a-short-review-of-histology

Orientation of Skeletal Muscle Cells:

The orientation of muscle cells within a muscle, and their relationship to the line of pull of the muscle, will determine the amount by which the points of attachment of the muscle can be brought together when the muscle contracts
In strap muscle the muscle cells lie in parallel with the line of pull
This organisation will maximise the amount by which the points of attachment can be brought closer together when the muscle contracts
In pennate (uni-, bi-, multi- ) muscles, the muscle cells lie at an angle to the line of pull and the amount by which the points of attachment can be brought together is reduced
However, this arrangement allows more muscle cells (sarcomeres), and therefore more power, to be applied to the action
Where there is a long tendon, which can not contract, the amount by which the two points of attachment can be brought together is reduced

Contraction by Strap Muscles:

Skeletal muscle cells shorten their length by 30% when they contract
If the muscle cells run directly between two attachment sites (as occurs in strap muscles), with very little tendon connecting them at each end, then when the muscle cells contract the distance between the two attachment sites will be reduced by 30%
If the muscle cells only extend for 50% of the distance between the two attachment sites (the other 50% being occupied by tendons) then when they contract the distance between the attachment sites will only be reduced by 15%

Skeletal muscle cells in the tongue