(2-part post):
The Crown Prosecution Service provide guidance to their staff, to ensure that the correct charge is brought before the courts. This guidance is based upon both statute law and court precedents, so it's rarely wrong.
Unlike many other 'official' bodies, the CPS doesn't regard the advice it gives to its staff as confidential. The information is freely available to anyone, here:
http://www.cps.gov.uk/legal/section5/chapter_c .html
If you read through that document, you'll see that 'compound fractures, broken cheek bone, jaw, ribs, etc' fall into the category of grievous bodily harm ('GBH') rather than 'ABH' or 'Common Assault'.
If the CPS is convinced that 'GBH' is the correct charge, they then have to decide whether the charge should be brought under Section 20 (which is just 'GBH') or Section 18 (which is 'GBH with intent'). From that link, you'll see that
"Factors that may indicate the specific intent include:
* a repeated or planned attack;
* deliberate selection of a weapon or adaptation of an article to cause injury, such as breaking a glass before an attack;
* making prior threats;
* using an offensive weapon against, or kicking the victim's head."
If the charge is brought under Section 20, the offence is 'either way'. This means that it may be dealt with in the magistrates' court or it can be referred to the Crown court. The usual reasons for the case being transferred to the Crown court are either that the defendant elects trial by jury or that the magistrates decide that, if the defendant is convicted, their sentencing powers would be insufficient. The maximum penalty in a magistrates' court is 6 months imprisonment. The maximum in a Crown court is 5 years.