Abdominal cutaneous reflex testing indicating a lesion at which thoracic levels if reflex is absent on the lower abdomen?

Abdominal cutaneous reflex testing indicating a lesion at which thoracic levels if reflex is absent on the lower abdomen?

• A. Thoracic 10, 11, and 12
• B. Thoracic 8, 9, and 10
• C. Lumbar 5 and Sacral 1
• D. Sacral 2, 3, and 4

Answer: (A)

Abdominal cutaneous reflex is a segmental reflex that maps to specific thoracic nerves. The lower abdominal reflex is carried mainly by the lower thoracic nerves around T10 to T12. If this reflex is absent when you stroke the skin of the lower abdomen, it localizes to those thoracic segments. Since the reflex arc for the lower abdomen relies on T10–T12, a lesion at these levels best explains an absent response there. The other regions correspond to different dermatomes (for example, higher thoracic levels affect the upper abdomen, while lumbar and sacral levels would impact areas outside the lower abdominal region), so they don’t fit the pattern of an absent lower abdominal reflex.

Abdominal cutaneous reflex is a segmental reflex that maps to specific thoracic nerves. The lower abdominal reflex is carried mainly by the lower thoracic nerves around T10 to T12. If this reflex is absent when you stroke the skin of the lower abdomen, it localizes to those thoracic segments. Since the reflex arc for the lower abdomen relies on T10–T12, a lesion at these levels best explains an absent response there. The other regions correspond to different dermatomes (for example, higher thoracic levels affect the upper abdomen, while lumbar and sacral levels would impact areas outside the lower abdominal region), so they don’t fit the pattern of an absent lower abdominal reflex.