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 Table of Contents  
ORIGINAL ARTICLE
Year : 2020  |  Volume : 9  |  Issue : 3  |  Page : 127-131

Variations in the branching pattern of the tibial nerve in the posterior compartment of the leg


1 Assistant Professor, Department of Anatomy, JJM Medical College, Davangere, Karnataka, India
2 Assistant Professor, Department of Anatomy, PK DAS Institute of Medical Sciences, Palakkad, Kerala, India

Date of Submission05-Jul-2020
Date of Decision27-Aug-2020
Date of Acceptance07-Oct-2020
Date of Web Publication15-Oct-2020

Correspondence Address:
W Benjamin
Department of Anatomy, PK DAS Institute of Medical Sciences, Vaniamkulam, Ottapalam, Palakkad - 679 522, Kerala
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/NJCA.NJCA_25_20

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  Abstract 


Background: Tibial nerve is the largest branch of sciatic nerve. It innervates muscles of the posterior compartment of the leg. Knowledge of the variations in motor branching pattern may help the surgeons when certain procedures are done for calf reduction and also for spastic equinus foot where selective neurectomy is required. It is also required for anesthetists for inducing neurolytic blocks. The aim of the present study was to study the variations in its branching pattern of the tibial nerve in the posterior compartment of the leg. Materials and Methods: The study was done by dissecting forty formalin-fixed lower limbs from twenty adult human cadavers. The origin of tibial nerve, variations, branching pattern, number of muscular branches and termination of the tibial nerve were studied. The level of origin of these nerves was taken in relation to the apex of head of fibula. Results: 57.5% showed that the origin was <12 cm and 42.5% were between 12 and 24 cm above the level of apex of head of fibula. The flexor hallucis longus received one branch in 70% and two branches in 30% of the specimens. Forty percent of the branches showed two or three divisions. The flexor digitorum longus received one branch in 95% and two branches in 5% of the specimens. Eighty percent of the branches of the muscle showed 2–4 divisions. 82.5% of nerve to soleus muscle had one branch and 17.5% had two branches. In 17.5% of the specimens, nerve to soleus originated from the nerve to the lateral head of gastrocnemius. Thirty percent of the branches showed 2–3 divisions. All specimens had one branch which supplied the tibialis posterior muscle and 47.5% of the branches showed 2–3 divisions. In 77.5% of the specimens, the termination occurred above the malleolar calcaneal axis. Conclusion: The flexor hallucis longus, flexor digitorum longus, and soleus muscle had one or two branches from tibial nerve. Single branch innervates tibialis posterior. Nerves to flexor hallucis longus, tibialis posterior, and the soleus had up to three divisions and nerve to flexor digitorum longus had up to four divisions.

Keywords: Posterior compartment of the leg, tibial nerve, variations in branching pattern


How to cite this article:
Premchand S A, Benjamin W. Variations in the branching pattern of the tibial nerve in the posterior compartment of the leg. Natl J Clin Anat 2020;9:127-31

How to cite this URL:
Premchand S A, Benjamin W. Variations in the branching pattern of the tibial nerve in the posterior compartment of the leg. Natl J Clin Anat [serial online] 2020 [cited 2020 Nov 28];9:127-31. Available from: http://www.njca.info/text.asp?2020/9/3/127/298159




  Introduction Top


Tibial nerve is the largest component of sciatic nerve. It divides into medial and lateral plantar nerves. Tibial nerve supplies all the muscles in the posterior compartment of the leg.[1] Knowledge regarding the exact location and variation of the motor branches is necessary for nerve blocks and to treat spastic equinovarus foot.[2],[3],[4] The detailed knowledge about the branches of tibial nerve to the muscles is needed to perform neurotomy.[5] Tibial nerve branches to the flexor digitorum longus and flexor hallucis longus can be preferred for direct nerve transfer for restoration of motor function of deep peroneal nerve.[6] The safe and effective method for calf reduction is done by neurectomy of the nerve.[7]

Knowledge regarding the tibial nerve and its motor branching pattern may help to reduce iatrogenic injuries and motor loss of the foot during surgical procedures such as tibial osteotomy and fascial release procedures. Knowledge regarding the level of tibial nerve termination is essential for the treatment of tarsal tunnel syndrome.[8],[9] Tibial nerve injuries would lead to paralysis of all the muscles of the back of the leg and sole of the foot. Sole sensations are lost leading to trophic ulcers.[10] Proper understanding of the branching pattern of the tibial nerve would help the anesthetists, radiologists, and surgeons when they perform diagnostic as well as surgical procedures.

