Foramen spinosum

**The foramen spinosum** is an opening in the skull that connects the upper part of the middle ear to the middle ear. It is located between the pyramid of the temporal bone and the open neck vertebra. The hole diameter ranges from approximately 0.4 mm to 3.8 mm.

All turtles have spinous foramina, but they vary in size, shape, and location within the turtle. Typically, one foramen spinosum is located closer to the occipital edge of the apex of the middle cranial arch, and the other is on the opposite side of the skull.

Functions of the foramen spinosum:

1. Transmission of signals between the pyramids of the temporal bones and the middle ear 2. Formation of an air path between the upper parts of the middle ear and the nose 3. Stabilization of the skull in the plane