A Czech snowboarder has miraculously walked away from a crash that split her helmet on the "sketchy" slopestyle course at the Sochi Winter Olympics.

Sarka Pancochova, 23, was coming out of a big jump during the women's slopestyle event when she failed to fully rotate, fell and smashed her head.

Pancochova appeared to go limp in the process and lay still as emergency services personnel ran to her aid and helped her to her feet.

The Czech finished fifth in the event courtesy of a first-run score of 86.25.

The crash comes after the safety of the slopestyle course at Sochi was repeatedly questioned.

Riders who tested it out earlier in the week described it as "sketchy", "dangerous", and "obnoxiously tall", with ramp sizes a particular concern.

Kiwi rider Christy Prior withdrew from the event after sustaining a possible concussion in a crash on the course during practice.

Slopestyle features a long downhill course of obstacles followed by a series of large jumps - with vertical drops of up to 30 metres on the Sochi course.

This is the first time the event has featured at the Olympics.

American snowboarder Shaun White pulled out of the slopestyle event after he decided the potential risk of injury was too great to gamble his other Olympic goals on.

One of the medal favourites in the event, Norwegian Torstein Hormgo, broke his collarbone in practice on Monday while Finland's Marika Enne suffered a concussion on Tuesday.