Bones of the face and the skull
Bones of the face and the skull
The skull is of a spheroidal figure, compressed on the sides, broader behind ihan before, and supported by its base on the vertebral column.
It is divided by anatomists into two parts, the cranium and the face ; the former being composed of eight bones, viz., the occipital, two 'parietal, the frontal, two temporal, the sphenoid, and the ethmoid ; the latter is made up of fourteen bones, viz., two superior maxillary, two malar, two ossa nasi, two ossa palati, two ossa unguis, two inferior turbinated bones, the vomer, and inferior maxilla ; the frontal bone is so situated as to be common to the cranium and face. The bones of the ear are not included in this enumeration, as they belong rather to a special organ than to the skeleton considered as the framework of the body.
The bones of the face are fourteen in number
The occipital bone, (lat.: os occipitis, french: Os occipital) is situated at the posterior part of the base of the skull; broad behind, much narrowed before, of a trapezoid figure, presenting two surfaces, four borders, and four angles. To place the bone in its natural position, hold it so that the great foramen and the articulating processes beside it shall look directly downwards; the thick process in front of the foramen will then project forwards into the base of the Skull, Whilst the broad expanded part behind it arches upwards and a little forwards, forming the posterior wall of the Cavity.
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The vomer bone (Fench: le Vomer) is an irregular four-sided plate of bone constituting the lower portion of the nasal septum. It is usually described as resembling a ploughshare in shape. Each lateral surface is covered with the thick mucous membrane of the nasal sinus, and is traversed by a narrow but well-marked groove, which lodges the naso- palatine nerve from the spheno-palatine ganglion; hence it is sometimes called the naso-palatine groove.
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The parietal bones (Latin : ossa parietalia, verticis, bregmatis ; french : os pariétal) form a principal part of the roof of the skull; they are of a square form, convex externally, concave internally, and present each two surfaces and four borders. The external surface, rises towards its middle, where it presents a slight elevation, called the parietal eminence, 5 below which is a curved line, forming part of the temporal ridge, and bounding a flat surface (planum semicirculare), which forms a part of the temporal fossa. At the upper and back part of the bone, usually about two lines from the sagittal suture, is a small hole, 6 (foramen parietale) which transmits a communicating vein; its position is exceedingly variable; even its existence is not constant.
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The maxillary bone, (maxilla superior,) is very irregular. It presents an external convex surface, corresponding with the anterior and lateral parts of the face; another, internal, of considerable extent, corresponding with the nasal cavity ; one, superior, smooth, and inclined inwards, forming the floor of the orbit, and surmounted internally by a triangular process, forming the side of the nose ; lastly, a surface which projects horizontally inwards, to form the arch of the palate. The external surface is bounded inferiorly by a thick, dependent border (alveolar), for the lodgment of the teeth; to this as to a common point of union, all the other parts of the bone may be referred.
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The ethmoid (french: ethmoide) is a bone of delicate texture, situated at the anterior part of the skull-base; it is roughly cuboidal in shape, and its delicacy is due to the fact that it is honeycombed by air-cells. The bone consists of four parts: the horizontal or cribriform plate, two lateral masses, and a perpendicular plate.
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The bones which form the appendicular elements of the skullis group are the mandible (lower jaw), malleus, incus, stapes, hyoid, the styloid process of the temporal bone, and the internal pterygoid process of the sphenoid.
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These bones (often referred to as the bones of Bertin) are two hollow cones, flattened externally in three planes. They may be obtained as distinct ossicles about the fifth year. At this date they are wedged in between the under surface of the pre-sphenoid and the orbital and sphenoidal processes of the palate bone. The apex of the cone is directed backwards and appears near the vaginal process of the sphenoid. Of its three surfaces, the outer one is in relation with the spheno-maxillary fossa, and occasionally extends upwards between the sphenoid
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