The Determination of the Naso-frontal Suture and the Nasion in the Living

Abstract

IN the anthropometry of the living head perhaps the most important point is that at which the sagittal plane crosses the naso-frontal suture, a point known to anthropometrists as the nasion. The determination of this point in the living has always been a matter of considerable difficulty, and indeed, it is doubtful whether in the experience of the most competent investigator it has ever been accurately determined in more than a small percentage of cases. The methods which have been customarily used to determine the nasion in the living leave something to be desired, and with the purpose of finding some fairly reliable method of securing this point, the writer undertook an investigation which led to the successful solution of the problem. The preliminary findings of this investigation, based upon the dissection of 240 human dissecting-room cadavera and the small number of ten x-ray studies of the living human head, were published in “The American Journal of Physical Anthropology” for April–June, 1935. In the present communication the report upon two additional series of experiments is put before the readers of Radiology, together with the hitherto unpublished x-ray material, in the hope that it may be of some use to them in their work. In my original paper I told how, as a consequence of preliminary dissections on 140 dissecting-room bodies in search of some possible relationship between the soft structures of the head in the orbito-nasal region and the naso-frontal suture, with particular reference to the nasion, I was led to the conclusion that a very close relationship existed between the level of the superiormost points of the superior palpebral sulci when the upper eyelids were elevated, as when the individual is looking straight ahead, and the level of the nasion (Fig. 1). In order to test the constancy, if any, of this suggested relationship the following experimental procedure was adopted: The recumbent head was placed in the Frankfurt Plane (a plane determined by the two inferionnost points on the inferior orbital margins and the auricular points immediately above the external acoustic rings), and by means of a metal tape, a horizontal tangential to the superiormost projection of the arches of the superior palpebral sulci was defined by gently placing the upper border of the tape against these arches. Where this horizontal intersected the mid-sagittal plane, a point determined by the eye alone, a hole was bored vertically through the soft tissues until it was felt that the gimlet used had slightly penetrated the bone. The instrument used in this operation was a 2-mm. bore hand-gimlet with a sharpened point.