Variations in the Course of the Thenar Motor Branch of the Median Nerve and Their Relationship to the Hypertrophic Muscle Overlying the Transverse Carpal Ligament

AbstractWe report an unusual anatomical variant of the palmar cutaneous branch (PCB) of the median nerve in a 46-year-old man presenting with recurrent carpal tunnel syndrome. At surgery, after neurolysis, the PCB was visualized arising at the level of the proximal margin of the transverse carpal ligament, mimicking the appearance of the recurrent motor branch. To date, there has been no description of this branch arising at this level. We aim to remind surgeons of this variation and highlight the importance of maintaining vigilance to avoid iatrogenic nerve injury.

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Report of a Transligamentous Ulnar Nerve Sensory Branch

Hand ◽

10.1177/1558944719831338 ◽

2019 ◽

Vol 15 (1) ◽

pp. NP11-NP13

Author(s):

Christina R. Vargas ◽

Kyle J. Chepla

Keyword(s):

Median Nerve ◽

Ulnar Nerve ◽

Carpal Tunnel ◽

Carpal Tunnel Release ◽

Anatomical Variation ◽

Dominant Male ◽

Transverse Carpal Ligament ◽

Anatomical Variant ◽

Motor Branch ◽

Right Hand

Background: Several anatomical variations of the median nerve recurrent motor branch have been described. No previous reports have described the anatomical variation of the ulnar nerve with respect to transverse carpal ligament. In this article, we present a patient with symptomatic compression of the ulnar nerve found to occur outside the Guyon canal due to a transligamentous course through the distal transverse carpal ligament. Methods: A 59-year-old, right-hand-dominant male patient presented with right hand pain, subjective weakness, and numbness in both the ulnar and the median nerve distributions. Electromyography revealed moderate demyelinating sensorimotor median neuropathy at the wrist and distal ulnar sensory neuropathy. At the time of planned carpal tunnel and Guyon canal release, a transligamentous ulnar nerve sensory common branch to the fourth webspace was encountered and safely released. Results: There were no surgical complications. The patient’s symptoms of numbness in the median and ulnar nerve distribution clinically improved at his first postoperative visit. Conclusions: We have identified a case of transligamentous ulnar nerve sensory branch encountered during carpal tunnel release. To our knowledge, this has not been previously reported. While the incidence of this variant is unknown, hand surgeons should be aware of this anatomical variant as its location puts it at risk of iatrogenic injury during open and endoscopic carpal tunnel release.

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The History of Carpal Tunnel Syndrome

Journal of Hand Surgery (European Volume) ◽

10.1016/0266-7681_88_90046-0 ◽

1988 ◽

Vol 13 (1) ◽

pp. 28-34

Author(s):

G. B. PFEFFER ◽

R. H. GELBERMAN ◽

J. H. BOYES ◽

B. RYDEVIK

Keyword(s):

Carpal Tunnel Syndrome ◽

Median Nerve ◽

Carpal Tunnel ◽

Transverse Carpal Ligament ◽

Motor Branch ◽

Compressive Neuropathy ◽

Anatomical Localization ◽

History Of ◽

Idiopathic Carpal Tunnel Syndrome ◽

Tunnel Syndrome

Carpal tunnel syndrome is the most frequently diagnosed, best understood and most easily treated entrapment neuropathy. During the first half of the 20th century, however, most patients with carpal tunnel syndrome were diagnosed as having compression of either the brachial plexus or thenar nerve motor branch of the median nerve. As late as 1950, only twelve patients with operative release of the transverse carpal ligament for idiopathic carpal tunnel syndrome had been reported. The delay in accurate anatomical localization of this compressive neuropathy can be attributed both to the confusion caused by the diverse manifestations of median nerve compression in the carpal tunnel, and to some interesting developments that altered early investigations in this area.

