Are "joint" and "tendon" countable nouns? I don't know when to use plural or singular
Answer from a Native speaker
Yes! "Joint" and "tendon" are countable nouns! You generally use the plural form "joints" and "tendons" when you're referring to them in general. Here they use the singular form, since they're talking about an experience of one "joint" moving and "the tendon" directly linked to it - they're specific joints and tendons. Ex: My joints are sore. => all of them, or most in general Ex: I'm having trouble with a joint in my arm. => one specific joint Ex: She was running when a tendon snapped in her leg. Ex: His tendons were badly damaged.