Slide 14: Transition between the Mesencephalon and Diencephalon

Identify:

• Crus Cerebri
• Corticospinal Tract fibers (CST)
• Substantia Nigra (SN)
• Red Nucleus (RN)
• Cerebello-thalamic fibers (CBTh)
• Central Tegmental Tract (CTT)
• Hypothalamo-Autonomic Tract (HAT)
• Medial Lemniscus (ML)
• Spinothalamic Tract (STT)
• Medial Geniculate (MG)
• Brachium of the Inferior Colliculus (BIC)
• Optic Tract (OT, best seen on right)
• Posterior Commissure (PC)
• Cerebral Aqueduct just beneath the Posterior Commissure
• Pretectal Area (PTA)
• Pulvinar Nucleus of the thalamus (PUL)

Note:

• The Medial Geniculate is a major relay station in the central auditory pathway, receiving the terminations of the Brachium of the Inferior Colliculus and projecting to the Auditory Cortex in the temporal lobe.
• The Lateral Geniculate is a major relay station in the central visual pathway, receiving terminations from the Optic Tract and projecting via the Optic Radiations to the Visual Cortex in the occipital lobe.
• The Pretectal Area is a vital link in the pupillary light reflex.
• The Pulvinar Nucleus of the thalamus receives a large input from the Optic Tract.