11. Peripheral Nervous System Flashcards
Where (in terms of somites) does the divison between Brain and Spinal Cord occur?
Brain is 4th Somite and Superior
Spinal Cord is Inferior to the 4th Somite
What is grey matter mostly made of?
Unmyelinated cell bodies
What is White Matter mostly made of?
Myelinated Axons
What region of the spine contains the Lateral Horns?
T1 to L2
(absent in most of the spine)
What is the dorsal part of the Spinal Cord (grey and white matter) primarily responsible for?
Sensory input
Before the Epiblast invaginates, is the region of the Alar Plate medial or lateral to the region of the Basal Plate of the future Neural Tube?
Lateral -The Alar Plate will be on top of the Basal Plate in the Neural Tube
What is found in the Alar Plate of the Neural Tube?
Sensory Neurons that never leave the Central Nervous System
Where do the Sensory Neurons of the Peripheral Nervous System (First Order Neurons) come from?
The Neural Crest
What comes from the Basal Plate of the Neural Tube?
Motor Neurons
What separates the afferent from the efferent nerves in the Neural Tube?
The Sulcus Limitans
What is the name for the center space in the Neural Tube?
Central Canal
What does the Intermediate Zone of the early Spinal Cord become?
Gray Matter
What does the Marginal Zone of the early Spinal Cord become?
White Matter
What cell type does the Ventricular Zone contain?
What do these cells do within the Ventricular Zone?
Stem Cells
They become Ependymoblasts, which can then either become Ependymal Cells or Choroid Plexus Cells (which make CSF)
What do Ventricular Zone Stem Cells become in the Intermediate Zone of the Early Spinal Cord?
Neruons, Astrocytes (protoplasmic), Glial Cells
(and others)
What do Ventricular Zone Stem Cells become in the Marginal Zone of the Early Spinal Cord?
What precursor to these cells is found in the Intermediate Zone?
Oligodendrocytes, Astrocytes (fibrous)
Glioblasts
What do Schwann Cells do?
What embryological structure do they come from?
They myelinate neurons of the Peripheral Nervous System
Neural Crest
What do Oligodendrocytes do?
What embryological structure do they come from?
They myelinate neurons of the Central Nervous System
Neuroectoderm
What germ layer do Microglial Cells come from?
What do they do?
Mesoderm
They come from monocytes, which come from mesoderm
They are phagocytes
In an early fetus, the Vertebrae and the Spinal Cord are the same length. What causes the Spinal Cord to stop short of the Vertebrae in a newborn?
The Vertebrae grow faster than the Spinal Cord