week 4 - spinal cord Flashcards
What do barriers do?
Protect, support, maintain homeostasis
What barriers are there in the spinal cord?
- bony structures: vertebrae physically protect
- meninges: dura, arachnoid, pia mater surround and support
- barriers between the internal and external chemical environments
Name the two barriers between the internal and external chemical environments in the spinal cord
- Blood- CSF
- Blood - Brain barrier
How many spinal arteries are there in the spinal cord?
1 anterior
2 posterior
What secures the spinal cord within in the middle of the bony vertebrae?
Arachnoid trabeculae and denticulate ligaments
What reflects the spinal cord segmental organisation?
Associated vertebrae and dermatomes
In adults, where does the spinal cord end?
L1/2
What happens to the spinal cord at L1/L2?
Tapers into a conical end called the conus medullaris
How do the dorsal and ventral root exit the vertebral column?
Increasingly oblique, downwards course
Where is the lumbar cistern found?
L1/L2
What structures are in the cauda equina?
Dorsal and ventral roots
Explain a lumbar puncture
- hollow needle may be inserted into the lumbar cistern at levels below L2 to remove CSF
Is there any risk to a lumbar puncture?
No risk of impaling the spinal cord, and roots will move out of the way of the needle
What is the filum terminale?
The attachment of the spinal cord most distally to the dura and on the coccyx
Name the order to the structures making up the end of the spinal cord
Conus medullaris
Cauda equina
Filum terminale
What is grey matter?
Areas containing neuronal cell bodies, dendrites, connecting axons, synapses, supporting ganglia
What is white matter?
Areas where budnles or tracts of axons course
What is the position of white and grey matter in the spinal cord?
White matter tracts surround the grey matter
Describe the look of the grey matter in the spinal cord
Butterfly shaped and H shaped
What are the cervical (C4-T1) and lumbosacral enlargements (L1-S3)?
Regions of expanded grey matter serving the needs of the arms and legs respectively
What is the function of the Spinal cord?
- sensory processing
- motor outflow
- reflexes - somatic and autonomic
What os the sensory input?
Afferents with cell bodies in dorsal root ganglia input via the dorsal horn
What are redicular arteries?
Supply sacral and lower regions of spinal cord
Bypass rest of spinal chord in order to not have run out of oxygen
What is the motor output?
Mediated by lower motor neurons, receive inputs form reflex circuitry and descending motor pathways
How many laminae are there?
10 different ones based on their cytoarchitecture
What do laminae I-VI do?
- dorsal horn
- receives sensory information and is involved in its processing
What is the function of Lamina VII?
- intermediate zone
contains cell groups of sensory-motor integration, visceral sensory, and the preganglionic motor nuclei at thoracic and sacral levels
What do lamina VIII and IX (ventral horn) contain?
interneurons and lower motor neurones
What is the function associated with lamina X (Central zone)?
- interneurones, somatosensory and visceral processing
What is the input into the dorsal horn laminae (somatosensory processing)?
modality specific
Describe the association of the dorsal horn and pain
- nociceptive afferents (C and A-beta fibres) input to lamina 1, 2, 5
- interneuron processing in lamina 2 (substantia gelatinosa) modulates sensitivity to nociceptive stimuli