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 Table of Contents  
ORIGINAL ARTICLE
Year : 2017  |  Volume : 6  |  Issue : 2  |  Page : 120-125

Branching pattern of tibial nerve in the tarsal tunnel - a cadaveric study


1 Assistant Professor, Department of Anatomy, Madurai Medical College, M.S. Ramaiah Medical College, Bengaluru, India
2 Associate Professor, Department of Anatomy, M.S. Ramaiah Medical College, Bengaluru, India

Date of Web Publication24-Nov-2019

Correspondence Address:
Ramadoss Kalpana
Assistant Professor, Institute of Anatomy, Madurai Medical College, Madurai - 625 020. Tamilnadu
India
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Source of Support: None, Conflict of Interest: None


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  Abstract 


Background and aims: Tibial nerve is the larger terminal branch of sciatic nerve, ends by dividing into medial and lateral plantar nerves beneath the flexor retinaculum [Tarsal tunnel]. The level of bifurcation of the tibial nerve is differently quoted in text books and articles. The aim of the present study is to localize the level of bifurcation of tibial nerve. Materials and methods: 50 lower limbs from 25 cadavers available in the Department of anatomy, M.S. Ramaiah medical college and Bangalore medical college were used for the study. A reference line of 1 cm width ‘Medio Malleolar Calcaneal axis’ [MMC axis] made with OHP sheet was placed from tip of the medial malleolus of tibia to the medial tubercle of calcaneus and used as grid to classify the level of bifurcation of tibial nerve into 3 types. Type I, II, III represented the bifurcation proximal to, deep to and distal to this axis respectively. Results: Tibial nerve bifurcation was found to be type I in 92%, type II in 6%, type III in 2% of specimens. Most of the cases [32.6%] bifurcated between 5.1 to 10 mm proximal to MMC axis. The median distance of medial plantar nerve from medial malleolus was 21.28mm on left side and 20.735mm on right side. The mean of lateral plantar nerve from medial tubercle of calcaneus was 29.61mm on left side, and 28.6mm on right side. Conclusion: Detailed anatomical knowledge of tibial nerve prevents the damage to tibial nerve during various surgical procedures like fixation of fractures with external nailing of tarsal bones, medial displacement osteotomies and in tarsal tunnel surgeries.

Keywords: tibial nerve, tarsal tunnel, medial plantar nerve, lateral plantar nerve


How to cite this article:
Kalpana R, Komala N. Branching pattern of tibial nerve in the tarsal tunnel - a cadaveric study. Natl J Clin Anat 2017;6:120-5

How to cite this URL:
Kalpana R, Komala N. Branching pattern of tibial nerve in the tarsal tunnel - a cadaveric study. Natl J Clin Anat [serial online] 2017 [cited 2021 Jun 21];6:120-5. Available from: http://www.njca.info/text.asp?2017/6/2/120/295929




  Introduction Top


Human foot is a complex structure made of bones, muscles, tendons and ligaments. The tendons of the muscles of leg are kept in position by localized thickenings of the deep fascia, forming retinacular bands. Flexor retinaculum is a strong fibrous band, extending from the medial malleolus of tibia above to the medial tubercle of the calcaneus below. There is no clear demarcation between its border and the deep fascia of the leg both proximally and distally[1],[2],[3],[4],[5]. Tarsal tunnel is the region beneath the flexor retinaculum on the medial side of the ankle. This tunnel is bounded by the flexor retinaculum medially, posterior aspect of talus and calcaneus laterally and medial malleolus anteriorly. Flexor retinaculum sends in septa to the underlying bone and divides this region into four compartments. These compartments transmit the tendons of tibialis posterior, flexor digitorum longus, posterior tibial vessels, tibial nerve and flexor hallucis longus tendon [medial to lateral]. Tibial nerve and posterior tibial artery share a common compartment.

Tibial nerve also known as posterior tibial nerve is the larger terminal branch of sciatic nerve and is derived from the ventral branches of ventral rami of fourth lumbar [L4], fifth lumbar [L5], first sacral [SI], second sacral [S2], third sacral [S3]. It arises at the apex of popliteal fossa and descends through the popliteal fossa to reach the distal border of popliteus. In the leg, tibial nerve is medial to posterior tibial vessels initially, and then it crosses behind them and descends lateral to them until it bifurcates. Tibial nerve ends by dividing into medial and lateral plantar nerves beneath the flexor retinaculum[1],[2],[3],[4],[5].

The text book description of the level of bifurcation differs very much with that described in various articles. The present study is undertaken to localize the level of bifurcation point of tibial nerve with reference to medio malleolar calcaneal axis [MMC axis]. The distance of medial plantar nerve from the medial malleolus of tibia and the distance of lateral plantar nerve from the medial tubercle of calcaneus at the level of MMC axis is estimated. Knowledge of variations in the bifurcation of tibial nerve may prevent the damage to tibial nerve during various surgical procedures like fixation of fractures with external nailing of tarsal bones, medial displacement osteotomies. The study also provides data to identify the anatomical safe zone for percutaneous pin placement in medial side of calcaneus[6][7].