Objectives

The Objective of the present study was to study the variations in the branching pattern of the tibial nerve in the posterior compartment of the leg.


  Materials and Methods Top


The specimens for the present study were obtained from the Department of Anatomy, PK Das Institute of Medical Sciences, Vaniamkulam, Ottapalam, Kerala. The study was conducted over a period of 18 months. The study was done by dissecting forty formalin-fixed lower limbs from twenty adult human cadavers. It was a descriptive type of study. The tibial nerve was dissected out carefully from its origin. All the measurements were taken by keeping the apex of head of fibula (AHF) as a landmark. In inclusion criteria, all lower limbs of twenty adult human cadavers irrespective of sex and side were considered for the study. Cadaveric limbs with deformities, trauma, or surgical scars were excluded from the study. The measurements were taken using a measuring tape in centimeters. The branches of the tibial nerve were carefully dissected and studied regarding the branching pattern, number of branches given, and divisions to the flexor hallucis longus, flexor digitorum longus, soleus, and tibialis posterior muscles. In the present study, all the values were measured from the first branch in case when the muscle was supplied by more than one branch.

The tibial nerve was traced distally till its division into its terminal branches. The point of division of tibial nerve was studied in relation to malleolar-calcaneal axis which is a reference line extending from the tip of medial malleolus to the medial tubercle of calcaneus. The three levels – above malleolar-calcaneal axis (level I), at the level of malleolar-calcaneal axis (level II), and below malleolar-calcaneal axis (level III) – were studied. The percentage, range, mean, and standard deviation were calculated for the readings obtained using SPSS program version 20 (SPSS Inc., USA).


  Results Top


Level of origin of the tibial nerve from sciatic nerve above the level of apex of head of fibula

57.50% of the specimens (n = 23) showed that the site of origin was <12 cm above the level of apex of head of fibula. 42.50% of the specimens (n = 17) showed that the site of origin was between 12 cm and 24 cm above the level of apex of head of fibula. Mean distances of origin of the muscular branches from tibial nerve in relation to head of fibula are tabulated in [Table 1].
Table 1: Distance of origin of the nerves to supply the muscles in relation to apex of head of fibula (above and below)

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In 17.50% (n = 7) of the specimens, the nerve to soleus muscle originated from the nerve to the lateral head of gastrocnemius muscle instead directly from the tibial nerve. [Table 2] tabulates number of branches innervating specific muscles. Except soleus, multiple branches from tibial nerve innervates other muscles.
Table 2: Number of branches given by the nerve before it supplies the muscles

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Number of divisions given by the nerve before it supplies the muscles

In nerve to flexor hallucis longus, 40% (n = 16) of the branches to the muscle showed divisions [Table 3], of which 37.5% (n = 15) showed two divisions and 2.5% (n = 1) showed three divisions [Figure 1]. In nerve to flexor digitorum longus, 80% (n = 32) of the branches to the muscle showed divisions, of which 37.5% (n = 15) showed two divisions, 27.5% (n = 11) showed three division [Figure 2], and 15% (n = 6) showed four divisions [Figure 3].
Table 3: Number of divisions given by the nerve before it supplies the muscles

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Figure 1: Branch to flexor hallucis longus (FHL) showing three divisions (3D) (TN - Tibial Nerve)

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Figure 2: Branch to flexor digitorum longus (FDL) showing three divisions (3D) (TN - Tibial Nerve)

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Figure 3: Branch to flexor digitorum longus (FDL) showing ffour divisions (4D) 4 Divisions

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In nerve to soleus, 30% (n = 12) of the branches to the muscle showed divisions, of which 22.5% (n = 9) showed two divisions and 7.5% (n = 3) showed three divisions. In nerve to tibialis posterior, 47.5% (n = 19) of the branches to the muscle showed divisions, of which 32.5% (n = 13) showed two divisions and 15% (n = 6) showed three divisions [Figure 4].
Figure 4: Branch to tibialis posterior (TP) showing three divisions (3D) (TN - Tibial Nerve)

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Level of Termination of tibial nerve in relation to malleolar-calcaneal axis

In 77.5% (n = 31) of the specimens, the division occurred above the malleolar-calcaneal axis; in 17.5% (n = 7), it occurred at the level of malleolar-calcaneal axis; and in 5% (n = 2), it occurred below the malleolar-calcaneal axis.


