Spinal Cord Flashcards
where does the spinal cord run
- from foramen magnum to L1 or L2
- through vertebral canal of vertebral column
three functions of spinal cord
- sensory and motor innervation of entire body inferior to head via spinal nerves
- two-way conduction pathway between body and brain
- major centre for reflexes
where does spinal cord end at 3rd fetal month
at coccyx
where does spinal cord end at birth
at L3
where does adult spinal cord extend to
conus medullaris which tapers into causa equina, tethered to coccyx
how do spinal cord segments relate to their nerves
spinal cord segments are superior to where their corresponding spinal nerves emerge through intervertebral formina
denticulate ligaments
lateral shelves of pia mater anchoring to dura
what are the spinal nerves part of
PNS
where do spinal nerves lie
in intervertebral foramina
how many pairs of spinal nerves are there
31
how many pairs of cervical spinal nerve pairs
8
how many pairs of thoracic spinal nerve pairs
12
how many pairs of lumbar spinal nerve pairs
5
how many pairs of sacral spinal nerve pairs
5
how many pairs of coccygeal spinal nerve pairs
1
what is the cauda equina
a collection of nerve roots at the inferior end of the vertebral canal
where do the cervical spinal nerves exit
from above their respective vertebra (eg. nerve root 1 from abov C1, nerve root 2 between C1 and C2)
name the three meningeal membranes
- dura mater
- arachnoid mater
- pia mater
name the three potential meningeal spaces
- epidural - outside dura
- subdural - between dura and arachnoid
- subarachnoid - deep to arachnoid
four functions of CSF
- buffers CNS
- lightens brain
- removes toxic metabolites
- transports hormones
three types of protection given to spinal cord
- meninges
- bone
- CSF
what is a lumbar puncture also known as
spinal tap
how is a lumbar puncture carried out
needle is introduced into subarachnoidal space between L3 and L4 to collect CSF
safety consideration for carrying out lumbar puncture
lumbar spine must be flexed so needle can pass between spinal processes (injection into correct space is vital; errors can be lethal)
four functions of a lumbar puncture
- collection of CSF and its evaluation to determine infectious and inflammatory diseases affecting the CNS
- control of CSF pressure
- detection of CSF pressure
- anaesthetic delivery
what is the dorsal half of H-shaped cross section made up of
cell bodies of interneurons
what is the ventral half of H-shaped cross section made up of
cell bodies of motor neurons
grey matter pathway
Sensory neurons → cell body → sensory axon → interneuron → cell body (lower motor neurons)
what are visceral motor neurons and what do they control
- part of autonomic nervous system
- involuntary
- control organs
what are somatic motor neurons and what do they control
- part of somatic nervous system
- voluntary
- control skeletal muscle and skin
ascending pathways
sensory informaiton by three orders of neurons from body up tp more rostral regions of CNS
descending pathways
motor instructions via upper and lower order neurons from brain to more causal regions of CNS
two functions of descending pathways
- stimulate contraction of body’s muscles
- stimulate seceretion from body’s glands
commissural fibres
white matter fibres crossing from one side of the spinal cord to the other
name the three major ascending pathways
- spinocerebellar
- dorsal columns
- spinothalamic
is the spinocerebellar pathway ipsilateral or contralateral
ipsilateral
spinocerebellar function
proprioception from skeletal muscles to cerebellum
are the dorsal columns ipsilateral or contralateral
contralateral
where do the doral columns decussate
medulla
dorsal columns function
discriminative tough sensation through thalamus to somatosensory cortex
is the spinothalamic pathway ipsilateral or contralateral
contralateral
where does the spinothalamic pathway decussate
spinal cord
spinothalamic pathway function
nondiscriminate sensations (pain, temp, pressure) through thalamus to the primary somatosensory cortex
what do the major descending pathways synapse with
ventral horn interneurons
name two pyramidal tracts
- lateral corticospinal
- ventral corticospinal
where does the lateral corticospinal tract decussate
pyramids of medulla
lateral corticospinal tract function
voluntary motor to limb muscles
where does the ventral corticospinal tract decussate
spinal cord
ventral corticospinal tract function
voluntary to axial muscles
