SUPERIOR LONGITUDINAL SINUS. 371 



The Superior longitudinal sinus is situated in the attached margin 

 of the falx cerebri, and extends along the middle line of the arch of the 

 skull, from the foramen caecum in the frontal, to the inner tuberosity 

 of the occipital bone, where it divides into the two lateral sinuses. It 

 is triangular in form, is small in front, and increases gradually in size 

 as it passes backwards ; it receives the superior cerebral veins which 

 open into it obliquely, numerous small veins from the diploe, and near 

 the posterior extremity of the sagittal suture the parietal veins, from 

 the pericranium and scalp. Examined in its interior, it presents 

 numerous transverse fibrous bands (trabeculae) the chordae Willisii, 

 which are stretched across its inferior angle ; and some small \vhite 

 granular masses, the glandulae Pacchioni ; the oblique openings of the 

 cerebral veins, with their valve-like margin, are also seen upon the walls 

 of the sinus. 



The termination of the superior longitudinal sinus in the two lateral 



Fig. 132.* 



sinuses forms a considerable dilatation, into which the straight sinus 

 opens from the front, and the occipital sinuses from below. This dila- 



* The sinuses of the upper and back part of the skull. 1, The superior lon- 

 gitudinal sinus. 2, 2. The cerebral veins opening into the sinus from behind 

 forwards. 3. The falx cerebri. 4. The inferior longitudinal sinus. 5. The 

 straight or fourth sinus. 6. The venae Galeni. 7. The torcular Herophili. 8. 

 The two lateral sinuses, with the occipital sinuses between them. 9. The ter- 

 mination of the inferior petrosal sinus of one side. 10. The dilatations cor- 

 responding with the jugular fossae. 11. The internal jugular veins. 



