Muscle Architecture

Skeletal muscle fibres (cells) are arranged in bundles called fascicles within the muscles. The arrangement of these bundles will affect the muscle’s power and range of motion.There are several types of arrangements of muscle. These are:

Parallel
The fascicles run parallel to the longitudinal axis of the muscle

Convergent / Triangular

Fascicles spread over a broad area and converge at a thick central tendon.




Fusiform – Fascicles are nearly parallel to the longitundinal axis of the muscles. The muscle tapers towards the tendons, and the belly of the muscle is wider, i.e. the biceps muscle.




Pennate Muslces



Unipennate

Fascicles are arranged on only one side of the tendon.

Bipennate

Fascicles are arranged on both sides of a centrally positioned tendon.



Multipennate – Fascicles are attached obliquely from many directions to several tendons, i.e. the deltoid muscle.



It is the arrangement of the fascicle in relation to the tendons which determine the power or range of motion of a muscle.



Pennate muscles have a large number of fascicles distributed over their tendons. This gives these muscles greater power but with less range of movement. The strength of a muscle depends on the total number of fibres it contains.



Parallel muscles have fewer fascicles, and therefore have a greater range of motion but less power. Therefore, the longer the fibres are in a muscle, the greater the range of motion.