kristjan oddsson wrote:
> I have a question about the piriformis muscle. I have heard that this
>
> external hip rotator changes it`s function so that it become a
> internal hip
> rotator after app. 80 degrees of hip flexion. If this is true you can
> stretch it in external rotation over 60 degrees of hip flexion. Does
> anyone
> know more about this phenomenon? I need good references!
Kapandjii states in his work "Physiology of the Joints" vol 2 that many
hip muscles change roles as you go into increasing flexion. This applies
to most of the adductors as well as the deep external rotators, e.g.
turning the piriformis into an internal rotator after 90°. Unfortunately
Kapandjii rarely gives any references in his otherwise excellent work.
But if you look at the orientation of the muscle passing in a anteror,
lateral and inferior direction to insert into greater trochanter
Kapandjii´s point of view seems logical. After 90° of flexion an
external rotation movement would result in a downward motion of the
greater trochanter, thus stretching the piriformis. This approach I use
to stretch the piriformis.
Hope this helps.
Hilmir Agustsson
GASKI physiotherapy
Reykjavík
Iceland
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