  Discussion Top


The present study on the South Indian population provides considerable information on the branches given by the tibial nerve in the posterior compartment of the leg. The variation in branching pattern of the tibial nerve in the posterior compartment of the leg was at par with the studies done in other regions of the world.

Level of origin of the tibial nerve from sciatic nerve in relation to the apex of head of fibula

In the present study done on 40 specimens, the mean site of origin of tibial nerve from the sciatic nerve above the apex of head of fibula was 11.07 ± 2.79 cm. A study done by Abdelghany on 24 lower limbs showed that in 95.83% (n = 23) of the specimens, the tibial nerve originated from the sciatic nerve at a range of 12–24 cm with a mean of 17.91 ± 3.80 cm above the level of apex of head of fibula. They report just one case of origin of tibial nerve under 5 cm from apex of head of fibula.[5] In this study, none of the specimens showed the tibial nerve originating from the sciatic nerve very high up in the thigh, more than 24 cm above the level of apex of head of fibula.

Nerve to flexor hallucis longus

In the present study done on 40 specimens, the mean site of origin of flexor hallucis longus from the tibial nerve below the apex of head of fibula was 9.35 ± 2.53 cm.[5] In a study done by Abdelghany in 24 lower limb specimens, he found that in 41.67% of the specimens(n =10), the muscle received a single branch from the Tibial nerve and in 58.33% of the specimens (n=14) it received two branches from the Tibial Nerve.

Apaydin et al. from dissections of 36 specimens of tibial nerve observed that in 61.1% (n = 22) of the specimens, the flexor hallucis longus was innervated by proximal and distal branches, while in 38.9% (n = 14), it was supplied by only one proximal branch. The proximal branch arose from the tibial nerve 6.70 cm and the distal arose 19.70 cm below the level of apex of head of fibula.[11] Wongphaet et al demonstrated that single branch of tibial nerve innervates flexor hallucis longus in half of the specimen studied. However, we found the incidence of single branch to FHL is 70%.[12]

Nerve to flexor digitorum longus

Except for 2 specimens, single branch of TN innervates FDL. In contrast to our study, Sunderland and Hughes among 20 specimens found a single branch innervating 11 specimens and 2–3 branches innervating 9 specimens. In a study done by Sunderland and Hughes on 20 lower limb specimens, they found that a single branch from Tibial nerve innervated 11 specimens and 2-3 branch innervated 9 specimens. The nerve to flexor digitorum longus tends to be fairly long when it is single.[13] Abdelghany in 24 lower-limb dissections found the flexor digitorum longus muscle being supplied by 2 branches.[5] In the present study, 80% (n = 32) of the branches to the muscle showed divisions.

Nerve to soleus muscle

The study done by Abdelghany [5] showed that in 91.67%, the tibial nerve gave a branch 6.84 ± 0.91 cm above the level of apex of head of fibula. The soleus muscle also received another muscular branch from the tibial nerve 2.78 ± 0.66 cm above the level of apex of head of fibula.

In the present study, we found that 82.50% (n = 33) of the specimens had one branch which supplied the soleus muscle. arising at 6.33 ± 1.70 cm from AHF.

Sook Kim et al.[14] found one branch to the soleus muscle. Contrary to these results, Deltombe et al.[2] located one nerve branch to the soleus muscle, but it arose 1 ± 0.50 cm below the apex of head of fibula. Sekiya et al.[15] mentioned that the soleus muscle was supplied by two branches from the tibial nerve. The study done by Abdelghany [5] showed that 8.33% of the cases had a common branch for the soleus and the lateral head of the gastrocnemius that is divided into two branches to the upper border of the muscle. This is similar to the observations seen in the present study.

