Quiz #4 - CNS - Gross anatomy of the Nervous system (A&P)

1. Gray vs. White matter
a. Neural tissue in the brain and spinal cord appear either gray of white depending on the
cells contained within those regions.
b. Gray matter
i. Appears gray in dissection
ii. Composed mostly of cell bodies and synapses, but also contains dendrites,
short/non-myelinated axons and neuroglia.
iii. Gray matter is the site of integration within the CNS.
iv. Gray matter in the brain
1. The brain has 2 regions of gray matter
a. Inner gray matter
i. Some gray matter directly surrounds hollow spaces in the brain.
ii. Nuclei- clusters of gray matter in the brain stem, diencephalon,
cerebellum, and cerebrum
b. Outer gray matter
i. Outer most layer of the cerebrum and cerebellum generally called
cortex.
ii. Cerebral cortex- outer surface of gray matter covering the cerebrum.
iii. Cerebellar cortex- outer surface of gray matter covering the
cerebellum.
v. Gray matter in the spinal cord
1. The spinal cord has only 1 butterfly-shaped inner gray matter region.
c. White matter
i. Appears white in dissection
ii. Composed of myelinated axons and neuroglia
iii. Site where information travels from place to place in the CNS.
1. Axons carrying information to similar destinations form tracts.
iv. White matter in the brain
1. White matter in the brain is found around nuclei in the brain stem and
diencephalon and in a middle layer between inner gray matter regions to outer
gray matter regions.
v. White matter in the spinal cord
1. The spinal cord only has one outer layer of white matter.
2. The Brain
a. Basic Brain Regions and Structures
i. Cerebrum
1. Most superior region
2. Largest region of the brain
3. Covered in lots of surface folds

a. Gyri- high points of folds. “peaks” Singular = Gyrus
b. Sulci- low points of folds. “valleys” Singular = Sulcus
4. Fissures
a. Large folds in the CNS
b. Longitudinal fissure- sagittal fold that divides the cerebrum into R and L
cerebral hemispheres.
c. Transverse fissure- transverse fold that separates cerebrum from the
cerebellum.
ii. Cerebellum
1. Small bun shaped region.
2. Posterior to the brain stem, inferior to the cerebrum.
3. Contains surface folds called folia
4. Divided into R and L cerebellar hemispheres
iii. Diencephalon
1. Region of the brain deep inside the cerebrum, superior to the brain stem
2. Contains
a. Hypothalamus
i. Pituitary gland attached to the anterior surface
b. Thalamus
i. Pineal gland attached to the posterior surface
iv. Brain stem
1. Contains
a. Midbrain
i. Just inferior to the thalamus
b. Pons
i. “Big belly”
ii. Inferior to the midbrain
c. Medulla oblongata
i. “Little belly”
ii. Inferior to the pons
iii. Connects to the spinal cord
b. The Meninges
i. The brain and spinal cord are surrounded by bony enclosures and connective tissue
coverings called the meninges to protect them.
ii. The connective tissue coverings called the meninges cover and protect the CNS,
enclose and protect blood vessels that supply the CNS, and contains cerebrospinal
fluid.
iii. The layers of the meninges
1. Dura mater
a. Outer, leathery, dense fibrous layer
b. Very strong

c. In some places it forms folds called dural folds. Some dural folds contain
blood filled spaces called dural sinuses.
i. Dural folds and sinuses
1. Falx cerebri- dural fold in the longitudinal fissure. Separates R
and L cerebral hemispheres.
a. Contains superior sagittal sinus and inferior sagittal
sinus.
2. Tentorium cerebelli- dural fold in the transverse fissure.
Separates cerebrum and cerebellum.
3. Falx cerebelli- dural fold that separates the R and L cerebellar
hemispheres.
a. Transverse sinus- sinus that forms at the intersection
of all three dural folds.
2. Arachnoid mater/Arachnoid
a. Middle layer, deep to dura mater
b. Thin CT membrane with lots of tiny fibers called trabeculae that connect to
the pia mater.
c. The space between the thin membrane and the pia mater is filled with CSF.
3. Pia mater
a. Deep, thin, transparent layer.
b. Intimately attached to the surface of the brain and spinal cord.