The linea innominata.

Abstract

In reviewing the standard texts on the radiological anatomy of the skull, it is observed that the linea innominata is commonly considered to be a diagonal projection through the orbit (in the posteroanterior roentgenogram), i.e., a straight line joining superiorly with the ridge formed by the posterior border of the orbital plate and inferiorly with the upper margin of the inferior orbital fissure. This linea innominata is a radiological entity produced through a superimposition of densities attributed by present-day texts to the squamous portion of the temporal bone in tangential projection. Other authorities assert that it is produced by a tangential projection of the temporal squama, the greater wing of the sphenoid, or the junction of the two. A one-quarter section of skull including the temporal bone was examined roentgenographically. Films were obtained with and without the temporal bone. The appearance of the line was the same in both (Fig. 1). In order to demonstrate the origin of this line, four ...