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Anatomical Relationships between Muscles Overlying Distal Transverse Carpal Ligament and Thenar Motor Branch of the Median Nerve

Clinics in Orthopedic Surgery ◽

10.4055/cios.2018.10.1.89 ◽

2018 ◽

Vol 10 (1) ◽

pp. 89 ◽

Cited By ~ 1

Author(s):

Midum Jegal ◽

Sung Jong Woo ◽

Hyun Il Lee ◽

Jae Woo Shim ◽

Woo Jin Shin ◽

...

Keyword(s):

Median Nerve ◽

Transverse Carpal Ligament ◽

Motor Branch

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Mini-Open Carpal Tunnel Decompression

Neurosurgery ◽

10.1227/01.neu.0000103669.45726.51 ◽

2004 ◽

Vol 54 (2) ◽

pp. 397-400 ◽

Cited By ~ 29

Author(s):

Jason H. Huang ◽

Eric L. Zager

Keyword(s):

Carpal Tunnel Syndrome ◽

Median Nerve ◽

Carpal Tunnel ◽

Entrapment Neuropathy ◽

Transverse Carpal Ligament ◽

Motor Branch ◽

Tunnel Technique ◽

Tunnel Syndrome ◽

Mini Open ◽

Surgical Release

Abstract CARPAL TUNNEL SYNDROME is the most common entrapment neuropathy, and it is caused by compression of the median nerve at the wrist. The authors describe the mini-open carpal tunnel technique for surgical release of the transverse carpal ligament. The success of the procedure depends on meticulous technique with attention to certain important anatomic details and careful avoidance of injury to the palmar cutaneous nerve and the recurrent motor branch.

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Anomalous Thenar Musculature Associated with Aberrant Median Nerve Motor Branch Take-off: An Anatomic and Clinical Study

The Duke Orthopaedic Journal ◽

10.5005/jp-journals-10017-1013 ◽

2012 ◽

Vol 2 (1) ◽

pp. 18-22 ◽

Cited By ~ 1

Author(s):

Gary M Lourie ◽

R Glenn Gaston ◽

Allan E Peljovich ◽

Jason J Marshall ◽

Lee Patterson

Keyword(s):

Clinical Study ◽

Median Nerve ◽

Carpal Tunnel ◽

Carpal Tunnel Release ◽

Transverse Carpal Ligament ◽

Anatomic Study ◽

Thenar Muscle ◽

High Association ◽

Motor Branch ◽

Endoscopic Techniques

ABSTRACT Introduction Iatrogenic laceration of the median nerve motor branch during carpal tunnel release is a devastating complication that has been reported with both open and endoscopic techniques. The purpose of this study is to highlight a previously underreported relationship between an aberrant course of the median nerve motor branch and an anomalous thenar muscle that places the motor branch at high risk. Materials and methods This was a two part study. The first part was a retrospective review of over 500 cases of carpal tunnel release over a 7 year period. There were 530 carpal tunnel releases performed and 20/530 cases were found to have a characteristic anomalous thenar muscle associated with a consistent aberrant course of the motor branch of the median nerve. Part two was an anatomic study in which 42 cadaveric wrists were dissected to determine median nerve branching patterns, dimensions of the transverse carpal ligament, and thenar musculature dimensions. Results Twenty patients (3.8%) in the clinical arm were found to have anomalous musculature. In each case, the characteristics of the muscle were similar; the muscle was triangular in shape, was distal to the FPB, and had minimal fascial covering. In 100% of the cases the motor branch was found to be more anterior/central or ulnar in its take-off. In the anatomic study, two hands (5%) had aberrant musculature extending distal to the transverse carpal ligament (TCL). Both were associated with an anterior/central or ulnar median motor branch take-off with recurrent course. Larger thenar musculature dimensions and anomalous thenar muscle were associated with more anterior and ulnar motor branch take-off. Conclusion There appears to be a high association between anomalous thenar musculature and an aberrant course of the motor branch of the median nerve placing it a greater potential risk for iatrogenic injury. Lourie GM, Gaston RG, Peljovich AE, Marshall JJ, Patterson L. Anomalous Thenar Musculature Associated with Aberrant Median Nerve Motor Branch Take-off: An Anatomic and Clinical Study. The Duke Orthop J 2012;2(1):18-22.

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