Spinal Cord function and dysfunction Flashcards
LO6 Demonstrate on a diagram the main areas of grey matter and the main ascending and descending tracts
Label the diagram of the cross section of the spinal cord
Define dermatome and myotome.
Dermatome: an area of skin innervated by one single spinal nerve or spinal segment Myotome: muscles innervated by one single spinal nerve or spinal segment
Position of epidural/spinal anaesthetic.
L2-L3
LO7 Spinal cord horns: define the function of the cells in the dorsal, ventral and intermediate horns of the spinal cord
- Dorsal horns: sensor
- Ventral: motor
- Posterior horns of grey matter -> posterior rootlets -> posterior root
- anterior rootlets-> anterior root
- posterior and anterior roots join to form spinal nerve
- spinal nerve splits in posterior (small) and anterior (larger) ramus
LO8 Define the terms “nerve”, “root” and “ramus”.
- Nerve:
- Nerve Root: nerve fibres of ONE type (sensory or motor)
- Ramus: nerve fibres of BOTH sensory and motor
LO8 Explain the relationship between spinal and vertebral levels and the clinical significance
- Spinal column shorter than vertebral column. Spinal cord ends at L2
- lumber cistern can be used to sample CSF
LO8 Define the cervival and lumbar enlargements and recall the spinal segment involved
Cervical: C3-T1, innervation to upper limbs
Lumbar: L1-S3, innervation to lower limbs
LO9 Meninges: recall the meningeal layers of spinal cord and compare to those in brain
- 3 layers of spinal meninges:
pia mater, arachnoid matter, dura matter
- CSF in subarachnoid space
- Epidural space: when anesthesia is given
Differences:
- Little extradural space between ouside of the dura and bone, unlike cranial meninges
Describe the 3 principle pathways of conveying information
- Discriminative touch and proprioception: sensory fibres will enter the dorsal horn and then travel in dorsal columns without synapsing in the posterior horn 2. Pain & Temperature: fibres enter the dorsal horn may travel up or down 1-2 segments in the Lissauer tract, then synapse in the nucleus proprius. Fibres then cross the midline in anterior commissure and travel in the spinothalamic tract. 3. Motor: a-motor neurons are located in the anterior horn. they exit the spinal cord and travel to their target muscles. Interneuron circuits in the anterior horn filter the descending motor information and are part of localised reflex circuits.
Describe the 6 major tracts of the spinal cord.
- Fasciculus gracillis: sensory from ipsilateral to lower limb 2.Anterior white commissure: pain and temperature fibres cross. 3. Anterior corticospinal tract 4. Fasciculus cuneatus 5. Spino cerebellar tract 6. Lateral corticospinal tract 7. Spinothalamic tract
LO10 Spinal lesions: Define the motor and sensory deficits resulting from spinal cord lesions
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Factors affecting severity of spinal lesion:
- Loss of neural tissue
- Vertical level: higher the lesion, the greater disability
- Transverse plane
Injury to lateral corticospinal tract:
- Stage 1. Spinal shock: loss of reflex activity below the lesion, lasting for days or weeks = flaccid paralysis
- Stage 2. Return of reflexes: hyperreflexia and/or spasticity = rigid paralysis
Brown-Séquard syndrome: With unilateral lesions the relationship of the deficit to the lesion depends on where the tract decussates
With unilateral lesions the deficit depends on where the tract decussates.
What is Syringomyelia?
Loss of temperature sensation in the arms but not the legs is caused by the formation of a space in the spinal cord called a syrinx
There is a large space in the middle that is selectively damaging the spinothalamic axons that are crossing over at the level of the lesion but it does not affect the fibres that have already crossed over and are travelling up in the spinothalamic tract
The fibres from the legs would already have crossed over and would be travelling up the spinothalamic tract
Syringomyelia is caused by an enlargement of the central canal
