The X craneal nerve (vagus), it goes all the way to your diafragm

According to SOWPODS (the combination of Scrabble dictionaries used around the world) there are 11 words with the pattern T--F--I--. That is, nine letter words with 1st letter T and 4th letter F and 7th letter I. In alphabetical order, they are:

taffeties

taffrails

telfering

tiffanies

tiffining

trifacial

trifolies

trifolium

triforial

triforium

truffling

The longest cranial nerve in the human body is the vagus nerve (cranial nerve X). It is a major nerve that plays a vital role in the parasympathetic nervous system, controlling many important functions such as heart rate, breathing, and digestion.