What type of fracture occurs when a flat bone, particularly in the skull, is pushed inward due to external pressure?

A depressed fracture is characterized by a segment of the bone being pushed inward, typically seen in flat bones such as the skull. This type of fracture occurs as a result of external forces, which cause a part of the bone to bend inward rather than breaking cleanly along a fracture line, as seen in other types of fractures. In the case of a skull fracture, this can lead to potential complications, such as damage to the brain or surrounding tissues, due to the displacement of bone fragments.

In contrast, a greenstick fracture involves an incomplete fracture where the bone bends rather than breaking all the way through, commonly occurring in children since their bones are more flexible. A comminuted fracture entails the bone being shattered into multiple fragments, which is significantly different from the localized inward displacement seen in a depressed fracture. Lastly, a simple fracture refers to a clean break of the bone without any displacement or fragmentation and does not involve the inward deformation characteristic of a depressed fracture. Thus, understanding the specific mechanics of how the bone is impacted helps clarify why the classification of the depressed fracture is accurate in this case.