Background and ObjectiveThe course and branches of the median nerve (MN) in the wrist vary widely among the population. Due to significant differences in the reported prevalence of such variations, extensive knowledge on the anatomy of the MN is essential to avoid iatrogenic nerve injury. Our aim was to determine the prevalence rates of anatomical variations of the MN in the carpal tunnel and the most common course patterns and variations in its thenar motor branch (TMB).Study DesignA systematic search of all major databases was performed to identify articles that studied the prevalence of MN variations in the carpal tunnel and the TMB. No date or language restrictions were set. Extracted data was classified according to Lanz's classification system: variations in the course of the single TMB—extraligamentous, subligamentous, and transligamentous (type 1); accessory branches of the MN at the distal carpal tunnel (type 2); high division of the MN (type 3); and the MN and its accessory branches proximal to the carpal tunnel (type 4). Pooled prevalence rates were calculated using MetaXL 2.0.ResultsThirty-one studies (n = 3918 hands) were included in the meta-analysis. The pooled prevalence rates of the extraligamentous, subligamentous, and transligamentous courses were 75.2% (95%CI:55.4%-84.7%), 13.5% (95%CI:3.6%-25.7%), and 11.3% (95%CI:2.4%-23.0%), respectively. The prevalence of Lanz group 2, 3, and 4 were 4.6% (95%CI:1.6%-9.1%), 2.6% (95%CI:0.1%-2.8%), and 2.3% (95%CI:0.3%-5.6%), respectively. Ulnar side of branching of the TMB was found in 2.1% (95%CI:0.9%-3.6%) of hands. The prevalence of hypertrophic thenar muscles over the transverse carpal ligament was 18.2% (95%CI:6.8%-33.0%). A transligamentous course of the TMB was more commonly found in hands with hypertrophic thenar muscles (23.4%, 95%CI:5.0%-43.4%) compared to those without hypertrophic musculature (1.7%, 95%CI:0%-100%). In four studies (n = 423 hands), identical bilateral course of the TMB was found in 72.3% (95%CI:58.4%-84.4%) of patients.ConclusionsAnatomical variations in the course of the TMB and the MN in the carpal tunnel are common in the population. Thus, we recommend an ulnar side approach to carpal tunnel release, with a careful layer by layer dissection, to avoid iatrogenic damage to the TMB.
The demand for anatomical illustrations in the early modern period coincided with a scientific revolution. Starting out as a servant, Iulius Casserius became a great anatomist, who challenged the Galenic doctrine. The aim of this paper is to honor his memory and recreate the stylism of his anatomical illustrations. Online databases were searched for articles and original works. A medical graphic designer then recreated the figures presented in the article. Casserius was born around 1552. After moving to Padua, he served Fabricius in performing dissections. Obtaining his medical degree, he began working as an anatomical dissector and surgeon, later giving private anatomy lectures to students. He published De Vocis Auditusque and Pentaestheseion, and then became the lecturer of Surgery. In 1616, Casserius started his first Anatomy course and then died suddenly, at the height of his career. From the sixteenth century, illustrative techniques began focusing less upon artistry in favor of precise depictions of anatomical structures. Fabricius is considered to have used a strict scientific approach to illustrations for the first time. Anatomists of subsequent generations would still frequently use artistry in illustrations. Despite Casserius' mixed accuracy and artistry, his plates mark a new epoch in anatomic representation. Casserius left numerous eponyms and depicted, for the first time, many anatomical structures. Reprints in textbooks in the centuries following show convincing evidence of his success. Casserius contributed to medical education by taking the theatricality out of anatomy. Our article is a tribute to Casserius's achievements and depicts the revolution brought forth by a pioneer of his times.
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