Foramen ovale

Where is the foramen ovale of the skull located?

The foramen ovale is located at the internal base of the skull, specifically in the middle cranial fossa (fossa cranii media). Topographically, it belongs to the region of the greater wing of the sphenoid bone.

The opening serves as an important communication pathway: it connects the cranial cavity with the external base of the skull (basis cranii externa). The external base continues freely into the infratemporal fossa (fossa infratemporalis). Spatially at the external base, it lies posterior to the lateral plate of the pterygoid process of the sphenoid bone.

What passes through the foramen ovale?

The structures of the trigeminal nerve (cranial nerve V) exit the cranial cavity through this opening:

• Mandibular nerve (n. mandibularis) — the third branch of the trigeminal nerve. It is a mixed trunk containing sensory and motor fibers, with sensory branches making up the majority of the nerve.
• Motor fibers of the trigeminal nerve (portio minor) — exit the skull along with the mandibular nerve. They originate from the motor nucleus in the tegmentum of the pons and provide innervation to the masseter, temporal, lateral and medial pterygoid muscles, as well as the mylohyoid muscle, the anterior belly of the digastric muscle, and the tensor tympani muscle.

Clinical significance: trunk anesthesia

In dental and maxillofacial surgery, the foramen ovale serves as a target point for trunk anesthesia of the mandibular nerve. This type of pain relief is indicated in traumatic surgeries when anesthesia of the tissues of the entire mandible is required.

According to the anatomical rationale by S.N. Vaisblat, the main bony landmark is the lateral plate of the pterygoid process. The foramen ovale lies in the same plane as this plate, but posterior to it. A 7–8 cm needle is used to perform the anesthesia.

Do not confuse with: Foramen ovale of the heart

In anatomy, the term "foramen ovale" (foramen ovale cordis) is also applied to a structure of the fetal cardiovascular system.

• Prenatal period: This is an opening with a valve (flap) in the interatrial septum (septum interatriale). It acts as one of the arteriovenous shunts, directing blood from the inferior vena cava through the right atrium into the left atrium, bypassing the pulmonary circulation.
• After birth: The pressure in the left heart chambers exceeds that in the right chambers by 6–8 times. The flap closes, preventing left-to-right blood flow. Closure typically occurs within the first 3 months of life, sometimes taking 1–2 years. The fossa ovalis (fossa ovalis) is formed on the septum.
• Pathology: If the opening remains inappropriately large (defect), the flap fails to prevent shunting. A "white type" congenital heart defect occurs with left-to-right blood shunting. Enlargement of the right heart chambers and dilation of the pulmonary artery are observed; the left ventricle remains unaffected.

Class and exam questions

What else to study on this topic

• Trigeminal nerve (CN V)
• Middle cranial fossa
• Infratemporal fossa
• Fetal circulation (fetal shunts)

Other topics in the "Anatomical Structures" section

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