The plantaris muscle is a tapering down pencil sized fine tendon which runs beneath the gastrocnemius and soleus muscles and is attached to the Achilles tendon or to the medial side of the tubercle of the calcaneus. An injury to this muscle structure can lead to a very painful calf. The Plantaris muscle is small in size but is one of the important lower limb muscles. Plantaris muscle is very small muscle located along the posterior part of the leg and is a part of calf’s postersuperficial compartment. Generally, it is considered as vestigial muscle and in around 7 to 20% of limbs it is absent. The muscle function itself is not very important and an injury to it can cause pain due to torn fibers or hemorrhage.
The special highlight of plantaris muscle is its muscle belly which is small and thin. Also present is a thin yet long tubular tendon that makes up some part of the posterosuperficial compartment of calf. Along with gastrocnemius and soleus, in group they are termed as triceps surae muscle. Plantaris muscle emerges from the femur just superior’s lateral supracondylar line and medial to gastrocnemius muscles’s lateral head and also from the knee’s posterior aspect’s popliteal ligament. This plantaris muscle has varying size and form and ranges from 7 to 13 cm in length. Starting from the origin, the muscle then travels in medial as well as an inferior direction transverse to popliteal fossa.
Plantaris muscle works along with the gastrocnemius but is not a major contributory as a knee flexor or ankle’s plantar flexor. This muscle contributes more in the proprioceptive function during the major and highly powerful plantarflexors as it comprises of muscle spindles of huge density.
Tennis leg is the most famous and painful injury associated with Plantaris muscles. It is a very regular condition and mostly occurs while jumping or running or when heavy duty load is kept across the knee, more so when it is in extended position. This results in direct trauma to the calf region. The injury or trauma is as if struck harshly on the calf by heavy object. Many athletes face this type of injury and according to the severity of the problem; the patient might experience soreness in calf and severe pain. This can force the athlete to stop playing till the injury is healed out. This type of pain has been found to aggravate more the next day and go down to the ankle and even up to the foot. Any attempt made related to passive or active dorsiflexion or resisted plantarflexion results in acute pain.
The injury is instantly treated with RICE protocol involving rest, compression, ice and elevation. Resting is very important for the injury to heal quickly and hence for some time mostly immobilization is advised. This helps the body to provide new granulation tissue that adds tensile strength in the Plantaris muscles so that the contraction process can be withstood. Immobilization in itself is considered as the treatment in such injuries which help in natural healing process. While the patient is in immobilization period, RICE protocol along with ice or cryotherapy, compresson and elevation should be continued.