The distal attachment of the plantaris tendon is treated in VARIANTIS as a distinct anatomical classification domain from proximal attachment and muscle belly morphology.
This page summarizes the principal distal attachment classification systems described in the anatomical literature. The six-type adult classification reported by Olewnik et al. [1] represents an extension of the five-type system introduced by Olewnik et al. [2].
Anatomical Basis of Distal Attachment
The distal attachment of the plantaris tendon is highly variable. It determines the spatial relationship between the plantaris tendon, Achilles tendon, calcaneus, deep crural fascia, soleus muscle and flexor retinaculum [1-4]
The plantaris tendon may remain separate from the Achilles tendon, lie close to it, share a paratenon, cross anterior to it, encircle its posteromedial surface, attach to deep fascia, or continue toward the flexor retinaculum [1-4].
Because these structures belong to different anatomical regions of the posterior leg and posteromedial ankle, distal attachment should be classified separately from proximal attachment.
Classification Scope
Several classification systems have described the distal attachment of the plantaris tendon. They differ in anatomical focus, terminology and purpose. These systems should not be merged without explanation.
Published descriptions of distal plantaris tendon morphology include the historical observations of Cummins and Anson [5], the nine distal insertion sites described by van Sterkenburg et al. [3], the three-type system proposed by Dos Santos et al. [4], the five- and subsequently six-type systems reported by Olewnik et al.[1-2], and the branching-pattern classification proposed by Patra et al. [6].
Branching-pattern classifications describe a different morphological feature from classifications based primarily on the site of distal attachment and are therefore presented separately [6].
Tendon Course Variants
Table 1. Tendon course variants of the plantaris tendon.
| Course variant | Description | Usually associated with | Frequency |
|---|---|---|---|
| Variant A | Passes between gastrocnemius and soleus, then continues distally medial to the Achilles tendon | Distal Types I, II, V | 84.5% |
| Variant B | Initial course as in Variant A; distally runs directly anterior to the Achilles tendon | Distal Types III, IV, VI | 15.5% |
Frequencies are reported directly by Olewnik et al.¹ and should be interpreted together with the distal attachment type.
Published Distal Attachment Systems
Table 2. Published classification systems and descriptive frameworks for distal plantaris tendon morphology.
| Author / system | System type | What was classified | Morphological scope |
|---|---|---|---|
| Cummins and Anson⁵ | Historical four-pattern description | Four distal plantaris tendon insertion patterns | Early descriptive characterization of distal plantaris tendon morphology |
| van Sterkenburg et al.³ | Descriptive anatomical study | Nine distal insertion sites in relation to the calcaneus, calcaneal tendon and deep fascia | Topographical description of distal insertion sites |
| Dos Santos et al.⁴ | Formal three-type system | Calcaneal insertion in relation to the Achilles tendon, including a fusion pattern | Classification based on insertion topography relative to the Achilles tendon |
| Olewnik et al.¹ | Formal six-type adult system | Six distal attachment types with course variants A/B; extension of the earlier five-type system² | Classification integrating distal attachment pattern and tendon course |
| Patra et al.⁶ | Adult branching-pattern system | Distal tendon splitting / branching at the distal attachment level | Classification based on distal tendon branching morphology |
van Sterkenburg et al. — Nine Distal Insertion Sites
Table 3. Nine distal insertion sites described by van Sterkenburg et al.
| Pattern / site no. | Distal insertion site | n / 107 lower extremities | Calculated frequency |
|---|---|---|---|
| 1 | Medial attachment to the calcaneus | 21/107 | 19.63% |
| 2 | Medial fan-shaped attachment to the calcaneus | 26/107 | 24.30% |
| 3 | Medial attachment to the calcaneal tendon | 3/107 | 2.80% |
| 4 | Medial attachment with thin slips to the calcaneus | 5/107 | 4.67% |
| 5 | Anteromedial attachment to the calcaneus | 15/107 | 14.02% |
| 6 | Anteromedial fan-shaped attachment to the calcaneus | 18/107 | 16.82% |
| 7 | Posteromedial fan-shaped attachment to the calcaneus | 16/107 | 14.95% |
| 8 | Anterior attachment to the calcaneus | 2/107 | 1.87% |
| 9 | Attachment to deep fascia | 1/107 | 0.93% |
A plantaris tendon was identified in all 107 dissected lower extremities. Frequencies shown here were calculated by VARIANTIS from the reported counts using 107 lower extremities as the denominator. van Sterkenburg et al. described nine distal insertion sites rather than a formally numbered Type 1–9 classification.
Dos Santos et al. Three-Type Distal Attachment Classification
Table 4. Dos Santos et al. three-type distal attachment classification.
| Dos Santos type | Distal attachment pattern | n / 29 tendons present | Calculated frequency | VARIANTIS anatomical note |
|---|---|---|---|---|
| Type I | Calcaneal insertion anteromedial to the Achilles tendon | 16/29 | 55.17% | Achilles-related topography |
| Type II | Calcaneal insertion medial to the Achilles tendon | 12/29 | 41.38% | Achilles-related topography |
| Type III | Fusion with the Achilles tendon approximately 5 cm proximal to the calcaneus | 1/29 | 3.45% | Fusion pattern |
The plantaris tendon was present in 29 of 30 dissected lower limbs. Type frequencies shown here are calculated by VARIANTIS from the reported counts using the 29 present tendons as the denominator.
