. Tumours, innocent and malignant; their clinical characters and appropriate treatment. within the thorax, but a review ofthe mode of development of the sternum throws much clearlight on the subject. The two lateral halves of the sternumare, in the early embryo, widely separated from each other;gradually they coalesce in the middle line. Every anatomist 448 DERMOIDS is aware that this median coalescence is extremely liable to befaulty, and conditions occur like those which, happening inconnexion with the medullary folds, produce spina this line of coalescence, so far as sternal dermo
. Tumours, innocent and malignant; their clinical characters and appropriate treatment. within the thorax, but a review ofthe mode of development of the sternum throws much clearlight on the subject. The two lateral halves of the sternumare, in the early embryo, widely separated from each other;gradually they coalesce in the middle line. Every anatomist 448 DERMOIDS is aware that this median coalescence is extremely liable to befaulty, and conditions occur like those which, happening inconnexion with the medullary folds, produce spina this line of coalescence, so far as sternal dermoids areconcerned, we may get skin-lined recesses resembling thecoccygeal dimples. These sternal recesses, or dimples, occurnear the junction of the manubrium with the gladiolus,and may be more than a centimetre deep. Should a piece ofskin become sequestrated during coalescence of the thoracicwalls, it may, during the development of the sternum, bedislocated forwards to the outer surface, or backwards towards Fronto-nasal process. Maxillary process. Mandibular Interuasal fissure. Mandibular fissure. Fig. 226.—Head of an early embryo to show the fronto-nasal plate, globularprocesses, and associated fissures. {Modifiedfrom His.) the mediastinum, conditions in every way parallel to thevariations in the position of cranial dermoids. So long as adermoid on a deep surface of the sternum remains small itwill cause no trouble, but it is easy to understand that a largetumour would, if projecting into the thorax, encroach on thepleura. Even then it would not produce much disturbance solong as air did not gain access to it; but if by pressure thewall of the cyst becomes so thin as to allow air to enter itscavity, or an actual communication forms between the cystand a bronchus or the air-sacs of the lung, then suppurationwith all its disastrous consequences will ensue. (Intrathoracicdermoids and teratomas are considered
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectneoplasms, bookyear19
