ANATOMICAL STRUCTURES IN THE RABBIT CARPAL TUNNEL: COMPARISON WITH HUMAN

Abstract

In this study, it was aimed to reveal the morphological and morphometric changes of anatomical structures passing through the carpal tunnel, which is an en­trapment neuropathy location for the median nerve. It was also aimed to evaluate the potential of rabbits as an animal model for carpal tunnel research. New Zealand rabbit cadavers were enrolled, and their wrists were investigated using the histological method in this study. ImageJ was used to measure histological sections stained with hemox­ylin-eosin. The carpal tunnel was examined at three levels: entrance, inside, and exit. Flexor retinaculum comprises two layers, encircling the carpal tunnel from the palmar side. The deep and superficial digital flexor tendons, and radial carpal flexor tendon were observed within the carpal tunnel but not the flexor pollicis longus tendon. The median and ulnar vascular nerve bundles reside between two layers of flexor retinaculum in the carpal tunnel. The areas of these anatomical structures were measured from images at three levels. Since the flexor retinaculum was located at the entrance and inside, the carpal tunnel area was measured at both levels. The narrowing in the area from the carpal tunnel entrance to the inside of the carpal tunnel in rabbits and the decrease in connective tissue bring the anatomical structures here closer together. This clearly demonstrates that the carpal tunnel is an entrapment neuropathy area, particularly for the median nerve. Upon comparing rabbit and dog car­pal tunnel anatomy, it has been shown that rabbits exhibit a greater resemblance to humans, particularly with regard to the flexor retinaculum. This study emphasizes the importance of using the rabbit model to gain insights into carpal tunnel syndrome. It demonstrates similarities between rabbit and human anatomy, underscoring the value of this animal model for future research. Anatomske strukture v karpalnem kanalu kunca: primerjava s človekom Izvleček: Cilj te raziskave je bil raziskati spremembe v morfologiji in morfometriji anatomskih struktur v karpalnem kanalu, natančneje na mestu ukleščenja medianega živca. Poleg tega smo želeli oceniti primernost kuncev kot živalskega mod­ela za študije karpalnega kanala. V ta namen smo uporabili trupla novozelandskih kuncev in opravili histološki pregled njihovih zapestij. Histološke rezine, obarvane s hematoksilinom in eozinom, smo analizirali s programom ImageJ za pridobitev meritev. Naš pregled je bil osredotočen na tri nivoje karpalnega kanala: vhod, notranjost in izhod. Karpalni kanal je obdan z dvema plastema flektornega retinakuluma na palmarni strani. Znotraj karpalnega kanala smo opazovali globoke in površinske kite upogibalk prstov in radialnih upogibalk zapestja, ne pa tudi tetiv dolge upogibalke. Žilni živčni snopi medianega in ulnarnega živca se nahajata med obema plastema flektornega retinakuluma znotraj karpalnega kanala. Da bi ocenili velikost teh anatomskih struktur, smo izmerili njihove površine na podlagi slik, posnetih na treh prej omenjenih ravneh.Ob upoštevanju prisotnosti flektornega retinakuluma smo meritev površine karpalnega kanala izvedli tako na vhodu kot znotraj kanala. Pri kuncih zožitev območja od vhoda do notranjosti karpalnega kanala skupaj z zmanjšanjem vezivnega tkiva povzroči, da se anatomske strukture približajo. To zagotavlja jasen dokaz, da je karpalni kanal mesto, kjer se pojavi utesnitvena nevropatija, ki posebej vključuje mediani živec. S primerjavo anatomije karpalnega kanala pri kuncih in psih je bilo ugotovljeno, da so kunci bolj podobni ljudem, zlasti v smislu flektornega retinakuluma. Ta raziskava poudarja po­men uporabe kunčjega modela za preučevanje sindroma karpalnega kanala, saj prikazuje podobnosti med kunčjo in človeško anatomijo ter poudarja pomen tega živalskega modela za prihodnje preiskave. Ključne besede: karpalni kanal; morfometrija; histologija; mediani živec; ulnarni živec; flektorni retinaculum