Cerebral peduncle

The cerebral peduncle is the ventral part of the midbrain, located beneath the tectum and the mesencephalic aqueduc. Each cerebral peduncle is composed of three superimposed regions, arranged from dorsal to ventral:

• The tegmentum, made up of gray and white matter and containing numerous nuclei;

• The substantia nigra, a large nucleus of gray matter;

• The cerebral crus, also called the pillar of the brain, entirely composed of white matter.

The cerebral peduncle constitutes the point of emergence of the oculomotor cranial nerve (III). It plays a fundamental role in transmitting motor information between the cerebral cortex, the brainstem, and the spinal cord, and contributes to the coordination of voluntary movements in animals.

In equids, the cerebral peduncles are less divergent than in other species. In ruminants, they are relatively short, and in carnivores, they are broad and of medium length. In humans, the cerebral peduncles are short, broad, and thick, with a pronounced widening in their ventral part.