multipennat

Multipennat is a term used in anatomy to describe a muscle architecture in which muscle fibers are organized into several pennate units. In this sense, it aligns with the English term multipennate, though multipennat appears in some non-English anatomical texts. The key idea is that the muscle contains multiple pennations, rather than a single uniform pennation pattern.

Structurally, a multipennat muscle has numerous fascicles that insert obliquely into more than one tendon or into several tendinous partitions. This arrangement yields a relatively large physiological cross-sectional area, which supports greater force production. At the same time, the fiber shortening is more limited compared with parallel-fibered muscles, making such muscles typically bulky and strong rather than fast-contracting.

Commonly cited examples include the deltoid muscle, which is described as multipennate because its fibers attach to multiple tendinous septa and insert into the humerus at different angles. Other muscles may be described as multipennate in various species or contexts, depending on the exact fascicle and tendon organization observed.

Functionally, multipennat architecture is advantageous for generating high joint torque and stabilizing proximal joints, especially during sustained or powerful movements. The trade-off is reduced excursion and shortening velocity relative to muscles with more parallel fiber arrangements. Variations in pennation pattern can reflect evolutionary adaptations to specific biomechanics and locomotor tasks.

Etymology and usage: the term derives from Latin penna (feather) and reflects the feather-like arrangement of fibers. See also pennate muscle, unipennate, bipennate, multipennate.