Special Histology and Embryology: Practical Course - V. K. Napkhanyuk 2001

Nervous System
Brainstem

The brainstem comprises the Medulla Oblongata, Pons, Cerebellum, as well as structures of the Midbrain and Diencephalon.

The medulla oblongata contains the nuclei of the Cranial Nerves: the hypoglossal, accessory, vagus, glossopharyngeal, and vestibulocochlear nerves, as well as Relay nuclei—the inferior, medial accessory, and posterior accessory olivary nuclei. The reticular formation is also located here. Within the reticular formation, nerve fibers run in various directions to form a net-like Structure. The reticular formation regulates Muscle tone and stereotyped body movements, and activates the Cerebral Cortex.

The pons (pons Varolii) features a dorsal (tegmental) part and a ventral part. The dorsal part contains projection pathway fibers from the medulla oblongata, the nuclei of the cranial nerves V–VIII, and the pontine reticular formation. The ventral part contains its own pontine nuclei and longitudinally oriented fibers of the Pyramidal Tracts.

The midbrain (mesencephalon) consists of the tectum, the tegmentum, the substantia nigra, and the cerebral peduncles.

The corpora quadrigemina consist of the tectal plate, two rostral (superior) colliculi, and two caudal (inferior) colliculi.

The rostral colliculi (part of the visual system) feature a layered arrangement of neurocytes.

The caudal colliculi (part of the auditory system) are organized on a nuclear principle.

The midbrain tegmentum houses approximately 30 nuclei, including the red Nucleus, which is divided into magnocellular and parvocellular parts.

The substantia nigra got its name because its small fusiform Cells contain melanin.

The cerebral peduncles are formed by myelinated fibers descending from the cerebral cortex.

The diencephalon consists of the thalamus and the subthalamic (hypothalamic) region.

The thalamus contains numerous nuclei separated from one another by layers of White matter.

The Hypothalamus houses centers regulating body Temperature, Blood pressure, Water-electrolyte and Lipid METABOLISM, as well as neurosecretory nuclei.



Last update: 10/08/2026

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