Originally Posted by WildVolley
I had to look up what a plantaris muscle is. Never heard of it before.
Guess you hadn't heard of "tennis leg".
"An isolated injury to the plantaris tendon or myotendinous junction has been described as "tennis leg." Powell first described this clinical entity in 1883.4 While there has been controversy in the orthopedic literature as to whether the clinical entity of plantaris tendon rupture really exists,5 surgically confirmed cases of plantaris tendon rupture have been well documented.6 Tennis leg may be seen in young athletes or in sedentary older individuals. A tearing sensation or pop is often reported, with pain increasing over one to two days and with tenderness and swelling found at the calf.
The plantaris muscle is of questionable physiological importance. It is thought to be a vestigial structure and is absent in 7% to 10% of the population. Despite these facts, injuries to the plantaris are a not uncommon cause of patient pain, and can present with a confusing clinical picture, thus making an understanding of plantaris anatomy and related pathology important to those who utilize and interpret MRI."
PL = Plantaris muscle/tendon