The most widely used of all second inversions is the Cadential six-four, a second inversion tonic chord which moves to the dominant chord at a cadence. Normally, the sixth and fourth above the Bass note resolve down by step to a fifth and third respectively. A cadential six-four and its resolution to the dominant usually appear in a strong-weak rhythmic relationship. A weak-strong relationship may occur at a Half cadence. In triple meter it is often found on the second beat with the final tonic triad occurring on the first beat of the following measure.

FIGURE 6.7: Cadential Six-Four
Passing
A passing six-four occurs when a second inversion chord appears between root position and first inversion of another chord. Therefore, may appear between a I and I6 or a I6 and I. may appear between a IV and IV6 or a IV6 and IV. Passing six-fours must appear in a weak rhythmic position.

FIGURE 6.8: Passing Six-Four
Auxiliary
An auxiliary six-four (also called a pedal six-four) occurs between two root positions of the same chord where the fifth of the auxiliary six-four is the same note as the root of the root position chord. Expressed in terms of voice motion, an auxiliary six-four occurs when the third and fifth of a root position triad, with root doubled, Auxiliary six-fours must occur in a weak rhythmic position. ascend by step and return.

FIGURE 6.9: Auxiliary Six-Four
Arpeggiated
An arpeggiated six-four occurs when the second inversion of a chord is immediately preceded or followed by the same chord in root position and/ or first inversion.

FIGURE 6.10: Arpeggiated Six-Four