Answer to If you come to a fork on the road …
Correct answer is D. The aortic bifurcation is found between the levels of the L3-L4 vertebra. This generally corresponds to the umbilicus. The aortic bifurcation can be a reliable landmark for determining the lumbar vertebral segments on MRI or CT. The dermatome for the umbilicus, however, is T10, a landmark that is clinically relevant to understand referred pain to this region. Realize that surface projection of a structure and a dermatome can, and often do, represent distinct locations.
= T10
= T12
= L1
= L3-L4
= Sacrum
Answer to this question is based on material presented in lectures 7 of the Abdomen Lecture Series.
