Muuguzi alipaka marashi kwenye sehemu aliyokuwa ameikuna.

A helpful breakdown is:

• Muuguzi = nurse
• a-li-paka = he/she applied
  • a- = he/she
  • -li- = past tense
  • -paka = apply / smear / spread on
• marashi = ointment / salve / lotion
• kwenye = on / in / at / onto
• sehemu = part / area / spot
• a-li-yo-kuwa = that he/she had been / that he/she was
  • here it helps form a had ... idea inside the relative clause
• a-me-i-kuna = he/she has/had scratched it
  • a- = he/she
  • -me- = perfect
  • -i- = it referring to sehemu
  • -kuna = scratch

So the sentence structure is basically:

The nurse applied ointment on the area that he/she had scratched.

Because Swahili usually puts the subject inside the verb.

In alipaka:

• a- = he/she
• -li- = past
• -paka = apply

So alipaka already means he/she applied.

This is very normal in Swahili. You often do not need a separate pronoun unless you want extra emphasis or contrast.

Kupaka usually means to apply, smear, spread, rub on, or daub something onto a surface.

In a medical context, kupaka marashi means:

• to apply ointment
• to rub ointment onto
• to smear ointment on

So alipaka marashi is very natural for applied ointment.

Kwenye is a locative word that can mean on, in, at, or onto, depending on context.

Here, with sehemu meaning area/part, it is best understood as:

• on the area
• onto the spot
• to the affected part

So:

• kwenye sehemu = on the area / on the part

Because it is expressing a relative clause with a past-before-past idea.

The main action is:

• alipaka = applied

The scratching happened earlier than that, so Swahili uses a structure like:

• alikuwa ameikuna = he/she had scratched it

When that becomes a relative clause modifying sehemu, it turns into:

• sehemu aliyokuwa ameikuna = the area that he/she had scratched

So the long form is doing two jobs at once:

1. linking the clause to sehemu
2. showing that the scratching happened before the ointment was applied

-yo- is a relative marker here. It works like that / which in English.

It agrees with sehemu, which belongs to noun class 9.

So:

• aliyo... = that he/she ... referring to sehemu

This is why the sentence can mean:

• the part that he/she had scratched

A key point:

• a- tells you who did the action
• -yo- links the verb back to sehemu

That -i- is the object marker, and it refers back to sehemu.

So:

• amekuna = he/she has scratched
• ameikuna = he/she has scratched it

And that it = the area / part

This is very important in Swahili. Object markers often show what is being acted on, even when the noun has already appeared elsewhere.

Good question.

• ameikuna = he/she scratched it
• amejikuna = he/she scratched himself/herself

In this sentence, the clause is specifically describing sehemu — the part/area. So using the object marker -i- makes the link to sehemu very clear:

• the area that he/she had scratched

If you used amejikuna, the focus would be on the person scratching themself, not as directly on the specific area named by sehemu.

Even though marashi looks like a ma- noun, in many contexts it behaves like a mass noun in English.

So it can mean things like:

• ointment
• salve
• lotion

English often uses a singular-looking mass noun here, so ointment is a natural translation.

In other words, Swahili and English do not always package substances the same way. A form that looks plural-ish in Swahili may still be best translated with a singular mass noun in English.

By grammar alone, the clause gives a-, which means he/she, but it does not explicitly name the person.

So the sentence by itself can be a little ambiguous. The one who scratched the area could be:

• the nurse, if that is what the context suggests
• another previously mentioned person, such as the patient

Swahili often relies on context for this.

So if you want to know exactly who scratched it, you would usually look at the surrounding sentences.

Yes. That is a very natural alternative.

• sehemu aliyokuwa ameikuna
• sehemu ambayo alikuwa ameikuna

Both can mean:

• the area that he/she had scratched

The ambayo version is often easier for learners to recognize, because it feels more obviously like that/which.

The shorter relative form with -yo- is also very common and often sounds more compact and elegant.

So both are good; the original sentence is just using a more condensed Swahili relative structure.