Foramen rotundum

The foramen rotundum is a circular hole in the sphenoid bone that connects the middle cranial fossa and the pterygopalatine fossa.

Structure
The foramen rotundum is one of the several circular apertures (the foramina) located in the base of the skull, in the anterior and medial part of the sphenoid bone.

The maxillary nerve passes through and exits the skull via the pterygopalatine fossa and the foramen rotundum.

The mean area of the foramen rotundum/foramina is not considerable, which may suggest that it/they play(s) a minor role in the dynamics of blood circulation in the venous system of the head.

Morphology and morphometry
The foramen rotundum evolves in shape throughout the fetal period, and from birth to adolescence. It achieves a perfect ring-shaped formation in the fetus after the 4th fetal month. It is mostly oval-shaped in the fetal period, and round-shaped after birth (generally speaking). After birth, the rotundum is about 2.5 mm and in 15- to 17-year olds about 3 mm in length. The average diameter of the foramen rotundum in adults is 3.55 mm. This was according to a developmental study published in The Hokkaido Journal of Medical Science on the foramen ovale, the foramen spinosum and the foramen rotundum, and according to a study about the postnatal enlargement of the foramina rotundum, ovale and spinosum and their topographical changes published in the Anatomischer Anzeiger.