isya ha sinkei wo kakuninsita.

It is read:

いしゃ は しんけい を かくにんした。
Romanized: isha wa shinkei o kakunin shita

A word-by-word reading:

• 医者 = いしゃ
• は = written ha, but pronounced wa here
• 神経 = しんけい
• を = usually pronounced o
• 確認した = かくにんした

When は is used as the topic particle, it is pronounced wa.

So in this sentence:

• 医者は = As for the doctor, ...

This is one of the first pronunciation exceptions learners meet in Japanese. The spelling stays は, but the pronunciation is wa when it marks the topic.

は marks the topic of the sentence.

Here, 医者は means something like:

• As for the doctor, ...
• The doctor, ...

It tells you what the sentence is going to talk about. It does not automatically mean subject in exactly the same way English does, but in many simple sentences the topic and subject are the same person or thing.

So the structure is roughly:

• 医者は = topic
• 神経を確認した = comment about that topic

を marks the direct object of the verb.

So:

• 神経を = the nerve(s) as the thing being checked/confirmed

The verb 確認した is something the doctor did to the nerve(s), so 神経 takes を.

A very literal breakdown is:

• 医者は = as for the doctor
• 神経を = the nerve(s)
• 確認した = checked/confirmed

Japanese normally uses SOV order: Subject/Topic – Object – Verb.

So instead of English:

• The doctor checked the nerve.

Japanese uses:

• Doctor + topic
• nerve + object marker
• checked

That is why 確認した comes at the end. This is one of the biggest word-order differences between English and Japanese.

確認した is the plain past form of the verb 確認する.

• Dictionary form: 確認する = to check / to confirm
• Past plain form: 確認した = checked / confirmed

This form is casual/plain in grammar, but it is not necessarily rude by itself. It is the basic non-polite form used in dictionaries, casual speech, narration, and many written contexts.

The polite version would be:

• 確認しました

確認する usually means to check, to confirm, or to verify.

In this sentence, it suggests the doctor checked the nerve(s), probably to make sure of their condition, position, response, or status.

It is a little more like confirm/check carefully than a broad verb like to see.

Depending on context, a doctor might also use other verbs, but 確認した gives the idea of a deliberate check or confirmation.

No. 神経 can have several meanings depending on context, such as:

• a nerve in the body
• the nervous system
• nerves in the emotional sense
• sensitivity or being highly strung in some expressions

But in this sentence, because the subject is a doctor and the action is 確認した, the most natural meaning is the medical one: a nerve / the nerves.

Japanese often relies on context to narrow down which meaning is intended.

Japanese usually does not mark articles like a/an/the, and it often does not explicitly mark singular vs. plural unless needed.

So 神経 could mean:

• a nerve
• the nerve
• nerves
• the nerves

The exact interpretation depends on context.

Likewise, 医者 can mean:

• a doctor
• the doctor

English forces you to choose more often than Japanese does.

This is a very common learner question.

• は marks the topic
• が often marks the grammatical subject with more focus or new information

With 医者は, the sentence sounds like it is talking about the doctor as the current topic:

• As for the doctor, he/she checked the nerve(s).

If you said 医者が神経を確認した, it would put more focus on the doctor as the one who did it, as if answering a question like:

• Who checked the nerve(s)?
• The doctor did.

So は is natural if the doctor is already the topic of discussion, while が would be more contrastive or identifying.

医者 is a common everyday word for doctor.

However, depending on context, Japanese also uses:

• 医師 — a more formal/professional term for a physician
• 先生 — often used when addressing a doctor directly

So in a simple sentence like this, 医者 is perfectly fine and natural. It is just a general noun meaning doctor.

The spaces are just for learners. Normal Japanese writing usually does not put spaces between words.

So the sentence would normally be written as:

医者は神経を確認した。

Textbooks and beginner materials often add spaces to make word boundaries easier to see.