In the newborn, the foramen spinosum is about 2.25 mm long and in adults about 2.56 mm. The width of the foramen variesfrom 1.05 mm to about 2.1 mm in adults. The average diameter of the foramen spinosum is 2.63 mm in adults. It is usually between 3 and 4 mm away from the foramen ovale in adults.

The earliest perfect ring-shaped formation of the foramen spinosum was observed in the eighth month after birth and the latest seven years after birth in a developmental study of the foramen rotundum,