154 OUTLINES OF EQUINE ANATOMY. 



great transverse fissure, in which thej terminate in a sharp 

 edge. In their substance run the lateral sinuses from the 

 torcular HeropMli above to the cavernous sinus. The fifth 

 nerve (sensory portion) passes into them about their 

 centre, and they thus contain it with its gasserian ganglion. 

 The torcular Herophili, therefore, is a venous sinus, situated 

 against the ossific tentorium, which receives the straight 

 (and superior longitudinal) sinuses, and from which the 

 lateral sinuses and also the occipital sinuses run. The 

 latter pass backwards over the roof of the cerebellal cavity. 

 Between the fifth nerves, at the base of the brain, the layers 

 of the dura mater separate, forming the cavernous sinus, and 

 imbedding a peculiar reddish-black body, circular, and 

 flattened from above downwards, the use of which is un- 

 known, but which receives the inferior extremity of the 

 tuber cinereum — the pituitary body. Around the posterior 

 and lateral parts of this body is situated the cavernous sinus 

 lined by epithelium, to which run the lateral sinuses supe- 

 riorly, the anterior petrosal anteriorly, and the posterior 

 petrosal posteriorly, from the floor of the cranium ; the 

 latter blend with the sinuses of the floor of the spinal canal 

 posteriorly. It also receives anteriorly the posterior ex- 

 tremity of the superior varicose vein of the face, which 

 passes through foramen lacerum orbitale. Inferiorly it 

 sends off prolongations, which pass through foramen 

 lacerum basis cranii, and from which the jugular veins 

 commence. In the cavernous sinus run the internal 

 carotid arteries, covered by reflections of the epithelial 

 lining layer ; they pass from foramen lacerum basis cranii, 

 communicating by a transverse branch behind the pituitary 

 body, and emerging from the dura mater at the base of the 

 brain, opposite the commencement of the fissure of Sylvius. 

 The dura mater of the brain is continuous with that of the 

 cord through the medium of its attachment to the margin 

 of the foramen magnum of the occiput. It is attached to 

 almost all the foramina around their margins, and is con- 

 tinued over the optic nerve as far as the sclerotic, where it 

 terminates in forming the lamina cribrosa. On the outer 

 surface of the dura mater, especially at the attached 

 margin of the falx cerebri, have been distinguished minute 

 nodular bodies, largest in old subjects, glands of PaccMoni. 

 The arachnoid is a serous membrane, and presents a 

 parietal and a visceral portion. The parietal portion lines 



