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Soleus 3.jpg

Located in superficial posterior compartment of the leg Soleus is a powerful lower limb muscle, which is situated deep to the gastronemius muscle.  Together with gastronemius and plantaris, it forms the calf muscle or triceps surae. It runs from back of the knee to the ankle and is multipennate.

The soleus has the greatest physiological cross sectional area (CSA) of the calf muscles and is thought to provide up to 80% of triceps surae force[1].

Muscle Physiological CSA (cm²) %
Soleus 230 71
Medial Gastrocnemius 68 22
Lateral Gastrocnemius 28 7

Anatomy[edit | edit source]

Origin[edit | edit source]

  • Posterior surface of the head and upper 1/3 of the shaft of the fibula;
  • Middle 1/3 of the medial border of the tibia, tendinous arch between tibia and fibula.

Insertion[edit | edit source]

  • Posterior surface of the calcaneus via the Achilles tendon

Action[edit | edit source]

  • Plantar flexion of the foot at the ankle;
  • Reversed origin insertion action: when standing, the calcaneus becomes the fixed origin of the muscle;
  • Soleus muscle stabilizes the tibia on the calcaneus limiting forward sway.

Nerve supply[edit | edit source]

Tibial nerve, L4, L5, S1 , S2

No sensory supply to the intramuscular aponeurosis.

Synergists[edit | edit source]

Gastrocnemius, Plantaris, Tibialis posterior, Peroneus longus and Brevis, FHL and FDL.

Antagonists[edit | edit source]

Tibialis anterior

Blood supply[edit | edit source]

  • Blood supply of the soleus muscle is from peroneal artery proximally and the posterior tibial artery distally;
  • Muscle has a mixed blood supply;
  • Vascular supply of the soleus is from popliteal, posterior tibial, & peroneal vascular pedicles to the proximal muscle, peroneal pedicles to distal lateral belly, and segmental posterior tibial pedicles to distal medial belly;
  • With distal pedicles from the posterior tibial artery ligated & based on proximal pedicles from the posterior tibial and peroneal arteries, muscle can be transposed medially or laterally to cover defects in middle third of the leg;
  • Proximal vasculature arises directly from the popliteal vessels and can reliably carry all but the distal 4 to 5 cm of the muscle;
  • Intramuscularly, vasculature of the soleus divides into a bipenniform segmental pattern;
  • With this vascular pattern, either half of the soleus muscle can be used, leaving a functional hemisoleus muscle intact

Function[edit | edit source]

Soleus has two major functions:

  • To act as skeletal muscle:
    • Along with other calf muscles it is powerful plantarflexor and has a major contribution  in running, walking and dancing.
    • It is also a major postural muscle designed to stop the body from falling forwards at the ankle during stance.
    • In the seated calf raise (knees flexed approximately 90º), the gastrocnemius is virtually inactive while the load is borne almost entirely by the soleus.
    • In moderate force, the soleus is preferentially activated in the concentric phase, whereas the gastrocnemius is preferentially activated in the eccentric phase [2].
    • Human soleus muscle tissue consists predominantly of slow twitch fibers, though the composition can range between 60 and 100% slow fibers.[3][4][5].
  • To act as muscle pump:
    • The soleal pump assists with venous return from the periphery to the heart when upright as the venous circulatory system passes through the muscle tissue.

Palpation[edit | edit source]

When palpating the Soleus, plantarflex the ankle with the knee flexed to 90 degrees to ensure that gastrocnemius remains relaxed.  The lateral and medial aspects of the muscle can then be palpated from the lateral and medial sides of the Achilles tendon. The muscle is palpable for most of the distance from distal to proximal though the proximal attachments will become more difficult to palpate if the heads of gastrocnemius are large.

