mandible anatomy
Mandible, the largest and strongest bone of the face, serves for receiving the lower teeth. This consists of a partial, horizontal curve, body, and two perpendicular parts, hemp, which united with the tip of the body almost at right angles.
mandible anatomy
Body (corpus mandibulæ) .- The body is slightly curved like a horseshoe and has two surfaces and two borders.
Surfaces.-external surface (Fig. 176) are marked in the midline with a faint ridge, indicating the symphysis or line connection of two pieces of bone that is prepared in the early days of life. This ridge divides below and wrap a triangular hill, the mental protuberance, the base is pressed in the center but raised on both sides to form the mental tubercle. On either side of the symphysis, just below the tooth series, are depression, the fossa sharply, which gave origin to the mentalist and a small portion of the Orbicularis oris. Under the second premolars, on both sides, in the middle between the upper and lower body, is the mental foramen, to the mental vessels and nerve. Running backwards and upwards from each mental tubercle is a faint ridge, slashes, which is continuous with the anterior ramus border, but affords attachment Quadratus labii inferioris and triangularis, while Platysma mounted underneath.
Internal surface (Figure 177) concave from side to side. Near the bottom of the symphysis is a pair of laterally placed spines, referred to as the mental spines, which give origin to Genioglossi. Immediately below is a second pair of thorns, or more often a median ridge or impression, for the origin Geniohyoidei. In some cases the mental spines fused to form a single hill, on the other they were absent and their position is indicated only by surface irregularities.
mandible anatomy
On top of the mental spines a median foramen and the groove is sometimes visible, they mark the line of unity bone halves. Under the mental spines, on both sides of the median line, is an oval depression for attachment of the anterior abdominal Digastricus. Extending upward and backward on both sides of the bottom of the symphysis is the mylohyoid line, which gave origin to Mylohyoideus, the back of this line, near the alveolar margin, gives attachment to a small part of the Constrictor pharyngis superior, and the raphe pterygomandibular. On top of the front of this line is a smooth triangular region of the sublingual gland is located, and below the hinder part, an oval fossa for the submaxillary gland.
Borders.-superior or alveolar border, wider behind than in front, a hollow into the cavity, for receiving the teeth, these cavities are sixteen in number, and vary in depth and size in accordance with teeth that they contain. For the outer lips superior border, on both sides, which Buccinator mounted as far forward as the first molar tooth. Limit the inferior rounded, longer than the boss, and thicker in front than the rear, at the point where he was joined by the lower limit ramus shallow groove, because the external maxillary artery, may exist.
Fig. 177 - Mandible. Inner surface. Side view.
mandible anatomy
Ramus (ramus mandibulæ; section perpendicular) .- ramus is quadrilateral in shape, and has two surfaces, four borders, and the two processes.
Surfaces.-lateral surface (Fig. 176) is flat and marked with the back sloping to the lower part, but it gives attachment throughout nearly the entire breadth of the masseter. Medial surface (Figure 177) presents the central oblique mandibular foramen, for the entrance of the inferior alveolar vessels and nerves. Margin of this opening is irregular; it presents in front of the dorsal prominence, overcome by a sharp thorns, which mandibulæ tongue, which gives attachment sphenomandibular ligament; on the bottom and back is a notch from which the mylohyoid groove runs obliquely downward and forward, and cottages mylohyoid vessels and nerve.
mandible anatomy
Behind this groove is a rough surface, for insertion of Pterygoideus internus. Mandibular canal runs obliquely downward and forward in the ramus, and then horizontally to the front of the body, where he was placed under the alveoli and communicates with them by small openings. On arriving at the incisor, was returned to communicate with the mental foramen, giving from two small canals which run into the cavity containing the incisors. In two-thirds of the posterior canal bone is located near the internal surface of the lower jaw, and in the anterior third, near the external surface. It contains the inferior alveolar vessels and nerves, from which branches are distributed to the teeth. Lower limit ramus is thick, straight, and continuous with the inferior border of the body's bones.
mandible anatomy
At the junction with the posterior border is the angle of the mandible, which may be either inverted or everted and is marked by rough, oblique ridge on each side, for attachment of the lateral masseter, and medial Pterygoideus internus, stylomandibular ligaments attached to the angle between the muscle. Anterior boundary thin above, thicker below, and constantly with a slash. Posterior border is thick, smooth, round, and covered by the parotid gland. The upper limit of thin, and resolved by the two processes, in the front and rear koronoideus condyloid, separated by a deep concavity, the notch of the mandible.
mandible anatomy
Koronoideus Process (processus coronoideus) is a hill, thin triangle, which is flattened from side to side and vary in shapes and sizes. anterior border is convex and continuous below with the anterior ramus border; posterior border is concave and forms the anterior border of the mandibular notch. lateral surface is smooth, and affords insertion to the temporalis and masseter. Its medial surface gives insertion to the temporal, and presents the back that starts near the summit process and runs downward and forward into the inside of the last molar tooth. Between the ridge and the anterior border is a grooved triangular area, part of which gives attachment temporalis, bottom to some Buccinator fibers.
mandible anatomy
Condyloid Process (processus condyloideus) thicker than koronoideus, and consists of two parts: condyle, and the limited support it, the neck. presents the articular surface of condyle for articulation with the articular disc of temporomandibular joint, but convex from front to back and from side to side, and extends farther on the posterior than the anterior surface. long axis directed medialward and slightly backwards, and if too long middle line will meet that of the opposite condyle near the anterior margin of the foramen magnum. At the end of the lateral condyle is a small tubercle for the attachment of temporomandibular ligament. Neck flattened from before backward, and strengthened with the back down from the beginning and the condyle. posterior surface is convex; anterior depression presents for External Pterygoideus attachment.
Mandibular notch, separating the two processes, is a deep semilunar depression, and crossed by masseteric vessels and nerve.
Ossification.-The jaws ossified in the fibrous membrane covering the outer surface of Meckel's cartilage. These cartilages form a curved line cartilage of the lower jaw (see p. 66), and two in number, right and left. they are proximal or cranial ends are connected with the ear capsule, and distal extremities they join one another at the symphysis by mesodermal tissue. They walk straight ahead under the condyles and then, bending down, lies in the groove near the lower limit of the bone, in front of their canine teeth leaning over the symphysis. From the proximal end of each cartilage the malleus and incus, two middle ear bone, was developed, the next portion of the next, as far as the tongue, is replaced by fibrous tissue, which takes place to form the ligament sphenomandibular. Between tongue and teeth canine cartilage disappears, while the portion below and behind the incisors become ossified and combined with the lower jaw.
Hardening occurs in the membrane covering the outer surface of the ventral end of Meckel's cartilage (Fig. 178-181), and each half-bone is formed from a single center which appears, near the mental foramen, about the sixth week of fetal life. At the tenth week of the Meckel's cartilage which lies below and behind the incisor bone surrounded and attacked by a membrane. Somewhat later, the core accessory cartilage make their appearance, ie, wedge-shaped core in the process and expand condyloid downward through the ramus;. Small strip along the anterior border of koronoideus process, and a smaller core in the front of both the alveolar walls and along the front of the lower border of bone. Accessory nucleus has no separate ossific center, but the attack by the membrane surrounding bone and undergo absorption. Inner alveolar border, usually described as originating from separate ossific center (splenial center), formed in the human mandible by an ingrowth from the main mass of bone. At birth the bone consists of two parts, united by a fibrous symphysis, in which ossification occurred during the first year.