Exploration of a brain cut in frontal section at the splenium of the corpus callosum
Brachium conjunctivum and lateral lemniscus
Dissection of the brain stem was begun on the right side by the exposure of the brachium conjunctivum as it passes into the tegmentum of the mesencephalon. The lateral lemniscus (12), which carries ascending auditory impulses, can be seen to cross the lateral aspect of the brachium conjunctivum in its approach to the inferior colliculus and inferior quadrigeminal brachium. This latter, in turn, passes to the medial geniculate body. The origin of the lateral lemniscus in the caudal part of the pons is not clearly demonstrable by gross dissection.
Inferior colliculus
Trochlear nerve (IV)
Central gray matter
Fourth ventricle
Internal genu of roots of facial nerve
Facial nerve (VII)
Pyramid at medulla oblongata (cut across)
Medial geniculate body
Brachium of inferior colliculus
Cerebral peduncle
Medial lemniscus (lateral edge exposed by dissection)