Hindbrain Metencephalon Pons lum l e eb Cer

Hindbrain

Metencephalon Pons lum l e eb Cer Medulla Hindbrain (Rhombencephalon) Oblangat a Myelencephalon

Cerebellum • The cerebellum (“little brain”) resembles a miniature version of the cerebrum because of it’s two hemispheres.

• It is covered by cerebellar cortex and has a set of deep cerebellar nuclei. Two major fissures running mediolaterally divide the cerebellar cortex into three primary subdivisions. The posterolateral fissure separates the flocculonodular lobe from the corpus cerebelli, and the primary fissure separates the corpus cerebelli into a posterior lobe and an anterior lobe.

• The deep cerebellar nuclei receives projections from the cerebellar cortex and then sends projections out of the cerebellum to other parts of the brain.

• Each hemisphere of the cerebellum is attached to the dorsal surface of pons by bundles of axons – the superior, middle, & inferior cerebellar peduncles (“little feet”).

Functions • It receives visual, vestibular, & somatosensory information • Information about individual muscles movements being directed by the brain • It integrates this information & modifies the motor outflow, exerting a coordinating & smoothing effect on the movements. • Damage to the cerebellum impairs standing, walking, or performance of coordinated movements. • It also results in jerky, poorly coordinated, exaggerated movements. • Extensive damage makes it impossible even to stand.

Pons • Pons means “bridge” and it lies between the mesencephalon & medulla oblongata, ventral to the cerebellum. • It is the large bulge in the brain stem. • Pons contains, in its core, a portion of the reticular formation, including some nuclei that are important in sleep & arousal. • It also contains a large nucleus that relays information from the cerebral cortex to the cerebellum.

Medulla Oblongata • Medulla is the most caudal portion of the brain stem. Its lower border is the rostral end of the spinal cord. • It contains parts of the reticular formation, including nuclei that control vital functions such as regulation of the cardiovascular system, respiration & skeletal muscle tone. Medulla Oblongata