Organization of skeletal muscle fibers

Muscles classified on shape or arrangement of fibers

Parallel muscle fibers

-Muscle fascicles are parallel to the longitudinal axis

-Biceps brachii and rectus abdominis

Convergent muscle fibers

-Muscle fibers form a broad area but come together at a common point

-Pectoralis major and temporalis

Pennate muscle fibers (Unipennate)

-Form an oblique angle to the tendon of the muscle

-All the fibers are on the same side of the tendon

-Extensor digitorum

Pennate muscle fibers (Bipennate)

-Form an oblique angle to the tendon of the muscle

-Muscle fibers are on both sides of the tendon

-Rectus femoris

Pennate muscle fibers (Multipennate)

-Form an oblique angle to the tendon of the muscle

-The tendon branches within the muscle

-Deltoid muscle

Circular muscle fibers

Muscle fibers form concentric rings

-Orbicularis oris and obicularis oculi