| FYMS | fourth-year medical student |
|---|---|
| L1, | L2, L3, L4, L5 first, second, third, fourth, and fifth lumbar vertebrae |
| MS | I, II, III, IV medical student-first, second, third, and fourth year |
| S1-S4 | first to fourth heart sounds |
| CSN | cardiac sympathetic nerve; carotid sinus nerve |