  Materials and Methods Top


Randomly selected 50 lower limbs from 25 formalin embalmed cadavers from the Department of Anatomy, M.S.Ramaiah Medical College and Bangalore Medical College and Research Institute, Bangalore were dissected and studied over aperiod of two years.

Inclusion Criteria: Formalin embalmed lower limb specimens irrespective of age, sex or race.

Exclusion Criteria: Lower limbs showing gross asymmetry, ischemic ulceration or gangrene in heel, any surgical procedures done at ankle were excluded.

Using a standard skin incision, skin was reflected[8]. Subcutaneous tissue was removed; deep fascia along with the flexor retinaculum was severed in each foot. The tibial nerve was exposed from the distal end of leg towards plantar surface beyond its bifurcation. Soft tissues were cleared to expose the medial malleolus and medial tubercle of calcaneus. A reference line of 1 cm width ‘Medio Malleolar Calcaneal axis’ [MMC axis] made with OHP sheet was placed from the tip of the medial malleolus of tibia to the medial tubercle of calcaneus. This was used as grid to classify the bifurcation level of tibial nerve into Type I, II and III. Type I, II, III represented the bifurcations proximal to, deep to and distal to this respectively[6][7].

The level of bifurcation of tibial nerve with reference to MMC axis was noted and photographs were taken. The level of bifurcation of tibial nerve proximally [type I] from the midpoint of MMC axis were measured and the distance of level of bifurcation of tibial nerve distally [type III] from the midpoint of MMC axis were measured. When tibial nerve bifurcated beneath the axis [type II], the distance of level of bifurcation was not measurable.
Figure 1: showing OHP sheet used as MMC axis.

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Figure 2: Tibial nerve type I, II, III with reference to the MMC axis[8].
Abbreviatons : A-Medial malleolus of tibia, B-Medial tubercle of calcaneus


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Figure 3: Tibial nerve type I (bifurcation proximal to the MMC axis)

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Figure 4: Tibial nerve type II (bifurcation deep to the MMC axis)

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Figure 5: Tibial nerve type III (bifurcation distal to the MMC axis)
Abbreviations : TN - Tibial nerve, PTA - Posterior tibial artery, MMC axis - Medio malleolar calcaneal axis, Sp - specimen number


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If the tibial nerve bifurcated proximal to the axis and beneath the axis, the distance of medial plantar nerve from the tip of medial malleolus of tibia and the distance of lateral plantar nerve from medial tubercle of calcaneus was measured at the level of MMC axis. But in type III tibial nerve bifurcation was distal to the axis, so the distance of medial plantar nerve from the tip of medial malleolus of tibia and the distance of lateral plantar nerve from medial tubercle of calcaneus was not measurable.

The measurements were taken with the help of digital caliper and the findings were tabulated. Statistical analysis done and Non parametric test Mann Whitney U test was used to compare the values between independent groups.


  Results Top


Total number of lower limb specimens = 50. Out of which 25 are right lower limbs and 25 are left lower limbs.

Out of 25 left lower limbs, tibial nerve was predominantly type I [92%] and type II [8%]. In case of right lower limbs, type I [92%], type II [4%], type III [4%]-

In most of the cases, the bifurcation of tibial nerve lies between 5.1 to 10 mm from MMC axis.

The median value of distance of medial plantar nerve from medial malleolus was 21.28mm on left side and 20.735mm on right side. The median value of distance of lateral plantar nerve from medial tubercle of calcaneus was 29.61mm on left side, and 28.6mm on right side.

The median distance of medial plantar nerve from medial malleolus is found to be 20.76mm in type I, 20.49mm in type II. The median distance of lateral plantar nerve from medial tubercle of calcaneus is found to be 29.21mm in type I, 29.21mm in type II tibial nerve.
Table 1: Distribution of types of tibial nerve in percentages

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Table 2: Distribution of distance of bifurcation of tibial nerve (type I) from MMC axis in right and left lower limbs

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  Discussion Top


Bilge et al[6] studied the neurovascular bifurcation pattern where tibial nerve bifurcation was found to be type I in 84%, type II in 12%, type III in 4% of specimens. Joshi et al[7] described tibial nerve bifurcation as type I in 85.2% of specimens, type II in 14.7%, type III in 0.89%. In this study tibial nerve bifurcation was found to be type I in 92% of specimens, type II in 6%, type III in 2% of specimens.

Struijk et al[9] conducted a study to design tibial nerve cuff electrode implants in which the distance of bifurcation of tibial nerve ranged from 0-41 mm from medio malleolar calcaneal axis. In our study the distance of tibial nerve bifurcation ranged from 2.1 - 48.3 mm proximally from medio malleolar calcaneal axis. Majority of the cases [32.6%] bifurcated between 5.1 to 10 mm proximally from MMC axis.

In a study conducted by Davis et al[10] tibial nerve bifurcated within 2 cm of the medio malleolar calcaneal axis in 90% of feet. Similarly Ndiaye et al[11] noted the bifurcation of tibial nerve within one cm of the malleolo calcaneal line in 90% cases and Dellon et al[12] found the same within one cm of the malleolo calcaneal axis in 90% specimens. In present study tibial nerve bifurcated within one cm of axis in 50% of specimens, within 1.5 cm of axis in 67.4%, within 2 cm of axis in 76.1%, within 2.5 cm of axis in 84.8% of specimens.

