head injuries, neck injuries, chest and back injuries injuries, abdominal injuries and lower limb (ie leg) injuries would be high risk. (have i left anthing out)
Helmets are a big plus here to protect your pip from above and behind, if you are really concerned about your chest/back then you could probably get some protection with a moto-cross chest protector and firm kidney belt...

(although im not sure how practical this would be for flying).
The lapbelt type of seatbelts do not restrain the body from being thrown foward into the profile tube, (in addition to damaging the abdominal organs by blunt trauma), so a 3 point restrain system has benefit here aswell.
There have also been occurences of fuel tank ruptures with MP accidents and ensuing fires, unfortunately 50 liters of burning fuel does not give the pilot or pax much chance.
Hope i havent fueled any fears in you for future flights, just remember that all of the above applied everytime you drive your car to go and buy a loaf a bread.......
fly safe, land safer!!!

ZU-CPW..... t/bird mk2
Hoedspruit Civil Airfield
Hangar 8