• Home
  • Sitemap
  • Contact Us

open access eISSN 2093-3673

Impact Factor


Article View

Review Article

Anat Cell Biol 2023; 56(4): 415-420

Published online December 31, 2023


Copyright © Korean Association of ANATOMISTS.

Anatomical variations of the tibial nerve and their clinical correlation

Anita Soraya Soetoko1 , Dina Fatmawati2

1Departement of Anatomy, Faculty of Medicine, Universitas Islam Sultan Agung, Semarang, 2Departement of Biology, Faculty of Medicine, Universitas Islam Sultan Agung, Semarang, Indonesia

Correspondence to:Anita Soraya Soetoko
Departement of Anatomy, Faculty of Medicine, Universitas Islam Sultan Agung, Semarang 50112, Indonesia
E-mail: anitassoetoko@unissula.ac.id

Received: March 7, 2023; Revised: June 7, 2023; Accepted: June 30, 2023

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

The tibial nerve is a branch of the sciatic nerve, which innervates the legs and feet. Anatomical variations of this nerve at the ankle are commonly found. The variation of the tibial nerve in its branching point and cross-sectional area (CSA) at the ankle is commonly related to clinical condition such as foot neuropathy. Knowledge of these variations can support the clinician in making appropriate clinical decisions. This review aims at providing knowledge on the anatomical variations of tibial nerve at ankle, as well as its clinical correlation. This review outlined the variation of the terminal branching point and CSA of the tibial nerve at the ankle in cadaveric and clinical studies.

Keywords: Tibial nerve, Anatomy, Polyneuropathies

The tibial nerve is one of the major branches of the sciatic nerve, which is formed from the ventral roots of segments L4, L5, S1, S2, and S3 of the spinal nerves [1-4]. This nerve contains sensory and motor nerve fibers that travel on the posterior leg and terminal in the foot area [4, 5]. At the posteromedial of the medial malleolus, the tibial nerve has many anatomical variations that correlate to clinical conditions. One of those common clinical conditions is foot neuropathy.

Foot neuropathy is one of the symptoms of foot pain resulting from tibial nerve injuries, presenting as burning, heat, impaired temperature perception, and tingling in the heels and sole [6-8]. Diabetics also tend to experience foot neuropathy due to alterations in the microcirculation of the feet [9]. This condition is known as diabetic polyneuropathy (DPN). Previous studies confirmed the presence of tibial nerve swelling in the tarsal tunnel and chronic compression of the tibial nerve in DPN patients [10].

Ultrasonography (US) is a widely used diagnostic tool to help visualize peripheral nerve conditions, including cross-sectional area (CSA) [11]. There are various reports of anatomical variations in the size of the tibial nerve CSA and their terminal branching point. Understanding the anatomical variations of this nerve is essential for clinical practice. In this review, we describe anatomical variations of the tibial nerve in clinical and cadaveric studies, focusing on variations in the terminal branching point and CSA of the tibial nerve at the level of the proximal tarsal tunnel of ankle area using the medial malleolus as an anatomical landmark.


Sources of research data were obtained from PubMed and Google Scholar databases. The article search was limited to the English language. We did not attempt to limit the time of publication of the articles. The keywords used in the search were tibial nerve, posterior tibial nerve, cross-sectional area, tarsal tunnel syndrome, neuropathy, and diabetic polyneuropathy.

Type of anatomical variation of the tibial nerve terminal bifurcation point

In the ankle area, the tibial nerve, located on the posteromedial side of the medial malleolus, runs in the tarsal tunnel [12]. The tarsal tunnel is a narrow fibro-osseous space covered by the flexor retinaculum (laciniate ligament) [7, 13]. This tunnel includes multiple structures such as the tibialis posterior tendon, flexor digitorum longus tendon, posterior tibial artery, posterior tibial vein, tibial nerve, and flexor hallucis longus tendons [14]. Due to its narrow space and structures, this tunnel has been reported to be the most common site for entrapment of the tibial nerve [15].

