A 28-year-old man is brought to the emergency department after a motor vehicle collision with loss of consciousness at the scene. He regains consciousness and appears alert, conversing normally with paramedics during transport. Upon arrival, he suddenly becomes drowsy and develops a fixed, dilated right pupil. Non-contrast CT head is performed urgently. The structure marked **A** in the diagram shows a biconvex, hyperdense collection limited by suture lines overlying the right temporal region with an associated skull fracture. Which of the following best explains the mechanism of formation of this lesion?