Cadence

Cadence (from Latin cadere, to fall) is a resolution to a musical or poetic phrase. A musical cadence usually falls in descending notes and seems to imply ending, conclusiveness, the way a rising sequence of notes implies initiation.

The Spanish 11-syllable line has a distinctive cadence caused by the "feminine" ending and the accent on the sixth syllable. The cadence is what is most constant, whereas the beginning of the line is what is most variable.

There will typically be three substantive words (nouns, adjectives, verbs, adverbs) in each line, and the 2nd and 3rd of these words will be lined up so that their accents fall on the 6th and 10th syllables. Like this:

Yo quiero ser LLORANDO el HORTELANO
de la tierra que OCUPAS y ESTERCOLAS
compañero del ALMA, tan TEMPRANO.

Alimentando LLUVIAS, CARACOLAS
y órganos mi DOLOR sin INSTRUMENTO,
a las DESAMPARADAS AMAPOLAS

daré tu CORAZÓN por ALIMENTO...

The cadence really dominates this particular poem by Miguel Hernández. I've hypothesized that one reason why blank verse doesn't work in Spanish as well as it does in English is because of the strength of the cadence, which tends to emphasize line-endings. Interestingly, Góngora's more fluid line-endings avoid the cadence by putting accents on 4 and 8 (the so-called Sapphic line) with more frequency, producing lines of 5 + 6 rather than of 4 + 7.

Unamuno tried to write blank verse, but it didn't quite work. If the cadence is strong, enjambment gets awkward. If the cadence is weak, then the line lacks a spine.