Biology / Unit 13 Bio 3125 short lesson, about 20 seconds
"Muscles Only Pull, Never Push"
Captions available
The idea
Stating flatly that muscles never push overstates a real pattern — one muscle only pulls as it contracts, per Bio 3115, but bodies still achieve pushing motion.
In practice
Extending an elbow to push a door is the triceps contracting and pulling, not the arm pushing directly.
Where people slip
This entry states the popular framing — Bio 3127 gives the pairing mechanism it overlooks.
Your place on the trail
Every lesson rests on earlier ones and opens later ones. Tap any to jump.
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