Transverse Carpal Ligament Research Articles

Time-Dependent Change in Carpal Tunnel Cross-Sectional Area and Transverse Carpal Ligament Thickness Using Serial Magnetic Resonance Imaging Studies—An Anatomical Study

Idiopathic carpal tunnel syndrome (CTS) is a common compressive neuropathy. Aging and female sex are risk factors, but the reasons are unclear. The purpose of this study was to evaluate whether identifiable radiographic changes resulting in a decrease in carpal tunnel area (CTA) over time exist. A database search of a multicenter, academic, tertiary institution from 1998 to 2021 identified 433 patients with serial wrist magnetic resonance images (MRI) at least 5 years apart. Fifty-six met the inclusion criteria with adequate films to measure CTA and transverse carpal ligament (TCL) thickness at the same slice location-the carpal tunnel inlet, hook of the hamate, and carpal tunnel outlet-independently by two observers who were blinded to each other's measurements. Rates for the change in CTA and TCL thickness were calculated at all three locations. Thickness of the TCL increased, whereas that of the CTA decreased over time. Inlet CTA decreased by 0.9 mm2 per year (95% CI: 0.34-1.5), outlet CTA decreased by 1.8 mm2 per year (95% CI: 1.2-2.5), and CTA at the hook of the hamate decreased by 1.6 mm2 per year (95% CI: 1.0-2.0 per year). The TCL thickened by 0.02 mm per year at all three sections. Taller patients had a decreased rate of CTA loss. In this select cohort, TCL thickened and CTA decreased with time. TCL thickening accounted for about half of the variation in CTA, suggesting that this is a possible contributor to this change. Hypertrophy of the carpal tunnel floor may account for the remaining variation in CTA. The question of whether these results are reliable and generalizable to the general population, or a major influence in the pathophysiology of CTS, is unknown. Small decreases in CTA and thickening of the TCL occur with aging. Whether this is a contributing factor in the development of CTS requires further study.

РЕКОНСТРУКЦИЯ ПОПЕРЕЧНОЙ ЗАПЯСТНОЙ СВЯЗКИ В ЛЕЧЕНИИ СИНДРОМА ЗАПЯСТНОГО КАНАЛА. ОБЗОР ЛИТЕРАТУРЫ

Introduction. Carpal tunnel syndrome is a compression of the median nerve at the wrist, a common compression neuropathy of the upper extremities in medical practice. The most effective treatment for this condition is considered to be surgical and the most common approach is either dissecting the carpal ligament without subsequent stitching or reconstructing it. A study of the efficacy of transverse carpal ligament reconstruction approaches helps in the search for treatment improvement. The aim of the study is to compare the effectiveness and safety of different surgical techniques according to Russian and foreign literature sources containing information on the immediate and long-term results of treatment of patients with carpal tunnel syndrome using the transverse carpal ligament reconstruction method. Materials and methods. Scientific publications on the topic for 2013-2023 were studied. Results and discussion. It was found out that reconstruction of the transverse carpal ligament contributes not only to the increase of carpal tunnel volume, but also to normalization of biomechanics of carpal movements after the operation. Conclusion. Currently, there is no unequivocal evidence of significant advantages of reconstructing the transverse carpal ligament. The majority of authors consider reconstructive surgery effective in conditions of morphologically distorted median nerve or carpal tunnel as well as peculiarities of the patient history, which may require earlier restoration of the upper extremity functional state and ability to work.

Ultrasound-guided interventions in primary carpal tunnel syndrome: perineural injection to thread carpal tunnel release.

Carpal tunnel syndrome (CTS), the most common entrapment neuropathy, is compression of the median nerve deep to transverse carpal ligament at wrist. Ultrasonography and electrophysiological study are complementary in the diagnosis and grading of CTS in appropriate clinical settings. The initial management of patients with CTS is conservative with medical therapy and splinting. However, surgical interventions are indicated in patients in whom medical management has failed. With evolution of the concept of safe zone on ultrasonography and identification of the sonoanatomical landmarks of carpal tunnel in greater detail, Ultrasonography-guided interventions are safer and preferred over surgical management in CTS. The primary ultrasonography-guided interventions include perineural injection, perineural hydrodissection and ultrasonography-guided release of transverse carpal ligament. This review article presents the principles of ultrasonography-guided perineural injection, perineural hydrodissection in CTS, the merits and demerits of injectant used in perineural injection/ hydrodissection, and percutaneous ultrasonography-guided thread release of transverse carpal ligament utilizing the concept of safe zone of the ultrasonography-guided interventions for CTS.

