La doloro iras de la ŝultro al la spino.

La is the definite article, meaning the. Esperanto often uses la when talking about a specific thing that is known in context.

So la doloro means the pain.
If you said just doloro, it would sound more like pain in a general sense.

Yes. In Esperanto, iri literally means to go, but it is also commonly used in expressions where something extends, spreads, or runs from one place to another.

So La doloro iras de la ŝultro al la spino means the pain goes/runs/spreads from the shoulder to the spine.

This is normal Esperanto usage, even if English might prefer something like the pain radiates or the pain goes from ... to ...

• de = from
• al = to

So:

• de la ŝultro = from the shoulder
• al la spino = to the spine

Together, they show the path or direction of the pain.

Because they are objects of prepositions, not direct objects.

In Esperanto, the -n ending is mainly used for:

• the direct object
• direction toward a place in some cases

Here we have:

• de la ŝultro
• al la spino

Since de and al already show the relationship, you do not add -n.

No, because ŝultro is governed by the preposition de.

Prepositions already mark the role of the noun:

• de la ŝultro = from the shoulder
• al la spino = to the spine

You do not add -n after de.
And after al, you also normally do not need -n, because al already expresses direction.

Iras is the present-tense form of iri.

Esperanto verb endings are very regular:

• -as = present
• -is = past
• -os = future
• -us = conditional
• -u = command/wish
• -i = infinitive

So:

• iri = to go
• iras = goes / is going

Because the sentence is talking about pain as one thing or one sensation.

Doloro = pain or a pain

If you wanted the plural, it would be doloroj, meaning pains. But here singular is the natural choice.

Spino literally means spine. Depending on context, English might also say backbone.

So al la spino means to the spine. In medical or body-related contexts, this is a normal word.

Ŝ is pronounced like English sh.

So ŝultro is pronounced roughly like SHOOL-tro.

A breakdown:

• ŝul ≈ shool
• tro = tro with a clear rolled or tapped r if possible

Remember that Esperanto spelling is very regular, so ŝ always has the sh sound.

Because both nouns are treated as specific body parts in the situation being described.

• la ŝultro = the shoulder
• la spino = the spine

This is very natural in Esperanto. Since the sentence is about a particular pain path in a particular body, the definite article makes sense for both nouns.

Yes, Esperanto word order is fairly flexible, as long as the sentence remains clear.

For example, you could also say:

De la ŝultro al la spino iras la doloro.

That puts more focus on the path. But the original sentence:

La doloro iras de la ŝultro al la spino.

is the most straightforward and neutral order.

Ŝultro specifically means shoulder. If you mean another nearby body part, Esperanto usually uses a different word.

So in this sentence, it clearly means the pain starts at or near the shoulder, not generally the whole arm.

Usually de is better here.

• de means from
• el means out of

El often suggests movement out from inside something. Since the shoulder is not being thought of as a container here, de la ŝultro is the normal choice.

So:

• de la ŝultro al la spino = natural
• el la ŝultro al la spino = possible only in a more unusual, very literal sense of coming out from inside the shoulder