The tibial nerve is divided into two terminal branches, the medial plantar nerve (MPN) and the lateral plantar nerve (LPN), which innervate the sole of the foot [13, 16]. While the MPN innervate the medial aspect of the sole, the LPN innervate the lateral aspect [4]. Studies have reported several different branching points of the tibial nerve in the ankle. Some researchers use the malleolar-calcaneal axis (MCA), extending from the medial malleolus to the medial calcaneal tuberosity, as a reference line to classify the branching points. Based on that axis, there are five types of tibial nerve branching points: type I (above the axis and within the tarsal tunnel); type II (as high as the axis); type III (distal end of the axis and within the tarsal tunnel); type IV (proximal axis and outside the tarsal tunnel); type V (distal axis and outside the tarsal tunnel) [17].

The difficulty of identifying the flexor retinaculum in cadaver specimens has led some researchers to use the 2 cm proximal and distal axis as a determinant of the area of the tarsal tunnel. Most researchers reported that the branching point of the tibial nerve at the ankle is found in the tarsal tunnel area and proximally of the MCA (Table 1) [13, 16-22]. Tibial nerve branches include not only the MPN and LPN but also the medial calcaneus nerve (MCN) and the inferior calcaneus nerve (ICN). MCN and ICN provide sensory innervation to the heel and the anterior aspect of the calcaneus area, respectively [16, 17]. Thus, Compression on the two nerves can result in pain in the two difference areas; while compression of MCN result in heel pain and compression of the ICN result in Baxter neuropathy [23]. The two nerves vary in origin and number (Table 2) [13, 16, 20].

Table 1 . Types of tibial nerve terminal branching point

AuthorsCountrySpecimenNumber of feetType of branching point (%)
Type 1Type 2Type 3Type 4Type 5
Banik, 2021 [18]IndiaEmbalmed cadaver and lower limbs20453015100
Zhang, 2021 [13]ChinaMRI401000000
Inthasan, 2020 [16]ThailandFresh cadaver405000500
Farhan, 2018 [19]USAFresh cadaver1100a)0000
Iborra, 2018 [20]SpainFresh cadaver1291.67008.30
Kim, 2015 [21]KoreaEmbalmed cadaver907b)1.1b)82.2b)NRNR
Torres, 2012 [17]BrazilFresh cadaver50521422120
Davis, 1995 [22]USAEmbalmed cadaver209000100
Total mean66.955.6314.911.280

MRI, magnetic resonance imagining; NR, not reported. a)Not clearly described. b)The axis lines: from the medial malleolus to the tuberosity of the Calcanei postero superior.

Table 2 . Variation of MCN’s origin

Number of branchesAuthorsOrigin
Tibialis nerveMPNLPNTibialis nerve and MPNTibialis nerve and LPNTibialis nerve, MPN, and LPN/trifurcation
1Zhang, 2021 [13]16/18-2/18---
Inthasan, 2020 [16]5/81/82/8---
Iborra, 2018 [20]6/12--
2Zhang, 2021 [13]6/21---15/21-
Inthasan, 2020 [16]7/15--1/157/15-
Iborra, 2018 [20]----1/65/6*
3Zhang, 2021 [13]----1/1
Inthasan, 2020 [16]11/17--4/17-2/17

MCN, medial calcaneus nerve; MPN, medial plantar nerve; LPN, lateral plantar nerve.

Tibial nerve cross-sectional area (CSA) variation in the ankle

Ultrasonography (US) is a common imaging technique used to depict the peripheral nerves, including the CSA of nerves [24]. Several studies have measured tibial nerve CSA using US with a frequency range of 5–18 MHz. It was found that the mean tibial nerve CSA in the ankle area ranged from 6.36 to 15.25 mm2 (Table 3) [11, 24-30]. This broad variation in mean values is likely due to the utilization of diverse research subjects. According to studies, the CSA of the tibial nerve at the level and 1 to 7 cm proximal of medial malleolus in Asian subject was between 11.1 and 12.7 mm2 [11, 24, 25]. Meanwhile, the mean CSA of tibial nerve in European varied between 6.36 and 13.7 mm2 [26-29]. Based on a study of 81 cadaveric lower limbs, the average CSA of the tibial nerve at the tip of medial malleolus in fresh and frozen cadaver lower limbs was 15.25±4.65 mm2 and 13.71±5.66 mm2, respectively [30].

