Slide 20: Midbrain - Inferior Colliculus

Identify:

• Crus Cerebri of the Cerebral Peduncles
• jCorticospinal Tract (CST)
• Substantia Nigra (SN)
• Decussation of the Superior Cerebellar Peduncles (SCPDX)
• Rubrospinal Tract (RST)
• Medial Lemniscus (shifting dorsolaterally) (ML)
• Spinothalamic Tract (STT)
• Medial Longitudinal Fasciculus (MLF)
• Periaqueductal Gray (PAG)
• Central Tegmental Tract (CTT)
• Hypothalamo-Autonomic Tract (HAT)
• Inferior Colliculus

Note:

• The massive Crus Cerebri of the Cerebral Peduncles contain Corticospinal, Corticobulbar, and Corticopontine Fibers.
• The Lateral Lemniscus fans out as it terminates in the Inferior Colliculus (golf ball on tee).
• The Inferior Colliculus is a major element of the auditory system.
• Note the course of the 4th nerve fibers from the nucleus to where they exit the brainstem.