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 mandible [mandibula] or lower jaw-bone is the largest and strongest bone of the face. It supports the mandibular teeth, and by means of a pair of condyles, moves on the skull at the mandibular fossae of the temporal bones. It consists of a horizontal portion — the body — strongly curved, so as to somewhat resemble in shape a horseshoe, from the ends of which two branches or rami ascend almost at right angles.
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The zygomatic [os zygomaticum] or malar bone forms the prominence known as the cheek and joins the zygomatic process of the temporal with the maxilla. It is quadrangular in form with the angles directed vertically and horizontally. The malar (or external) surface is convex and presents one or two small orifices for the transmission of the zygomatico-facial nerves and vessels. It is largely covered by the orbicularis oculi and near the middle is slightly ele- vated to form the malar tuberosity, which gives origin to the zygomaticus and zygomatic head of quadrate muscle of upper lip.
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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 nasal bones are two small oblong bones situated at the upper part of the face and forming the bridge of the nose. Each bone is thicker and narrower above, thinner and broader below, and presents for examination two surfaces and four borders.
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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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These are two oblong bones situated in the middle line at the upper part of the face and forming the bridge of the nose. Each bone has two surfaces and four borders. The facial surface is concave from above downwards, but convex from side to side. Near its centre is a foramen for the transmission of a small tributary to the facial vein. The posterior or nasal surface is concave laterally and traversed by a longitudinal groove for the nasal branch of the ophthalmic nerve.
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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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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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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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