Final answer:
A blow to the lateral side of the head can cause bleeding in extradural haemorrhages, leading to the formation of a hematoma between the brain and the skull. Radiographic imaging of extradural haemorrhages shows a localized high-density area on a CT scan, typically with a convex shape and confined within the dura mater.
Step-by-step explanation:
A blow to the lateral side of the head can fracture the bones of the pterion, leading to damage of a major artery that supplies the skull and brain. When the artery is damaged, bleeding can occur, resulting in the formation of a hematoma (collection of blood) between the brain and the skull. This bleeding is likely the origin of bleeding in extradural haemorrhages.
In radiographic imaging, extradural haemorrhages appear as a collection of blood between the skull and the brain. They can be visualized as a localized high-density area on a CT scan, typically with a convex shape. The bleeding is confined within the dura mater and does not cross the midline of the brain.