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Posterior View of the Midbrain with Deep Structures Dissected

Surgical Correlation


Posterior view of the midbrain with deep structures dissected. The superior and inferior colliculi are visible on the left side of the specimen. The trochlear nerve (CN IV) emerges from the dorsal aspect of the midbrain below the inferior colliculus and courses around the lateral aspect of the brainstem. The brachium of the inferior colliculus carries auditory afferent fibers from the inferior colliculus to the medial geniculate nucleus of the thalamus. The pineal gland and habenula are components of the epithalamus, which is located superior to the superior colliculus. The deep structures of the midbrain have been dissected on the right side of the specimen. The red nucleus is located within the midbrain tegmentum at the level of the superior colliculus. The medial lemniscus is a fiber bundle that ascends through the midbrain just lateral to the red nucleus.  It is part of the dorsal column-medial lemniscus pathway, which carries somatic sensation from the body to the thalamus. (Image courtesy of AL Rhoton, Jr.)