Final Answer:
The concavities below the medial and lateral inferior margins of the zygomatic bones are known as the infraorbital grooves or infraorbital sulci. These grooves serve as pathways for nerves and blood vessels, including the infraorbital nerve and vessels, which supply sensation to the face.
Step-by-step explanation:
The infraorbital grooves, or sulci, are anatomical features located below the medial (towards the nose) and lateral (towards the ear) inferior margins of the zygomatic bones, which are the cheekbones of the skull. These grooves create channels or passages that house important structures, including the infraorbital nerve and vessels.
The infraorbital nerve is a branch of the maxillary nerve, which itself is a branch of the trigeminal nerve (cranial nerve V). This nerve provides sensory innervation to the skin of the midface, including the lower eyelid, upper lip, and part of the nose.
The infraorbital vessels consist of arteries and veins that supply and drain blood from the same region. These vessels play a role in nourishing and draining the tissues around the infraorbital nerve.
Together, the infraorbital grooves serve as protective channels for these nerves and blood vessels as they traverse the facial skeleton, ensuring proper sensory function and vascular supply to the specified areas of the face.