Abstract
In this article we describe a variant accessory muscle found in the deep posterior compartment of the leg in a 96 year-old female human cadaver. The flexor digitorum accessorius longus was found bilaterally, originating by two heads from the shafts of the tibia and fibula. The two heads of the muscle were observed to be subequal in size and none of the fleshy fibers of the muscle entered the tarsal tunnel. This stands in contrast with previous descriptions of accessory digital flexors, which are typically asymmetrical or single-headed, and which almost always introduce fleshy fibers into the tarsal tunnel. This variant structure has the potential to entrap the tibial nerve and compress the posterior tibial vessels either proximal to the talocrural joint or within the tarsal tunnel, and may be implicated in clinical scenarios involving imaging, surgery, compartment syndromes, or deep-vein thromboses.
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References
Brodie JT, Dormans JP, Gregg JR, Davidson RS (1997) Accessory soleus muscle. Clin Orthop Relat Res 337:180–186
Buckingham RA, Winson IG, Kelly AJ (1997) An anatomical study of a new portal for ankle arthroscopy. J Bone Joint Surg Br 79:650–652
Burks JB, DeHeer PA (2001) Tarsal tunnel syndrome secondary to an accessory muscle: a case report. J Foot Ankle Surg 40:401–403
Buschmann WR, Cheung Y, Jahss MH (1999) Magnetic resonance imaging of anomalous leg muscles: accessory soleus, peroneus quartus and the flexor digitorum longus accessorius. Foot Ankle Int 12:109–116
Canter DE, Siesel KJ (1997) Flexor digitorum accessorius longus muscle: an etiology of tarsal tunnel syndrome? J Foot Ankle Surg 36:226–229
Deroy AR, Clause CC, Baskin ES, Bauer GR (2002) Recognition of the flexor digitorum accessorius longus. J Am Podiatr Med Assoc 92:463–466
Driver JR, Denison AB (1914) The morphology of the long accessorius muscle. Anat Rec 8:341–347
Eberle CF, Moran B, Gleason T (2002) The accessory flexor digitorum longus as a cause of flexor hallucis syndrome. Foot Ankle Int 23:51–55
Gümüşalan Y, Kalaycioğlu A (2000) Bilateral accessory flexor digitorium longus muscle in man. Ann Anat 182:573–576
Jaijesh P, Shenoy M, Anuradha L, Chithralekha KK (2006) Flexor accessorius longus: a rare variation of the deep extrinsic digital flexors of the leg and its phylogenetic significance. Indian J Plast Surg 39:169–171
Kinoshita M, Okuda R, Morikawa J, Abe M (2003) Tarsal tunnel syndrome associated with an accessory muscle. Foot Ankle Int 24:132–136
Lau JTC, Daniels TR (1999) Tarsal tunnel syndrome: a review of the literature. Foot Ankle Int 20:201–209
Liu PT, Moyer AC, Huettl EA, Fowl RJ, Stone WM (2005) Popliteal vascular entrapment syndrome caused by a rare anomalous slip of the lateral head of the gastrocnemius muscle. Skeletal Radiol 34:359–363
Madhavi C, Holla SJ (2003) Anomalous flexor digiti minimi brevis in Guyon’s canal. Clin Anat 16:340–343
Moore KL, Dalley AF (2006) Clinically oriented Anatomy, 5th edn. Lippincott Williams & Wilkins, Philadelphia
Nathan H, Gloobe H, Yosipovitch Z (1975) Flexor digitorum accessorius longus. Clin Orthop Relat Res 113:158–161
Peterson DA, Stinson W, Lairmore JR (1995) The long accessory flexor muscle: an anatomical study. Foot Ankle Int 16:637–640
Sammarco GJ, Conti SF (1994) Tarsal tunnel syndrome caused by an anomalous muscle. J Bone Joint Surg Am 76:1308–1314
Sammarco GJ, Stephens MM (1990) Tarsal tunnel syndrome caused by the flexor digitorum accessorius longus. A case report. J Bone Joint Surg Am 72:453–454
VanCourt RB, Siesel KJ (1996) Flexor digitorum accessorius longus muscle. J Am Podiatr Med Assoc 86:559–560
Wittmayer BC, Freed L (2007) Diagnosis and surgical management of flexor digitorum accessorius longus-induced tarsal tunnel syndrome. J Foot Ankle Surg 46:484–487
Wood J (1864) On some varieties in human myology. Proc R Soc Lond 13:299–303
Wood J (1866) Variations in human myology observed during the Winter Session of 1865–66 at King’s college, London. Proc R Soc Lond 15:229–244
Wood J (1867) Variations in human myology observed during the winter session of 1866–67 at King’s college, London. Proc R Soc Lond 15:518–546
Wood J (1868) Variations in human myology observed during the winter session of 1867–68 at King’s college, London. Proc R Soc Lond 16:483–525
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Hwang, S.H., Hill, R.V. An unusual variation of the flexor digitorum accessorius longus muscle—its anatomy and clinical significance. Anat Sci Int 84, 257–263 (2009). https://doi.org/10.1007/s12565-009-0021-6
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DOI: https://doi.org/10.1007/s12565-009-0021-6