CNS Flashcards
Meninges
- Singular meninx; composed of specialized epithelial cells (meningothelial cells)
- Supported by connective tissue; have protective function
- Confined to outer layer of brain & cord in CNS
What are the 3 meninges laters?
- Dura Mater
- Arachnoid
- Pia Mater
Thick layer of dense connective tissue, internally lined by ____?
mesothelium
In cranium, fuses with___of skull
periosteum
In spinal cord, dura is surrounded by what?
epidural space
what is beneath the dura? what what does it separate?
subdural space; separates dura from underlying arachnoid mater
subarachnoid space is lined by what?
lined by flattened mesothelial cells
subarachnoid space
contains CSF & is continuous with ventricles of brain
pia mater is ___ to surface of brain and cord?
adherent; it is highly vascular
what makes up of leptomeninges?
pia + arachnoid
Denticulate ligaments
support cord; extend from pia, anchor cord to arachnoid, dura & periosteum
Neurons in CNS are derived from what?
neuroectodermal cells of neural tube
what does the brain and cord contain?
gray and white matter
peripheral gray matter
neuron cell bodies, dendrites & axons
central white matter
contains mostly myelinated axon
what is neuroglia and its structure & function
- Large # of support cells in CNS
- Structure: Highly branched
- Function: provide structural & metabolic support for neurons
Types of neuroglia? (4)
- oligodendrocytes
- astrocytes
- microglia
- ependymal
oligodendrocytes
CNS equivalent of Schwann cells; elaborate myelin sheaths
astrocytes
- most highly branched; largest neuroglial cells
- Provide structural & metabolic support & aid in tissue repair following injury
microglia
- phagocytic, fixed-tissue macrophages
- part of monocyte-macrophage lineage
- smallest neuroglial cells; originally mesodermal, have immune function
ependymal cells
- Frequently ciliated; microvilli for reabsorbtion of CSF
- cuboidal epithelium lining ventricles & central canal of spinal cord
what are the largest neuroglial cells?
astrocytes
what are the smallest neuroglial cells
microglia
Choroid plexus
- secretes CSF
- vascular structure arising from walls of ventricle in brain
- Contains modified ependymal cells
- fluid acts like shock absorber
Cerebrum
=cerebral cortex
- composed of gray matter peripherally; contains large # of neuron cell bodies
-
neocortex
in mammals, evolved to include sensory, motor, and association areas
gyri
grossly organized folds
nuclei in cerebrum
clusters of neuron cell bodies form small islands of gray matter in cerebrum and cerebellum
in gray matter, neuroglial cells include what?
astrocytes and microglial cells
deep to cortex is____
subcortical white matter (=medulla)
white matter
Contains mostly myelinated axons surrounded by oligodendrocytes
tracts
axons leading in and out of gray matter is grouped in bundles
cortical neurons
- Histologically, neurons of neocortex divided into five morphological categories
- Anatomically, divided into six layers, designated with Roman numerals I-VI, from superficial to deep
- Functionally, arranged in vertical columns or units
types of cortical neurons (5)
- pyramidal cells
- stellate cells
- cells of martinotti
- fusiform cells
- horizontal cells of cajal
pyramidal cells
- Largest include upper motor neurons in motor cortex, known as Betz cells
- pyramid-shaped neurons with long, slender axons, varying in size from small to large
Betz cells
upper motor neuron in motor cortex, associated with pyramidal cells