Lecture 4 Flashcards
What is the division on the somite of where the brain and spinal cord are formed?
between the 4th and 5th somite
Everything about the 4th somite is what?
Brain
Below the 4th somite
Spinal cord
What is the peripheral nervous system?
Everything that leaves the CNS.
Ganglia, cranial nerves, enteric plexus and sensory receptors
Divisions of the PNS
- Somatic (controls voluntary movements; motor and sensory)
2. Autonomic (involuntary; motor and sensory as well)
Ex. Nerves in the somatic NS
- Greater occipital N
- Ulnar nerve
- Median nerve
MOTOR components of the Autonomic NS
The SYMPATHETIC and PARASYMPATHETIC NS are both motor components of the autonomic nervous system.
Is the autonomic NS voluntary and involuntary?
involuntary.
What is grey matter?
Grey matter is a collection of unmyelinated CB and neurons. Grey matter is made up of 3 parts:
- Dorsal horns (sensory information).
- Lateral horns (autonomic information)
- Anterior horns (motor information)
Dorsal horns
Dorsal horns are located in grey matter. They hold the CB of sensory neurons
Lateral horns
Lateral horns are located in grey matter. They hold the CB of autonomic neurons.
Anterior horns
Anterior horns are located in grey matter. They hold the CB of motor neurons.
We only see lateral horns that hold autonomic neurons where?
T1-L2
What is white matter?
white matter is made up of mylenated axons that are stored in three areas:
- Dorsal funiculus (sensory pathway)
- Lateral funiculus (sensory and motor pathways)
- Anterior funiculus (primarily motor pathways)
What is the structure of the neural tube?
The neural tube will be made up of 2 plates separated by the sulcus limitans:
- Alar plate
- Basilar plate
The neural tube also has a central canal called a neural canal.
What is the alar plate?
The alar plate will contains CNS sensory neurons
What is the basilar plate?
The basilar plate will contain CNS motor neurons.
Zones of the spinal cord
The spinal cord will have 3 zones
- Ventricular zone (located directly next to the central canal)
- Intermediate zone
- Marginal zone
====VIM=====
What does the intermediate zone make?
Grey matter
What does the marginal zone make?
white matter
What cells are found in the ventricular zone of the spinal cord?
In the ventricular zone, we find stem cells. Stem cells can either migrate to the intermediate zone create cells that stay in the ventricular zone of the spinal cord.
Ependymoblasts are found here and can make
- Ependymal cells
- Choroid plexus cells, which make CSF
What cells are made in the intermediate zone?
Grey matter- neurons and glial cells
What cells are made in the marginal zone
Marginal is white matter
So axons and oligodendrocytes
Cells of the nervous system that are from the neuroectoderm (specially the neural tube)
- Ependyma
- Epithelium of choroid plexus
- Oligodendrocytes
- Astrocytes
- Axons
Cells from the NS from MESODERM
Mesenchymal cells and microglial cells
Development of the spinal cord
During development (in utero), the spinal cord and the vertebral column are the same length.
However, by the time of birth, the vertebral column is bigger because it has grown faster and the spinal cord extends roots to form the cauda equina.
If you wanted to give a newborn a lumbar puncture, where would it be at?
L3/L4 because their spinal cord ends at L2/L3.
Adult spinal cord will end where?
L1/L2.
How do we form the spinal cord?
In order to create our spinal cord; we have to begin with our neural tube.
Our neural tube must have a dorsal (sensory) end and a ventral (motor) end as a precursor for our spinal cord.
This is created by a concentration gradient of BMP and SHH.
High levels of BMP= + PAX 3 and PAX 7= cause the formation of our alar plate (location of sensory neurons)
High levels of SHH= +NXK2.2 and NKX 6.1= formation of our basilar plate (location of motor neurons)
How do we create our ventral motor neurons to go into our basilar plate?
Slightly decrease levels of SHH and slightly increase levels of BMP.
Formation of the spinal cord is the formation of what?
CNS.
So yay. We just made our CNS!
What cells are going to form the PNS?
