bipennate

Of, pertaining to, or having the nature of a muscle, the fibres of which attach to a tendon on two sides (as a feather barbed on both sides).

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.

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

Bipinnate (pinnate and having a pinnate leaflet).

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.

But this Burnet Pimpinella is of a different (Umbelliferous) order, though similarly styled because its leaves are likewise bipennate.

Having two wings; bipennated.