interspinalis

noun

in·​ter·​spi·​na·​lis ˌint-ər-ˌspī-ˈnal-əs  -ˈnā-ləs 

plural interspinales -ˌlēz 

: any of various short muscles that have their origin on the superior surface of the spinous process of one vertebra and their insertion on the inferior surface of the contiguous vertebra above