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Anatomy Atlases: Illustrated Encyclopedia of Human Anatomic Variation: Opus I: Muscular System: Alphabetical Listing of Muscles: Q: Quadratus Plantae

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

Quadratus Plantae

Ronald A. Bergman, PhD
Adel K. Afifi, MD, MS
Ryosuke Miyauchi, MD

Peer Review Status: Internally Peer Reviewed

Also known as flexor accessorius this muscle is commonly reduced in size: the lateral head may be missing, as may, the medial head or whole muscle. Heads may be duplicated or divided into superficial or deep parts. The manner of attachment to the tendon of flexor digitorum longus longus varies. The muscle may be inserted in part or wholly into the long flexor of the great toe. Quadratus plantae may recieve (in about 5% of cases) an accessory slip from the fibula or tibia, one of the muscles of the leg or foot, or the medial surface of the calcaneus or related areas (see m. flexor hallucis longus).

Macalister has reported the variations of this muscle as follows:

1. It may have a high origin from the lower third of the fibula, ending in a distinct tendon which passes under the annular ligament, joins with the rest of accessorius (Gantzer);
2. A high origin from the fascia over the flexor hallucis longus, with a course like the last. This has been seen in two bundles, one beside the tibia, and one over the flexor hallucis, the tendon of this bifurcated, and one inserted into the hallucis communis brevis (flexor digitorum brevis);
3. With an origin from the insertion of the plantaris tendon and the upper part of the os calcis;
4. With an origin from the calcaneo-cuboid ligament;
5. Wood described a variation of this muscle, which possessed a fibular head and heads like those described in 3. an 4. above, together with a usual attachment; these all uniting, formed with the flexor hallucis a distinct, deep, or third set of flexors for the four lateral toes, each of these joined the perforans inside the sheath, opposite the first joint;
6. Mr. Wood. found the accessorius to arise by a tendon from the medial side of the os calcis;
7. A tendon from the lateral head of accessorius joined the perforated tendon of the middle toe;
8. The accessorius may have no connection to the fourth, or fifth toe tendons;
9. Sending a few fibers to flexor hallucis;
10. With a slip from the medial side, or, from the deep surface of the soleus (Turner);
11. A slip from the fascia of the back of the leg to the inside of the os calcis, close to the accessorius, is described by Gantzer as the accessorius ad calcaneum;
12. An accessory muscle in a deformed limb was found by Ringhoffer, it arose from the middle third of the limb, along with the flexor digitorum communis, and was inserted into the caro quadrata (quadratus plantae);
13. The plantar accessorius receiving a slip from the peroneus brevis;
14. Its insertion may be to the outer (lateral) border of the tendons;
15. Or to their undersurface;
16. With no connection to the third and fourth tendons;
17. Sending an accessory slip to the deep tendon of the little toe;
18. It may be inserted into the communis, partly to the connecting slip from the hallucis, and to tendons of the second, third, and fourth toes;
19. Sometimes a few fibers go to the hallucis;
20. Inserted into the connecting link alone;
21. A slip from the muscle to the tendon of the flexor brevis digitorum for the third toe;
22. A slip from the inner side of the os calcis sending a tendon to the distal phalanx of the little toe, and one to the point of insertion of the accessorius.

Syn.: m. caput plantae flexoris digiti plantae longi, Caro quadrata Sylvii, quadratus plantae pedis, Accessorius perforantis, Biemuskel, Kurzer Bauch des gemeinsch. Beugers, Accessoire du long fléchisseur (Cruveilhier).


Anson, B.J., Ed. (1966) Morris' Human Anatomy, 12th ed., The Blakiston Division, McGraw-Hill Book Company, New York.

Gruber, W. (1877) Uber den Musculus peroneo-tibialis beim Menschen. Arch. Anat. Physiol. Wissen. Med. 1877:401-410.

Macalister, A. (1866-69) On muscular anomalies in human anatomy, and their bearing upon homotypical myology. Proc. Roy. Irish Acad. 10:126-164.

Ouchi, H. (1953) On the variation of the muscles (M. sternocleidomastoidens, M. flexor digitorum brevis, M. quadratus plantae). Kaibogaku Zasshi 28:Supple. Kanto 9-10. In Japanese.

Perkins, J.D. (1914) An anomalous muscle of the leg: peroneo-calcaneus internus. Anat. Rec. 8:21-25.

Winckler, G. (1928-29) La morphogénèse de la chair carée de Sylvius. Arch. Anat. Hist. Emb. 9:311-341.

Winckler, G. (1955) La veritable terminasion de la chair caree de Sylvius (musc. quadratus plantae). Arch. Anat. Hist. Emb. 38:46-66.

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

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