Metencephalon

The metencephalon is a subdivision of the rhombencephalon (hindbrain) that develops into the pons and the cerebellum. It is located caudal to the mesencephalon and rostral to the myelencephalon, forming the rostral portion of the hindbrain.

During embryonic development, the rhombencephalon differentiates into the metencephalon and the myelencephalon. The metencephalon subsequently gives rise dorsally to the cerebellum and ventrally to the pons.

The metencephalon surrounds part of the fourth ventricle and is associated with several cranial nerves, including the trigeminal nerve (CN V), abducens nerve (CN VI), facial nerve (CN VII), and part of the vestibulocochlear nerve (CN VIII).

• The pons forms the ventral portion of the metencephalon and constitutes an important relay center between the cerebrum, cerebellum, and medulla oblongata. It contains ascending sensory tracts, descending motor tracts, pontine nuclei, and transverse pontine fibers that connect the cerebral cortex with the cerebellum. The pons also contains components of the reticular formation and nuclei associated with cranial nerves.

• The cerebellum develops dorsally from the metencephalon and is connected to the brainstem through the cerebellar peduncles. It is composed of a central vermis and paired cerebellar hemispheres.

The metencephalon therefore serves as both a major conduction and integration center between higher encephalic structures, the cerebellum, and the spinal cord.

The cerebellum is highly developed in the dog and plays a major role in coordination of movement and motor control.