|Origin||Lateral supracondylar line of the femur|
|Insertion||Posterior surface of the calcaneus|
|Action||Assists in plantar flexion of the foot|
Assists in flexion of the knee
Potentially has an important proprioceptive role
|Nerve||Tibial nerve (S1- S2)|
Superior lateral genicular artery
Location & Overview
The plantaris muscle is a long and thin muscle which runs down the posterior aspect of the lower leg. It is located superficial to the soleus muscle and deep to the gastrocnemius muscle . Anatomical variation of this muscle can sometimes be present, such as: it being absent entirely (absent in only 7–20% of limbs ), terminating proximally into the calcaneal tendon, or even terminating into the gastrocnemius sometimes .
The plantaris muscle has become less significant during human evolution. The plantaris, a muscle once used for tree-climbing in primates, has become less important in human evolution due to the shift towards bipedal locomotion (using two legs for walking). In modern humans, the plantaris muscle mainly acts in conjunction with the gastrocnemius muscle, serving as an accessory to it. This understanding is based on the research conducted by Sichting et al. (2020) in their article “Evolutionary Anatomy of the Plantar Aponeurosis in Primates, Including Humans,” published in the Journal of Anatomy .
Origin & Insertion
The plantaris muscle originates from the lateral supracondylar line of the femur. The origin is superior and medial to the gastrocnemius’ lateral head. The plantaris then continues down the leg located between the soleus and gastrocnemius and then along the medial aspect of the calcaneal tendon, which is inserts right next to, on the calcaneus  .
The action of the plantaris muscle is to provide weak plantar flexion at the ankle joint and weak flexion at the knee joint. The gastrocnemius is able to perform these actions much better and the soleus is a stronger plantar flexor too (though the soleus does not cross the knee joint so it can’t assist in knee flexion, unlike the gastrocnemius)   Some studies have suggested the plantaris plays an important proprioceptive role too   . Proprioception is your body’s way to sense movement, action, and its location.
The plantaris muscle is innervated by the tibial nerve (S1- S2). This nerve is the larger branch of the sciatic nerve which divides into the tibial nerve. It also provides innervation for other muscles of the posterior lower leg compartment  .
Blood is supplied to the plantaris muscle via the sural, popliteal, and superior lateral genicular arteries .
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|↑1, ↑5, ↑7, ↑12||Spina AA. The plantaris muscle: anatomy, injury, imaging, and treatment. J Can Chiropr Assoc. 2007;51(3):158-65. PMID: 17885678; PMCID: PMC1978447.|
|↑2||Simpson SL, Hertzog MS, Barja RH. The plantaris tendon graft: an ultrasound study. J Hand Surg [Am] 1991;16:708–711.|
|↑3||Egan KG, Emanuelli E, Przylecki W, Endress RD. Variant Plantaris Anatomy During Tendon Harvest. J Hand Surg Am. 2021 May;46(5):431.e1-431.e4. doi: 10.1016/j.jhsa.2021.01.004. Epub 2021 Mar 16. PMID: 33741215.|
|↑4||Sichting, Freddy; Holowka, Nicholas B.; Ebrecht, Florian; Lieberman, Daniel E. (2020-02-26). “Evolutionary anatomy of the plantar aponeurosis in primates, including humans”. Journal of Anatomy. Wiley. 237 (1): 85–104. doi:10.1111/joa.13173. ISSN 0021-8782. PMC 7309290. PMID 32103502|
|↑6, ↑14||Moore KL, Agur AMR, Dalley AF. Clinically Oriented Anatomy. 8th ed. Philadelphia: Lippincot Williams & Wilkins; 2017.|
|↑8, ↑10||Moore KL, Dalley AF, editors. Clinically Oriented Anatomy. 5. Philadelphia: Lippincott Williams & Wilkins; 2006. pp. 648–649.|
|↑9||Vlaic J, Josipovic M, Bohacek I, Jelic M. The plantaris muscle: too important to be forgotten. A review of evolution, anatomy, clinical implications and biomechanical properties. J Sports Med Phys Fitness. 2019 May;59(5):839-845. doi: 10.23736/S0022-4707.18.08816-3. PMID: 30936418.|
|↑11||Greene BD, Smith SE, Smith JT. Snapping Plantaris Tendon: A Rare Case in a Competitive Dancer. J Am Acad Orthop Surg Glob Res Rev. 2021;5(5):e21.00008. Published 2021 May 4. doi:10.5435/JAAOSGlobal-D-21-00008|
|↑13||Binstead JT, Munjal A, Varacallo M. Anatomy, Bony Pelvis and Lower Limb, Calf. [Updated 2021 Jun 3]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK459362/|