Table 3 . Mean of tibial nerve CSA

AuthorCountryGroup (n)Mean (range) age (yr)ModalityMean±SD CSA (mm2)Reference range of CSA
Singh et al. 2022 [24]India200>18 (18–50)US 5–18 MHz11.1±1.1NR
Warchoł et al. 2021 [30]Poland





Cadaveric dissection





Bedewi et al. 2018 [25]Asian13838.33 (20–73)US L18–5 MHz12.7±4.52–30
Seok et al. 2014 [11]Korea9443.9 (20–69)US 5–12-MHz12.1±3.18.5–22.8c)
Boehm et al. 2014 [26]Caucasian5651.8e) dan 48.5f)US 15 and 12 MHz9.6±2.2NR
Kerasnoudis et al. 2013 [27]Germany7553.46US-18 MHz6.36±1.453.46–9.26
Tagliafico et al. 2012 [28]Italy5847 (18–81)US 17–5-MHz9.6±4d)NR
Cartwright et al. 2008 [29]Caucasian6045.9 (21–80)US 15-MHz13.7±4.35.1–22.3

CSA, cross-sectional area at the tarsal tunnel; US, ultrasonography; NR, not reported; L, linear transducer. a)Lower limb fresh cadaver; b)lower limbs fresh frozen cadaver. c)7-cm proximal malleolus medial. d)Standard error measurement. e)Germans, f)Hungarians.

Several studies have shown that the CSA of nerves increases with age [25, 27, 31]. In apart from age, the CSA value is related to body mass index (BMI) and weight. However, a meta-analysis reported no relationship between age, weight and tibial nerve CSA value [32]. Changes in tibial nerve’s form and size can be caused by the position of the ankle joint. Previous studies showed that CSA of tibial nerve in the plantarflexed was greater than that of dorsiflexed [33].

Variation of the cross-sectional area (CSA) of the tibial nerve in foot neuropathy

The increase of the tibial nerve CSA may indicate abnormality. Tarsal tunnel syndrome (TTS) and diabetic polyneuropathy (DPN) are conditions caused by prolonged tibial nerve compression, which is related to an increase in the CSA of this nerve [10]. DPN has several symptoms, including paranesthesia, loss of sensory sensation, and hyperesthesia [9]. Several previous studies was reported differences in the mean value of the tibial nerve CSA between healthy subjects and patients with symptomatic neuropathy (Table 4) [9, 10, 34-37].

Table 4 . Tibial nerve CSA in healthy vs neuropathy subjects

AuthorsCountryModalityGroup (n)Mean age (yr)CSA (mm2)
Narayan et al. 2021 [35]IndiaUS 6–20 MHz and 5–18 MHzDPN (100)55.9813.61±4.99a)
NN (100)53.669.27±1.53
Fantino et al. 2020 [34]FranceUS 18 MHzSusp. TTS (27)5420.1±8.8a)
NN (21)3910.3±2.3
Kelle et al. 2016 [9]TurkeyUS between 3 and 15 MHzDPN (53)53.57



NN (53)51.87



Kang et al. 2015 [37]KoreaUS 7–12 MHzDPN (20)6612.25±2.88
NN (20)6512.36±2.85
Riazi et al. 2012 [36]TorontoUS 6–13 MHzDPN (55)61.422.05±7.40a)
Diabetic non DPN (43)46.817.25±4.68
Lee and Dauphinée, 2005 [10]TexasUS 10–12 MHzDPN (24)57.424a)

CSA, cross sectional area of tibial nerve; DPN, diabetic polyneuropathy; NN, nonneuropathy; TTS, tarsal tunnel syndrome; NR, not reported. R, right; L, left. a)Significant different.

