The Brain Stem and Cerebellum

Medulla Oblongata

The most inferior portion of the brain, passing through the foramen magnum and connecting to the spinal cord

Cranial Nerve Nuclei (Medulla/midbrain)

Gray matter that serves as a relay center for information into and out of the cranial nerves

Reticular Formation (Medulla/Pons)

Column-shaped nuclei extending from the medulla to the midbrain, Contains important autonomic reflex centers

Cardiovascular Centers (Medulla/Pons)

Regulate heart rate, force of contraction, and blood flow in blood vessels (in the reticular formation)

Respiratory Centers (Medulla/Pons)

Regulate breathing rate and depth (in reticular formation)

Two relay nuclei

Inferior Olivary nuclei and Nucleus fasiculatus and nuckeus cuneatus

Inferior Olivary Nuclei

Relay station for proprioceptive information between the cerebral cortex, red nucleus, and cerebellum

Nucleus Fasiculatus and Nucleus Cuneatus

Relay stations for touch, pressure, and proprioception to the parietal lobe via the thalamus

Pyramids (Medulla)

White matter tracts that carry somatic motor information and crossing over of motor information occurs here in decussation tracts

Inferior Cerebellar Peduncles

White matter tracts that connect medulla to cerebellum

Pons

A “big belly” region of the brain stem located between the medulla and the midbrain, bridge across the 4th ventricle to connect the brain stem to the cerebellum

Apneustic and Pneumotaxic Centers

Respiratory control centers located in the pons that adjust the activity of respiratory centers in the medulla oblongata (gray matter in pons)

Pontine Nuclei

Relay centers connecting motor tracts from the cerebrum to the cerebellum (gray matter in pons)

Cranial Nerve Nuclei (Pons)

Gray matter in the pons that serves as a relay center for information into and out of the cranial nerves

Ascending Tracts (Pons)

White matter tracts that carry information up to superior regions of the brain

Descending Tracts (Pons)

White matter tracts that carry information down to inferior regions of the CNS

Transverse Pontine Fibers

White matter fibers that connect the right and left cerebellar hemispheres

Midbrain

The region of the brain stem located between the diencephalon and pons, containing a central tube called the cerebral aqueduct

Tectum

The posterior region (ceiling) of the midbrain

Cerebral Peduncles

The anterior region (walls and floor) of the midbrain

Substantia Nigra

A dark band of gray matter deep to the cerebral peduncles in the midbrain, involved in controlling voluntary movement and functionally linked to the basal nuclei, Degeneration in this area is the cause of Parkinson’s disease

Red Nucleus

rich blood supply and iron pigments, helping to regulate control of limb movements

Periaqueductal Gray Matter

links the perception of fear to the production of the fight or flight response and controls responses to visceral pain

Corpora Quadrigemina

Located in the tectum of the midbrain, consisting of two superior colliculi and two inferior colliculi

2 Superior Colliculi

a relay center for visual reflexes and object location

2 Inferior Colliculi

a relay center for auditory reflexes

Cerebral Peduncles (Midbrain White Matter)

containing pyramidal tracts that carry somatic motor information from the cerebral cortex

Cerebellar Peduncles (Midbrain)

connect the midbrain to the cerebellum

Cerebellum

Located dorsal to the pons and medulla oblongata, separated by the fourth ventricle. It has two cerebellar hemispheres separated by the vermis, with surface folds called folia

Cerebellar Cortex

The outer layer of gray matter that coordinates planned body movements and is involved in the storage and retrieval of motor memory

Arbor Vitae

The inner layer of white matter that carries information to and from the cerebellar cortex