pennate muscle

The Physiological cross sectional area of a pennate muscle.

Pennate muscles are usually found where their length change is less important than maximum force, such as the rectus femoris.

The shortening velocity of the pennate muscle as a whole is greater than that of the individual fibers.

Thus the short fibres of pennate muscles are more suitable where power rather than range of contraction is required.

Pennate muscles, in which the muscle fibers are oriented at an angle to the line of action, typically have two aponeuroses.

Changes in pennation angle allow for variable gearing in pennate muscles.

Pennate muscles generally also tire easily.

When pennate muscles are used, sonomicrometry is often used to accurately determine fiber length during the test.

Pennate muscles are fascicle that are attached to tendons.

In a pennate muscle, aponeuroses run along each side of the muscle and attach to the tendon.

In pennate muscles, segments with higher pennation angles put out less force per shortening muscle fiber.

For example, the pennation angle determines the architectural gear ratio at which a pennate muscle operates.

This theorizes that pennate muscle force generation increases until a 45 degree pennation angle is achieved.

Pennate muscles can be further divided into uni-, bi- or multipennate.

As the pennate muscle is activated, the fibers rotate as they shorten and pull at an angle.

If all the fascicles are on the same side of the tendon, the pennate muscle is called unipennate (Fig. 1A).

The muscle architecture of pennate muscles, such as the human quadriceps, is highly plastic and strongly influences contractile properties.

The Extensor digitorum longus is a pennate muscle, situated at the lateral part of the front of the leg.

Due to the rotational motion; pennate muscles operate at low velocities (low shortening distance).

ACSA of a non-pennate muscle with the same force as the pennate muscle.

The force produced by pennate muscles is greater than the force produced by parallel muscles.

Instead, the physiological cross-sectional area (PCSA) must be used for pennate muscles.

Azizi and Brainerd demonstrated that the gear ratio of pennate muscle can vary; dependant on external load.

In a pennate muscle one or more tendons run through the body of the muscle with the fascicles forming an oblique angle to the tendons.

In a pennate muscle, PCSA is always larger than ACSA.