Structural head injuries
Blows to the head that are sufficient to damage the brain, blood vessels or fracture the skull can be very difficult to tell apart from concussion in the initial stages, but have much greater consequences over the subsequent hours, including disability and even death. Injury to any of these structures results in bleeding and swelling. As the brain is very soft and sits in a rigid box, any bleeding or swelling within the skull will press inwards squash the brain. This is one of the reasons why all head injuries should be taken seriously and players removed from the field of play should not be left alone.
Any force that results in a sudden twisting or rotational injury can tear delicate brain tissue or blood vessels. The temple (temporal bone) that is in front of and above the level of the ear is the thinnest part of the skull and has a large blood vessel underneath it. Hence, a direct blow here can fracture the skull and damage the artery, resulting in bleeding from relatively minor force.