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| The Skull |
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| The skull is the bony framework of the head, arranged in two parts-the cranium which has eight bones and facial skeleton having fourteen bones |
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| Human Skull |
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| Cranium |
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| It is the large, hollow, rounded part of the skull. Its cavity is termed as cranial cavity which encloses the brain during life. Hence, the cranium is also called brain box. The cavity of cranium presents an upper surface known as the vault of the skull which, is smooth on its outer surface and marked by ridges and depressions to accommodate the brain and its blood vessels on the inner surface. The lower surface of the cavity is known as the base of the skull. It is perforated by many holes for the passage of nerves and blood vessels. |
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| The cranium is formed by 8 flattened bones which include 1 frontal, |
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| 2 parietals, 1 occipital, 2 temporals, 1 sphenoid and 1 ethmoid bone. |
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| The cranial bones fit together by wavy, immovable boundries called sutures. The sutures help to dissipate the shock of a blow to the head. Parietal bones are demarcated from the frontal bone by a coronal suture, from the occipital bone by a lambdoidal suture and from the temporals by lateral sutures. |
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| Human Skull |
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| A large hole, called foramen magnum, at the base of the skull allows the brain to continue into the spinal cord located within the backbone. On either side of the foramen magnum are masses of bone which form the condyles of the skull called occipital condyles, that movably articulate with the atlas vertebra(first vertebra), forming a hinge joint that permits nodding of the head. On either side of the cranium is an auditory capsule that contains 3 small bones called ear ossicles, individually named outer malleus, middle incus and inner stapes. These bones are movable and help in hearing. |
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| Bones of the face |
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| There are 14 facial bones, all except the mandible being united by sutures that are immovable. |
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| Two nasal bones form the bridge of the nose. |
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| Two palatine bones form the roof of the mouth and the floor of the nose. |
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| Two lacrimal bones form the tear ducts and part of the orbit at the inner angle of the eye. Through tear ducts the fluid from the eye is carried to the nasal cavity. |
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| Two zygomatic bones form the cheek bones. Processes from these bones unite with the zygomatic processes of the temporal bones to from the zyogmatic arch. |
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| One vomer forms the lower part of the bony partition in the nose. |
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| Two inferior turbinate bones are the larger pair of three projections, nasal conchae, from the lateral wall of the maxilla. |
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| Two maxillae form the upper jaw and contain the upper teeth. |
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| The mandible forms the lower jaw, It is the only movable bone in the skull apart from the ossicles of the ear. It consists of a body which is centrally curved horizontal part containing the lower teeth and forms the chin, and two upright portions called rami,one at each side, which join the body at the angle of the jaw. |
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| Bones of the Face |
| Hyoid Bone |
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| This bone lies at the base of the tongue. It also called tongue bone. Certain muscles of the tongue and throat are attached to the hyoid bone. |
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