Flashcards in Practical Neuroanatomy 4: Spinal Cord and Spinal Nerves Deck (22):
What is the functional difference between the dorsal and ventral nerve roots?
Dorsal root carries somatic and visceral SENSORY
Ventral root carries somatic and visceral MOTOR
Where do the dorsal and ventral roots unite to form the spinal nerves?
At the dorsal root ganglion (spinal ganglion)
What are the dorsal and ventral rami of spinal nerves? What does each supply?
Dorsal rami - very small, innervate back muscles and adjacent skin
Ventral rami - much larger, innervates rest of body except head (mostly innervated by cranial nerves).
At what vertebral level does the spinal cord terminate in the adult?
At what vertebral level does the spinal cord terminate in a neonate?
At what vertebral level does the spinal cord terminate in a foetus?
Near the end of the vertebral canal.
Where does the subarachnoid space terminate?
Inferiorly - S2
Superiorly - most superior aspect of brain
Where does the epidural space terminate?
Inferiorly - tip of the sacrum, at the sacrococcygeal membrane
Superiorly - foramen magnum
Name three conditions where the composition of CSF may be altered.
- bacterial/fungal/viral/parasitic contamination
24hrs following SAH (24hr LP if not visible on scan)
- xanthochromia - bilirubin from breakdown of RBCs
- lymphocytosis etc...
Starting with the skin, list the layers pierced by the lumbar puncture needle.
(Epidural space and fat)
What are the typical symptoms of a lumbar disc prolapse causing unilateral compression of a spinal nerve?
Unilateral Sciatic pain and numbness/tingling
Lower back pain
What are the symptoms of cauda equina syndrome?
- *Saddle anaesthesia - numbness of S3-5 dermatomes, also tingling
- Bilateral sciatic pain
- Severe back pain
- *Urinary retention - flaccid bladder (also post-void incontinence)
- *Bowel incontinence
- *Lower limb weakness
Which section of the spinal cord (cervical, thoracic, lumbar & sacral) has the most white matter, and why?
Higher levels (i.e. cervical) contain greater amounts of white matter versus grey matter. This is because ascending tracts gain fibres at each successive level, whereas the opposite is true of descending tracts.
In which section is the dorsal white matter subdivided into two columns on each side? What type of information runs in these columns?
Fasciculus gracilis and fasciculus cuneatus. The tracts carry impulses concerned with proprioception and discriminative (fine) touch.
In which spinal cord segment is the ventral grey horn enlarged due to the accumulation of motor neurones for innervation of the limbs?
Cervical enlargement for upper limbs - cuneocerebellar fibres
Spinocerebellar tract in lumbar region for lower limbs
What types of sensory information are carried by the spinothalamic tract?
- Information related to pain and thermal sensations
- Non-discriminative (coarse) touch and pressure
Does the spinothalamic pathway run contralaterally or ipsilaterally in the spinal cord?
Contralaterally - crosses as soon as is has synapsed
In which region of the cerebral cortex does the spinothalamic pathway terminate?
Ventral posterior nucleus of the thalamus
Where does the secondary sensory area for somaesthetic information lie?
The parietal operculum on the ceiling of the lateral sulcus.
What types of sensory information are carried by the dorsal column system?
i.e. fasciculus gracilis and fasciculus cuneatus
Carry impulses concerned with proprioception (movement and joint position sense) and discriminative (fine) touch.
Where do the fibres of the dorsal column system run in the spinal cord?
Fasciculus gracilis and fasciculus cuneatus