Minireview of connective tissue features and selected forearm structures

Abstract Connective tissue is an extremely divaricated structure and, unlike other tissues, made up of proteins combined in various configurations. This construction is characterized by high variability and the ability to adapt through the appropriate selection of synthesized matrix components. That feature helps properly stabilize the body’s joints. The content of receptors enables information transfer about stimuli acting on itself and on neighboring structures. This work aims are to collect information about selected forearm structures, its features, functions and receptors content. One of the objectives is to improve the knowledge organization, indicate possible areas to expand and to inspire exploration diversity of connective tissue. Structures described in the article include the transverse carpal ligament, the superficial and deep fascia of the forearm, the interosseous membrane, the flexor retinaculum system and the palmar aponeurosis. These structures are well-known even to inexperienced science students. However, acquired knowledge is still incomplete and possible to explore.

Initial Outcomes of a Novel Modification of Looped Threaded Carpal Tunnel Release Method.

Various surgical techniques are available for the alleviation of symptoms in carpal tunnel syndrome and each of them has its pros and cons. This study was designed and performed to present a novel approach for cutting transverse carpal ligament by the thread looping technique without the use of ultrasonography. The novel modification of looped threaded carpal tunnel release was performed on 10 hands of 10 patients. The disabilities of arm, shoulder, and hand score, visual analog scale, and 2-point discrimination were used for assessing the outcomes. No patients developed pillar pain or scar discomfort after surgery. Complete elimination of paresthesia, pain, and numbness occurred in all patients. There was a significant reduction in the disabilities of arm, shoulder, and hand and visual analog scale scores (P value<0.05). This technique is safe, available, and effective for carpal tunnel release and minimizes postoperative complications, such as pillar pain, and scar discomfort with avoiding unnecessary injuries to the surrounding soft tissue.

Anatomical considerations of US-guided carpal tunnel release in daily clinical practice.

Carpal tunnel syndrome is the most frequent compression neuropathy with an incidence of one to three subjects per thousand. As specific anatomical variations might lead to unintended damage during surgical interventions, we present a review to elucidate the anatomical variability of the carpal tunnel region with important considerations for daily clinical practice: several variants of the median nerve branches in and around the transverse carpal ligament are typical and must - similarly to the variant courses of the median artery, which may be found eccentric ulnar to the median nerve - be taken into account in any interventional therapy at the carpal tunnel. Unintended interference in these structures might lead to heavy arterial bleeding and, in consequence, even underperfusion of segments of the median nerve or, if neural structures such as variant nerve branches are impaired or even cut, severe pain-syndromes with a profound impact on the quality of life. This knowledge is thus crucial for outcome- and safety-optimization of different surgical procedures at the volar aspect of the wrist and surgical therapy of the carpal tunnel syndrome e.g., US-guided carpal tunnel release, as injury might result in dysfunction and/or pain on wrist motion or direct impact in the region concerned. For most variations, anatomical and surgical descriptions vary, as official classifications are still lacking.

Proximity of the Ulnar Neurovascular Structures in Endoscopic Carpal Tunnel Release Surgery: A Cadaveric Study

To evaluate the proximity of the ulnar neurovascular structures to the endoscopic blade during endoscopic carpal tunnel release (CTR). Ten fresh-frozen cadaver hands were used to perform endoscopic CTR using devices from two manufacturers. The skin was excised from the palm, and the endoscopic carpal tunnel blade was deployed at the distal edge of the transverse carpal ligament (TCL). The blade's proximity to the ulnar neurovascular bundle, deep ulnar motor branch, superficial palmar arch, and median nerve was recorded. Following release of the TCL, the device was turned ulnar to the maximal extent to determine if direct injury to the ulnar neurovascular bundle was possible. The average longitudinal distance from the end of the TCL to the superficial palmar arch was 13.3 mm (range, 8.4-20.9) and to the ulnar motor branch was 10.8 mm (range, 4.0-15.0). The average transverse distance from the end of the TCL to the ulnar neurovascular bundle was 5.9 mm (range, 3.1-7.8) and to the median nerve was 3.3 mm (range, 0-6.5). In two of our specimens, the median nerve subluxated volarly over the cutting device. When placing the blade at the distal edge of the TCL, injury to the deep motor branch of the ulnar nerve, ulnar neurovascular bundle, or superficial palmar arch was not possible in any specimens using the tested devices, even when turning the blade directly toward these structures. There is a low likelihood of direct injury to the ulnar neurovascular bundle during endoscopic CTR. These results suggest that injury to the ulnar neurovascular bundle is unlikely during endoscopic CTR if the distal aspect of the transverse carpal ligament can be clearly identified prior to release. Control of the median nerve is also important to prevent subluxation over the cutting device.

