For her poem "I felt a Funeral, in my Brain," Emily Dickinson chose to use a standard ballad structure known as the "fourteener." This is a stanza consisting of fourteen syllables in iambic rhythm arranged in alternating lines of eight and six syllables. A ballad is a poem that tells a story, and this poem has a story arc with a beginning, rising action, climax, and denouement. However, the story is not a story of outer action but of what is taking place in the speaker's mind and emotions. One could take it to be the loss of sanity, the spiraling into depression, or being consumed by grief.
The consistency of the rhythm and meter of the poem reinforces the ruminating thoughts that continue to plague the speaker from which she cannot seem to break free. The repetitious iambic beat corresponds to the "beating - beating" of the "Drum" in her head and the feeling that her brain is going numb.
Although the rhythm and meter are monotonous, Dickinson uses enjambment and caesura to contribute variety as the poem progresses, thus adding to the development of the story. In the first three stanzas, she uses enjambment--places where there is not a stop at the end of a line. This shows that at this point there is still some fluidity of thought, although she is oppressed. But in the last two stanzas, each line ends with punctuation, and even within lines, commas break the thoughts into little pieces, showing the fragmentation of her thought process is increasing, building to the last line of the fourth stanza, "Wrecked, solitary, here."
The next line is the climax when the "Plank in Reason broke." Here she goes over the edge, whether into insanity, depression, or grief. In the final line she uses caesura at the final word "- then -" as if she has hit bottom.
While this poem uses one of Dickinson's oft-used structures, the fourteener, she uses it to great effect in this poem to advance the central idea of the poem.