Neuroanatomy Flashcards
What are the 2 main cell types of the CNS?
neurones and glial cells
Name the 4 major types of glial cells.
astrocytes
oligodendrocytes
microglia
ependymal cells
Which cell type is more numerous in the CNS?
glial cells more numerous than neurones
Role of astrocytes?
support, maintaining BBB and environmental homeostasis
Role of oligodendrocytes?
produce myelin in CNS
Role of microglia?
immune monitoring and antigen presentation
Describe ependymal cells.
ciliated cuboidal/columnar epithelium that line the ventricles
Describe the resting and activated state of microglial cells.
resting: elongated nucleus and short, spiny cell processes
activated: rounder and similar appearance to macrophage
Which matter contains most neurones, cell processes, synapses and support cells?
grey matter
Which matter contains axons and their support cells?
white matter (medullary centre)
Which lobe lies anterior to the central sulcus and superior to the lateral sulcus?
frontal
Which lobe is posterior to central sulcus, superior to lateral sulcus and anterior to parieto-occipital sulcus?
parietal
Which lobe is posterior to a line from the parieto-occipital sulcus to the pre-occipital notch?
occipital
Which lobe is inferior to lateral sulcus and anterior to the parieto-occipital sulcus line?
temporal
Which lobe is normally hidden and important in a patient’s experience of pain?
insular lobe / insula
Name the two nerve plexuses in the walls of the gut and which nervous system are they part of?
enteric nervous system myenteric plexus (between outer layers of SM) submucosal plexus (in the submucosa)
Which artery supplies the majority of the lateral surface of the cerebral hemispheres?
middle cerebral artery
Which artery supplies the medial aspect of the frontal and parietal lobes?
anterior cerebral artery
Which area of the brain does the posterior cerebral artery supply?
inferior aspect of cerebral hemisphere and occipital lobe.
The name for the spinal cord terminating in a tapered shape?
conus medullairs
The spinal cord continues as thin connective tissue cord (name?) which anchors it to the dorsal of the coccyx.
film terminale
What is the spinal cord suspended by? It is found on the lateral surfaces of the cord - what it is formed by?
denticulate ligament
formed of pia & arachnoid tissue - attaches to dura at points along the length of the cord
What does white matter contain?
longitudinally orientated nerve fibres (axons)
glial cells
blood vessels
What are the subdivisions of the white matter?
posterior, lateral and anterior funiculi - each have a variety of fibre sizes
What does grey matter contain?
neuronal soma, cell processes, synapses, glia and blood vessels
What are the sections of grey mater?
left and right posterior horns
left and right anterior horns (H)
horizontal part of H =dorsal and ventral grey commissures which surround the central canal
Which spinal segments would contain lateral horns of grey matter?
T1-L2
Describe the arterial supply of the spinal cord.
3 major longitudinal arteries (1 ant. 2 post.) - originate from vertebral arteries
Segmental arteries - from vertebral, intercostal & lumbar arteries.
Radicular arteries - follow the dorsal and ventral roots - exit spinal cord at each level.
In the spinal canal what is found between the dura and bone and what does it contain?
Epidural space - contains adipose tissue and the anterior and posterior venous plexuses
Why is there less white matter in the spinal cord as you descend it?
it delivers axons to the brain so the further away it is from the brain, the smaller the proportion of white matter vs. grey matter
Which spinal tract is responsible for fine touch and proprioception?
dorsal column / medial lemniscus system
Where is the 1st order neurone of the dorsal column/medial lemniscus system?
in nucleus gracilis of medulla
How do the fibres travel up the dorsal column?
enter spinal cord and ascends until they cross in the medulla, travel up to thalamus and synapse in the primary somatosensory cortex
which fasiciuli of the dorsal column correspond to arms and which to legs?
arms - fascicles cuneatus
legs - fascicles gracilis
Which tract carries pain, temperature and deep pressure?
spinothalamic tract
aka. anterolateral tract
How do the fibres cross in the spinothalamic tract?
cross segmentally - enter spinal cord at posterior horn and synapse - axon crosses into contralateral anterior with matter and ascends to thalamus.
How does information from the motor cortex reach the motor neurone?
via descending spinal cord tracts - the corticospinal tracts (lateral and ventral)
What is the corticospinal tract responsible for?
fine, precise movement, especially in distal limb muscles
What visible feature does the CST form?
visible ridges (pyramids) on the anterior surface of the medulla - hence pyramidal tract name.
What percentage of fibres cross the pyramids at the medulla?
85% cross and the rest continue down ipsilateral side of spinal cord
What is the term for the fibres crossing in the caudal medulla?
decussation of the pyramids
What is decorticate posturing?
spastic paralysis of the corticospinal tract with hyperflesion of the upper limbs
- a consequence of CVA of the internal capsule
What are the 3 tracts of the “extra-pyramidal system”?
Tectospinal tract
Reticulospinal tract
Vestibulospinal tract
What is the tectum?
the posterior portion of brain - mediates reflex head and neck movements due to visual stimuli
Where does the tectospinal tract supply and where does it cross?
Motor input to cervical segments
crosses midline then projects down spinal cord to C level
synapse in anterior horn of cord
Which extra-pyramidal tract influences voluntary movement?
reticulospinal
What do fibres originating in areas of reticular formation (P&M) control?
pons - flexor movements
medulla - extensor movements
What input does the vestibulospinal tract facilitate?
excitatory input to ‘antigravity’ extensor muscles
e.g. finds balance after pushed
What is the consequence of lateral semi-section of spinal cord?
Brown-Sequard’s syndrome
- > ipsilateral paralysis
- > ipsilateral hyperreflexia & extensor plantar reflex (CST)
- > ipsilateral loss of vibratory sense & proprioception (dorsal column)
-> contralateral loss of pain & temperature (spinothalamic)