Compression of the Ulnar Nerve Following Carpal Tunnel Release

Given the proximity and shared structures of Guyon's canal and the carpal tunnel, compression of the ulnar nerve is a rarely observed but possible complication of carpal tunnel release. In this case report, a patient underwent previous carpal tunnel release and immediately experienced ipsilateral hand weakness in keeping with an ulnar nerve compression syndrome. Clinical, electrodiagnostic, and magnetic resonance imaging findings after carpal tunnel release demonstrated a compression or injury to the deep motor branch of the ulnar nerve not previously present. Subsequent release of Guyon's canal identified a separate compartment of the deep motor branch of the ulnar nerve within the ulnar leaflet of the transverse carpal ligament. After the release of the motor branch from this compartment, the patient experienced recovery from their neuropathic symptoms. This case report outlines the relevant anatomy and clinical data surrounding an anomalous compartment of the deep motor branch of the ulnar nerve.

Awareness of Carpal Tunnel Syndrome Among Adults in the Western Region of Saudi Arabia: A Cross-Sectional Study.

Introduction Carpal tunnel syndrome (CTS) is a peripheral neuropathy that happens when the median nerve is compressed by the transverse carpal ligament within the carpal tunnel. Public awareness is crucial for early detection and intervention; therefore, this study aims to assess the awareness of CTS among the adult population in the western region of Saudi Arabia. Methods The study design was a cross-sectional study where 1400 participants (although 1199 answers were included) from the western region were randomly asked to fill in an online questionnaire that was delivered to them via social media applications. Results The study sample was predominantly females (57.1%), and 88.7% were Saudi, mostly students and professionals (53% and 25.2% respectively); predominant chronic illness among study participants was diabetes mellitus (7%), and only 2% of the sample (27 participants) were diagnosed with CTS. Participants showed more level of awareness regarding the causes and features of CTS, 630 participants (52.5%) had a good awareness of the causes, and 652 (54.4%) had a good awareness of the features. Meanwhile, participants showed a poorer level of awareness regarding treatment, effects, and prevention; percentages of poor awareness were 56% (672) for treatment, 51.9% (622) for effects, and 52.8% (633) for prevention. Conclusion The study shows that the adult population in the western region of Saudi Arabia had insufficient awareness of CTS, especially regarding treatment, effects, and prevention. Therefore, more campaigns should be made to enhance population awareness of CTS, and the study also suggests a link between CTS and chronic diseases.

A comparative study on efficacy of modified endoscopic minimally invasive treatment and traditional open surgery for primary carpal tunnel syndrome

Background and ObjectiveCarpal tunnel syndrome (CTS) is the most common type of median nerve entrapment neuropathy. This study aims to comparatively assess the effectiveness and clinical efficacy of modified transforaminal endoscopic minimally invasive incision of transverse carpal ligament against traditional open incision of transverse carpal ligament in the treatment of CTS.MethodThe clinical data of 35 patients (57 wrists) with primary CTS treated in Shanxi Bethune Hospital, China, were retrospectively analyzed. The patients were divided into observation group (21 cases, 33 wrists) and control group (14 cases, 24 wrists), respectively, who underwent modified endoscopic minimally invasive incision of transverse carpal ligament and traditional open incision of transverse carpal ligament release. The Boston Carpal Tunnel Questionnaire (BCTQ) was assessed at for points: before the operation; 2 weeks; 1 month; and 3 months after operation. The BCTQ scores of the two groups were compared on all four points. The incidence of intraoperative and postoperative complication was used as the evaluation index. The study variables were comparatively assessed before and postoperation and also between the groups.ResultsThe BCTQ scores at 2 weeks, 1 month and 3 months after the operation were significantly lower than preoperative BCTQ scores (P < 0.005) for both the groups. There was no significant difference in BCTQ scores between the two groups at the four assessment points (P > 0.005). The scar size and wound healing time were significantly better with modified transforaminal endoscopic minimally invasive transverse carpal ligament incision.ConclusionThe clinical effects of both modified transforaminal minimally invasive incision of transverse carpal ligament and traditional open incision of transverse carpal ligament are significant, while the treatment efficacy of modified transforaminal minimally invasive transverse carpal ligament incision is better in terms of operation time, wound size, postoperative scar size and incision healing time.

