The Anatomy of Plantaris Muscle from Redundancy to Relevance

Background:The plantaris muscle (PM) is present in the superficial posterior compartment of the leg.Though vestigial, it has various morphological and morphometric variations with clinical relevance, particularly in surgical interventions and diagnostic imaging of the posterior leg.Objective: To evaluate the anatomical variations and morphometric features of the PM in cadavers and compare the findings with existing literature.Methods: A descriptive cadaveric study was conducted on 21 formalin-fixed lower limbs during routine dissections over 2 academic years in the Department of Anatomy, Pt BD Sharma PGIMS, Rohtak.The origin, insertion, course, and nerve supply were documented based on Olewnik's classification.Morphometric parameters, including the length and width of the muscle belly and tendon, were measured using a digital Vernier caliper.Results: Type Ia origin and type I insertion were the most prevalent patterns (42.9% each).A novel type VII origin (Y-shaped belly) was observed in 4.8% of specimens.The plantaris tendon typically followed a normal anatomical course in 90.5% of cases, while two specimens exhibited a unique intramuscular course through the soleus.All muscles were innervated by the tibial nerve.Morphometric analysis revealed no statistically significant side-to-side differences.The mean tendon length was ~35.4 cm, and the belly length was ~8.5 cm. Conclusion:The study highlights considerable variation in the morphology and morphometry of the PM, including a newly identified Y-shaped origin and an unusual tendon course.Variants can be mistaken for pathological masses on imaging or can cause entrapment syndrome.Knowledge of its variations is crucial to retrieve the tendon for reconstructive surgeries, as its long tendon is frequently used in grafting procedures.These findings have potential implications for surgical procedures and anatomical education.