Principal English Translation: 

tendons of the neck and head (only attested in possessed form)
(See Karttunen)

Orthographic Variants: 
Frances Karttunen: 

-QUECHTEMĒMECAPAL only attested in possessed form tendons of the neck and head / sus tendones del cerebro (T) [(1)Tp.133]. T has a reflex of a long vowel in the second syllable, but it should not be. As attested, this is a possessed form with reduplicated stem but no plural suffix. The absolutive singular should probably be QECHTEMECAPAL-LI See QUECHTE-TL, MECAPAL-LI.
Frances Karttunen, An Analytical Dictionary of Nahuatl (Norman: University of Oklahoma Press, 1992), 207.