[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Anatomy](https://durgical.com/en/anatomy/) › [Lower limb](https://durgical.com/en/anatomy/region/lower-limb/) › Plantaris [Muscular system](https://durgical.com/en/anatomy/system/muscular-system/) · [Lower limb](https://durgical.com/en/anatomy/region/lower-limb/) # Plantaris The plantaris is a small muscle behind the knee with one of the body's longest, thinnest tendons, which runs down to the heel. Official name: Plantaris muscle [See in 3D →](https://durgical.app/?from=durgipedia&lang=en#region=lower_limb&select=plantaris&side=r) Opens in the Durgical app, no sign-up needed. ## What it is A small muscle behind the knee with a long, thin tendon. ## What it does Helps the calf muscles a little. ## Key points - Small belly with one of the longest tendons in the body, which runs between gastrocnemius and soleus to the medial side of the Achilles tendon - Can be taken as a free tendon graft with no noticeable loss of function, so its presence is checked before a graft is planned - Its rupture was long blamed for "tennis leg"; most of these injuries are actually tears of the medial gastrocnemius head - Its tendon lies close against the medial Achilles tendon and may contribute to midportion Achilles tendinopathy ## Key facts **Origin** Lower lateral supracondylar line of [femur](https://durgical.com/en/anatomy/femur/); oblique popliteal ligament **Insertion** Posterior [calcaneus](https://durgical.com/en/anatomy/calcaneus/), with or medial to calcaneal tendon **Action** Weakly assists gastrocnemius (plantar flexes ankle, flexes knee); absent in about 10% **Nerve** [Tibial nerve](https://durgical.com/en/anatomy/tibial-nerve/) (S1–S2) **Blood supply** Sural branches of [popliteal artery](https://durgical.com/en/anatomy/popliteal-artery/) ## Relations **Course** From above the lateral femoral condyle the belly runs down and medially across the back of the knee; its tendon then passes between gastrocnemius and [soleus](https://durgical.com/en/anatomy/soleus-muscle/) to reach the medial border of the [Achilles tendon](https://durgical.com/en/anatomy/calcaneal-tendon/) **Superficial** [Lateral head of gastrocnemius](https://durgical.com/en/anatomy/lateral-head-of-gastrocnemius/) at the knee, then the gastrocnemius bellies in the calf **Deep** Knee capsule and [oblique popliteal ligament](https://durgical.com/en/anatomy/oblique-popliteal-ligament/), [popliteus](https://durgical.com/en/anatomy/popliteus-muscle/), then the soleus **Medial** Near the heel, the Achilles tendon, beside which it inserts ## How to find it It cannot be felt as a separate muscle. In dissection it is a short belly next to the lateral head of gastrocnemius with a thin, pale, ribbon-like tendon between gastrocnemius and soleus; on ultrasound the tendon is seen beside the medial edge of the Achilles tendon. ## On imaging Ultrasound or MRI shows whether the tendon is present before graft harvest and how it relates to the medial Achilles tendon. In a calf tear, fluid between gastrocnemius and soleus with an intact [plantaris tendon](https://durgical.com/en/anatomy/tendon-of-plantaris/) points to a gastrocnemius injury. ## Clinical notes - Donor tendon for tendon and ligament reconstructions in the hand and around the ankle - In some resistant cases of midportion Achilles tendinopathy the plantaris tendon is released or removed ## Anatomical variants - Absence is its best-known variant; how often it is missing depends on the study - Its insertion varies: on the calcaneus beside the Achilles tendon, merged with that tendon, or into the flexor retinaculum or deep fascia; several insertion types are described ## Development From the ventral (flexor) muscle mass, supplied by the tibial nerve. It is often compared with the [palmaris longus](https://durgical.com/en/anatomy/palmaris-longus/) of the forearm: both are small, long-tendoned and inconstant. ## Memory aid Nicknamed the "freshman's nerve": its long, pale tendon is easily mistaken for a nerve by new dissectors. ## Related conditions - [Achilles tendon rupture](https://durgical.com/en/conditions/achilles-tendon-rupture/) ## Test yourself Think of the answer, then tap the question to see it. ## Why can the plantaris tendon be used as a free tendon graft? Its long tendon can be taken with no noticeable loss of function, since the plantaris only weakly assists the gastrocnemius; its presence is checked first, as it may be absent. ## Is plantaris rupture the usual cause of «tennis leg»? No. It was long blamed, but most of these injuries are tears of the medial gastrocnemius head. ## Between which muscles does the plantaris tendon run in the calf? Between the gastrocnemius and the soleus, to the medial side of the Achilles tendon. [Add to my cards (3)](https://durgical.app/estudiar/?add=/en/anatomy/plantaris-muscle/) Educational information, not medical advice. For any symptom, see a health professional. ## Its names **Official Latin (TA2)** musculus plantaris TA2 2663 **Official Spanish (DeCS)** Músculo plantar **English (TA2)** Plantaris muscle ## Related - [Tibial nerve](https://durgical.com/en/anatomy/tibial-nerve/) - [Popliteal artery](https://durgical.com/en/anatomy/popliteal-artery/) - [Plantaris tendon](https://durgical.com/en/anatomy/tendon-of-plantaris/) - [Calcaneus](https://durgical.com/en/anatomy/calcaneus/) - [Femur](https://durgical.com/en/anatomy/femur/) Sources: Terminologia Anatomica (TA2); [Anatomy, Bony Pelvis and Lower Limb: Calf](https://www.ncbi.nlm.nih.gov/books/NBK459362/); [Anatomy, Bony Pelvis and Lower Limb: Leg Posterior Compartment](https://www.ncbi.nlm.nih.gov/books/NBK537340/). ## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake Representative model, for educational purposes only. --- Source: https://durgical.com/en/anatomy/plantaris-muscle/ License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/anatomy/plantaris-muscle/