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The foramina of the skull refers to the several holes, passages or canals in this part of the skeletal system. The term "foramina" is the plural version of "foramen," which is an anatomical term used for openings that carry or connect different types of arteries, veins and nerves in the body. Those in the skull are no different, as they are instrumental in the storage of these organs.
Most of the foramina of the skull can be found in the sphenoid bone. It is named for its wedge-like shape and helps form the orbits where the eyes and its accompanying parts are located. The optical canal, superior orbital fissure, foramen rotundum, foramen ovale, foramen spinosum and foramen lacerum can be found here. The triangle-shaped foramen lacerum is particularly notable for accommodating the internal carotid arteries, which supply the brain with blood.
Other major sites for the foramina of the skull include the frontal, ethmoid, temporal and occipital bones. The frontal bone, which comprises the forehead, has two foramina: the supraorbital foramen and the foramen cecum, the latter of which is formed by the frontal bone's crest. The ethmoid bone, which functions as the barrier between the brain and nasal cavity, has three foramina: the foramina of cribriform plate, anterior ethmoidal foramen and posterior ethmoidal foramen.
At the sides and back of the skull is the temporal bone, which contains the internal auditory meatus for carrying nerves to certain parts of the ears. Also located at the back of the skull, in the lower region, is the occipital bone. This part of the skull has the foramen magnum, which houses the lower part of the brainstem called the medulla oblongata.
Some foramina of the skull are actually formed by more than one type of cranial bone. For instance, the maxilla, which has the infraorbital foramen, and incisive foramen and canals, is also the site of the lesser palatine foramina and inferior orbital fissure, which it shares with the palatine bone and sphenoid bone, respectively. The lesser palatine foramina serves as the tunnel of the lesser palatine artery, vein and nerve. The inferior orbital fissure carries an assortment of vessels and nerves that include parts of the pterygopalatine ganglion, one of the major tissue masses of the head and neck. The palatine bone, which forms the roof of the mouth and separates the oral and nasal cavities, has the greater palatine foramen in addition to its aforementioned lesser counterpart.