8 The Central Nervous System Flashcards
Q: What is the nervous system for? 2 divisions? Examples (2,3).
A: Mainly communication
- bodies and external environment (somatic senses and special senses)
- within our bodies (higher cognitive function and movement and visceral sensation)
Q: What is meant by afferent? efferent?
A: periphery to centre, centre to periphery
Q: What doesn’t make a species smarter? (2) What does make a difference?
A: more neurons, larger brain
cortex structure eg smooth in mice but human= v folded= larger SA
-> number of cerebral cortex neurons makes a difference
Q: What is brain morphology related to? Why is the brain described as an onion?
A: function
has layers with increasing complexity
Q: What makes up the brain stem? What is above it? Describe each component.
A: top
-midbrain: has lots of of nuclei and groups of neurons with different functions including substantia nigra= degenerates in parkinsons disease
-pons: contains grey nuclei and connects 2 halves of cerebellum
-medulla oblongata: similar structure to spinal cord with the grey and white matter- just larger
bottom
diencephalon
Q: Planes:
sagittal?
transverse?
coronal?
References:
cranial? caudal? anterior? posterior? proximal? distal? lateral? medial?
A: -longitudinal that divides the body into right and left parts
- aka horizontal= separating top and bottom (inferior and superior parts)
- dividing the body into dorsal and ventral parts (front and back)
-towards head
-towards feet
-ventral/front
-dorsal/back
-towards centre (used in reference to relative locations of parts or places on the limbs)
-away from (used in reference to relative locations of parts or places on the limbs)
-outwards from midline
midline
Q: What is the spinal cord? Protection? What does this structure also provide?
A: thin column of nervous tissue
well protected within bony vertebral column= made of a stack of vertebrae (form vertebral canal within where spinal cord sits)
flexibility/movement
Q: When vertebrae are stacked, what do they form? Function?
A: form intervertebral foramen (between them)= holes
spinal nerves emerge from them
Q: Where is the barrier between the CNS and the PNS?
A: intervertebral foramen where the spinal nerves emerge
Q: How many nerves do we have? Relationship to spinal cord? exception?
A: 31 pairs
come out below corresponding vertebra except in cervical tract where we have 8 nerves but 7 vertebrae
Q: Length relationship between spinal cord and vertebral column? means that? Results in? (2)
A: spinal cord is shorter than vertebral column (ends around L1/2) -> so there is some empty space at bottom (lower nerves need to travel down a little to reach their corresponding vertebra)
results in lumbar cistern = subarachnoid space in the lower lumbar spinal canal
cauda equina= only have fibres and no spinal cord (bundle of spinal nerves)
Q: What’s handy about space in lower vertebral column? How? Benefit?
A: when we want samples of cerebrospinal fluid that fills space
can insert needle between L3 and L4, 4 and 5
-> take sample without risking damage to the spinal cord itself
Q: How does the spinal cord vary in thickness? (4) Why?
A: cervical (enlargement)
thoracic
lumbar (enlargement)
sacral
innervate upper and lower limbs respectively
Q: What does each spinal cord segment innervate?
A: particular skin area- dermatome
Q: Describe a spinal cord cross section structure.
A: REFER
groove at front and back
symmetrical
dorsal and ventral rootlets coming out
(have lump = dorsal root ganglian)
white matter on outer part
grey matter = core where cell bodies are-> has dorsal horn (2 of them) and 2 ventral horns
central canal right in centre= small and fluid filled
dorsal median sulcus
ventral median fissure (longer)
Q: What’s in the dorsal root ganglion?
A: cell bodies of the sensory neurons are
Q: What happens in dorsal and ventral horn? Direction of information travel?
A: dorsal is where sensory neurons come in and synapse with inter neurons with in (go to brain)
ventral contains cell bodies of motor neurons
out from ventral horn and in from dorsal horn
Q: What are the functions of the spinal cord?
A: Connects the PNS and ANS to the brain
Carries sensory signals to the brain
Carries motor signals to the muscles
Coordinates reflexes- some information is processed at level of spinal cord without reaching brain