. Tumours, innocent and malignant; their clinical characters and appropriate treatment. ojecting into the opening from above is thefronto-nasal process, which ultimately forms the nose. As itdevelops, a rounded prominence, known as the globularprocess, forms at each angle and gives rise to a portion of theala of the nostril and the corresponding premaxilla. Theseglobular processes fuse together in the middle line to -formthe central piece, or philtrum, of the upper lip. The elonga-tion of the fronto-nasal process necessarily lengthens theorbito-nasal fissures. Eventually the sides of the front
. Tumours, innocent and malignant; their clinical characters and appropriate treatment. ojecting into the opening from above is thefronto-nasal process, which ultimately forms the nose. As itdevelops, a rounded prominence, known as the globularprocess, forms at each angle and gives rise to a portion of theala of the nostril and the corresponding premaxilla. Theseglobular processes fuse together in the middle line to -formthe central piece, or philtrum, of the upper lip. The elonga-tion of the fronto-nasal process necessarily lengthens theorbito-nasal fissures. Eventually the sides of the fronto-nasal plate coalesce superficially with the maxillary processes2 D 450 DERMOIDS in such a way as to leave a cleft on each side, which becomesthe orbit; the line of union being permanently indicated inthe adult by the naso-facial sulcus or groove, and indicatedstill more deeply by the lachr3^mal duct, which is a persistentportion of the original orbito-nasal fissure. The union of thefronto-nasal plate with the maxillary processes completes thenose, cheeks, and upper lip (Fig. 227).. Fig. 228.—Eight side of the head of a fcetus, showing a large mandibular tubercleand an accessary tragus. The above account indicates in a general way the relationof these fissures to each other; but it will be necessary, inconsidering dermoids arising in them, to mention certaindetails connected with each. But here it may be stated thatthe defects associated with any of them are of four kinds:1, the fissure may persist ; 2, it may close imperfectly andleave a recess or puckering of the skin; 3, portions of thesurface epithelium may be sequestered and give rise todermoids ; 4, there may be excessive coalescence. These conditions may be illustrated by the mandibular MANDIBULAR TUBEBGLE8 451 fissure. In the embryo this fissure or cleft is relatively moreextensive than the opening of the mouth which in the adultultimately represents it. In fishes the whole of the mandi-bular fissure persists as the
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectneoplasms, bookyear19
