The accessory soleus muscle is an

accessory muscle An accessory muscle is a relatively rare anatomical variation where duplication of a muscle may appear anywhere in the muscular system. Treatment is not indicated unless the accessory muscle interferes with normal function. Examples Examples are ...

of the calf which is rarely present in humans; it is, however, the most common accessory muscle of the

ankle The ankle, the talocrural region or the jumping bone (informal) is the area where the foot and the leg meet. The ankle includes three joints: the ankle joint proper or talocrural joint, the subtalar joint, and the inferior tibiofibular joint. The ...

. The muscle inserts on the anterior aspect of the soleus muscle or on the posterior aspect of the

tibia The tibia (; : tibiae or tibias), also known as the shinbone or shankbone, is the larger, stronger, and anterior (frontal) of the two Leg bones, bones in the leg below the knee in vertebrates (the other being the fibula, behind and to the outsi ...

or the muscles of the deep posterior compartment. It lies anterior to the calcaneal tendon and terminates on the calcaneal tendon or the superior or medial aspect of the calcaneus via fleshy fibers or a distinct

tendon A tendon or sinew is a tough band of fibrous connective tissue, dense fibrous connective tissue that connects skeletal muscle, muscle to bone. It sends the mechanical forces of muscle contraction to the skeletal system, while withstanding tensi ...

. Present in approximately 3% (or 10%)Kouvalchouk JF, et al. 2018. of people, this muscle usually appears as a distant belly, medial to the

Achilles tendon The Achilles tendon or heel cord, also known as the calcaneal tendon, is a tendon at the back of the lower leg, and is the thickest in the human body. It serves to attach the plantaris, gastrocnemius (calf) and soleus muscles to the calcane ...

. Clinically, the accessory soleus may be associated with pain and edema during periods of prolonged exercise.Moore, Keith L; & Dalley Arthur R (2006). ''Clinically Oriented Anatomy'' (5th ed.). Lippincott Williams and Wilkins.

References

Muscles of the lower limb Accessory muscle {{muscle-stub