Hwang et al.[16] described that one nerve branch supplied the soleus muscle, and in 30% of the cases, the nerve originated from the nerve innervating the lateral head of the gastrocnemius muscle. This also correlates with the current study. In the present study, we observed that in 17.50% (n = 7) of the specimens, the nerve to soleus muscle originated from the nerve to the lateral head of gastrocnemius muscle. In the study done by Abdelghany,[5] the upper branch to the soleus muscle is divided into three branches entering the upper border of the muscle. The lower branch is also divided into three branches to supply the deep surface of the muscle.

Nerve to tibialis posterior muscle

According to Sunderland and Hughes, the tibialis posterior was supplied by 1 nerve in 9 specimens and 2–4 nerves in 11 specimens.[13] Apaydin et al. from dissections of 36 specimens opined that the muscle was innervated by a proximal and distal branch.[11] In a study done by Wongphaet et al., 83.01% (n = 44) of the soleus were innervated by one branch, 11.32% (n = 6) by two branches, and 5.67% (n = 3) by three branches.[12] Dissection of 36 lower limbs found that all specimens had 1 branch from the tibial nerve that innervated tibialis posterior muscle.[17] In the present study, all the specimens had one branch which supplied the tibialis posterior muscle.

Level of termination of tibial nerve in relation to malleolar-calcaneal axis

Bilge et al reports majority (82%) type 1 branching.[8] We found 77% type 1 branching. In 77.5% of specimens (n = 31) type 1 branching pattern was seen, in 17.5% of specimens (n = 7) it showed type II branching pattern and in 4% of specimen (n = 2) it showed type III branching pattern.

In a dissection study by Joshi et al. in 112 lower-limb specimens, the following results were obtained: Type I seen in 85.2%, Type II seen in 14.7%, and Type III seen in 0.89%.[9] In a study by Gupta et al. on a cadaver, the tibial nerve bifurcation bilaterally was of Type II.[18]

Tibial neurotomy led to the disappearance of spasticity with improvement of the gait in all patients.[19],[20] Mu et al.[21] treated 52 cases with neurotomy, and the spastic gait was improved. The study done by Wang et al.[22] found that 85% of the cases of equinus foot have improved after selective neurotomy. A detailed knowledge of these variations and motor branching pattern may help the surgeons operating around this area and also in certain procedures done for calf reduction where selective neurectomy is required and also to treat spastic equinovarus foot. It is also required for anesthetists for inducing neurolytic blocks. If the division of the sciatic nerve occurs at the gluteal region, it can alter the position of the first branch that emerges out. The knowledge regarding the level of division of tibial nerve into terminal branches is essential for the treatment of tarsal tunnel syndrome. The limitations of the present study are that male and female limb comparison was not made during the study.


  Conclusion Top


The flexor hallucis longus, flexor digitorum longus, and soleus muscle had one or two branches which supplied the muscle. The tibialis posterior muscle had only one branch. The nerve to flexor hallucis longus, tibialis posterior, and the soleus had up to three divisions before it enters the respective muscle and nerve to flexor digitorum longus had upto four divisions.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Standring S, Borley NR, Collins P, Crossman AR, Gatzoulis MA, Healy JC, et al. Gray's Anatomy: The Anatomical Basis Of Clinical Practice. 40th ed. London: Elsevier Churchill Livingstone; 2008. p. 1421-27, 1331, 1338.  Back to cited text no. 1
    
2.
Deltombe T, De Wispelaere JF, Gustin T, Jamart J, Hanson P. Selective blocks of the motor nerve branches to the soleus and tibialis posterior muscles in the management of the spastic equinovarus foot. Arch Phys Med Rehabil 2004;85:54-58.  Back to cited text no. 2
    
3.
Buffenoir K, Roujeau T, Lapierre F, Menei P, Menegalli-Boggelli D, Mertens P, et al. Spastic equinus foot: Multicenter study of the long-term results of tibial neurotomy. Neurosurgery 2004;55:1130-7.  Back to cited text no. 3
    
4.
Yoo WK, Chung IH, Park CI. Anatomic motor point localization for the treatment of gastrocnemius muscle spasticity. Yonsei Med J 2002;43:627-30.  Back to cited text no. 4
    
5.
Abdelghany AH. Anatomical study of the tibial nerve. Bull. Alex Fac Med 2009;45:759-70.  Back to cited text no. 5
    
6.
Bodily KD, Spinner RJ, Bishop AT. Restoration of motor function of the deep fibular (peroneal) nerve by direct nerve transfer of branches from the tibial nerve: An anatomical study. Clin Anat 2004;17:201-5.  Back to cited text no. 6
    