According to a study conducted in France, patients with TTS had higher mean CSA tibial nerve than in healthy subject at the inside of tarsal tunnel. CSA tibial nerve in TTS patients was 20.1 mm2 and in healthy subjects was 10.3 mm2 [34]. The difference in the CSA tibial nerve between DPN and healthy subjects was also noted. A study in India reported that the mean value of CSA tibial nerve at 3 cm proximal medial malleolus in patient with DPN was 13.61 mm2 and in healthy subjects was 9.27 mm2 [35]. A study in Texas also reported a higher mean value of CSA tibial nerve in patients with DPN than in healthy subject, which was 24 mm2 and 12 mm2, respectively [10].

Another study comparing the right and left leg was also found the difference in the CSA tibial nerve value between DPN and healthy subjects. In patients with DPN, the mean tibial nerve CSA value was 33.83 mm2 on the right and 31.94 mm2 on the left leg, whereas in healthy subjects, the CSA tibial nerve was 18.67 mm2 on right leg and 18.43 mm2 on the left leg [9]. In diabetic subject with DPN and those without DPN, the CSA of tibial nerve had different mean values of 22.05 mm2 and 17.25 mm2, respectively [36]. A study conducted in Korea showed there was no significant difference between the mean CSA of the tibial nerve at the level of medial malleolus in DPN patients and healthy subjects (12.25 mm2 vs 12.36 mm2, respectively) [37].

The CSA of the tibial nerve seems to be similar on both sides of the leg, so the value of tibial nerve CSA on the contralateral side can act as internal control in predicting abnormality [24, 28].

In this review, the MCA was used as the baseline for determining the tibial nerve branching point and the tarsal tunnel was defined as the area 2 cm proximal and distal to the MCA. According to these baselines, the most common location of the tibial nerve branching point was type I. It was difficult to provide concise data since the studies used various baselines in determining the branching point of the tibial nerve in the ankle. Therefore, in the future, the agreement will be required to determine that baseline.

Another anatomical variation we have review was CSA of tibial nerve at the ankle. In healthy subject there was various size of CSA tibial nerve. Hence there was an increase CSA tibial nerve in neuropathy patient. On both sides of the leg, there was no significant difference in CSA of tibial nerve at the ankle, so that it can be used as an internal control in establishing the diagnosis.

This review was supported by Institute for Research and Community Service of Universitas Islam Sultan Agung.

Conceptualization: ASS. Data acquisition: ASS, DF. Data analysis or interpretation: ASS, DF. Drafting of the manuscript: ASS. Approval of the final version of the manuscript: all authors.

No potential conflict of interest relevant to this article was reported.

