Variation in Gantzer muscle origin, insertion, and innervation

Abstract

Gantzer muscles are inconsistent muscular variations in the anterior forearm. When present, Gantzer muscles usually arise from the flexor digitorum superficialis (FDS) and insert into the flexor pollicis longus (FPL) or, less often, the flexor digitorum profundus (FDP). The presence of Gantzer muscles can cause a compressive neuropathy affecting the anterior interosseous nerve (Kiloh‐Nevin syndrome), and these muscles must be considered when anterior forearm fasciotomies are performed for the management of acute compartment syndrome. While Gantzer muscles have been commonly reported, many studies neglect to report the innervation of the muscle and its relationship with nearby nerves. This study assessed 40 forearms from 20 cadaveric specimens to determine the prevalence of the origin and insertion of the Gantzer muscle. Furthermore, innervation was assessed along with the potential for nearby nerve compression. Gantzer muscles were present in 26 of 40 (65.0%) forearms, and all of the 22 intact muscles originated from the FDS, after noting four proximal attachments were damaged during student dissections. Concerning the 24 intact distal attachments of the Gantzer muscles, 20 (83.3%) muscles inserted into the FPL, two (8.3%) muscles inserted into the FDP solely, and one (4.2%) inserted at both the FDP and FPL. In addition, one forearm presented with duplicated and bifurcated Gantzer muscles with one tendon inserting into the FDP and the other one into the FPL. The innervation of the 21 Gantzer muscles was identified with the anterior interosseous nerve innervating 16 muscles (76.2%). In the five remaining Gantzer muscles, four (19.0%) were innervated solely by the median nerve, and one (4.8%) had a dual innervation from both of the two aforementioned nerves. In the one forearm with a bifurcated Gantzer muscle, the authors agreed upon an inherent anatomical predisposition for median nerve entrapment.Support or Funding InformationWest Virginia University Initiation to Research Opportunities (WVU – INTRO); WV Research Challenge Fund [HEPC.dsr.17.06] and [HEPC.dsr.14.13]This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.