Spinal Cord Flashcards
Function of spinal cord
co-ordinates movement and sensation
Where is the spinal cord found?
inside the vertebral column
What does the spinal cord arise from?
specialised dorsal ectoderm
Neural tube closure
occurs at multiple sites from anterior to posterior neuropore in multiple stages
genes for neural tube closure
82 in humans - MTHFR involved in folate metabolism
Primary neurulation
day 22-26
neural ectoderm fold and fuse to form neural tube
secondary neurulation
tail bid cells condense and form secondary neural tube caudally - coccyx and cauda equina
DRG formation
neural folds fuse to form brain and spinal cord
after fusion neural crest cells migrate peripherally to form sensory neurons of DRG
3 layers of the neural tube
ventricular - undifferentiated, lining of central canal
mantle - differentiating neurons form grey matter
marginal - nerve fibres - white matter
alar and basal plate
alar plate - dorsal - sensory
basal - ventral - motor
where do cells in DRG extend sensory fibres?
peripherally and centrally
5 main layers of spinal cord periphery
dura mater - tough, fibrous outer layer
epidural space - between dura and vertebra - loose connective tissue
arachnoid mater
subarachnoid space - CSF
pia mater - vascularised, attached to brain and spinal cord
How does the spinal cord transmit information?
ascending and descending white matter tracts
How does the spinal cord involve reflex integration?
grey matter - spinal reflexes eg knee jerk not initiated voluntarily by the brain
where does human spinal cord end?
L1
2 spinal cord enlargements
cervical C3-T1
lumbar T11-L2
control of limbs
What is the name for the nerve roots which radiate from L1 to coccyx?
cauda equina
How many spinal nerves and what do they contain?
31 pairs - sensory and motor
where are sensory nerve bodies located?
DRG
cervical plexus
C1-5 = neck, head and shoulders
brachial plexus
C5-T1 - shoulder and upper limb
lumbar plexus
T12-L4 - lower abdomen and lower limb
sacral plexus
L4-S4 - legs and feet
central pattern generator
produce rhythmic patterns eg walking
fictive motor patterns - motor output in paralysed/isolated spinal cord
alternate muscle extension and flexion
what are CPGs co-ordinated by?
propriospinal neuron path
cervical and lumbar enlargements
what is cpg refined by?
supraspinal signals - motor cortex
sensory feedback to spinal cord
main problems with NTD
neural tissue exposed to amniotic fluid liable to damage and progressive degeneration over time before birth
examples of neural tube defects
anencephaly, encephalocele, spina bifida