. Anatomy, descriptive and applied. Anatomy. 80 SPECIAL ANATOMY OF THE SKELETON The border of the horizontal portion is thin, serrated, and articulates with the lesser wing of the sphenoid. Structure.—The frontal portion and external angular processes consist of diploic tissue sur- rounded by compact bone. In the frontal sinus region the cancellous tissue is wanting. The horizontal portion is thin, translucent, and composed entirely of compact tissue. Development (Fig. 46).—The frontal bone is formed in membrane, being developed from two primary centres, one for each lateral half, which make t
. Anatomy, descriptive and applied. Anatomy. 80 SPECIAL ANATOMY OF THE SKELETON The border of the horizontal portion is thin, serrated, and articulates with the lesser wing of the sphenoid. Structure.—The frontal portion and external angular processes consist of diploic tissue sur- rounded by compact bone. In the frontal sinus region the cancellous tissue is wanting. The horizontal portion is thin, translucent, and composed entirely of compact tissue. Development (Fig. 46).—The frontal bone is formed in membrane, being developed from two primary centres, one for each lateral half, which make their appearance about the seventh or eighth week, above the orbital arches. From this point ossification extends, in a radiating manner, upward into the forehead and backward over the orbit. The nasal spine is developed from two secondary centres, while additional cen- tres appear in the regions of the internal and external angular processes. Sometimes a centre appears on either side at the lower end of the coronal suture. This latter centre sometimes re- mains ununited, and is known as the pterion. , ossicle, or it may join with the parietal, sphenoid, ;. ° ° or temporal bone. At birth the bone consists of two pieces, which afterward become united, along the median line, by a suture (metopic) which runs from the vertex to the root of the nose. This suture usually becomes obliterated within a few years after birth, but it occasionally remains throughout life. Articulations.—With twelve bones—two parietal, the sphenoid, the ethmoid, two nasal, two maxillse, two lacrimal, and two malar. Attachment of Muscles.—To three pairs—the Corrugator supercilii, Orbicularis palpe- brarum, and Temporal, on each side. The Temporal Bone (Os Temporale). The temporal bone consists of three parts—(a) the squamous, (6) the petro- mastoid, and (c) the tympanic portions—which, though separate in early life, become united in the adult. The three parts meet and form a part of the oute
Size: 1856px × 1346px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1910, booksubjectanatomy, bookyear1913
