18.2.3 Spinal Cord Neuroanatomy Flashcards
Spinal cord and spinal nerve roots are surrounded by what
Meninges:
- Dura mater
- Arachnoid mater
- Pia mater
Space between two layers of dura mater (periosteal and meningeal)
Epidural space
Space between arachnoid and pia mater
CSF-filled subarachnoid space
As peripheral nerves enter the CNS, the epineurium becomes continuous with
Dura mater
As peripheral nerves enter the CNS, the perineurium and endoneurium become continuous with
Arachnoid and pia mater
Where do Schwann cells terminate as peripheral nerves enter the CNS?
Sub-pial layer of astrocytic end feet
Blood supply to spinal cord
Vertebral artery -> spinal arteries
Posterolateral spinal arteries originate from
PICA
Spinal level of supplementary artery of Adamkiewicz
T9-T12
Dorsal roots allow which neurons to enter the spinal cord
Sensory neurons
Ventral roots allow which neurons to exit the spinal cord
Motor neurons
Each dorsal root is accompanied by
Dorsal root ganglion
Dorsal root ganglia contain
Cell bodies of sensory neurons
Number of nerve roots
31 pairs
Number of cervical nerve root pairs
8
Number of thoracic nerve root pairs
12
Number of lumbar nerve root pairs
5
Number of sacral nerve root pairs
5
Number of coccygeal nerve root pairs
1
Dorsal and ventral nerve roots fuse to give a
Spinal nerve
Dorsal root ganglia
What type of neuronal is found in the dorsal root ganglia?
Pseudounipolar
Main function of spinal ganglion cells
Transmit sensory nerve signals from the peripheral to central nervous system
Green structure is
Cauda equina
Cauda equina
Collection of spinal nerves below the end of the spinal cord at L1
Spinal cord runs from x to y
X = Foramen magnum
Y = L1/L2 vertebra
Newborn spinal cord termination
L3; retracts to L1 ish by end of first year
Conus medullaris
Cone-shaped terminal portion of spinal cord
Filum terminale
Fibrous cord stabilising the conus medullar is to the coccyx
Core of spinal cord
Gray matter
Outer mantle of spinal cord
White matter
Functional regions of gray matter
Dorsal horn, ventral horn, lateral horn
Lateral horn
Dorsal horn
Ventral horn
Which level of the spine are these sections taken from?
Cervical
Which level of the spine are these sections taken from?
Thoracic
Which level of the spine is this section taken from?
Lumbar
Which level of the spine is this section taken from?
Sacral
Layers of gray matter
10 layers (Rexed laminae) on basis of cytoarchitecture
Divisions of white matter
Dorsal, lateral and ventral funiculi
Lamina I
Lamina I
Marginal zone
Marginal zone is the site of
Terminating fine, unmyelinated C fibres (nociceptive)
Neurotransmitter of unmyelinated nociceptive C fibres in spinal cord
Substance P
Neurotransmitter of A-delta fibres to spinal cord
Glutamate
Lamina 2
Lamina II
Substantia gelatinosa
Substantia gelatinosa is site of
Small, spindle shaped interneurons that regulate transmission of pain by inhibiting small (C) and large diameter (A-delta) afferent fibres
Lamina III/IV is site of
Main sensory nucleus
Main sensory nucleus (nucleus proprius)
Nucleus proprius (main sensory nucleus) comprised of what cells
Second order neurons that project up the spinal cord and are responsive to touch, nociception and temperature
Lamina IX contains
Motor neurons innervating axial and limb muscles
Gamma motor neurons supplying muscle spindles
Motor neuron pool
Group of motor neurons innervating a particular muscle
Dorsal ventral horn motor pools innervate
Flexor muscles
Ventral ventral horn motor pools innervate
Extensor muscles
Lateral ventral horn motor pools innervate
Distal limb muscles
Medial ventral horn motor pools innervate
Proximal limb muscles
Where does the gracilis dorsal column arise?
Lower limb
Where does the cuneatus dorsal column arise?
Upper limb
Clarke’s column
Nucleus in the thoracic spine sending fibres conveying proprioceptive information from muscle spindles and Golgi tendon organs of the lower limb to the cerebellum
Clarke’s column is found in which Rexed lamina?
VII
Clarke’s column
What are the features of the level this section of the spinal cord was taken from?
Cervical segment:
- Large ventral horn; increased number of motorneuons to supply upper limb
- 2 dorsal columns; gracilis (lower limb) and cuneatus (upper limb)
What are the features of the level this section of the spinal cord was taken from?
Thoracic segment:
- Reduced gray matter
- Prominent lateral horns; preganglionic sympathetic nerve cells
- Clarke’s column
- Reduced cuneate fasciculus (no upper limb fibres)
What are the features of the level this section of the spinal cord was taken from?
Lumbar segment:
- Enlarged gray matter; increased presence of efferent and afferent supply to lower limb
- Gracilis dorsal column increases in size rostrally
From which segments of the spinal cord do preganglionic sympathetic axons emerge?
Thoracic and upper lumbar ventral roots
Motor neuron disease affecting the lumbar spinal cord is likely to cause what signs
- Muscle weakness/atrophy in the legs/feet
- Spasticity in legs
- Loss of reflexes in the lower limb
A woman goes to her physician with several cuts and burns on her fingers. On testing she is found to have loss of light touch and nociception in both her hands and arms which spreads in a cape-like fashion over her shoulders. What is the condition?
Syringomyelia
Syringomyelia
Central neurological disorder characterised by the formation of a fluid-filled cavity in the spinal cord; damages spinal cord tissues
A woman goes to her physician with several cuts and burns on her fingers. On testing she
is found to have loss of light touch and nociception in both her hands and arms which spreads in a cape-like fashion over her shoulders. Why is the loss of sensation symmetrical?
Caused by distension of central canal; affects both left and right decussating pathways
A woman goes to her physician with several cuts and burns on her fingers. On testing she is found to have loss of light touch and nociception in both her hands and arms which spreads in a cape-like fashion over her shoulders. Why is there no sensory loss in her lower limbs?
Localised cavity does not extend to level of decussating fibres serving lower limb
A woman goes to her physician with several cuts and burns on her fingers. On testing she is found to have loss of light touch and nociception in both her hands and arms which spreads in a cape-like fashion over her shoulders. Which tracts are affected?
Dorsal columns and spinothalamic tracts
A woman goes to her physician with several cuts and burns on her fingers. On testing she is found to have loss of light touch and nociception in both her hands and arms which spreads in a cape-like fashion over her shoulders. Where is a lesion causing these symptoms most likely to be located?
Cervical spine
Afferent axons conveying nociceptive information synapse in the outer layers of the dorsal horn of the spinal cord - why?
Smaller fibres, e.g. nociceptive C fibres, synapse in the outer laminae
What is Brown-Sequard syndrome?
Lateral lesion causing ipsilateral mechanosensory deficit and contralateral proprioceptive/thermoceptive deficit
Spinal cord site of enkephalin neurons modifying pain transmission
Substantia gelatinosa (dorsal horn)
Lissauer’s tract
Amplifies C-fibre input, related to lamina II
What are the characteristic features of Brown-Sequard syndrome?
- Ipsilateral upper motor neuron paralysis
- Loss of proprioception
- Contralateral loss of pain and temperature sensation
Vestibulospinal tract function
Controls balance and posture
Reticulospinal tract function
Ipsilateral control of posture, influences locomotion
Tabes dorsalis
Demyelination of dorsal columns, causing paraesthesia and weakness
