Bipennate

It then follows that bipennate muscles generate even more force than unipennate ones of similar volume, and the force increases with the angle of pennation.

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Beneath the deltoid lies the external rotators of the shoulders, including the bipennate infraspinatus and the teres minor (Fig. 5-20B).

Source: wiktionary

Bipennate muscles have a central tendon with oblique insertion fibers on both sides, eg, the rectus femoris (Figure 1.3c).

Source: wiktionary

Its bipennate leaves are composed of a slightly straightened general petiole, of four partial petioles, situated, two at the extremity of the proceeding, and convergent, two a little lower, and growing almost at right angles; each of them bearing more than twenty pairs of small horizontal petioles.

Source: wiktionary