In a study, Bilge at al[6] observed the distance of medial plantar nerve from medial malleolus of tibia as 26.95 ± 4.13 mm and the distance of lateral plantar nerve from medial tubercle of calcaneus as 27.06 ±6.06 mm. Whereas Joshi et al[7] in his study noted the distance of medial plantar nerve from medial malleolus of tibia was 21.84 ± 5.22 mm on right side, 23.43 ± 5.2 mm on left side and the distance of lateral plantar nerve from medial tubercle of calcaneus was 29.5 ±6.18 mm on right side and 28.29 ± 5.69 on left side. In present study, the median value of the distance of medial plantar nerve from medial malleolus of tibia was 21.28 mm on the left side, where as on the right side median value was 20.74mm. The median value of the distance of lateral plantar nerve from medial tubercle of calcaneus was 29.61mm on the left side, where as on the right side, median value was 28.60 mm.

Bilge et al[6] has described the areas approximately 25 mm anterosuperior from the medial tubercle of calcaneus and 25 mm posteroinferior from the medial malleolus along the medio malleolar calcaneal axis as safe zone for calcaneal pin insertions but Joshi et al[7] concluded there is no safe zone on the medial aspect of calcaneus along the medio malleolar calcaneal axis for blind external fixation of calcaneal fractures. We noted the area beyond 30.5 mm posteroinferior to the medial malleolus and the area 36 mm anterosuperior to the medial tubercle of calcaneus along medio malleolar calcaneal axis was devoid of neurovascular structures. So this area can be considered as safe zone for calcaneal pin insertions.


  Conclusion Top


Knowledge of variations of the level of bifurcation of tibial nerve is helpful in podiatric medicine and in designing neural cuff electrode implants. The proper understanding of anatomy of tibial nerve, its branching pattern becomes necessary for the surgeons to achieve higher success rate in tarsal tunnel release surgeries and in many orthopedic surgeries to avoid iatrogenic injury to the neurovascular structures.

Acknowledgement

I would like to thank Dr. Sheshgiri.C, Professor and Head, Department of Anatomy, Dean, DM Wayanad Institute of Medical Sciences, Wayanad, Kerala for his valuable guidance in carrying out this study



 
  References Top

1.
Standring S, Borley NR, Collins P, Crossman AR, Gatzoulis MA, Mahadevan V et al. Gray’s anatomy: The anatomical basis of clinical practice. 40th edition. Spain: Elsevier Churchill Livingstone; 2008. p. 1425- 30.  Back to cited text no. 1
    
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Datta AK. Essentials of human anatomy: Superior and Inferior Extremities. 4th edition. Volume 3. Kolkata: Current books international; 2009. p. 197-215.  Back to cited text no. 2
    
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Sinnatamby CS. Last’s Anatomy: Regional and Applied. 11th edition. Edinburgh: Elsevier Churchill Livingstone; 2006. p. 151-60.  Back to cited text no. 3
    
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Moore KL, Dalley AF, Agur AMR. Clinically oriented anatomy. 6th edition. New Delhi: Wolters Kluwer Health; 2010. p. 586-620.  Back to cited text no. 4
    
5.
Hollinshead WH. Anatomy for surgeons: the back and limbs. 3rd edition. Volume 3. Philadelphia: Harper & Row; 1982. p. 784-850.  Back to cited text no. 5
    
6.
Bilge O, Ozer MA, Govsa F. Neurovascular branching in the tarsal tunnel. Neuroanatomy. 2003; 2:3 9-41.  Back to cited text no. 6
    
7.
Joshi SS, Joshi SD,Athavale SA. Anatomy of tarsal tunnel and its applied significance. J.Anat.Soc.India. 2006; 55[1]: 52-56.  Back to cited text no. 7
    
8.
Romanes GJ.Cunningham’s manual of practical anatomy - upper and lower limbs. 15th edition. Volume 1. United Kingdom: Oxford medical publications; 1986. p. 130  Back to cited text no. 8
    
9.
Struijk LNSA, Birn H, Teglbjaerg PS, Haase J, Struijk JJ. Size and separability of the calcaneal and the medial and lateral plantar nerves in the distal tibial nerve. Anat Sci Int. 2010; 85[l]:13-22.  Back to cited text no. 9
    
10.
Davis TJ, Schon LC. Branches of the tibial nerve: anatomic variations. FootAnkle Int. 1995; 16[1]: 21-9.  Back to cited text no. 10
    
11.
Ndiaye A, Dia A, Konate I, Diop M, Sow ML. Topographic anatomy of the tibial nerve in the medial malleolus: application to the effect of nerve block anesthesia. Morphologie. 2003; 87[277]: 25-7.  Back to cited text no. 11
    
12.
Dellon AL, Mackinnon SE. Tibial nerve branching in the tarsal tunnel. Arch Neurol. 1984;41[6]: 645-6.  Back to cited text no. 12
    


    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]
 
 
    Tables

  [Table 1], [Table 2]



 

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