There are multiple definitions:
sympathetic nerve activity(English)
- contributes appreciably to the control of physiological function, and pathological alterations can lead to a variety of diseases
- MSNA, RSNA, SpSNA
- Nervous activity - (para)sympathetic
- https://www.ncb…les/PMC5743742/
sinus nodal artery(English)
sella, nasion, and A point(English)
- i.e. the angle formed by these points
- ANB, GTA, MMA, OSA
- Sleep medicine, Dentistry
- https://doi.org…oms.2014.10.018