# The vessel that was supposed to disappear

Press gently on your wrist, where you'd take your pulse: underneath the skin, two arteries usually run there, the radial and the ulnar. In a recent cadaveric study, a third one was also present in **43% of limbs**: the median artery, a vessel that normally regresses during embryonic development, well before birth. In some of the limbs where it stays, it runs through the carpal tunnel and can become the sole blood supply of a finger. A surgeon who isn't looking for it risks cutting it.

Source: Ellis, Thibault, Lencke and Hemric, "Prevalence and anatomical significance of the persistent median artery: A cadaveric study," *PLOS One*, 31 March 2025.

## Documented facts

- A study of 56 adult cadavers (89 measurable limbs out of 112): a persistent median artery was present in 43% of limbs — 28% antebrachial-type, 15% palmar-type.
- The artery forms around the fifth week of embryonic development and normally regresses by the eighth week.
- When the palmar type is present, the superficial palmar arch is significantly wider: 2.47 mm versus 2.02 mm (p = 0.03).
- Hand and wrist injuries account for 11–22% of emergency-department visits in the United States.

## From one vessel, to three, to just two

In the fourth week of embryonic development, the arm is a small bud, and the hand doesn't have a hand's shape yet. The brachial artery branches for the first time in the fifth week: one of those branches, the median artery, feeds the forming hand at this stage. The radial and ulnar arteries develop alongside it and gradually take over. By the eighth week, in most embryos, the median artery regresses. In the rest, it stays.

## Where the artery that never disappeared ends up

Of the 43 limbs in 100 where the median artery stays: in 28 of 100 (antebrachial type), the vessel ends somewhere in the forearm, before the wrist. In 15 of 100 (palmar type), it crosses the carpal tunnel and reaches the palm, where it can become the sole blood supply of a finger.

## The vessel leaves a mark on the arteries around it

- Superficial palmar arch: 2.02 mm without the palmar type, 2.47 mm with it (p = 0.03, a significant difference in this sample).
- Ulnar artery: 2.75 mm without the palmar type, 3.02 mm with it (p = 0.08, a trend only).

## A secondary finding: your left arm barely predicts your right

The left arm's radial-artery diameter explains only 9.8% of the variation in the same artery's diameter on the right arm (r² = 0.098); for the ulnar artery, the link is even weaker (r² = 0.005).

## The risk for a surgeon who isn't looking for it

In an ordinary carpal tunnel release, the surgeon cuts the ligament covering the tunnel. If a palmar-type median artery is present and has become the sole blood supply of a finger, accidentally tying it off or cutting it can lead to necrosis. A link between the palmar type and carpal tunnel syndrome has been proposed, but causation remains unproven. This page explains the anatomy; medical decisions stay with the surgeon.

## What this study doesn't cover

The 56 cadavers were between 62 and 100 years old at death; information about their medical history was not available. The overall rate of 43% sits close to a prior meta-analysis (Solewski and colleagues, 10,394 limbs, which reported 8.6% palmar-type and 34.0% antebrachial-type separately, summing to about 42.6%), but the split between types differs a great deal: this study found nearly double the palmar-type share against a much larger meta-analysis sample.

## Sources

- Ellis, Thibault, Lencke, Hemric — "Prevalence and anatomical significance of the persistent median artery: A cadaveric study," *PLOS One* 20(3):e0320288, 31 March 2025. https://journals.plos.org/plosone/article?id=10.1371%2Fjournal.pone.0320288
- Solewski, Lis, Pękala et al. — "The persistent median artery and its vascular patterns: A meta-analysis of 10,394 subjects," *Clinical Anatomy* 34:1173–1185, 2021. https://pubmed.ncbi.nlm.nih.gov/34371525/
- Anatomical plate — Henry Vandyke Carter, *Anatomy of the Human Body* (Gray's Anatomy, 1918), public domain, via Wikimedia Commons.

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Romanian edition: https://mariuscomper.uk/vasul-care-trebuia-sa-dispara/