ANATOMY OF THE MESENCEPHALON 131 



The Brachia of the Corpora Quadrigemina. From each colliculus there runs 

 ventrally and rostrally on the lateral aspect of the mesencephalon an arm or 

 brachium (Figs. 87, 88). The inferior quadrigeminal brachium is the more con- 

 spicuous and is the only one that can be readily identified in the sheep. It 

 runs from the inferior colliculus to the medial geniculate body. This is an oval 

 eminence, belonging to the diencephalon, which has been displaced caudally so 

 as to lie on the lateral aspect of the mesencephalon. The superior quadrigeminal 

 brachium runs from the superior colliculus toward the lateral geniculate body, 

 passing between the pulvinar of the thalamus and the medial geniculate body. 

 Some of the fibers can be traced beyond the lateral geniculate body into the 

 optic tract. 



