In a pennate muscle, the fascicles form a common angle with the tendon. Because the muscle fibers pull at an angle, contracting pennate muscles do not move their tendons as far as those of a parallel muscle do.
Each muscle fiber (cell) is covered by endomysium and the entire muscle is covered by epimysium. When a group of muscle fibers is “bundled” as a unit within the whole muscle by an additional covering of a connective tissue called perimysium, that bundled group of muscle fibers is called a fascicle.
Definition: A pennate muscle (also called a penniform muscle) is a muscle with fascicles that attach obliquely (in a slanting position) to its tendon. These types of muscles generally allow better stabilization and force production but less flexibility.
Four distinct patterns of fascicles are seen within the whole of the muscle: parallel, convergent, pennate, and circular (Figure 2).
The loose connective tissue of the perimysium (1) surrounds a muscle fascicle and continues as the endomysium (2) between the muscle fibers (3).
The tendon fascicle, however, is a distinct entity within the tendon hierarchy. The ability of the fascicle to transmit force to the adjacent parallel fascicle was recently examined in human patellar and Achilles tendon tissue obtained during surgery.
Muscle shape The deltoid muscle is apennate muscle which has its fascicles arranged in a feather-like arrangement. Pennate muscles may be uni-, bi- or multipennate muscles, examples of each being the extensor digitorum longus, rectus femoris and the deltoid, respectively.
Types of pennate muscle Figure 1 Pennate muscle fiber arrangements: A, unipennate; B, bipennate; C, multipennate. Blue: anatomical cross-section.
Pennate muscles resemble the shape of a feather, with muscle fibers approaching a central tendon at an oblique angle (Fig. 3.7D). The diagonal orientation of the fibers maximizes the muscle's force potential. Many more muscle fibers fit into the muscle compared with a similarly sized fusiform muscle.
Fascicle. A bundle of muscle fibers.
This arrangement is referred to as multipennate. A common example is the deltoid muscle of the shoulder, which covers the shoulder but has a single tendon that inserts on the deltoid tuberosity of the humerus.Apr 25, 2013
The large muscle on the chest, the pectoralis major, is an example of a convergent muscle because it converges on the greater tubercle of the humerus via a tendon. The temporalis muscle of the cranium is another.