A system of practical medicine. By American authors. Vol. 5

by Unknown

Upon the median line at the top of the head an allowance of full 15 mm. should be made for the width of the superior longitudinal sinus separating the hemisphere.

FIG. 14.

The same Topographical Lines applied to the Left Cerebral Hemisphere in Henle's Skull. The motor centres are approximately indicated by dotted lines. (The leg centre should be reduced in size as it lies near to and in the longitudinal fissure.) The Rolandic line is placed a little behind the fissure for the sake of clearness.

The location of the middle meningeal artery, which so often furnishes the blood that compresses the brain after various injuries to the head, is surgically of great importance. The course of its two principal branches is approximately indicated upon Fig. 13 by the branching lines drawn on the anterior inferior angle of the parietal and the upper part of the squamous portion of the temporal bone. In the living subject the main trunk of the artery would be found under the horizontal line (2-2) a little posterior to the speech-centre, about 30 mm. behind the external angular process, and in front of the beginning of the fissure of Sylvius.

Upon the shaven head of a patient seated in a chair or lying in bed the principal landmarks and relations above defined can be mapped out with sufficient approximation to accuracy by the use of a ruler to mark the alveolo-condyloid plane, and a cardboard cut so as to stand astride the head in the auriculo-bregmatic vertical. A light wooden apparatus can easily be made to indicate these two lines, while the remaining measurements can be made with a steel tape-measure, and the points marked with carmine ink or an aniline pencil.

The value of cranio-cerebral topography is obvious for ordinary surgical purposes, but it may in the future prove of great utility in the treatment of cerebral diseases (tumors, abscesses, etc.) by surgical means. A bold and nearly successful attempt at removing a tumor of the brain has already been made,¹⁵ and doubtless there are surgeons who will not hesitate to follow the path thus opened up when physicians give them a diagnosis of localized tumor or abscess in parts of the cortex cerebri to serve as a basis.

¹⁵ Bennett and Godlee, The Lancet, 1884, ii. 1090; 1885, i. p. 891.

The indications for trephining or raising bone after cranial injuries, for the relief of symptoms of cerebral irritation, compression, or disorganization, may be provisionally stated as follows: