Introduction Flashcards
What are neurons & what do they do?
-Electrically active cells
-Receive info from synapses in their dendritic tree = causing changes in their memb pot
—> so neurones generate AP from axon hillock down axon - stimulates
What occurs at synapses?
AP opens Ca2+ channels -> synaptic vesicles fuse with pre-synaptic memb = neurotransmitters released into synaptic cleft
Examples of neurotransmitters?
-Glutamate (excitatory)
-GABA (inhibitory)
What are the 4 classifications of neurons?
-Multipolar = many poles
-Bipolar = 2 poles
-Unipolar = 1 pole
-Pseudounipolar = start as bipolar then converted to unipolar
What are neuroglia?
Support cells - 3 types
What are the 3 types of neuroglia?
-Astrocyte
-Oligodendrocyte
-Microglial cell
What are astrocytes?
-Star shaped
-Maintain ionic balance & metabolic requirements of neurones - maintain large axons, & have to send neurotransmitters along axons
–> neurones under such metabolic demand = why lots die before end of our lives
What are oligodendrocytes?
Myelinate axons in CNS
What are microglia?
Immune cells in brain - responsible for inflammation
What can the nervous system be classified of structurally?
-CNS
-PNS
What is the CNS made up of?
-Brain
-Spinal cord
What is the PNS made up of?
-Cranial nerves
-Spinal nerves
What can the nervous system be classified as functionally?
-Sensory VS motor
OR
-Somatic (conscious) VS autonomic (unconscious)
Draw a PNS division ‘tree’.
What are afferent fibres/neurones?
Carry signals towards structures
–> carry info from sensory recs of skin to other organs to CNS
AFFERENT = ARRIVES
What are efferent fibres/neurones?
Carry signals away from structures
–> carry motor info away from CNS to muscles & glands of body
EFFERENT = EXITS
What does ipsilateral mean?
An axon arrangement in CNS into tracts that are on same side
What does contralateral mean?
An axon arrangement in CNS into tracts that are on different sides
Ganglion VS nucleus?
G = cluster of neurons outside CNS (so in PNS)
N = inside CNS
Sulcus VS fissure?
S = groove on brain surface - less deep –> PRODUCES GYRI - increases SA of brain
F = ‘valley’ - i.e., really big groove (often blood vs come through) - long, narrow, v. deep splitting of brain surface –> PRODUCES LOBES - separates brain into functional lobes
Fissure separates one lobe from another, while a sulcus is within a lobe & delimits gyri
Sulcus VS gyrus?
S = groove (produces gyri)
G = folded cortex - ridges of the grooves/folds
Fasciculus VS funiculus?
F’a’siculus = particular cluster of ‘a’xons
Funiculus = general area of white matter
How is the spinal cord segmented?
-Into cervical, thoracic, lumbar & sacral
-There are cervical & lumbar enlargemnts - as are more neurones - so more cell bodies - needed to operate limbs in these regions
What are the 3 meninges?
-Dura mater (most outer/sup)
-Arachnoid mater
-Pia mater (most inner/inf)
Where are the most important regions that the dura mater extends into the cranial cavity = called the dural reflections
-Falx cerebri
-Tentorium cerebelli
Describe CSF formation & path.
-Choroid plexus = creates CSF
-CSF moves into subarachnoid space
-CSF is then absorbed into venous sinuses
Where is the choroid plexus?
On inner lining of brain ventricles
What section of the brain is this image?
Coronal section
(shows flow of CSF)
What is the dentate ligament?
-Runs down spinal cord
-Is extensions/continuation/lateral projections of pia mater
–> bilateral triangular lateral extensions
-Firmly attach to arachnoid mater & dura mater at apex
-Originate on either side of spinal cord - stop spinal cord moving laterally
–> this is essentially responsible for suspending the meninges from the brain go the spinal cord
-Main function = stabilise spinal cord within vertebral canal
What does it mean if the spinal cord finishes before end of vertebral column?
-Forms lumbar cistern = enlargement of subarachnoid space in lower lumbar spinal canal
–> contains CSF & nerve roots of cauda equina
-Cauda equina = collection of spinal nerve roots (L2-S5) & coccygeal nerve (Co)
–> nerve pairs exiting vertebral column from L2, L3, L4, L5, S1, S2, S3, S4, S5, Co - extend down inside vertebral column then exit out @ appropriate level - forms cauda equina (looks like horse’s tail)
-Conus medullaris = terminal part of spinal cord (L2-S5 & coccygeal element) - tip of which is found @ L1/L2 & end of it tethers to coccyx - tied to coccyx by the filum terminale (stabilising distal end of spinal cord)
Why is the cauda equina clinically useful?
Gives a place that a needle can be inserted e.g., lumbar puncture for CSF sample (or for delivering antibiotics, dyes or epidurals = anaesthesia) - which won’t damage spinal cord - as it ends @ L1/L2
–> but will usually insert needle @ around L3/L4 due to anatomical variations
What are the 2 divisions/components of the PNS?
-Somatic
-(Efferent motor) Visceral (autonomic)
Give the number of each type of spinal nerve - & total number.
Total = 31 pairs of spinal nerves
*Cervical = 8 pairs (but are 7 cervical vertebrae!)
*Thoracic = 12 pairs
*Lumbar = 5 pairs
*Sacral = 5 pairs
*Coccygeal = 1 pair
Where do spinal nerves emerge in relation to their corresponding vertebrae?
-Cervical nerves = emerge sup. to their respective vertebrae
-Thoracic, lumbar, sacral, coccygeal nerves = emerge inf. to their respective vertebrae
Organisation of peripheral (cranial & spinal) nerves & what surrounds them?
-Peripheral nerve - surrounded by epineurium
-Fascicles - surrounded by perineurium
-Nerve fibres - surrounded by endoneurium
What does the green and the red represent here?
-Red = epineurium
-Green = perineurium
What can be said about the nerve axons shown?
Some are lightly (thinner & less dark) & some are heavily (thicker & darker) myelinated
What are dermatomes?
Single area of skin innervated by a single nerve root
What is shingles (varicella zosta virus)?
Infection that spreads from dorsal root ganglia - down nerve & exits at peripheral nerve terminals = outlines a dermatome
What are myotomes?
Group of muscles innervated by a single nerve root (spinal nerve)
