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The facial skeleton comprises the facial bones that may attach to build a portion of the skull. [1] The remainder of the skull is the neurocranium. In human anatomy and development, the facial skeleton is sometimes called the membranous viscerocranium, which comprises the mandible and dermatocranial elements that are not part of the braincase.
The ethmoid bone (/ ˈ ɛ θ m ɔɪ d /; [1] [2] from Ancient Greek: ἡθμός, romanized: hēthmós, lit. 'sieve') is an unpaired bone in the skull that separates the nasal cavity from the brain. It is located at the roof of the nose, between the two orbits. The cubical bone is lightweight due to a spongy construction.
The skull is composed of three types of bone: cranial bones, facial bones and ossicles, which is made up of a number of fused flat and irregular bones. The cranial bones are joined at firm fibrous junctions called sutures and contains many foramina, fossae, processes, and sinuses.
The separation of the cranial bone plates at time of birth facilitate passage of the head of the fetus through the mother's birth canal, or pelvic girdle. The parietal bones, and occipital bone can overlap each other in the birth canal, and form the unusual looking "cone head" appearance in a newborn when delivered in a natural, or vaginal ...
The mastoid process is located posterior and inferior to the ear canal, lateral to the styloid process, and appears as a conical or pyramidal projection. It forms a bony prominence behind and below the ear. [1] It has variable size and form (e.g. it is larger in the male than in the female). It is also filled with sinuses, or mastoid cells.
The sphenoid bone is in red (directly in the middle of the orbital cavity) Wedge-shaped sphenoid bone seen laterally. It is divided into the following parts: a median portion, known as the body of sphenoid bone, containing the sella turcica, which houses the pituitary gland as well as the paired paranasal sinuses, the sphenoidal sinuses [5]
Frontal sinuses are rarely symmetrical as the septum between them frequently deviates to either side of the midline. [3] [1] The two sinuses also vary in extent compared to one another. [2] Their size of the frontal sinuses is highly variable. [2] Rarely, one or both sinuses is hypoplastic [1] or even absent. [1] [2]
Including the bones of the middle ear and the hyoid bone, the head contains 29 bones. Cranial bones (8) Occipital bone; Parietal bones (2) Frontal bone; Temporal bones (2) Sphenoid bone (sometimes counted as facial) Ethmoid bone (sometimes counted as facial) Facial bones (15) Nasal bones (2) Maxilla (upper jaw) (2) Lacrimal bone (2) Zygomatic ...