Quiz #4 - CNS - The Brain Stem and Cerebellum (A&P)

1. Functional anatomy of Brain Regions
a. Medulla Oblongata
i. Most inferior portion of the brain, passes through the foramen magnum and connects to
the spinal cord.
ii. Gray matter
1. Cranial nerve nuclei
a. Relay center for info into and out of the cranial nerves
2. Reticular formation- medial group, lateral group, raphe nuclei
a. Column shaped nuclei that extend from medulla to midbrain
b. Contains important autonomic reflex centers
c. Cardiovascular centers
i. Regulate heart rate, force of contraction, and blood flow in blood vessels
d. Respiratory centers
i. Regulate breathing rate and depth.
3. Relay nuclei
a. Inferior Olivary nuclei
i. Relay station for proprioceptive info between cerebral cortex, red
nucleus and cerebellum.
b. Nucleus fasiculatus and nucleus cuneatus
i. Relay station for touch, pressure and proprioception to parietal lobe via
the thalamus.
iii. White matter
1. Pyramids
a. Carry somatic motor info
b. Crossing over of motor info occurs here in decussation tracts
2. Inferior Cerebellar peduncles
a. Connect medulla to cerebellum
b. Pons
i. Bulged region between medulla and midbrain, bridge across 4th ventricle to connect
brain stem to cerebellum.
ii. Gray matter
1. Apneustic and Pneumotaxic centers
a. Respiratory control centers that adjust activity of respiratory centers in the
medulla oblongata
2. Pontine nuclei
a. Relay centers connecting motor tracts from the cerebrum to the cerebellum.
3. Cranial nerve nuclei
a. Relay center for info into and out of the cranial nerves
4. Reticular formation

a. See previous
iii. White matter
1. Ascending tracts
a. Carry info up to superior regions of the brain
2. Descending tracts
a. Carry info down to inferior regions of the CNS
3. Transverse pontine fibers
a. Connect R and L cerebellar hemispheres
c. Midbrain
i. Between diencephalon and pons, and has a central tube called the cerebral aqueduct.
ii. The cerebral aqueduct divided the midbrain into the tectum and cerebral peduncles.
1. Tectum (ceiling)- posterior region
2. Cerebral peduncles (walls and floor)- anterior region
iii. Gray matter
1. Substantia nigra
a. Dark band deep to the cerebral peduncles
b. Dark due to accumulation of melanin pigment
c. Functionally linked to basal nuclei
d. Involved in controlling voluntary movement
e. Degeneration in this area is the cause of Parkinson’s disease
2. Red nucleus
a. Rich blood supply and iron pigments = red
b. Help regulate control of limb movements
3. Cranial nerve nuclei
a. Relay center for info into and out of the cranial nerves
4. Periaqueductal gray matter
a. Links perception of fear to production of Fight or flight response
b. Controls response to visceral pain
i. Nausea
ii. Cold sweat, etc...
5. Corpora quadrigemina (Tectum)
a. 2 Superior colliculi
i. Relay center for visual reflexes
ii. Object location
b. 2 Inferior colliculi
i. Relay center for auditory reflexes
iv. White matter
1. Cerebral peduncles
a. Pyramidal tracts (somatic motor information from cerebral cortex)
2. Cerebellar peduncles
a. Connect midbrain to cerebellum
d. Cerebellum

i. Dorsal to pons and medulla oblongata.
ii. Separated from the pons and medulla oblongata by the fourth ventricle
iii. Two wide regions called cerebellar hemispheres separated by a worm shaped vermis.
iv. Surface folds are called folia
v. Layers and functions
1. Outer gray matter called cerebellar cortex
a. Coordinates planned, body movements
b. Storage and retrieval of motor memory
2. Inner white matter called arbor vitae
a. Carries info to and from the cerebellar cortex
3. Deep gray matter called deep cerebellar nuclei
a. Relay center for info leaving cerebellum to other brain regions