Following a fall, a crying 8-month-old infant is admitted. What is the reason for the increased severity of brain injuries in this age group?

The increased severity of brain injuries in 8-month-old infants can primarily be attributed to the characteristics of their developing cranial structure. At this age, the skull is thinner and more pliable compared to that of older children and adults. This anatomical feature allows for less protection against external forces. When an infant falls, the softer skull can absorb impact more easily, leading to a greater likelihood of sustaining brain injuries, including contusions and bleeding within the brain.

The other options do not account for the physical characteristics of the infant's skull structure effectively. For instance, while blood volume and neurological monitoring or myelination may play roles in various aspects of brain function, they do not explain the immediate biomechanical vulnerability that contributes to the severity of injuries from falls in infants. The pliability of the cranium in young children significantly heightens the risk of severe injuries upon impact, making this characteristic the primary reason for increased injury severity in this age group.