Läkaren ska undersöka foten imorgon.

Because läkaren is the definite singular form: the doctor.

In Swedish, the definite article is usually attached to the end of the noun:

• en läkare = a doctor
• läkaren = the doctor

So läkaren ska undersöka foten imorgon means the doctor will/is going to examine the foot tomorrow, not just doctor in a general sense.

For the same reason: foten is the definite form, meaning the foot.

• en fot = a foot
• foten = the foot

Swedish often marks the by adding an ending to the noun instead of putting a separate word before it.

Very often, yes. That is one of the big differences from English.

For many common nouns:

• en bok = a book
• boken = the book
• en läkare = a doctor
• läkaren = the doctor

So in this sentence:

• läkaren = the doctor
• foten = the foot

This is completely normal Swedish grammar.

Here ska is used to talk about the future, especially something planned, expected, or decided.

So ska undersöka means something like:

• will examine
• is going to examine
• is supposed to examine

In this sentence, the most natural understanding is that the examination is planned for tomorrow.

Not exactly. Ska can have a few related meanings, depending on context.

It can express:

• a future plan: Jag ska resa imorgon = I’m going to travel tomorrow
• obligation or instruction: Du ska gå nu = You must/should go now
• something expected or arranged

So in Läkaren ska undersöka foten imorgon, it most likely means a planned future action.

Because after ska, Swedish uses the infinitive form of the main verb.

So:

• ska undersöka = will examine / is going to examine

This is similar to English structures like:

• will examine
• going to examine

The base form undersöka is the infinitive, meaning to examine.

No. After modal verbs like ska, Swedish normally does not use att.

So:

• Jag ska läsa = I will read
• Hon kan simma = She can swim
• Läkaren ska undersöka foten = The doctor will examine the foot

This is similar to English, where we say will examine, not will to examine.

Because time expressions often come later in a normal Swedish main clause, especially after the object.

So this order is very natural:

• Läkaren ska undersöka foten imorgon

That said, Swedish word order is somewhat flexible. You can also move imorgon to the front for emphasis:

• Imorgon ska läkaren undersöka foten

Both are correct, but when you move something to the front, Swedish keeps the verb in second position.

Then Swedish uses V2 word order, which means the finite verb stays in the second position.

So:

• Läkaren ska undersöka foten imorgon becomes
• Imorgon ska läkaren undersöka foten

Notice that ska still comes second. You do not say:

• Imorgon läkaren ska undersöka foten

That would be wrong in Swedish.

Yes. That is also possible Swedish.

The present tense is often used for future meaning when the time is clear from context:

• Läkaren undersöker foten imorgon

Since imorgon already shows the future, Swedish does not always need ska.

The difference is roughly:

• ska undersöka = more explicitly planned/intended
• undersöker ... imorgon = present tense used for a scheduled future event

Both can be natural.

Because Swedish usually expresses definiteness with a suffix on the noun itself.

English:

• the doctor
• the foot

Swedish:

• läkaren
• foten

A separate definite word can appear in some other situations, especially with adjectives:

• den gamla läkaren = the old doctor

But in your sentence there is no adjective, so the noun ending alone is enough.

In a way, yes. That is a helpful way to think about it when you are learning.

• läkare = doctor
• -n / -en = the definite ending here

So läkaren is roughly doctor-the, even though in natural English we translate it as the doctor.

Imorgon is a time adverb meaning tomorrow.

It tells you when the action happens:

• Läkaren ska undersöka foten imorgon = the examining happens tomorrow

You may also see it written as i morgon. Both spellings are used, though imorgon is very common in modern Swedish.

A few pronunciation points often help learners:

• ä sounds somewhat like the e in bed, though the exact sound is Swedish.
• ö is a rounded vowel that English does not really have. It takes practice.
• k in läkaren is pronounced like a normal k sound here.
• undersöka has stress on sö: un-der-SÖ-ka

A rough learner-friendly approximation might be:

• läkaren ≈ LEH-ka-ren
• undersöka ≈ un-der-SUR-ka or un-der-SUH-ka

These are only approximations, but they can help at the start.

Yes, in many contexts you could.

• läkaren = the doctor / the physician
• doktorn = the doctor

Läkare is the standard word for a medical doctor. Doktor is also common, but it can feel a little different depending on context and style. In many everyday situations, both are understood.

So:

• Läkaren ska undersöka foten imorgon and
• Doktorn ska undersöka foten imorgon can both work.

Yes. It follows a very common pattern:

subject + finite verb + infinitive/main verb + object + time expression

Here that gives:

• Läkaren = subject
• ska = finite verb
• undersöka = infinitive/main verb
• foten = object
• imorgon = time expression

So it is a very typical and natural Swedish sentence.