Modifies a noun

• bursitis: In the knee, this is ' housemaid's knee ' - in the elbow ' olecranon bursitis ' .

• fossa: Full extension of the joint is blocked by the olecranon of the ulna contacting the olecranon fossa on the back of the humerus.

• fracture: Ulnar failure as a greenstick olecranon fracture occurs first.