20 Dr. Foville on the Anatomy of the Brain. 



perforated by a great number of vascular holes, and its greatest 

 dimension is from within outwards and backwards. 



Its anterior margin is curved, and bears the external root 

 of the olfactory nerve. 



Its posterior margin, equally curved, bears a part of the 

 optic nerve, which is prolonged outwards and backwards from 

 the commissure. 



At the anterior border of the same quadrangle is seen the 

 base of the convolution which is in relation with the olfactory 

 nerve. 



To the extreme limit of its posterior margin is attached in 

 some sort by its base the great tuberosity of the most inter- 

 nal convolution of the temporal lobe of the brain. This con- 

 volution is not less remarkable for its form and situation than 

 for its surface, which appears invested by a whitish layer of 

 matter perforated with holes like lace. 



Internally this quadrangle is inclined towards the inferior 

 part of the septum lucidum, and presents a swelling corre- 

 sponding to the commissure of the optic nerves. 



With the fibres composing the surface of this quadrangle 

 are united all the roots of the olfactory nerve, except the 

 anterior one, which is continued into the substance of the 

 convolution on which this nerve rests. 



With the fibres of the same quadrangle are also combined 

 a layer of nervous matter and some radicular prolongations 

 given off from the optic nerve. 



The most internal portion of the quadrangle goes up under 

 the septum lucidum to the base of the anterior part of the 

 lateral ventricle. Its external portion, combined with the great 

 tuberosity of the convolution of the cornu ammonis, or the 

 convolution displaying the hippocampus major on its ventri- 

 cular surface, corresponds with the deepest part of the de- 

 scending cornu of the same ventricle in the temporal lobe. 



By its adherent surface this quadrangle covers a part of 

 the inferior extra-ventricular portion of the corpus striatum 

 and thalamus nervi optici, and also receives a delicate layer of 

 fibres which come from the corpus striatum and optic thala- 

 mus, in a line as distinct from that by which the fibrous planes 

 proceed from the same parts to the internal surface of the 

 convolutions, as that in which the anterior roots of the spinal 

 nerves originate is distinct from that in which the posterior 

 roots of the same nerves arise. Several radicular prolonga- 

 tions of the olfactory nerve go into the slight fibrous layer 

 which is observable in the substance of the corpus striatum. 



The anterior boundary of the fibrous quadrangle whose 

 relations I have just now sketched, sends off a fibrous band, 



