Sinus- from Gray's Anatomy- Page 1
| It is interesting to read the original Gray's anatomy entries about the sinuses in the human body. This article first appeared in "Anatomy of the Human Body" published by Dr. Henry Gray (1821-1865) in 1918. It appears a number of names describing sinuses have changed. One does not see much of the familiar names used today for the various sinus cavities in the head, that is, ethmoid, frontal, maxillary, and sphenoid. Nonetheless, Gray's Anatomy had a profound effect on the medical community, and it is interesting to examine his original text regarding the sinuses and veins which pass near or through them. |
The Sinuses of the Dura Mater- (Sinus Duræ Matris). Ophthalmic Veins and Emissary Veins
| The sinuses of the dura mater are venous channels which drain the blood from the brain; they are devoid of valves, and are situated between the two layers of the dura mater and lined by endothelium continuous with that which lines the veins. They may be divided into two groups: (1) a postero-superior, at the upper and back part of the skull, and (2) an antero-inferior, at the base of the skull. | 1 | ||||||||
| The postero-superior group comprises the | 2 | ||||||||
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FIG. 566– Superior sagittal sinus laid open after remova of the skull cap. The chordæ Willisii are clearly seen. The venous lacunæ are also well shown; from two of them probes are passed into the superior sagittal sinus. (Poirier and Charpy.)
| The superior sagittal sinus (sinus sagittalis superior; superior longitudinal sinus) (Figs. 566, 567) occupies the attached or convex margin of the falx cerebri. Commencing at the foramen cecum, through which it receives a vein from the nasal cavity, it runs from before backward, grooving the inner surface of the frontal, the adjacent margins of the two parietals, and the superior division of the cruciate eminence of the occipital; near the internal occipital protuberance it deviates to one or other side (usually the right), and is continued as the corresponding transverse sinus. It is triangular in section, narrow in front, and gradually increases in size as it passes backward. Its inner surface presents the openings of the superior cerebral veins, which run, for the most part, obliquely forward, and open chiefly at the back part of the sinus, their orifices being concealed by fibrous folds; numerous fibrous bands (chordæ Willisii) extend transversely across the inferior angle of the sinus; and, lastly, small openings communicate with irregularly shaped venous spaces (venous lacunæ) in the dura mater near the sinus. There are usually three lacunæ on either side of the sinus: a small frontal, a large parietal, and an occipital, intermediate in size between the other two (Sargent 106). Most of the cerebral veins from the outer surface of the hemisphere open into these lacunæ, and numerous arachnoid granulations (Pacchionian bodies) project into them from below. The superior sagittal sinus receives the superior cerebral veins, veins from the diploë and dura mater, and, near the posterior extremity of the sagittal suture, veins from the pericranium, which pass through the parietal foramina. | 3 |
| The numerous communications exist between this sinus and the veins of the nose, scalp, and diploë. |
FIG. 567– Dura mater and its processes exposed by removing part of the right half of the skull, and the brain.
| The inferior sagittal sinus (sinus sagittalis inferior; inferior longitudinal sinus) (Fig. 567) is contained in the posterior half or two-thirds of the free margin of the falx cerebri. It is of a cylindrical form, increases in size as it passes backward, and ends in the straight sinus. It receives several veins from the falx cerebri, and occasionally a few from the medial surfaces of the hemispheres. | 5 |
| The straight sinus (sinus rectus; tentorial sinus) (Figs. 567, 569) is situated at the line of junction of the falx cerebri with the tentorium cerebelli. It is triangular in section, increases in size as it proceeds backward, and runs downward and backward from the end of the inferior sagittal sinus to the transverse sinus of the opposite side to that into which the superior sagittal sinus is prolonged. Its terminal part communicates by a cross branch with the confluence of the sinuses. |