When dealing with body parts, we use the definite article as in the following:

Juan se lava las manos. Juan washes his hands.

Juan la lava las manos. Juan washes her hands.(he washes someone else's hand)

La serpiente se come la cola. The snake eats its tail.

Is it grammatically incorrect to use possessive pronouns with body parts? or are there instances where it can be used?

  • "Juan la lava las manos" is incorrect. The correct one is "Juan le lava las manos".
    – Jdamian
    Mar 18 '18 at 17:20
  • 1
    I support keeping this question open. Obviously (as explained in the other question about body parts) it is idiomatic and preferred to say, "se lava las manos" etc. But here the question is, just how bad will it sound to say, for example, "Lávame mis manos, por favor," (imagine I'm somehow incapacitated), or "Me lavo mis manos". Mar 19 '18 at 3:34