Peripheral Nervous System Case 1

Question 1

Identify A B C and D

Answer 1

A - dorsal (afferent) root
B - dorsal root ganglion
C - spinal nerve
D - ventral (efferent) root

Question 2

state the deficits produced by a lesion at V

Answer 2

.V –Damage to dorsal root leads to loss of sensation in dermatome supplied by the
corresponding spinal nerve. (Probably not detectable if only one root affected as there
is considerable overlap of dermatome innervation by adjacent spinal nerves)

Question 3

Effects produced by a lesion at W

Answer 3

loss of motor function to the segment of the body innervated by the specific spinal nerve

Damage to ventral root leads to weakness of muscles supplied by the
corresponding spinal nerve. (Most limb muscles are innervated by 2 or more spinal
nerves therefore paralysis is unlikely unless all spinal roots are damaged)

Question 4

effects of a lesion at X

Answer 4

combined effects of V and W above - weakened muscles supplied by corresponding spinal nerve
and loss of sensation in dermatome supplied by corresponding spinal nerve

Question 5

effects produced by a legion at Y

Answer 5

Damage to a sensory nerve (eg. in the skin) leads to loss of sensation in the area of
distribution of that peripheral nerve

Question 6

effects produced by a legion at Z

Answer 6

–Damage to a muscle nerve leads to weakness/paralysis of muscle supplied by that
peripheral nerve

Question 7

Common medical scenarios which might result in a lesion occuring at each point

Answer 7

Spinal root and spinal nerve damage is most often a consequence of strain injuries to
the spine, eg. prolapsed disc.
Peripheral nerves may be affected by trauma or disease (peripheral neuropathy)
The brachial plexus may be affected by trauma to the shoulder joint. The lumbosacral
plexus is much better protected and therefore unlikely to be injured.