Neuro

Question 1

Chapter 3

Answer 1

Facts

• Lumbar puncture in children is done at L4 level and in adults it is done at L3 level.
• Conus medullaris syndrome occurs due to injury to S2-S4 segments of spinal cord. In this bladder and lower bowel movement and sexual function are also affected.
• Cauda equina syndrome in which Cauda equina is damaged leading to late bladder and bowel movement as well as lower motor neuron type of paralysis in lower limbs.
• Poliomyelitis is a viral disease which involves anterior horn cells leading to flaccid paralysis of affected segment.
• Tabes dorsalis occurs during tertiary stage of syphills. It’s main feature is pain in lower limbs.

•Amyotrophic lateral sclerosis: It is a degenerative
disease which is caused due to damage of the cells
in the ventral horn. The clinical features involve
weakness,atrophy of muscles of hands and arms and
later extending to the lower limb.
•Subacute combined degeneration The posterior and
lateral funiculi are degenerated bilaterally and it is
caused due to deficiency of intrinsic factor which
helps in absorption of vitamin B12. The symptoms
include upper motor neuron lesion with loss of
position and vibratory sensation of lower limbs.
•Complete transaction of spinal cord - Severe trauma usually results in complete cutting
(transaction) of spinal cord. The result is loss of
sensation and paralysis of muscles on both the sides
at the level of section and below the level of section
of spinal cord.
•In spina bifida, the vertebral arches and
spines of a few vertebrae do not develop.
a. Spina bifida occulta: The defect is only bony.
b. Meningocele: Meninges protrude through the bony
defect.
c. Meningomyelocele: Meninges and spinal cord
protrude through the bony defect.
d. Rachischisis: The spinal cord and meninges do not
develop.

> Spinal cord shows cervical enlargement for the supply
of upper limb muscles. It also shows lumbar
enlargement for the supply of lower limb muscles.
Spinal cord in adult is much shorter than the
vertebral canal. The cord ends at the lower border
of lumbar one (L1) vertebra.
Lateral horn is only present in T1–L2 and S2–S4
segments of spinal cord.
Corticospinal fibres cross to the opposite side; 80%
cross in pyramidal decussation, 15% cross in the
spinal cord and 5% do not cross.
Poliovirus affects the neurons of anterior horn cells
of the spinal cord.

> In spinal cord myelin sheath is formed by oligodendrocytes.
Medial leminiscus carries Proprioceptive sensations from trunk and limbs
Pyramidal fibres mostly arise from Brodmann’s
cortical area 4.