Unlike most of the muscles of the human body, which had been categorized several centuries ago, Sphenomandibularis was discovered in the mid-1990s at the University of Maryland at Baltimore. The findings were published in 1996.
Sphenomandibularis is considered by many sources to be a portion of the temporalis, rather than a distinct muscle.
^Geers C, Nyssen-Behets C, Cosnard G, Lengelé B (2005). "The deep belly of the temporalis muscle: an anatomical, histological and MRI study". Surg Radiol Anat27 (3): 184–91. doi:10.1007/s00276-004-0306-3. PMID15821860.