- Neural crest cells
2. Ectodermal placode
Cells that develop from the neural tube are
- motor neurons
2. pre-ganglionic autnomic neurons
Cells the develop from neural crest cells are what?
Sensory neurons and ganglia,
schwaan cells
Sympathetic and parasympathetic ganglia
What are dorsal roots and where do they come from?
Hold sensory information
neural crest cells
What are ventral root neurons and where do they come from
transfer motor infomation
neuroectoderm
What are spinal nerves and where do they come from
Sensory nerves and motor nerves. It depends
Sensory= neural crest
Motor= neuroectoderm
What are dorsal ramus
where do they go
What are they derived from
Dorsal rami are a mix of motor and spinal nerves that send infornation from the TRUE back muscles and the skin.
They are derived from the epimere.
What are the ventral ramus
Where do they go
What are they derived from
Ventral rami are a mix of motor and spinal nerves that innervate muscles of the hypomere.
Motor and sensory info go to limbs, lateral and ventral body wall.
What are efferent neurons
carry signals away from your brain–> muscle to carry out motor movements
What are afferent neurons
Sensory neurons that carry info to your spine
General somatic efferent neurons
Where are they derived from
motor neurons that carry information to somatic muscles (from somites)
From neuroectoderm
General visceral efferent neurons
Where are they derived from
motor neurons that carry information to smooh muscle, cardiac and glands
Derived from neuroectoderm
Special visceral efferent neurons
Where are they derived from
motor neurons that send information to muscles derived from pharyngeal arches
From neuroectoderm
General somatic neurons
Sensory neurons that send info to your spine from skin (integuins), joint capsule, tendon, muscle
From neural crest
Anything derived from the ectoderm will be innervated by what?
General somatic afferent
Skin will be innervated by what?
General somatic afferent
General visceral afferent neurons
Where are they derived from
Sensory neurons that send info from visceral organs to your brain.
From neural crest
Your GI system will be innervated by what?
General visceral afferent
Anything derived from the endoderm will be inervated by what?
GVA (general visceral afferent)
special somatic afferent neurons
sensory neurons that are responsible for
hearing
balance
sight
special visceral afferent neurons
sensory neurons responsible for taste and smell
Autonomic nervous system
Involuntary.
has a motor and sensory component.
Parasympathetic (rest and digest)
Sympathetic (fight or flight)
What does the autonomic NS innvervate?
smooth muscle,
cardiac
glands
What is the ANS pathway like?
pre and post ganglionic neuron (innervates with pre in a autonomic ganglia)
Somatic NS pathway neurons
Consist of a afferent (sensory neurons) and efferent (motor neuron.
Autonomic NS pathway
Consists of 2 neurons in a row: pre-ganglionic has its CB in the grey matter of spinal cord or brain
Post ganglionic neurons synapses with the pre-ganglionic in a autonomic ganglion
Ganglia and post ganglionic neurons are from where>
Neural crest cells
because they are outside of the CNS, in the PNS.
Preganglionic cells are from where
Neuroectoderm
because they originate in the brain or spinal cord
Arrangement of neurons in the sympathetic NS
Spinal cord in the thoraco-lumbar region (T1-L2)
Sympathetic pre-ganglionic neuron goes from [spinal cord–> symapthetic ganglion]
Pre-ganglionic is SHORT and MYELINATED
Sympathetic post-ganglionic neuron goes from [sympathetic ganglia to viscera organ]
Post-ganglionic is LONG and NOT MYELNATED
Where are Sympathetic neurons found
Spinal cord in the thoraco-lumbar region (T1-L2)
Where are parasympathetic neurons found?
- Cranial nerves 3, 7, 9, 10 in the cranial region
2. 2nd-4th sacral spinal nerves (GVE)
Arrangement of neurons in the parasympathetic
Preganglionic is LONG and MYELINATED
Postganglionic are SHORT and UNMYELENATED
Where are parasympathetic ganglia located?
Walls of the viscera
cranial nerves in head and neck
Where are the ganglia of 2-4 sacral spinal nerves located?
Pelvic wall
Where is BMP released from?
Roof plate and surface ectoderm
Where is SHH released from?
Notochord and floor plate