Final answer:
The tenseness of an infant's anterior fontanel can indeed indicate a rise in intracranial pressure. This tenseness can suggest a critical medical condition and is associated with various factors leading to increased pressure within the skull, influencing the skull's growth and the brain's health.
Step-by-step explanation:
The question addresses whether tenseness of the anterior fontanel indicates an increase in intracranial pressure. An anterior fontanel is one of the soft spots on a baby's skull where the bones have not yet fully fused. When intracranial pressure rises, it can cause the fontanel to appear tense or bulge, suggesting abnormal pressure within the skull. Intracranial pressure can be caused by various medical conditions and can be an important clinical sign in assessing an infant's health. The accumulation of fluid, or an increase in brain volume, may exert an outward force on the skull, potentially leading to abnormal growth. Normally, the fontanels, such as the diamond-shaped anterior fontanel at the top front of the skull and the smaller triangular-shaped posterior fontanel at the back, allow for the movement and change of shape of the bony plates during birth and growth of the child. The ossification process is expected to close the posterior fontanel within the first few months after birth and the anterior fontanel between nine to 18 months.
Concerning cranial expansion due to increased pressure, gauge pressure in the fluid surrounding the brain can become abnormally high, resulting in an outward force. For instance, when gauge pressure reaches 85.0 mm Hg, which is far above the normal range of 5 to 12 mm Hg, this pressure can lead to the skull growing abnormally large. To calculate the force exerted on an infant's skull, one would multiply this increased pressure by the effective area of the skull in contact with this pressure.