Foramen ovale (skull)

Structure

The foramen ovale is an opening in the greater wing of the sphenoid bone. The foramen ovale is one of two cranial foramina in the greater wing, the other being the foramen spinosum. The foramen ovale is posterolateral to the foramen rotundum and anteromedial to the foramen spinosum. Posterior and medial to the foramen is the opening for the carotid canal.

Contents

The following structures pass through foramen ovale:

• mandibular nerve (CN V₃) (a branch of the trigeminal nerve (CN V))
• accessory meningeal artery
• lesser petrosal nerve (a branch of the glossopharyngeal nerve)
• an emissary vein connecting the cavernous sinus with the pterygoid plexus
• (occasionally) meningeal branch of the mandibular nerve

Variation

In a study conducted on 100 skulls, the foramen ovale was divided into 2 or 3 components in 4.5% of the cases. The borders of the foramen in some skulls were also irregular and rough. This may suggest, based on radiological images, the presence of morbid changes, which might be the sole anatomical variation in the foramina ovalia of humans.

In newborn, the foramen ovale is about 3.85 mm and in the adults about 7.2 mm in length. The average maximal length is about 7.48 mm and its average minimal length is 4.17 mm in the adult. The width extends from 1.81 mm in the newborn to 3.7 mm in adults.

Development

Similar to other foramina, the foramen ovale differs in shape and size throughout life. In a study using over 350 skulls, the earliest perfect ring-shaped formation of the foramen ovale was observed in the 7th month of fetal life, and the latest in 3 years after birth.