The first description of the absence of the palmaris longus muscle.

Background: While Realdo Colombo from Cremona, Italy has, to date, been acknowledged to be the first to describe the possible absence of the palmaris longus muscle in men in 1559, the authors found this absence to be recorded in the first edition of "De Humani Corporis Fabrica Libri Septum" by Andreas Vesalius, published in 1543.

Method: To commemorate Vesalius' 500th birthday, this earlier record is quoted and discussed.

Results And Conclusion: It remains unknown whether the observation on the absence of the palmaris longus was first done by Vesalius or was based on joined work by Vesalius and Colombo.