Demonstrations of anatomy : being a guide to the knowledge of the human body by dissection / by George Viner Ellis.

  • Ellis, George Viner, 1812-1900.
Date:
1856
Catalogue details

Licence: Public Domain Mark

Credit: Demonstrations of anatomy : being a guide to the knowledge of the human body by dissection / by George Viner Ellis. Source: Wellcome Collection.

    31/866 (page 11)
    joins a horizontal piece of the dura mater named the ten- tach- torium cerebelli. The upper border is convex, and is fixed to the middle line of the skull as far backwards as the occi- pital protuberance; and the lower, or free border, is con- cave, and turned towards the corpus callosum of the brain, with which it is in contact posteriorly. In this fold of the sinuses dura mater are contained the following sinuses :—the supe- rior longitudinal along the convex border, the inferior lon- gitudinal in part of the lower edge, and the straight sinus at the line of junction between it and the tentorium. The superior longitudinal sinus extends from the ethmoid superior bone to the occipital protuberance. Its position in the con- ^d\uti^^' vex border of the falx will be made manifest by the escape ' of blood through numerous small veins, if the finger is carried backwards along the middle line of the head. When situa- the sinus is opened, it is seen to be narrow in front, and to enaing.^ become wider as it proceeds backwards, till it ends in a com- mon point of union of certain sinuses (torcular Herophili) at the centre of the occipital bone. Its cavity is triangular its in. \ in form, with the apex of the space turned to the falx; and across it are stretched small tendinous cords—chordse Wil- lisii, near the openings of some of the cerebral veins. Oc- casionally small glandulae Pacchioni are present in the sinus. This sinus receives small veins from the substance and Veins exterior of the skull, and larger ones from the hemispheres intTu. of the brain. The cerebral veins open chiefly at the poste- rior part of the brain, and lie for some distance against the wall of the sinus before they perforate it; their course is likewise directed from behind forwards, so that the motion Current of the blood in them is evidently opposed to the direction of in it. the current in the sinus. This disposition of the veins may be seen on the left side of the brain, where the parts are undisturbed. Dissection.—Before the rest of the dura mater can be seen, Dissec- the brain must be taken from the body. To facilitate its re- remova! moval, let the head incline backwards, whilst the shoulders are raised on a block, so that the brain may be separated somewhat from the base of the skull. Cut across now the anterior part of the falx cerebri, and the different cerebral veins entering the longitudinal sinus ; raise and throw back- wards the falx, but leave it uncut behind, where it is con-