Could you help to explain the usage of either a definite article or a possessive pronoun in the following sentences:

  1. He had a thorn in his/the leg.
  2. The snake bit him in the/his leg.
  3. Before you go to bed, make sure you wash your/the face and brush your/the teeth.
  4. They lay on their/the backs and close their/the eyes.
  5. Grandpa has a constant pain in his/the back.
  6. The President had an operation on his/the heart.

Is there any rule about this choice?

  • Interesting question. I don't think there is a hard and fast rule. We usually use the possessive for parts of the body except, for some reason, for injuries (bit him in the leg - wounded in the arm). 'Pain in the (...)' is idiomatic, although you could use his in No. 5. NB 'They lay on their backs' is past tense so it should be 'closed their eyes'. Aug 18, 2021 at 7:57
  • I'd not thought about it but looking at the examples given I think there is a tendency to use the possessive pronoun where the owner of the body part is the subject of the main verb in the sentence and the definite article where they are not. For example "He had a thorn in his leg" and "The snake bit him in the leg". However it is a tendency and not a rule, as @KateBunting says. There's also a tendency for medical professionals to use the article rather than the pronoun when discussing a patient with other professionals, particularly when the patient isn't present or is unconscious.
    – BoldBen
    Aug 18, 2021 at 8:17

1 Answer 1


There isn't a "rule", but there are some things to consider.

Some noun phrases exist for things like medical conditions that contain the definite article. For example, a patent foramen ovale is commonly referred to as "a hole in the heart", and so it is common to say of a person with the condition "they have a hole in the heart" because it is akin to saying "they have angina" (or any other named medical condition). This is one reason why you might use the definite article rather than a possessive pronoun.

Beyond this, and other similar scenarios involving noun phrases, it is more idiomatic to refer to a person's body parts as their own, using an appropriate possessive pronoun.

Most of your examples should use a possessive pronoun and not the definite article, because none of them are really noun phrases. The exception is example 2, which is not idiomatic. We would say "the snake bit him in the leg", or "the snake bit him on his leg". I can't explain why these are idiomatic except to say that "in his leg" sounds like something is inside his leg, which a surface bite is not.

  • "bit me in the leg" sounds fine in my English, especially for a bite from a larger animal -- a dog, snake, or bear might bite me "in" the leg, but an ant or spider might bite me "on" the leg. If it was something like being shot by an arrow or a bullet from a gun, it's definitely "in the leg", not "on".
    – Marq
    Aug 18, 2021 at 11:51

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