European Journal of Cardiovascular Medicine

The median artery is considered a remnant of the original axial stem of the limb. Its formation is likely influenced by a variety of factors, including specific cell adhesion molecules, transcription factors, mechanical forces, as well as processes of vascular regression and remodeling. These elements play a crucial role during the early stages of embryogenesis, contributing to the establishment of the initial vascular architecture. Consequently, the persistence of this vascular framework in adulthood accounts for the presence of the persistent median artery (PMA)¹.

The median artery is a transient vessel that serves as the principal arterial supply to the forearm during early embryonic development. Typically, this artery regresses by the end of the second month of gestation. However, in some individuals, the median artery persists into adulthood, exhibiting two distinct anatomical patterns: the palmar type, characterized by a long vessel that extends to the hand, and the antebrachial type, which is shorter and terminates before reaching the wrist.

Functionally, the median artery has been debated in terms of its role. It may act as a nutrient artery for the median nerve or serve as an arteria comitans—a satellite artery that primarily supplies structures other than the median nerve. Thus, the terms “median artery” and “arteria comitans nervi mediani” can be considered synonymous.

The persistence of the median artery in adults is viewed as a retention of a primitive arterial configuration. The palmar type reflects the complete retention of the embryonic pattern, while the antebrachial type indicates partial regression, typically to the middle or lower third of the forearm. This suggests that the regression of the median artery occurs in a distal-to-proximal manner. In its most regressed form, the median artery may still function as a muscular trunk supplying the flexor muscles of the forearm, a feature common to both persistence patterns².

This cadaveric study was conducted at the Department of Anatomy, Indira Gandhi Medical College and Research Institute, Pondicherry after due approval of Institutional Ethics Committee. A total of 40 upper limb specimens from 12 cadavers and 16 separate upper limbs were included in the investigation. The dissection protocol followed was: First, a transverse incision was made at the middle of the arm, which was subsequently connected with a longitudinal incision running down the center of the anterior surface of the forearm. The skin, the subcutaneous tissue and antebrachial fascia were incised and reflected. The forearm muscles were separated and retracted. The pronator teres was cut at the incision site and retracted. The flexor digitorum superficialis muscle belly was rotated to expose the median nerve and the neurovascular bundle.

If a vessel accompanying the median nerve was observed, it was considered a persistent median artery (PMA). Findings regarding the frequency of PMA, its anatomical type, origin, termination, and relation to the anterior interosseous nerve (AIN), as well as any instances of PMA piercing the median nerve, were documented and photographed.

In this descriptive study examining the prevalence and morphological characteristics of persistent median artery (PMA), a total of 40 forearms were analysed. The presence of PMA was observed in seven forearms (17.5%), with a slight predilection for the left side (n=4) compared to the right side (n=3). The origin of the PMA demonstrated variation between the right and left forearms. In right-sided specimens, all three PMAs originated from the common interosseous artery (CIA). Conversely, left-sided PMAs exhibited a more diverse origin pattern, with two arising from the CIA and two from the anterior interosseous artery (AIA).

The extent of the PMA varied among the specimens: in right-sided forearms (n=3), all three PMAs extended to the middle of the forearm whereas in left-sided forearms (n=4), two specimens showed PMA extended up to mid-forearm and in one specimen up to distal forearm and in the other specimen, up to the wrist. Notably, none of the observed PMAs reached the superficial palmar arches.  Of the seven PMAs identified, two exhibited a crossing relationship with the anterior interosseous nerve (AIN), one passed beneath the AIN and the other passed above the AIN.

The prevalence of the persistent median artery (PMA) exhibits substantial variability across diverse populations and studies, with reported rates ranging from 1.5% to 60%. In the present study, a prevalence of 17.5% (n=7/40) was observed. This finding aligns with the moderate range of prevalence reported in the literature. However, the range of reported prevalence is remarkably wide. Singla et al.³ reported the lowest frequency at 6.6% (n=4/60), followed by Agarwal et al.⁴ at 11.53% (n=6/52), and Khan and Shrestha⁵ at 12% (n=6/50). Moderate to high prevalence rates were documented by Saenz et al.⁶ and Lucas et al.⁷, with 20.83% (n=25/120) and 33.3% (n=26/78), respectively. Notably higher prevalence rates were reported in studies conducted by Berskys and Suchomlinov⁸ at 62.5% (n=10/16) and Aragao et al.⁹ at 81.25% (n=26/32). Strikingly, Matsunaga et al.¹⁰ found an exceptionally high prevalence of 98% (n=98/100) in their study. These disparate findings underscore the considerable variability in PMA prevalence across different study populations and methodologies.