Carpal Tunnel Release With Ultrasound Guidance: Intermediate-Term Clinical Outcomes and Magnetic Resonance Imaging Findings

The purpose of this study was to report intermediate-term outcomes following carpal tunnel release using ultrasound guidance and wide-awake local anesthesia no tourniquet, including a subset of patients with preoperative and postoperative magnetic resonance imaging (MRI). In this observational study, patients with carpal tunnel syndrome were treated with carpal tunnel release using ultrasound guidance and wide-awake local anesthesia no tourniquet in a procedure room at a single center. Main outcomes were complications; return to activity and work at 2 weeks; Quick Disabilities of the Arm, Shoulder, and Hand and Boston Carpal Tunnel Questionnaire scores through 6 months; and postoperative morphological changes of the transverse carpal ligament, median nerve, and carpal tunnel evaluated using MRI. No complications were reported among 65 patients (68% women, 96 wrists). By 2 weeks, 97% of patients returned to normal activity and 100% returned to work. Statistically significant improvements in Boston Carpal Tunnel Questionnaire symptom severity scale, Boston Carpal Tunnel Questionnaire functional status scale, and Quick Disabilities of the Arm, Shoulder, and Hand scores occurred by the 2-week follow-up interval and persisted at 6 months (all P < .001). Pre- and postoperative MRI scans were available for 13 patients (17 wrists) at the 3-month mean follow-up. Complete transverse carpal ligament transection was documented in all wrists. Key MRI findings included a 22% increase in carpal tunnel cross-sectional area at the hamate (P < .001), a 52% increase in median nerve cross-sectional area at the hamate (P < .001), an 18% reduction in median nerve signal intensity (P= .002), a 38% reduction in the flattening ratio of the median nerve at the hamate (P < .001), a 33% reduction in the flattening ratio of the median nerve at the pisiform (P < .001), a 20% reduction in the flattening ratio of the carpal tunnel at the hamate (P < .001), and a palmar shift of the median nerve relative to the hamate in all cases. Carpal tunnel release using ultrasound guidance using wide-awake local anesthesia no tourniquet in a procedure room setting was safe, effective, and resulted in morphological changes that were consistent with carpal tunnel decompression as demonstrated by MRI. Therapeutic IV.

The relationship between shear wave velocity in transverse carpal ligament and carpal tunnel pressure: A finite element analysis.

Elevated carpal tunnel pressure in carpal tunnel syndrome (CTS) patients is one of the major causes of nerve damage but cannot be measured non-invasively. This study proposed to use shear wave velocity (SWV) in the transverse carpal ligament (TCL) to measure the surrounding carpal tunnel pressure. The relationship between the carpal tunnel pressure and the SWV in the TCL was investigated through a subject-specific carpal tunnel finite element model reconstrued by MRI imaging. Parametric analysis was conducted to study the effect of TCL Young's modulus and carpal tunnel pressure on the TCL SWV. The SWV in TCL was found to be strongly dependent on the carpal tunnel pressure and TCL Young's modulus. The calculated SWV ranged from 8.0m/s to 22.6m/s under a combination of carpal tunnel pressure (0-200mmHg) and TCL Young's modulus (1.1-11MPa). An empirical equation was used to fit the relationship between the SWV in TCL and carpal tunnel pressure, with TCL Young's modulus as a confounding factor. The equation proposed in this study provided an approach to estimate carpal tunnel pressure by measuring the SWV in the TCL for a potential non-invasive diagnosis of CTS and may shed light on the mechanical nerve damage mechanism.

Non-Surgical Carpal Arch Space Augmentation for Median Nerve Decompression.

The carpal tunnel is a tightly bounded space, making the median nerve prone to compression and eventually leading to carpal tunnel syndrome. Carpal tunnel release surgery transects the transverse carpal ligament to expand the tunnel arch space, decompress the median nerve, and relieve the associated symptoms. However, the surgical procedure unavoidably disrupts essential anatomical, biomechanical and physiological functions of the wrist, potentially causing reduced grip strength, pillar pain, carpal bone instability, scar tissue formation, and perineural fibrosis. It is desirable to decompress the median nerve without surgically transecting the transverse carpal ligament. This paper is to review several approaches we have developed for nonsurgical carpal arch space augmentation (CASA), namely, radio ulnar wrist compression, muscle-ligament interaction, palmar pulling, and collagenolysis of the transverse carpal ligament. Briefly summarized is the research work on the CASA topic about theoretical considerations, in vitro and in situ experiment, computational modeling, and human subject studies with asymptomatic and carpal tunnel syndrome hands.

