The cerebral sinuses and their variations / by J.F. Knott.

  • Knott, John, 1853-1921.
Date:
[1881]
Catalogue details

Licence: Public Domain Mark

Credit: The cerebral sinuses and their variations / by J.F. Knott. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    sagittalis and upper branch of the linea cruciata, on inner surface ok' occipital bone; of thirty-eight calvaria, on which I carefully examined the position of the groove which marked the course of this canal, I found it to occupy the median plane, as accurately as possible, in nine specimens. In seven other cases it deviated only at the posterior extremity, terminating in the right lateral sinus in four, and in that of the left, in three instances. In fourteen specimens the sulcus was more on the right side along the whole length of the sagittal suture, but in three of them it bent to the opposite side on the occipital bone, at about an inch and a half above the protuberance to terminate in the groove for lateral sinus. In two, the termination was medial; in the others it was on the same side as the original deviation. In the remaining eight the sagittal groove was better marked on the left parietal bone, and in six it terminated in the corresponding lateral grooves of occipital. In one case, it gained the median line at the protuberance, and in one it crossed to the opposite side. The lumen of this sinus Presents a distinctly triangular outline with a slightly concave ase, which is placed above, and its diameter gradually increases as it passes backwards from 1.5 mm., at the level of the apex of the crista galli to 11. mm. at its termination. The diameter of the sinus is, however, subject to very great variations, the in- constancy of size being indeed the most striking feature in its abnormal anatomy. In some cases, a second small sinus may be found between the layers of the falx immediately below this normal superior longitudinal, or, in such cases, it would be more accurate to describe the sinus as divided into two by a horizontal septum. The upper is then quadrilateral in section; the lower is triangular, with the apex downwards. The canals so arranged have been described by Malacarne under the name of seni tubalterni. I have seen an instance of this division; it reached along the posterior half of the sinus only. Varieties.—A case of complete absence of the superior longi- tudinal sinus is mentioned by Portal (Gours. d' Anat Med. iv. 29.) This must, of course, be a very rare anomaly. I have not met with an instance, but I have certainly seen three specimens (out of forty-four, in which I was carefully examined), in which the size was so small that it could hardly be looked upon as a representative of the normal sinus. The usual tributaries in these cases turned down between the layers of the falx cerebriti and joined the inferior longitudinal sinus, and the normal tributaries of the superior petrosal sinuses were larger than usual. In two the straight sinuses received the termination of the superior longitudinal, which did not groove the occipital bone for the last inch of its course, but turned a little forwards as well as downwards, likewise the layers of the falx. The superior longitudinal sinus was found in two of the forty- four to bifurcate in each case a little behind the coronal suture. The two branches re-united after a course of an inch and a half, in