The present study identified seven median arteries, all of which were classified as the antebrachial type. This finding aligns with observations from Khan and Shrestha (n=6) and Matsunga et al. (n=98), who reported similar results^5,10. In contrast, studies conducted by Karlsson and Niechajev (n=5) and Singla et al. (n=4) exclusively observed the palmar type^11,3. Notably, Agaro et al. (n=26), Berskys and Suchomlinov (n=10), and Saenz et al. (n=25) reported the presence of both types in their respective cohorts^9,8,6.

An intriguing observation was made by Kopuz C and Baris S¹², who found that all five median arteries in infant dissections were of the palmar type, while no median arteries were observed in 35 adult cadaver dissections. This finding supports the hypothesis that the median artery typically regresses around the eighth week of intrauterine life, transforming into a small nervi comitans artery. Consequently, the incidence of median arteries may differ between neonates and adults, suggesting that atrophy of the median artery might continue postnatally.

The considerable variability in the prevalence and type frequency of median arteries across studies may be attributed to disparate identification criteria. For instance, Henneberg and George¹³ documented the presence of a median artery only when it supplied structures in the hand beyond the median nerve and its branches, potentially excluding antebrachial type arteries from their analysis. This methodological heterogeneity underscores the need for standardized criteria in future investigations to facilitate more accurate comparisons across studies.

The present study reveals that the common interosseous artery (CIA) serves as the primary origin of the median artery (MA), accounting for 71.4% (n=5/7) of cases, while the anterior interosseous artery (AIA) is the source in the remaining 28.5% (n=2/7). These findings align with previous research, albeit with varying percentages. Aragao et al. and Berskys and Suchomlinov similarly reported the CIA as the predominant source (38.5% and 50%, respectively), followed by the AIA (34% in Aragao et al.'s study) and the ulnar artery (40% in Berskys and Suchomlinov’s work)^9,8.

Conversely, several studies have identified the AIA as the primary origin of the MA, including Singla et al. (100%), Henneberg and George (60%), and Matsunga et al. (33%)^3,13,10. Other researchers have observed alternative primary sources: Sanez et al. (48%) and Kopuz C and Baris S (80%) reported the ulnar artery as the major origin^6,12. Notably, Henneberg and George¹³ documented the radial artery as the source in 7.69% (n=2/26) of MA cases, while Khan and Shrestha⁵ observed an atypical origin from the posterior interosseous artery in 83.3% (n=4/6) of MA instances.

These diverse findings underscore the anatomical variability of the MA’s origin, highlighting the need for comprehensive understanding in clinical and surgical contexts. Further research with larger sample sizes may elucidate the factors contributing to this variability and its potential clinical implications.

In the present study, no instances of median artery (MA) penetration of the median nerve were observed; rather, in all specimens, the MA supplied the nerve while coursing alongside it. Additionally, two MA (28.57%, n=2/7) were found to supply neighboring muscles in the forearm. These findings contrast with several previous studies that documented median nerve penetration by MA. Sanez et al. reported a 60% (n=15/25) incidence of MA penetrating and dividing the median nerve in the forearm⁶. Singla et al. observed a 25% (n=1/4) rate of median nerve penetration by MA, while Berskys and Suchomlinov noted a 10% (n=1/10) incidence^3,8. Agarwal et al., focusing solely on hand dissections, found that the presence of MA was consistently associated with early branching of the median nerve, early branching of the second common digital nerve, and multiple motor branches to thenar muscles⁴.

Regarding the relationship between MA and the anterior interosseous nerve (AIN), the current study found one MA (14.28%, n=1/7) anteriorly related to the AIN and one MA (14.28%, n=1/7) posterior to it. These findings differ from those of previous studies, which reported a higher prevalence of anterior relationships. Berskys and Suchomlinov observed 90% (n=9/10) of MA passing anterior to the AIN and only 10% (n=1/10) posterior⁸. Similarly, Matsunga et al. reported a majority (80.6%, n=79/98) of MA passing anterior to the AIN, with a smaller proportion (10.2%, n=10/98) passing posteriorly¹⁰. The discrepancy between these findings and those of the present study may be attributed to variations in sample size or potential anatomical differences in the studied populations.