The structure indicated is the infraorbital foramen of the skull.

The infraorbital foramen are a pair of external foramina of the skull which are visible anteriorly on the skull. Foramen (foramina is plural), are holes in the human body which allow other structures to pass through. In the case of the skull, foramina permit the passage of arteries, veins and nerves.

There are three pairs of foramina visible from an anterior view of the skull:

1. Infraorbital foramen
2. Supraorbital foramen
3. Mental foramen

The infraorbital foramen is located in the maxillary bone of the skull just below the inferior margin of the orbit.

The infraorbital foramen permits the passage of three structures:

1. Infraorbital artery
2. Infraorbital vein
3. Infraorbital nerve (a branch of the maxillary division (V2) of the trigeminal nerve [cranial nerve V])

Learn more about the skull and the cranial nerves.