A finite element analysis of the carpal arch with various locations of carpal tunnel release.

The purpose of this study was to investigate the effects of the location of transverse carpal ligament (TCL) transection on the biomechanical property of the carpal arch structure. It was hypothesized that carpal tunnel release would lead to an increase of the carpal arch compliance (CAC) in a location-dependent manner. A pseudo-3D finite element model of the volar carpal arch at the distal carpal tunnel was used to simulate arch area change under different intratunnel pressures (0-72 mmHg) after TCL transection at different locations along the transverse direction of the TCL. The CAC of the intact carpal arch was 0.092 mm2/mmHg, and the simulated transections ranging from 8 mm ulnarly to 8 mm radially from the center point of the TCL led to increased CACs that were 2.6-3.7 times of that of the intact carpal arch. The CACs after radial transections were greater than those ulnarly transected carpal arches. The TCL transection in the radial region was biomechanically favorable in reducing carpal tunnel constraint for median nerve decompression.

Recurrent carpal tunnel syndrome: Outcomes after neurolysis and synovial flap

ObjectivesIf symptoms recur after primary neurolysis of the median nerve, surgical revision is required. Soltani et al. (2013) demonstrated that surgical revision with vascularized flap coverage had a higher success rate (86%) than surgical revision without a flap (75%). The aim of this retrospective study was to present clinical outcomes in 36 cases of secondary open neurolysis of the median nerve, with synovial flap in case of recurrent carpal tunnel syndrome. MethodThirty-three patients (36 hands) who had undergone secondary neurolysis of the median nerve combined with synovial flap coverage between 2012 and 2019 were selected for this study. We included only recurrent carpal tunnel syndrome cases presenting with scarring of the transverse carpal ligament or epineural fibrosis of the median nerve and with a symptom-free period of at least 3 months. The results were ranked on a 4-point scale as excellent, good, null or poor, depending on progression at last follow-up. ResultsDescriptive analysis showed that 80% of patients had a positive outcome (excellent 33%, good 47%), 6% null outcome and 14% poor outcome. ConclusionThis is an interesting, relatively non-invasive surgical option, and should be part of the therapeutic armamentarium for recurrent carpal tunnel syndrome in case of adherence of the nerve to the transverse carpal ligament.

Endoscopic release of the carpal tunnel using the Agee technique modified by Neumann

Decompression of the median nerve by complete endoscopic release of the transverse carpal ligament (TCL) and the distal antebrachial fascia. Minimization of surgical trauma results in decreased postoperative morbidity and earlier return to work and daily activities. Symptomatic carpal tunnel syndrome. Revision surgery after open or endoscopic procedure, rheumatic diseases. Small transverse incision at the ulnar border of the palmaris longus tendon, and proximal to the distal wrist flexion crease. Exposure and incision of the antebrachial fascia, dilatation of the carpal tunnel and dissection of synovial tissue from the undersurface of the TCL. With the wrist in extension, the endoscopic blade assembly with integrated camera is inserted into the canal. Exposure of TCL and short incision in the middle portion. Gradually, dissection of the distal portion of the TCL then completion by retraction of the blade distally to proximally. Slightly compressive dressing, selfcare on day1 after procedure. More than 25years of experience, more than 8000 treated patients, and 3 documented cases with intraoperative lesions of the median nerve requiring revision. High acceptance and patient satisfaction in AQS1patient-reported surveillance.

Bilateral carpal tunnel syndrome and motor dysfunction caused by gout and type 2 diabetes: A case report

Carpal tunnel syndrome (CTS) has been associated with gout and type 2 diabetes mellitus (T2DM). However, due to insufficient clinical understanding of gout-related CTS and reliance on the diagnostic importance of elevated serum uric acid levels, such cases are prone to missed diagnosis, misdiagnosis, and delayed treatment. In addition, the effect of T2DM on gout - induced carpal tunnel syndrome has not been reported. Herein, we present an unusual case of CTS and motor dysfunction caused by miliary tophaceous gout and T2DM. The patient presented to the hand and foot clinic with paresthesia of the fingers of both hands, especially at night. The patient was diagnosed with type 2 diabetes a month ago. Ultrasonography revealed bilateral transverse carpal ligament thickening with median nerve compression during hospitalization. The patient was successfully treated with carpal tunnel decompression and tendon release. The postoperative pathological examination revealed typical gout nodules. This case suggests that the presence of T2DM could accelerate tophi formation and worsen CTS symptoms, although no definitive proof in this regard has been described previously. Tophi formation may most likely cause the co-occurrence of CTS and flexor dysfunction in gout and incipient diabetes patients.

