The Achilles tendon is a strong fibrous cord that connects the muscles in the back of your calf to your heel bone
Henry Gray, Public domain, image from Gray’s Anatomy
Mysid, Public domain, via Wikimedia Commons
Henry Vandyke Carter, Public domain, via Wikimedia Commons
OpenStax College, CC BY 3.0 <https://creativecommons.org/licenses/by/3.0>, via Wikimedia Commons