The median nerve is one of the most important peripheral nerves in the upper limb. It supplies most of the flexor compartment of the forearm and gives the hand important sensory and motor capabilities. The path it takes through the forearm is usually thought to be predictable, although many investigations have shown that there are many anatomical differences in its branching pattern, muscular interconnections, and neurovascular connections [1, 2]. Even while these differences don't often cause symptoms, they can have big effects on how doctors treat patients, especially during surgeries like carpal tunnel release, tendon transfers, decompression surgeries, and vascular interventions of the forearm. Unrecognized alterations from the standard anatomical configuration may result in iatrogenic damage, inadequate decompression, or erroneous interpretation during diagnostic assessments, including nerve conduction investigations or imaging [3, 4]. Variations pertaining to the anterior interosseous nerve (AIN), aberrant neuronal connections like the Martin–Gruber anastomosis, and supplementary muscular formations such as the Gantzer muscle are particularly significant. These changes might affect how nerve entrapments show up in patients, change the landmarks for surgery, and make regional anesthetic techniques more difficult. Additionally, it is important to know how the median nerve is connected to blood vessels, since being proximal to the radial, ulnar, and anterior interosseous arteries can raise the risk of neurovascular injury during invasive procedures [5, 6]. Even though anatomical variations are known to be important, their frequency and shape differ greatly amongst groups of people. Numerous prior investigations are constrained by inadequate sample sizes or insufficiently comprehensive classification of neurovascular patterns. Consequently, thorough cadaveric studies are necessary for cataloging the spectrum and prevalence of anatomical variants and for enhancing the reliability of anatomical references for medical practitioners [7, 8]. The goal of this study is to look into the neurovascular differences in the median nerve in the forearm by carefully dissecting 60 upper limbs. The project aims to improve anatomical knowledge and provide therapeutically useful information to make surgery safer, more accurate, and better planned in the forearm area by finding and grouping these differences.

This descriptive cadaveric research study was conducted on 60 upper limbs from 30 formalin-fixed adult cadavers available in the Department of Anatomy, Dr VRK Women’s Medical College, Teaching Hospital and Research Centre. This study was conducted between July 2023 to June 2024. Cadavers ranged in age from 45 to 75 years at the time of death. The study aimed to identify and categorize neurovascular variations of the median nerve and its branches within the anterior compartment of the forearm. Inclusion Criteria: • Cadavers with intact upper limbs suitable for dissection • Limbs without previous anatomical dissection in the forearm region • Adult cadavers aged 45–75 years Exclusion Criteria: • Limbs with visible deformities, congenital anomalies, or muscular atrophy • Previous surgical scars or orthopedic implants in the forearm • Evidence of trauma, infection, or pathological lesions affecting nerve integrity • Severely damaged or poorly preserved specimens Clinical Significance: • Helps surgeons during forearm decompression • Useful for regional anesthesia • Prevents iatrogenic nerve injury • Relevant for orthopedics and neurophysiology Statistical Analysis: All the data that was collected was looked at in a descriptive way. We counted and displayed the frequency and proportion of each neurovascular change in a table. Continuous measurements were represented as mean ± standard deviation. No inferential statistical tests were utilized, as the objective was solely observational. Results were compared with variations documented in current anatomical literature to evaluate prevalence and anatomical consistency.

We looked at 60 upper limbs from 30 adult cadavers in all. Several specimens showed differences in the median nerve, its branches, and other tissues that are connected to it. The following tables show a summary of the results. Table 1. Prevalence of Major Median Nerve Variations in the Forearm Variation Type Number of Limbs (n) Percentage (%) Presence of Gantzer muscle (Accessory head of FPL) 15 25% High origin of AIN 6 10% Common trunk giving AIN and muscular branches 3 5% Martin–Gruber Anastomosis 4 6.6% Aberrant vascular relationship (close adherence or crossing) 11 18.3% Median nerve splitting or bifurcation 0 0% Table 1 shows that the Gantzer muscle was the most common variation seen (25%). There was no full bifurcation of the median nerve. There were also a lot of differences connected to AIN and blood vessels. Table 2. Types and Frequency of Accessory Muscles Encountered Accessory Muscle Number of Limbs (n) Percentage (%) Relation to Median Nerve Gantzer muscle (Accessory head of FPL) 15 25% Superficial in 10 cases; deep in 5 cases Accessory belly of FDS 2 3.3% Crossed superficial to the median nerve Accessory palmaris longus slips 3 5% No compression noted Table 2 shows differences in muscles. The Gantzer muscle was most commonly observed and regularly positioned in proximity to the median nerve, potentially predisposing it to compression or modifying its trajectory. Table 3. Variations in the Anterior Interosseous Nerve (AIN) Origin and Branching AIN Variation Number of Limbs (n) Percentage (%) High origin of AIN (>3 cm above normal level) 6 10% AIN arising from a common trunk with muscular branches 3 5% Early branching into medial & lateral divisions 5 8.3% AIN with aberrant course (medial deviation) 2 3.3% Table 3 shows different ways that AIN might start and branch. High origin was the most common, happening in 10% of limbs. These changes may affect the clinical manifestations of AIN syndrome and surgical methodologies. Table 4. Vascular Relationships of the Median Nerve Vascular Variation Number of Limbs (n) Percentage (%) Median nerve superficial to ulnar artery 5 8.3% Median nerve closely adherent to anterior interosseous artery 6 10% Radial artery anomaly affecting nerve relation 2 3.3% Persistent median artery 0 0% Table 4 illustrates variations in neurovascular relationships, indicating that the median nerve is superficial to the ulnar artery in five limbs and closely associated with the anterior interosseous artery in six limbs. There was no middle artery that stayed the same. Table 5. Summary of Total Neurovascular Variations Identified per Limb Number of Variations per Limb Number of Limbs (n) Percentage (%) No variations 38 63.3% One variation 14 23.3% Two variations 6 10% Three or more variations 2 3.3% Table 5 shows how neurovascular variances are spread out in general. Most limbs (63.3%) had no differences, but about one-third (36.6%) did, and a small group had more than one variant at the same time, showing how unpredictable the anatomy of the area is. Figure 1. Anatomical variations of the median nerve and anterior interosseous nerve in the forearm. This composite illustration depicts four major neurovascular variations observed in the study. (A) Gantzer muscle (accessory head of flexor pollicis longus) superficial to the median nerve. The accessory head crosses over the median nerve before the origin of the anterior interosseous nerve (AIN). (B) Gantzer muscle with associated vascular variation. The accessory head lies adjacent to the median nerve, with the ulnar artery positioned unusually close to the AIN. (C) High-origin anterior interosseous nerve. The AIN branches from the median nerve more proximally than usual, coursing distally along the interosseous membrane. (D) Common trunk for the anterior interosseous nerve. The AIN arises from a shared trunk with additional muscular branches, with the ulnar artery lying in close relation to the neurovascular bundle.

