Normally the definite article (le/la/les) is used with body parts (j'ai mal à la tête) but there are exceptions.
See Using le, la, les with body parts and clothing (definite articles)
The possessive adjectives with body parts in French
In the following special cases:
- when special emphasis on the body part is desired, or
- when another person is involved
the possessive adjective (sa,son,ta,ton etc.) is used instead of the definite article (le/la/les) to reduce ambiguity.
Also, when the body part is the subject of the verb (rather than the object), possessive adjectives are used:
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