  1. Vloka JD, Hadzić A, April E, Thys DM. The division of the sciatic nerve in the popliteal fossa: anatomical implications for popliteal nerve blockade. Anesth Analg 2001;92:215-7.
    Pubmed CrossRef
  2. Güvençer M, Iyem C, Akyer P, Tetik S, Naderi S. Variations in the high division of the sciatic nerve and relationship between the sciatic nerve and the piriformis. Turk Neurosurg 2009;19:139-44.
  3. Gaur NL, Soni J, Gaur S, Ghosh B, Chaudhari H. Anatomical variation of sciatic nerve division - a case report. Eur J Biomed Pharm Sci 2015;2:1078-82.
  4. Granger CJ, Cohen-Levy WB. Anatomy, bony pelvis and lower limb: posterior tibial nerve [Internet]. StatPearls Publishing; 2023 [cited 2023 May 23].
    Available from: https://www.ncbi.nlm.nih.gov/books/NBK546623/
  5. Sobotta J, Paulsen F, Waschke J, Klonisch T, Hombach-Klonisch S. Sobotta atlas of human anatomy. Volume 1, general anatomy and musculoskeletal system. 15th ed. Urban & Fischer; 211.
  6. Krishnan KS, Raju G, Shawkataly O. Prevalence of work-related musculoskeletal disorders: psychological and physical risk factors. Int J Environ Res Public Health 2021;18:9361.
    Pubmed KoreaMed CrossRef
  7. Ferkel E, Davis WH, Ellington JK. Entrapment neuropathies of the foot and ankle. Clin Sports Med 2015;34:791-801.
    Pubmed CrossRef
  8. Singh G, Kumar VP. Neuroanatomical basis for the tarsal tunnel syndrome. Foot Ankle Int 2012;33:513-8.
    Pubmed CrossRef
  9. Kelle B, Evran M, Ballı T, Yavuz F. Diabetic peripheral neuropathy: correlation between nerve cross-sectional area on ultrasound and clinical features. J Back Musculoskelet Rehabil 2016;29:717-22.
    Pubmed CrossRef
  10. Lee D, Dauphinée DM. Morphological and functional changes in the diabetic peripheral nerve: using diagnostic ultrasound and neurosensory testing to select candidates for nerve decompression. J Am Podiatr Med Assoc 2005;95:433-7.
    Pubmed CrossRef
  11. Seok HY, Jang JH, Won SJ, Yoon JS, Park KS, Kim BJ. Cross-sectional area reference values of nerves in the lower extremities using ultrasonography. Muscle Nerve 2014;50:564-70.
    Pubmed CrossRef
  12. Bilal F, Gamal G. The tibal nerve (posterior tibal nerve): anatomical course and relation at the ankle. Open Acc Res Anatomy 2018;1:3-5.
  13. Zhang Y, He X, Li J, Ye J, Han W, Zhou S, Zhu J, Wang G, Chen X. An MRI study of the tibial nerve in the ankle canal and its branches: a method of multiplanar reformation with 3D-FIESTA-C sequences. BMC Med Imaging 2021;21:51.
    Pubmed KoreaMed CrossRef
  14. Awadelseid KMF. Morphological study of the posterior tibial nerve in tarsal tunnel of the human foot. Int J Hum Anat 2020;2:1-9.
  15. De Prado M, Cuervas-Mons M, Golanó P, Rabat E, Vaquero J. The tarsal tunnel syndrome. German J Foot Ankle Surg 2015;13:227-36.
  16. Inthasan C, Vaseenon T, Mahakkanukrauh P. Anatomical study and branching point of neurovascular structures at the medial side of the ankle. Anat Cell Biol 2020;53:422-34.
    Pubmed KoreaMed CrossRef
  17. Torres AL, Ferreira MC. Study of the anatomy of the tibial nerve and its branches in the distal medial leg. Acta Ortop Bras 2012;20:157-64.
    Pubmed KoreaMed CrossRef
  18. Banik S Sr, Guria LR. Variable branching pattern of tibial nerve in the tarsal tunnel: a gross anatomical study with clinical implications. Cureus 2021;13:e13729.
    Pubmed KoreaMed CrossRef
  19. Farhan B, Ghoniem G. The tibal nerve (posterior tibal nerve): anatomical course and relation at the ankle. Open Access Res Anat 2018;1:1-2.
  20. Iborra A, Villanueva M, Barrett SL, Rodriguez-Collazo E, Sanz P. Anatomic delineation of tarsal tunnel innervation via ultrasonography. J Ultrasound Med 2018;37:1325-34.
    Pubmed CrossRef
  21. Kim DI, Kim YS, Han SH. Topography of human ankle joint: focused on posterior tibial artery and tibial nerve. Anat Cell Biol 2015;48:130-7.
