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J Wrist Surg 2022; 11(02): 150-153
DOI: 10.1055/s-0041-1735887
Scientific Article

Thenar and Hypothenar Muscle Coverage on the Transverse Carpal Ligament

Farah Alsafar
1   Hand Research Laboratory, Department of Orthopaedic Surgery, University of Arizona College of Medicine, Tucson, Arizona
,
Zong-Ming Li 
1   Hand Research Laboratory, Department of Orthopaedic Surgery, University of Arizona College of Medicine, Tucson, Arizona
› Author Affiliations Funding This research was funded by NIH/NIAMS R01AR068278.
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Abstract

Background The purpose of the study was to examine the coverage of thenar and hypothenar muscles on the transverse carpal ligament (TCL) in the radioulnar direction through in vivo ultrasound imaging of the carpal tunnel. We hypothesized that the TCL distance covered by the thenar muscle would be greater than that by the hypothenar muscle, and that total muscle coverage on the TCL would be greater than the TCL-alone region.

Methods Ultrasound videos of human wrist were collected on 20 healthy subjects. Automated algorithms were used to extract the distal cross-sectional image of the trapezium-hamate level. Manual tracing of the anatomical features was conducted.

Results Thenar muscles covered a significantly larger distance (11.9 ± 1.8 mm) as compared with hypothenar muscles (1.7 ± 0.8 mm) (p < 0.001). The TCL covered by thenar and hypothenar muscles was greater than the TCL-alone length (p < 0.001). The thenar and hypothenar muscle coverage on the TCL, as normalized to the total TCL length, was 61.0 ± 7.5%.

Conclusions More than 50% of the TCL at the distal carpal tunnel is covered by thenar and hypothenar muscles. Knowledge of muscular attachments to the TCL improves our understanding of carpal tunnel syndrome etiology and can guide carpal tunnel release surgery.

Keywords

hand - carpal tunnel - thenar - hypothenar - transverse carpal ligament


Publication History

Received: 30 June 2021

Accepted: 03 August 2021

Article published online:
01 October 2021

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  • References

  • 1 Shen ZL, Li ZM. Biomechanical interaction between the transverse carpal ligament and the thenar muscles. J Appl Physiol (1985) 2013; 114 (02) 225-229
    CrossrefPubMedGoogle Scholar
  • 2 Morizaki Y, Zhao C, van Doesburg MHM, Zhao K, An KN, Amadio PC. The gliding characteristics of the flexor pollicis longus tendon in the carpal tunnel: potential implications for manual pipette users. J Orthop Res 2012; 30 (03) 457-460
    CrossrefPubMedGoogle Scholar
  • 3 Mhanna C, Marquardt TL, Li ZM. Adaptation of the transverse carpal ligament associated with repetitive hand use in pianists. PLoS One 2016; 11 (03) e0150174
    CrossrefPubMedGoogle Scholar
  • 4 Sergeant AC, Badr S, Saab M, Demondion X, Cotten A, Jacques T. Carpal tunnel ultrasound: is the “safe zone” on the ulnar side of the median nerve really avascular?. Eur Radiol 2020; 30 (02) 887-894
    CrossrefPubMedGoogle Scholar
  • 5 Sacks JM, Kuo YR, Mclean K, Wollstein R, Lee WPA. Anatomical relationships among the median nerve thenar branch, superficial palmar arch, and transverse carpal ligament. Plast Reconstr Surg 2007; 120 (03) 713-718
    CrossrefPubMedGoogle Scholar
  • 6 Chern TC, Jou IM, Chen WC, Wu KC, Shao CJ, Shen PC. An ultrasonographic and anatomical study of carpal tunnel, with special emphasis on the safe zones in percutaneous release. J Hand Surg Eur Vol 2009; 34 (01) 66-71
    CrossrefPubMedGoogle Scholar
  • 7 Sytsma TT, Ryan HS, Lachman N, Kakar S, Smith J. Anatomic relationship between the hook of the hamate and the distal transverse carpal ligament. Am J Phys Med Rehabil 2018; 97 (07) 482-487
    CrossrefPubMedGoogle Scholar
  • 8 Kung J, Budoff JE, Wei ML, Gharbaoui I, Luo ZP. The origins of the thenar and hypothenar muscles. J Hand Surg [Br] 2005; 30 (05) 475-476
    CrossrefPubMedGoogle Scholar
  • 9 Loss J, Li ZM. Biometry of thenar muscle origins on the flexor retinaculum. Clin Anat 2020; 33 (08) 1176-1180
    CrossrefPubMedGoogle Scholar
  • 10 Lakshminarayanan K, Shah R, Li ZM. Sex-related differences in carpal arch morphology. PLoS One 2019; 14 (05) e0217425
    CrossrefPubMedGoogle Scholar
  • 11 Woo SL-Y, Gomez MA, Woo Y-K, Akeson WH. Mechanical properties of tendons and ligaments. II. The relationships of immobilization and exercise on tissue remodeling. Biorheology 1982; 19 (03) 397-408
    CrossrefPubMedGoogle Scholar
  • 12 Marquardt TL, Gabra JN, Evans PJ, Seitz Jr WH, Li ZM. Thickness and stiffness adaptations of the transverse carpal ligament associated with carpal tunnel syndrome. J Musculoskelet Res 2016; 19 (04) 1650019
    CrossrefPubMedGoogle Scholar
  • 13 Fuss FK, Wagner TF. Biomechanical alterations in the carpal arch and hand muscles after carpal tunnel release: a further approach toward understanding the function of the flexor retinaculum and the cause of postoperative grip weakness. Clin Anat 1996; 9 (02) 100-108
    CrossrefPubMedGoogle Scholar
  • 14 Brooks JJ, Schiller JR, Allen SD, Akelman E. Biomechanical and anatomical consequences of carpal tunnel release. Clin Biomech (Bristol, Avon) 2003; 18 (08) 685-693
    CrossrefPubMedGoogle Scholar