In mammals, the jugal is often called the zygomatic bone or malar bone. The jugal is a skull bone found in most reptiles, amphibians, and birds. Subsquamosal fenestra, an opening between two parts of the squamosal bone in some rodentsĬhimpanzee skull Goat skull Bones.The fenestrae (from Latin, meaning windows) are openings in the skull. Other vertebrates Fenestrae A Centrosaurus skull Scheme of Spinosaurus skull The many processes of the skull include the mastoid process and the zygomatic processes. The largest of these is the foramen magnum that allows the passage of the spinal cord as well as nerves and blood vessels. Their known functions are the lessening of the weight of the skull, the aiding of resonance to the voice and the warming and moistening of the air drawn into the nasal cavity. The sinuses are lined with respiratory epithelium. The skull also contains sinuses, air-filled cavities known as paranasal sinuses, and numerous foramina. Some of these bones-the occipital, parietal, frontal, in the neurocranium, and the nasal, lacrimal, and vomer, in the facial skeleton are flat bones.Ĭavities and foramina CT scan of a human skull in 3D Some sources count a paired bone as one, or the maxilla as having two bones (as its parts) some sources include the hyoid bone or the three ossicles of the middle ear but the overall general consensus of the number of bones in the human skull is the stated twenty-two. The bones of the facial skeleton (14) are the vomer, two inferior nasal conchae, two nasal bones, two maxilla, the mandible, two palatine bones, two zygomatic bones, and two lacrimal bones. In the neurocranium these are the occipital bone, two temporal bones, two parietal bones, the sphenoid, ethmoid and frontal bones. The human skull is generally considered to consist of twenty-two bones-eight cranial bones and fourteen facial skeleton bones. Most commonly these are found in the course of the lambdoid suture. Sometimes there can be extra bone pieces within the suture known as wormian bones or sutural bones. The facial skeleton is formed by the bones supporting the face.Įxcept for the mandible, all of the bones of the skull are joined by sutures- synarthrodial (immovable) joints formed by bony ossification, with Sharpey's fibres permitting some flexibility. The sutures are fairly rigid joints between bones of the neurocranium. The membranous viscerocranium includes the mandible. The upper areas of the cranial bones form the calvaria (skullcap). The neurocranium (or braincase) forms the protective cranial cavity that surrounds and houses the brain and brainstem. The skull consists of three parts, of different embryological origin-the neurocranium, the sutures, and the facial skeleton (also called the membraneous viscerocranium). Like the skulls of other vertebrates, it protects the brain from injury. It supports the structures of the face and forms a cavity for the brain. The human skull is the bone structure that forms the head in the human skeleton. Skull in situ Anatomy of a flat bone – the periosteum of the neurocranium is known as the pericranium Human skull from the front Side bones of skull In zoology there are openings in the skull called fenestrae.įor details and the constituent bones, see Neurocranium and Facial skeleton. The skull is made up of a number of fused flat bones, and contains many foramina, fossae, processes, and several cavities or sinuses. The human skull fully develops two years after birth.The junctions of the skull bones are joined by structures called sutures. The English word skull is probably derived from Old Norse skulle, while the Latin word cranium comes from the Greek root κρανίον ( kranion). In some animals, such as horned ungulates (mammals with hooves), the skull also has a defensive function by providing the mount (on the frontal bone) for the horns. In humans these sensory structures are part of the facial skeleton.įunctions of the skull include protection of the brain, fixing the distance between the eyes to allow stereoscopic vision, and fixing the position of the ears to enable sound localisation of the direction and distance of sounds. The skull forms the anterior-most portion of the skeleton and is a product of cephalisation-housing the brain, and several sensory structures such as the eyes, ears, nose, and mouth. In humans, these two parts are the neurocranium and the viscerocranium ( facial skeleton) that includes the mandible as its largest bone. However two parts are more prominent: the cranium ( PL: craniums or crania) and the mandible. The skull is composed of four types of bone i.e., cranial bones, facial bones, ear ossicles and hyoid bone. The skull is a bone protective cavity for the brain.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |