Assertion: spider's muscle | /r/AtLocation | the inside of the exoskeleton
Facets:
value: to flex spiders
type: PURPOSE
value: to flex their limbs
type: PURPOSE
Source sentences:
text: Although all arthropods use muscles attached to the inside of the exoskeleton to flex their limbs, spiders and a few other groups still use hydraulic pressure to extend them, a system inherited from their pre-arthropod ancestors.