7.
Liu DL, Li XI, Shan L, Li Q, Yuan JL, Yuan Q. The anatomic study and clinical observation of the neurectomy of the nerve to the medial gastrocnemius muscle for calf reduction. Zhonghua Zheng Xing Wai Ke Za Zhi 2007;23:125-7.  Back to cited text no. 7
    
8.
Bilge O, Ozer MA, Govsa F. Neurovascular branching in the tarsal tunnel. Neuroanatomy 2003;2:39-41.  Back to cited text no. 8
    
9.
Joshi SS, Joshi SD, Athavale SA. Anatomy of tarsal tunnel and its applied significance. J Anat Soc India 2006;55:58-62.  Back to cited text no. 9
    
10.
Snell RS. Clinical Anatomy by Regions. 9th ed. Philadelphia: Lippincott Williams and Wilkins; 2012. p. 479.  Back to cited text no. 10
    
11.
Apaydin N, Loukas M, Kendir S, Tubbs RS, Jordan R, Tekdemir I, et al. The precise localization of distal motor branches of the tibial nerve in the deep posterior compartment of the leg. Surg Radiol Anat 2008;30:291-5.  Back to cited text no. 11
    
12.
Wongphaet P, Chinsethagij K, Suarchawaratana S, Dangprasert T, Wongphaet W. Precise localization of motor branching and motor points: A cadaveric study. J Med Assoc Thai 2005;8:1884-90.  Back to cited text no. 12
    
13.
Hollinshead WH. Anatomy for Surgeons: Volume 3, the Back and Limbs. 3rd ed. Pennsylvania: Harper & Row; 1982. p. 55, 788-91.  Back to cited text no. 13
    
14.
Sook Kim H, Hye Hwang J, Lee PK, Kwon JY, Yeon Oh-Park M, Moon Kim J, et al. Localization of the motor nerve branches and motor points of the triceps surae muscles in Korean cadavers. Am J Phys Med Rehabil 2002;81:765-9.  Back to cited text no. 14
    
15.
Sekiya S, Kumaki K, Yamada TK, Horiguchi M. Nerve supply to the accessory soleus muscle. Acta Anat (Basel) 1994;149:121-7.  Back to cited text no. 15
    
16.
Hwang K, Kim YJ, Chung IH, Won HS, Tanaka S, Lee SI. Innervation of calf muscles in relation to calf reduction. Ann Plast Surg 2003;50:517-22.  Back to cited text no. 16
    
17.
Lee JH, Lee BN, An X, Chung RH, Han SH. Location of the motor entry point and intramuscular motor point of the tibialis posterior muscle: For effective motor point block. Clin Anat 2011;24:91-6.  Back to cited text no. 17
    
18.
Gupta G, Chhabra S, Gupta V, Jain P. Study of anatomy of tarsal tunnel in amputated (CHOPART) foot and normal foot and its applied significance. Int J Recent Adv Pharm Res 2012;2:26-30.  Back to cited text no. 18
    
19.
Deltombe T, Detrembleur C, Hanson P, Gustin T. Selective tibial neurotomy in the treatment of spastic equinovarus foot: A 2-year follow-up of three cases. Am J Phys Med Rehabil 2006;85:82-8.  Back to cited text no. 19
    
20.
Decq P, Cuny E, Filipetti P, Fève A, Kéravel Y. Peripheral neurotomy in the treatment of spasticity. Indications, techniques and results in the lower limbs. Neurochirurgie 1998;44:175-82.  Back to cited text no. 20
    
21.
Mu XH, Xu L, Xu SG, Cao X, Zhang P, Zheng CY, et al. Treatment of equinovarus caused by cerebral palsy with neurotomy of muscular branch of tibial nerve. Zhongguo Gu Shang 2009;22:31-2.  Back to cited text no. 21
    
22.
Wang SJ, Chen GQ, Xiu B, Zuo HC. Neurotomy of the tibial nerve for treatment of the talipes equinovarus. Zhonghua Wai Ke Za Zhi 2005;43:605-7.  Back to cited text no. 22
    


    Figures

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

  [Table 1], [Table 2], [Table 3]



 

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