The current study offers comprehensive insights into the neurovascular variations of the median nerve and its branches inside the anterior compartment of the forearm. Out of 60 investigated upper limbs, changes were noted in about one-third of the specimens (36.6%), indicating that deviations from classical anatomical descriptions are reasonably frequent. These findings corroborate the conclusions drawn from prior research, which documented significant diversity in the trajectory and branching pattern of the median nerve, underscoring its clinical significance [10-12]. A significant result in this study was the identification of the Gantzer muscle (accessory head of the flexor pollicis longus) in 25% of limbs. This incidence aligns with prior research, which have reported its existence in 20–65% of specimens, contingent upon demographic and methodology. In this study, the median nerve or its anterior interosseous branch (AIN) predominantly traversed superficially to this muscle, while in a minority of instances, it traversed deeply to it. Prior research has suggested that these associations may render the nerve susceptible to entrapment or exacerbate AIN syndrome, hence underscoring the therapeutic relevance of our findings [13-15]. The current investigation also revealed variations in the anterior interosseous nerve, with a high origin noted in 10% of cases and a common trunk in 5%. These findings are consistent with other anatomical studies that identified significant variability in the origin, branching pattern, and initial division of the AIN. Such variances may affect the manifestation of AIN neuropathies and should be taken into account during surgical planning, as indicated by prior research [16-18]. In this study, 18.3% of limbs had vascular alterations. For example, the median nerve was on top of the ulnar artery in some cases and very close to the anterior interosseous artery in others. Prior anatomical studies have documented heterogeneous neurovascular linkages in this area, underscoring the risks associated with arterial cannulation, vascular repair, and reconstructive surgeries. Interestingly, the current investigation did not find any persistent median artery, while earlier studies have indicated its occurrence in 2–20% of instances, underscoring population disparities and specimen variability [19, 20]. The presence of several variations in this study—23.3% of limbs presenting one variation and 13.3% displaying two or more—indicates that anatomical variability in the median nerve region is prevalent. This discovery aligns with prior observations indicating that the presence of numerous variants may enhance the probability of nerve entrapment and increase the risk of iatrogenic harm during surgical interventions [21, 22]. The current study, notwithstanding its merits, possesses drawbacks. The results derive from cadavers sourced from a particular region and may not comprehensively reflect the diversity of the wider population. Moreover, cadaveric investigations naturally lack functional assessment, distinguishing them from prior clinical research that correlated anatomical changes with symptomatic neuropathies. Subsequent investigations utilizing larger multicentric samples and radiological correlation may yield a more thorough comprehension [23, 24]. In conclusion, our investigation validates that neurovascular variants of the median nerve are prevalent and varied, with numerous findings that corroborate or enhance those documented in prior research. A comprehensive understanding of the anatomical variances is crucial to avert iatrogenic injuries and improve surgical accuracy in the forearm [25, 26].

The current study illustrates that neurovascular variations of the median nerve in the forearm are quite prevalent, occurring in almost one-third of the studied limbs. The most common observations were the presence of the Gantzer muscle, differences in where the anterior interosseous nerve comes from and how it branches, and different ways that main forearm arteries connect to each other. These findings align with other research that similarly highlights the anatomical diversity of the median nerve and its related tissues. The findings of this study underscore the therapeutic significance of identifying such variances, as they may lead to nerve compression syndromes, affect surgical landmarks, and elevate the risk of iatrogenic damage during procedures involving the flexor compartment of the forearm. Surgeons, anatomists, neurologists, and doctors who do regional blocks or vascular treatments need to have a deep awareness of these anatomical patterns. Funding None Conflict of Interest: None

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