Dan injured the spinal nerves emerging from the lower lumbar and sacral region of the spinal cord during a horse-riding accident. After his injury, he reported numbness in his feet. Explain the connection between the loss of sensation he has described
and the plexus responsible for serving this area.
What will be an ideal response?
The sacral plexus forms from the anterior rami of spinal nerves L4 - S4. Rami are mixed nerves, housing both sensory and motor neurons. The sciatic nerve is the largest nerve of this plexus. It splits into two main branches, the tibial nerve and the common fibular nerve. The tibial nerve divides into its terminal branches which serve the muscles and skin of the foot at the level of the medial malleolus of the tibia. Since Dan reported loss of sensation in his feet, the sensory neurons of the sciatic nerve must have sustained injury after his accident.
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