Accessory soleus muscle (ASM)
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It is present in 0.7 to 5.5% of humans.[6]It is usually observed during the second or third decade of life and is more commonly seen in females than males at a ratio of 2:1. It is mostly unilateral.[7][8][9][10][11]. This supernumerary muscle is located under the gastrocnemius muscle, in the posterior upper third of the fibula, in the oblique soleus line, between the fibular head and the posterior part of the tibia. From its origin, the ASM runs anteriorly and medially until it reaches the Achilles tendon.[12]

            ASM.jpg       ASM2.jpg      

Depending upon its insertion it is of 5 types, or in other words it can origininate from 5 sites

  • Achilles tendon
  • Upper calcaneus region
  • Insertion in the upper calcaneus,
  • Medial calcaneus region,
  • Medial part of the calcaneus

Sometimes it is impossible to precisely identify the ASM origin and insertion, since the MRI fails to show details, depending on the slices[12]. It may cause pain on exercise. One may suspect a soft-tissue tumor, such as lipoma, hemangioma, and even sarcoma, but the anomalous muscle has a typical appearance on plain radiographs, and the appearance on computed tomography is diagnostic. If the patient is asymptomatic, no therapy is required, but if pain or other discomfort is provoked by exercise, exploration with fasciotomy or excision of the accessory muscle is recommended, as was done in six of our eleven patients who were seen between 1968 and 1985[7].

Pathology[edit | edit source]

Strain/Rupture[edit | edit source]

A muscle strain occurs when muscle fibers are damaged by the loads placed on them by activity. A gradual onset of pain is commonly reported during soleus strain and often with no specific mechanism of injury (MOI). This may be due to the limited sensory innervation to the intramuscular aponeurosis.  In cases where a specific MOI is identified, steady-state running appears to be the commonest cause of injury[13].


  • Pain with active or resisted plantar flexion
  • Pain during walking, running, jumping or hopping
  • Tenderness on palpation of the injury site


Diagnostic ultrasound or MRI can be advantageous to confirm an injury diagnosis and ensure that injuries accurately assessed as full ruptures can be overlooked with clinical exam on occasion. [14]

Further information about soleus and calf strains is available here

References[edit | edit source]

  1. Fukunaga T, Roy RR, Shellock FG, Hodgson JA, Day MK, Lee PL, et al. Physiological cross-sectional area of human leg muscles based on magnetic resonance imaging. J Orthop Res. 1992;10(6):928–34.
  2. Nardone A, Romanò C, Schieppati M. Selective recruitment of high-threshold human motor units during voluntary isotonic lengthening of active muscles. J Physiol. 1989;409(1):451–71.
  3. Ariano MA, Armstrong RB, Edgerton VR. Hindlimb muscle fiber populations of five mammals. J Histochem Cytochem. 1973;21(1):51–5.
  4. Burke RE, Levine DN, Salcman M, Tsairis P. Motor units in cat soleus muscle: physiological, histochemical and morphological characteristics. J Physiol. 1974;238(3):503–14.
  5. Gollnick PD, Sjödin B, Karlsson J, Jansson E, Saltin B. Human soleus muscle: a comparison of fiber composition and enzyme activities with other leg muscles. Pflugers Arch. 1974;348(3):247–55.
  6. Sookur PA, Naraghi AM, Bleakney RR, Jalan R, Chan O, White LM. Accessory muscles: anatomy, symptoms and radiology evaluation. Radiographics. 2008;28(2):481-99.
  7. 7.0 7.1 Romanus B, Lindahl S, Sterner B. Accessory soleus muscle. A clinical and radiographic presentation of eleven cases. J Bone Joint Surg Am. 1986; 68(5):731-4.
  8. Salomão O, Carvalho Junior AE, Fernandes TD, Romano D, Adachi PP, Sampaio Neto R. Músculo solear acessório: aspectos clínicos e achados cirúrgicos. Rev Bras Ortop. 1994;29(4):251-5.
  9. Leswick DA, Chow V, Stoneham GW. Resident's corner. Can Assoc Radiol J. 2003;54(5):313-5.
  10. Featherstone T. MRI diagnosis of accessory soleus muscle strain. Br J Sports Med. 1995;29(4):277-8.
  11. Doda N, Peh WC, Chawla A. Symptomatic accessory soleus muscle: diagnosis and follow-up on magnetic resonance imaging. Br J Radiol. 2006;79(946):e129-32.
  12. 12.0 12.1 Del Nero FB, Ruiz CR, Aliaga Junior R. The presence of accessory soleous muscle in humans. Einstein (Sao Paulo). 2012;10(1):79–81.
  13. Pizzari T. The risks, epidemiology and return to play of calf muscle strain injuries [Internet]. 2021 Mar. Available from:
  14. urtehave_com. Rupture of the soleus muscle - Sportnetdoc [Internet]. 2011 [cited 2013 Aug 31]. Available from: