A manual of anatomy . l and ethmoidal bones. The grooved bone on each sideof the nasal process constitutes the roof of a nasal fossa. Just withinthe medial part of the orbital margin is the trochlear pit, or spine{fovea vel spina trochlearis) to which is attached the pulley of the superior of the eyeball. Just within the lateral part of the THE PARIETAL BONES 43 orbital margin is the lacrimal fossa for the lacrimal gland (fossaglandulcB lacrimalis). The cerebral surface is concave and accommodates the frontallobes of the cerebrum. It is smooth but uneven due to the pressureof the me


A manual of anatomy . l and ethmoidal bones. The grooved bone on each sideof the nasal process constitutes the roof of a nasal fossa. Just withinthe medial part of the orbital margin is the trochlear pit, or spine{fovea vel spina trochlearis) to which is attached the pulley of the superior of the eyeball. Just within the lateral part of the THE PARIETAL BONES 43 orbital margin is the lacrimal fossa for the lacrimal gland (fossaglandulcB lacrimalis). The cerebral surface is concave and accommodates the frontallobes of the cerebrum. It is smooth but uneven due to the pressureof the meningeal vessels and the gyri of the frontal lobes. Fromthe center of the upper margin a groove {sulcus sagittalis) descendsand terminates in a crest at the end of which is the foramen the superior sagittal sinus begins. Articulations.—Dorsally, with the parietals and sphenoid; laterally, with thezygomatic bones; inferiorly and medially, with the nasals, maxiBae, lacrimals andethmoid bones. Sagittal groove. Zygomaticprocess Cerebral surface (of orbital portion) Foramen caecum ? Orifice of frontal sinus•Frontal spine Fig. 21.—The frontal bone seen from behind (cerebral surface). (Sobotta and McMurrich.) Ossification.—Two lateral primary centers and three pairs of secondary primary centers appear about the sixth or seventh week of fetal life andform the bulk of the bone. The secondary centers appear later, one pair for thefrontal spine, one center for each zygomatic process and a center on each sideat the region of the trochlear pit. These centers fuse on each side by the seventh month of fetal life and the two hahes are usually fused by the seventhyear. Muscles Attached.—Mm. corrugator superciUi, orbicularis palpebras and tem-poralis (three pairs). THE PARIETAL BONES (OSSA PARIETALES) The two parietal bones form the lateral portions of the vault of thecranium. Each has tiuo surfaces, parietal and visceral, and fourmargins and foitr angles


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Keywords: ., bookcentury1900, bookdecade1910, booksubjecthumananatomy, bookyea