. A treatise on diseases of the eye . ngrowth of mesodermictissue, forming the laeltrymal canaliculi and ending on the margin ofthe lids to form the puiicta lachrymalia. Shortly before the birth of the child the cells occupying the centreof the cylinder disintegrate and disappear, establishing the lumen ofthe lachrymal canaliculi, lachrymal sac, and lachrymal canal. Failureor arrest of the development at any stage may occur. CHAPTER 11. ANATOMY. Orbits.—The orbits are two pyramidal cavities in the anterior por-tion of the skull, which lodge the eyes. They are symmetrically placed,and are separ
. A treatise on diseases of the eye . ngrowth of mesodermictissue, forming the laeltrymal canaliculi and ending on the margin ofthe lids to form the puiicta lachrymalia. Shortly before the birth of the child the cells occupying the centreof the cylinder disintegrate and disappear, establishing the lumen ofthe lachrymal canaliculi, lachrymal sac, and lachrymal canal. Failureor arrest of the development at any stage may occur. CHAPTER 11. ANATOMY. Orbits.—The orbits are two pyramidal cavities in the anterior por-tion of the skull, which lodge the eyes. They are symmetrically placed,and are separated by a distance of approximately 22 mm. The innerwalls of the orbits are placed in the vertical plane, and are almost paral-lel to each other, being, however, very slightly convex. The roof of theorbit is placed approximately in the horizontal plane. The surfaceof the roof is not a plane, but is irregularly concave, the concavity beingmore acute near the margin of the orbit. The angle between the inner OF Fig. 10 /.S. Fe As. ON £, J^ ^ »»^>^ c , ^N Right orbit: OF, frontal bone; OZ, malar bone; OM, superior maxillary; ON, nasal bone;, optic foramen; Fos, sphenoidal fissure; Fox, sphenomaxillary fissure; Fe, ethmoidalforaminae; , lachrymal fossa; Ci, inferior orbital canal; Ci, anterior opening of the same;Zt, zygomatico-temporal canal; ZU zygomatico-facial canal; Sri, spine of the external rectusmuscle; /. <S., supra-orbital fissure; As, superciliary arch (Merkel and Kallius.) wall and the roof of the orbit is quite acute. The outer wall divergessharply from the median plane of the head; it inclines slightly inwardbelow, the angles of union with the roof and floor of the orbit are wellrounded. The floor of the orbit slopes outward and downward, andjoins the inner wall by a rounded ol)tuse angle. The axes of the orbits, if continued backward, would cross eachother just back of the sella turcica at an angle of 42 to 46 degrees. Thejilane of the axes of
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Keywords: ., bookcentury1900, bookdecade1910, booksubjecteyediseases, bookyear
