Lecture 8. CNS Flashcards
What constitutes the central nervous system
brain and spinal cord
What are the 3 segments of the brain (What are the embrologic names)?
- forebrain (prosencephalon)
- midbrain (mesencephalon)
- hindbrain (rhombencephalon)
What are the subdivisions of the forebrain?
- telecephalon ( cerebrum)
2. diencephalon (thalamus)
Describe the diencephalon
structures which surround the 3rd cerebral ventricle and is a narrow gap sitting at the midline
What are the subdivisions of the midbrain
It has no subdivision
What are the subdivisions of the hindbrain
- metencephalon ( pons +cerebellum)
2. mylencephalon ( medulla oblongata)
What constitutes the Peripheral nervous system?
- cranial nerves (12 pairs)
- spinal nerves (31 pairs)
What constitutes the brain stem?
medulla oblongata + pons+ midbrain
What surrounds the diencephalon
- right and left hemisphere
What is the purpose of the foldings on the cerebral hemisphere?
To increase the surface area.
How many grades of the foldings are there?
3 grades
grade 1: present in everyone
grade 2: present in 70%-75% of people
grade 3: present in 10-15% of people
What is the functional classification of the nervous system
- somatic nervous system
2. autonomic nervous system
What is the somatic nervous system
collects sensory information from the external environment and initiates motor info to skeletal muscles
What is the autonomic /visceral nervous system
it collects sensory info from the internal environment targets motor info to smooth muscles and glands
Where are the enlargements of the spinal cord?
- cervical enlargement
2. lumbar enlargement
Why are there enlargements
- there are more nerve cell bodies due to the formation of motor neurons
- will give rise to nerves that will supply the upper limbs for cervical and lumbar for lower limbs
What is the end of the spinal cord called
conus medullaris
What is the position on the vertebrae level ( NOT vertebrae segments) where the conus medullaris is (end of spinal cord).
In between L1 and L2 of the vertebrae
What is the arrangement of white matter and gray matter in the spinal cord
white matter surrounds the gray matter ( which is a core)
what are the grooves present at the anterior(=ventral) and posterior(=dorsal) end of the spinal cord
- ventral median fissure (= anterior median fissure)
2. dorsal median sulcus ( =posterior median sulcus)
What is the difference between fissure and sulcus
fissure is typically deeper and wider
There are nerve fibers extending from the anterior median fissure - what structure arises as a result
ventral root/anterior root
There are nerve fibers extending from the posterior median fissure - what structure arises as a result
dorsal root/ posterior root - which associates with the ganglion
What is a ganglion?
cluster of nerve cell bodies sitting outside the CNS
What are the 3 regions of the gray matter in the spinal cord?
- anterior horn
- posterior horn
- lateral horn
Which horns are present throughout the length of the spinal cord
anterior and posterior horn are present throughout the length of the spinal cord
What does the anterior horn of the spinal cord contain
carries cell bodies of motor neuron
What does the posterior horn of the spinal cord contain
sensory neurons are contained along the posterior horn of the spinal cord
Where can the lateral horn be found
found in T1 -L2 AND S2-S4
What neurons are found in the lateral horn
T1-L2 houses sympathetic neurons
S2-S4 houses parasympathetic neurons
What are the regions of white matter
- dorsal (=posterior) funiculus( = column )
- ventral funiculus
- lateral funiculus
Describe the myleinated fibers at the white columns ( of the white matter)
fibers can be ascending or descending
ascending: carry sensory info
descending: carry motor impulses
What are bundles
millions of nerve fibers
AKA specific tracks that carry either sensory or motor information
What does the posterior column typically contain
carries sensory tracks
What does the lateral column carry
they carry mix tracks - both sensory and motor
What does the anterior column carry
they carry mix tracks - both sensory and motor
What are spinal cord segments
they refer to a sectioned part of the spinal segments
Which part of the brain gathers proprioceptor information
cerebellum
What does the medial lemiscus track do
connects information regarding touch and unconscious proprioception
Where does the 1st order neuron sit
dorsal root ganglia
Where are the 2nd order neuron
for the medial lemniscus the 2nd order neuron site in the medulla oblongata
What do we call when the nerve sections crosses the midline
Decussation
What is the medial lemiscus
are the axons of the 2nd order neuron that crosses the midline (only AFTER it crosses midline)
What is the nucleus gracilis and nucleus cuneatus
are the locations of the axons of the 2nd order neuron
Where does the medial lemiscus go to meet the 3rd order neuron
It passes through the pons and cerebellum to enter the midbrain and meets the 3rd order neuron at the thalamus. The 3rd order neuron sends information to the cortex
What is the disease that attacks the dorsal column of the spinal cord - what happens?
patient loses sense of touch and position. Syphilis. tabes dorsalis
What does the cortex of the brain refer to?
gray matter of the brain
Where is the start and end of the spinal cord
starts at the magnum foraman and ends at the L1-L2 vertebrae level
