Illustrated Encyclopedia of Human Anatomic Variation: Opus I: Muscular System: Alphabetical Listing of Muscles: P

Plantaris

Ronald A. Bergman, PhD
Adel K. Afifi, MD, MS
Ryosuke Miyauchi, MD
Peer Review Status: Internally Peer Reviewed

A variant, tensor fasciae plantaris (Wood), arises from the oblique line of the tibia and inserts on the fascia overlying the calcaneus.

Unlike palmaris longus, plantaris, which is poorly developed in humans, is a remnant of the superficial layer of the original common flexor of the digits. It is separated by the calcaneous into proximal and distal parts. It is frequently absent or represented as a fibrous band. In a series of 392 limbs, the plantaris was absent in about 8%, more commonly from the left limb. In another series of 552 limbs, it was absent in 5.4%, also predominantly from the left limb (6.5%), on the right 4.3%. In yet another study of 750 limbs, plantaris was recorded absent in 6.6% of limbs.In the Japanese it is absent in about 4% of the population.

Its tendon is commonly used (as a spare part) for repairs when a tendon from palmaris longus is inadequate or absent. There is no correlation between the presence or absence of palmaris longus and plantaris, hence one cannot estimate the probablity of the simultaneous, or alternate, presence or absence of the two muscles.

Macalister reported the variations in plantaris as follows: Absence was described by many authors but there is considerable difference of opinion as to its relative frequency. Macalister thought that its absence was to that of palmaris in the proportion of one to three;

1. Both Wood and Macalister found plantaris blended with the external (lateral) head of gastrocnemius;
2. Wood reported a muscle with a doubled muscular belly;
3. With a slip nearly its own size from the the medial side of its origin inserted into the ligamentum posticum (posterior tibiofibular) of Winslow;
4. Having its tendon enclosed in a sheath inside that of the soleus;
5. Ending in a widely expanded aponeurosis, half way down the leg, between the gastrocnemius and the soleus;
6. Arising from the fascia over the popliteus muscle (Hyrtl);
7. Or from the fibula between peroneus longus and flexor hallucis longus;
8. It may receive a second head from the popliteal plane (Hall, 1808);
9. Or from the knee capsule, near the intercondyloid notch;
10. It may be attached by fibers to the medial margin of the tibia, and inserted midway between the inner malleolus and the os calcis (Sandifort, 1769);
11. Lost partly in fat, and partly in the tendo Achillis;
12. With a loose coiled tendon (Harrison);
13. Origin sometimes lower down (Winslow);
14. Inserted into the plantar fascia (Blandin);
15. Inserted into the medial annular ligament (Brown, 1684).

Syn.: Langer Sohlenmuskel s. dünner Sohlenmuskel.

References

Dasleler, E.H. and B.J. Anson. (1943) The plantaris muscle. An anatomical study of 750 specimens. J. Bone Joint Surg. 25:822-827.

George, R. (1953) Co-incidence of palmaris longus and plantaris muscles. Anat. Rec. 116:521-523.

Gruber, W. (1874) Über den Musculus plantaris bicaudatus mit Endigung seines supernumerären Schwanzes im Ligamentum popliteum. Arch. Anat. Physiol. Wissen Med. 1874)467-473.

Henle, J. (1871) Handbuch der Muskellehre des Menschen, in Handbuch der systematischen Anatomie des Menschen. Verlag von Friedrich Vieweg und Sohn, Braunschweig.

Kudo, T. (1916) On the aponeurosis plantaris. Hokuetsu Igakkai Zasshi 31:98-107. In Japanese.

Macalister, A. Observations on muscular anomalies in the human anatomy. Third series with a catalogue of the principal muscular variations hitherto published. Trans. Roy. Irish Acad. Sci. 25:1-130.

Mori, M. (1964) Statistics on the musculature of the Japanese. Okajimas' Fol. Anat. Jap. 40:195-300.

Wood, J. (1864) On some varieties in human myology. Proc. Roy. Soc. Lond. B 13:299-303.

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