Olewnik et al. Distal Attachment Classification
Table 5. Olewnik et al. distal attachment classification of the plantaris tendon.
| Olewnik distal type | Distal attachment / relationship | Course variant | n / 116 lower limbs with plantaris tendon present | Frequency | VARIANTIS anatomical note |
|---|---|---|---|---|---|
| Type I | Fan-shaped attachment to the medial aspect of the calcaneal tuberosity | A | 51/116 | 44.0% | Separate medial calcaneal pattern |
| Type II | Insertion to the medial aspect of the calcaneal tuberosity, with the plantaris and Achilles tendons enclosed within a common paratendon | A | 26/116 | 22.4% | Close Achilles-related pattern |
| Type III | Attachment to the calcaneus anterior to the Achilles tendon | B | 8/116 | 6.9% | Anterior crossing trajectory |
| Type IV | Deep crural fascia, no calcaneal attachment | B | 4/116 | 3.4% | Fascial distal attachment |
| Type V | Encircling the posterior and medial surfaces of the Achilles tendon | A | 21/116 | 18.1% | Extensive Achilles-related contact |
| Type VI | Insertion at a point near the flexor retinaculum of the tarsal canal | B | 6/116 | 5.2% | Distal insertion near the flexor retinaculum / tarsal canal region |
Frequencies refer to the 116 lower limbs in which the plantaris tendon was present, not to the total dissected material of 130 lower limbs.
Patra et al. Branching-Pattern Classification
Table 6. Patra et al. branching-pattern classification of the plantaris tendon.
| Patra branching type | Branching pattern | n / 52 lower limbs with plantaris present | Frequency among present plantaris tendons | VARIANTIS anatomical note |
|---|---|---|---|---|
| Type A | Single tendon without splitting or branching | 37/52 | 71.15% | Non-branching distal morphology |
| Type B | Bifurcation into two branches | 10/52 | 19.23% | Bifid distal morphology |
| Type C | Trifurcation into three distinct branches | 4/52 | 7.69% | Trifid distal morphology |
| Type D | Quadrifurcation into four branches or slips | 1/52 | 1.92% | Four-slip distal morphology |
| Type E | Multiple splitting into more than four branches or irregular branching | 0/52 | 0% | Complex branching category; not observed in this series |
Patra et al.⁶ proposed a separate classification based specifically on distal plantaris tendon splitting and branching patterns. This system describes tendon branching morphology and should be considered separately from classifications based on the site of distal attachment.
The plantaris muscle was present in 52 of 58 lower limbs (89.65%). Frequencies for Types A–E are presented using the 52 lower limbs with a present plantaris tendon as the denominator, consistent with the detailed Results reported by Patra et al.⁶
Key Classification Points
- Distal attachment / insertion represents a distinct anatomical domain from proximal attachment / origin.
- The six-type classification reported by Olewnik et al. [1] represents an extension of the earlier five-type system [2] and incorporates two tendon course variants.
- van Sterkenburg et al. [3] described nine distal insertion sites, whereas Dos Santos et al. [4] proposed a three-type system based on the relationship of the plantaris tendon insertion to the Achilles tendon.
- Patra Types A–E classify distal tendon splitting and branching and therefore describe a different morphological domain from classifications based primarily on the site of distal attachment.
References:
1. Olewnik L, Wysiadecki G, Podgorski M, Polguj M, Topol M. The plantaris muscle tendon and its relationship with the Achilles tendinopathy. BioMed Research International. 2018;2018:9623579. doi:10.1155/2018/9623579.
2. Olewnik L, Wysiadecki G, Polguj M, Topol M. Anatomic study suggests that the morphology of the plantaris tendon may be related to Achilles tendonitis. Surgical and Radiologic Anatomy. 2017;39(1):69-75. doi:10.1007/s00276-016-1682-1.
3. van Sterkenburg MN, Kerkhoffs GMMJ, Kleipool RP, van Dijk CN. The plantaris tendon and a potential role in mid-portion Achilles tendinopathy: an observational anatomical study. Journal of Anatomy. 2011;218(3):336-341. doi:10.1111/j.1469-7580.2011.01335.x.
4. Dos Santos MA, Bertelli JA, Kechele PR, Duarte H. Anatomical study of the plantaris tendon: reliability as a tendo-osseous graft. Surgical and Radiologic Anatomy. 2009;31(1):59-61. doi:10.1007/s00276-008-0391-9.
5. Cummins EJ, Anson BJ. The structure of the calcaneal tendon (of Achilles) in relation to orthopedic surgery, with additional observations on the plantaris muscle. Surg Gynecol Obstet. 1946;83:107-116.
6. Patra A, Tiwari V, Chaudhary P, Asghar A, Kaur H, Trzeciak M, Paziewski M, Sychta M, Mazur M, Walocha JA. Newly proposed classification of plantaris tendon insertion based on branching patterns: a morphological study. Folia Morphologica. 2025;84(4):1003-1011. doi:10.5603/fm.103897.
VARIANTIS. Plantaris muscle: distal attachment classification. In: VARIANTIS Encyclopedia of Human Anatomical Variation [Internet]. 2026 [cited 2026 Aug 27]. Available from: View entry URL
VARIANTIS (2026) ‘Plantaris muscle: distal attachment classification’. VARIANTIS Encyclopedia of Human Anatomical Variation. Available at: View entry URL (Accessed: 27 August 2026).
VARIANTIS, ‘Plantaris muscle: distal attachment classification’, VARIANTIS Encyclopedia of Human Anatomical Variation (2026), View entry URL [accessed 27 August 2026].