Origin & development of the CNS Flashcards
How many cerebral ventricles are there?
4! They are interconnected.
1) Right lateral ventricle
2) Left lateral ventricle
3) Third ventricle
4) Fourth ventricle
What are the 1st and 2nd ventricles called?
The ‘lateral ventricles’. They form C shaped lakes underlying the cerebral cortex and there is one is each hemisphere.
Where to the third and fourth ventricle lie?
In the midline of the brain
What are ALL 4 ventricles filled with?
Cerebrospical fluid (CSF)
What produces CSF?
The ependymal glial cells located adjacent to the ventricles
Where does CSF flow?
From the lateral ventricles through the 4th ventricle and eventually into the circulatory system
Where do the 3rd and 4th ventricles extend to?
They extend into the brainstem and spinal cord
The spinal cord can also be regarded as the:
‘Tube of nerves’
Afferent fibres (enter the spinal cord) and…
Bring information from sensory receptors to the body
The spinal nerves that converge as they enter the spinal cord form a strand of fibres called the:
Dorsal root
Efferent fibres (leave the spinal cord) and…
Carry information from the spinal cord to the muscles
Fibres that leave the ventral part of the spinal cord
Ventral root
Dorsally located tracts are:
SENSORY
Ventrally located tracts are:
MOTOR
What do spinal tracts do?
Carry information to and from the brain
What colour is the OUTER part of the spinal cord?
White matter. White matter fibre tracts carry info to and from the brain
What colour is the INNER part of the spinal cord?
Grey matter (compased largely of neural cell bodies)
Fibres LEAVING the ventral root of the spinal cord:
Carry motor information to the muscles
Fibres ENTERING the dorsal root of the spinal cord:
Bring sensory information from sensory receptors
Collateral branches of sensory neurons may cross to the other side and influence motor neurons on that side. This might…
Extend to adjacent segments to influence adjacent body parts
The Bell-Magendie law states that…
The dorsal part of the spinal cord is sensory and the central part is motor
What does the SNS consist of?
The spinal and cranial nerves that produce movement and transmit incoming sensory information to CNS.
Why is sensory information important?
It plays a central role in eliciting different kinds of movements organised by the spinal cord.
Movements dependent only on spinal-cord function are called…
Reflexes
What kinds of sensory receptors in the bdoy are there?
Pain, temperature, pressure and sensations from joint or muscle movement
The size of the spinal nerve fibre coming from each receptor is distinctive..
Generally, pain and temperature are smaller and those for touch and muscle sense are larger.
The stimulation or pain and temperature receptors in a limb usually produce
Flexion movements (which bring the limb inward)
If the stimulus is MILD only the ___ part of the limb flexes in response to it
Distal
The ___ reflex causes the limb to extend outward, away from the body and causes the touched part of the limb to remain in contact with the surface
Extension
