pro tem: frequently used short form for the Latin 'pro tempore' -- for the time being, in the short term.
Readers might also enjoy a verse on the same part of the anatomy presented in September 2021 in the collection "The Bottom Line of Medical Humor". Click HERE.
Flying straight is a casual metaphor associated with performing expected or routine function.
Authors' Note: Avitaminosis, an absence of vitamins, causes specific deficiency diseases, as discussed for some other vitamins by (Dr.) SheilaB, a prolific contributor to OEDILF.