noun
tendon
Anatomical term for the fibrous tissue connecting muscle to bone. Also used in everyday contexts for meat or cooking.
アキレス腱を痛めた。
I injured my Achilles tendon.
この肉は腱が多い。
This meat has a lot of tendons.
靭帯 is a ligament (bone-to-bone), while 腱 is a tendon (muscle-to-bone).
筋 can refer to muscle, sinew, or a line/stripe, and is broader than 腱, which specifically means tendon.
The kanji 腱 is composed of 月 (flesh) and 建 (build/establish), suggesting a structural part of the body. The reading けん is the on'yomi.