Neuro 6 - Organisation of the CNS Flashcards
How many paris of nerves emerge from the CNS?
31 pairs
Equal number of nuerves for each vertebra except extra nerve above C1 so 8 cervical nerves, 7 verterbrae
C1 is above C1 so C8 above T1 and under C7
T1 under T1
Thoracic - 12
Lumbar - 5
How is the spinal cord protected, where does it lie?
Protected by vertebrae
Lies in vertebral canal
Series of holes alongside vertebrae –> intervertebral foramina –> where nerves come out
What is the structure called cauda equina?
cauda is a “tail”
It is when the spinal cord is shorter than the vertebral column so the nerves emerge from it and form a nerve tail
Where can CSF fluid be sampled?
L3/L4
or L4/L5
What is the name of the area inside the vertebral canal beneath the point at which the spinal cord ends?
Lumbar cistern ("tank") Where you find the cauda equina
What is the difference between the dorsal horns and the ventral horns?
Dorsal -> sensory (has dorsal ganglion) - in from dorsal route
Ventral -> motor - out from ventral route
What is the difference between the white and grey matter?
White matter -> myelinated fibres - go up and down
Grey matter -> neuronal cell bodies, glial cells, unmyelinated fibres
Myelin is WHITE
What are the functions of the spinal cord?
- connects PNS and ANS to the brain
- carries sensory signal to the brain
- carries motor signals to the muscles
- coordinates reflexes - information processed at the spinal cord level
What structure connects the right and left hemispheres?
Corpus callosum
What lies beneath the corpus callosum?
Diaencephalon ie. thalamus + hypothalamus
What are the two parts of the diencephalon and what is their function?
Thalamus - relay station for information going between the cerebral cortex and other areas of the CNS. Somatic and special senses, emotional, consciousness
Hypothalamus - integration hub - important in coordinating homeostasis (hypothalamo-hypophysial axis)
Thalamus is above hypothalamus
–> know everything that is going on in body, however, to make sense of it needs cortex
What are the two classifications of the brain?
—>Based on embryonic development:
It initially developed as the forebrain, midbrain and hindbrain.
The forebrain became the cerebral cortex and diencephalon
The midbrain remained as the midbrain (part in between diencephalon and pons)
The hindbrain became the pons, medulla and cerebellum
—>Other classification:
Brainstem -> Midbrain + pons + medulla
Cerebrum -> hemispheres + diencephalon
Cerebellum
What composes the brainstem?
Midbrain
Pons
Medulla
All sensory and motor fibres that connect the cerebrum, cerebellum and spinal cord run through it
Continuation of spinal cord (medulla still has its structure but enlarged)
What makes the pons recognisable?
It bulges anteriorly
What is the function of the brainstem?
Control of many vital functions such as breathing, HR, BP, swallowing, balance, etc.
Defensive reflexes, sleep-wake cycles, alertness, consciousness
NOTE
Lesion of the brainstem can lead to locked-in syndrome
Midbrain includes substantia nigra which degenerates in Parkinson’s