    Pubmed KoreaMed CrossRef
  22. Davis TJ, Schon LC. Branches of the tibial nerve: anatomic variations. Foot Ankle Int 1995;16:21-9.
    Pubmed CrossRef
  23. De Maeseneer M, Madani H, Lenchik L, Kalume Brigido M, Shahabpour M, Marcelis S, de Mey J, Scafoglieri A. Normal anatomy and compression areas of nerves of the foot and ankle: us and mr imaging with anatomic correlation. Radiographics 2015;35:1469-82.
    Pubmed CrossRef
  24. Singh KP, Kaur S, Arora V. Reference values for the cross sectional area of normal tibial nerve on high-resolution ultrasonography. J Ultrason 2022;22:e144-52.
    Pubmed KoreaMed CrossRef
  25. Bedewi MA, Abodonya A, Kotb M, Kamal S, Mahmoud G, Aldossari K, Alqabbani A, Swify S. Estimation of ultrasound reference values for the lower limb peripheral nerves in adults: A cross-sectional study. Medicine (Baltimore) 2018;97:e0179.
    Pubmed KoreaMed CrossRef
  26. Boehm J, Scheidl E, Bereczki D, Schelle T, Arányi Z. High-resolution ultrasonography of peripheral nerves: measurements on 14 nerve segments in 56 healthy subjects and reliability assessments. Ultraschall Med 2014;35:459-67.
    Pubmed CrossRef
  27. Kerasnoudis A, Pitarokoili K, Behrendt V, Gold R, Yoon MS. Cross sectional area reference values for sonography of peripheral nerves and brachial plexus. Clin Neurophysiol 2013;124:1881-8.
    Pubmed CrossRef
  28. Tagliafico A, Cadoni A, Fisci E, Bignotti B, Padua L, Martinoli C. Reliability of side-to-side ultrasound cross-sectional area measurements of lower extremity nerves in healthy subjects. Muscle Nerve 2012;46:717-22.
    Pubmed CrossRef
  29. Cartwright MS, Passmore LV, Yoon JS, Brown ME, Caress JB, Walker FO. Cross-sectional area reference values for nerve ultrasonography. Muscle Nerve 2008;37:566-71.
    Pubmed CrossRef
  30. Warchoł Ł, Walocha JA, Mizia E, Liszka H, Bonczar M. Comparison of the histological structure of the tibial nerve and its terminal branches in the fresh and fresh-frozen cadavers. Folia Morphol (Warsz) 2021;80:542-8.
    Pubmed CrossRef
  31. Cartwright MS, Mayans DR, Gillson NA, Griffin LP, Walker FO. Nerve cross-sectional area in extremes of age. Muscle Nerve 2013;47:890-3.
    Pubmed CrossRef
  32. Fisse AL, Katsanos AH, Gold R, Krogias C, Pitarokoili K. Cross-sectional area reference values for peripheral nerve ultrasound in adults: a systematic review and meta-analysis-part II: lower extremity nerves. Eur J Neurol 2021;28:2313-8.
    Pubmed CrossRef
  33. Bueno-Gracia E, Salcedo-Gadea J, López-de-Celis C, Salcedo-Gadea E, Pérez-Bellmunt A, Estébanez-de-Miguel E. Dimensional changes of the tibial nerve and tarsal tunnel in different ankle joint positions in asymptomatic subjects. J Foot Ankle Surg 2019;58:1129-33.
    Pubmed CrossRef
  34. Fantino O, Bouysset M, Pialat JB. Can the axial cross-sectional area of the tibial nerve be used to diagnose tarsal tunnel syndrome? An ultrasonography study. Orthop Traumatol Surg Res 2021;107:102630.
    Pubmed CrossRef
  35. Narayan S, Goel A, Singh AK, Thacker AK, Singh N, Gutch M. High resolution ultrasonography of peripheral nerves in diabetic patients to evaluate nerve cross sectional area with clinical profile. Br J Radiol 2021;94:20200173.
    Pubmed KoreaMed CrossRef
  36. Riazi S, Bril V, Perkins BA, Abbas S, Chan VW, Ngo M, Lovblom LE, El-Beheiry H, Brull R. Can ultrasound of the tibial nerve detect diabetic peripheral neuropathy? A cross-sectional study. Diabetes Care 2012;35:2575-9.
    Pubmed KoreaMed CrossRef
  37. Kang S, Kim SH, Yang SN, Yoon JS. Sonographic features of peripheral nerves at multiple sites in patients with diabetic polyneuropathy. J Diabetes Complications 2016;30:518-23.
    Pubmed CrossRef

Share this article on :