La cabezada y el nervio aparecen en el lomo.

Because the subject is two things joined by y: la cabezada y el nervio. In Spanish, just like in English, a compound subject normally takes a plural verb.

• La cabezada aparece = one thing appears
• La cabezada y el nervio aparecen = two things appear

So aparecen is the correct 3rd person plural form of aparecer.

Aparecen is the present indicative, 3rd person plural, of aparecer.

Its basic pattern is:

• yo aparezco
• tú apareces
• él/ella aparece
• nosotros aparecemos
• ellos/ellas aparecen

In this sentence, it matches la cabezada y el nervio, which together count as they.

Because the two nouns have different genders and each one keeps its own definite article:

• la cabezada = feminine singular
• el nervio = masculine singular

Spanish normally uses the appropriate article with each definite noun in a coordination like this, especially when the genders are different. So la cabezada y el nervio sounds natural and correct.

En is the normal preposition for indicating location here. Depending on context, en can correspond to English in, on, or at.

So en el lomo means that this is where those parts are found / located / visible.

Other prepositions would change the meaning:

• a often suggests movement toward something
• sobre means more specifically on top of / over

Here, en is the most natural choice for simple location.

No. In Spanish, aparecer can be broader than English appear. It can mean:

• to appear
• to show up
• to be found
• to be visible

In descriptive or technical contexts, aparecen often means something like are found or show up rather than a sudden, dramatic appearance.

Because el points to a specific, identifiable thing. Spanish often uses the definite article when referring to a known part of something in a description.

So en el lomo means in/on the loin/back area as a specific part being discussed, not just any random lomo.

Using un lomo would sound more indefinite, as if you were talking about a loin/back in a more general or non-specific way.

Yes. Depending on context, nervio does not always mean a medical/anatomical nerve in the strict sense. In food, butchery, or descriptive contexts, it can refer to a tough fibrous strand, sinew, or something similar.

So learners should not assume that nervio always has exactly the same meaning as English nerve in every context.

This order is the most straightforward and neutral:

• La cabezada y el nervio aparecen en el lomo.

But Spanish word order is somewhat flexible. For example, you could also say:

• En el lomo aparecen la cabezada y el nervio.

That version puts more focus on where they appear. Both are grammatical, but the original sentence is the more neutral presentation.

In most of Spain, the z in cabezada and the c before e in aparecen are pronounced with the th sound of English think.

So roughly:

• cabezada → ka-be-THA-da
• aparecen → a-pa-re-THEN
• lomo → LO-mo
• nervio → NER-byo or NER-vyo, depending on speaker

A rough full pronunciation for much of Spain would be:

la ka-be-THA-da i el NER-byo a-pa-RE-then en el LO-mo

Because they follow the normal Spanish stress rules, so they do not need written accents.

• cabezada → stress naturally falls on da
• nervio → stress naturally falls on ner
• aparecen → stress naturally falls on re
• lomo → stress naturally falls on lo

Spanish only writes an accent mark when a word breaks the default stress pattern or for certain other spelling reasons. Here, the standard rules already give the correct stress.