Manipulative treatment of carpal tunnel syndrome: Biomechanical and osteopathic intervention to increase the length of the transverse carpal ligament.

To quantify the amount of transverse carpal ligament (TCL) elongation in response to osteopathic manipulation or sustained load bearing (or both), a study involving seven cadaver limbs was conducted. Distances from the trapezium to the hamate (distance A) and from the scaphoid to the pisiform (distance B) were measured in five mounted cadaver limbs during and after the limbs bore the weight (2 newtons [N] to 4 N) for 2 several-hour periods. A several-hour period occurred between the weight bearing to assess recoil. Distances A and B were measured before and after the limbs were manipulated, according to previously described techniques, as well as with a new maneuver, termed the "guy-wire" technique. Two dissected limbs also were subjected to further weight bearing, this time increased to 8 N. Greater weight loads produced greater lengthening of the TCL, and recoil after removal of weight loads was slower than recoil after manipulation. Manipulation was more effective than weight loading for increasing distance A (distal canal), but weight loading generally was more effective than manipulation for increasing distance B (proximal canal). The guy-wire manipulation combined with direct transverse extension appeared to have the greatest impact on lengthening the TCL distally. These results show promise for the effective use of manipulation and load bearing for TCL elongation and nonsurgical relief of pressure on the median nerve in patients with carpal tunnel syndrome.

Trapezial Fractures and Associated Fractures of the Ulnar Carpus: A Ring-Bone Model.

Fractures of the trapezium are rare; however, the incidence may be under-reported in the literature. The incidence of ulnar-sided carpal body fractures as a concomitant injury has not been reported. Our study aimed to evaluate the incidence of trapezium fractures in conjunction with ulnar-sided carpal body fractures. Over a five-year period, our electronic records were queried and charts reporting carpal bone fractures were reviewed. All cases of trapezium fracture were evaluated further and presented. Eight trapezial fractures were identified, representing 8% of all carpal fractures and 26% of all nonscaphoid carpal fractures. Of the eight trapezium fractures identified, five (62.5%) were associated with Bennett fracture and four (50%) were associated with ulnar-sided carpal fractures. Our study demonstrates a higher incidence of trapezial fractures than previously reported. Previously unreported concomitant ulnar-sided carpal body fractures are reported at a frequency nearly equal to that of concomitant Bennett fractures in our series. We propose a mechanism of injury where the carpal canal and overlying transverse carpal ligament function as a ring-bone construct similar to the pelvis. When a trapezium fracture is identified, we recommend additional evaluation for ulnar-sided injuries of the carpus.

Anatomic Study of the Motor Branch of the Ulnar Nerve Regarding Carpal Tunnel Surgery: A Cadaveric Study.

Background: Motor branch of the ulnar nerve (MUN) injury during carpal tunnel surgery is rare and it should never be injured during carpal tunnel release (CTR). However, an iatrogenic injury of the MUN can cause catastrophic physical and mental suffering. The aim of our study is to understand the anatomy of the MUN in relation to carpal tunnel in order to prevent iatrogenic injury during CTR. Methods: We dissected 34 fresh cadaver hands and located the MUN in relation to the anatomical axis used for carpal tunnel surgery. Possible mechanisms of injury and the vulnerable area of the MUN were determined along the dissection. Results: The MUN turned towards the thumb distal to hook of hamate. It then travelled on the floor of the carpal tunnel which was formed by intrinsic hand muscles under flexor tendons. The nerve located at 29.39 ± 7.41, 35.01 ± 3.14 and 38.79 ± 4.03 mm (Mean ± SD) in the central axis of ring finger, the vertical axis of the third web-space and the central axis of middle finger respectively. The nerve's turning point, 10.9 ± 2.63 mm distal to the centre of hook of hamate where it lies just below the level of the transverse carpal ligament. Conclusions: Surgeons should be aware of the nerve's location. Surgical dissection or passing of any surgical instruments around the hook of hamate should be done with care. Level of Evidence: Level IV (Therapeutic).