The spelling of the word "subtenial" may seem confusing at first, but it can easily be explained using IPA phonetic transcription. The first syllable "sub" is pronounced as "sʌb" and means "under". The second syllable "ten" is pronounced as "tɛn" and refers to the numerical value of 10. The final syllable "ial" is pronounced as "iəl" and means "related to or characterized by". Therefore, the word "subtenial" means "related to or characterized by a number less than ten".
Beneath or below any taenia of the brain.
A practical medical dictionary. By Stedman, Thomas Lathrop. Published 1920.