The forearm is a body region of numerous anatomical variations. Due to its favorable anatomy flexor digitorum superficialis muscle (FDS) is commonly used in tendon transfer surgeries. In this study a unique combination of abnormalities was found in a single forearm: the flexor digitorum superficialis muscle penetrated by the median nerve, one of the flexor digitorum superficialis tendons early division and absence of the palmaris longus muscle. Described variation potentially may lead to the clinical manifestation of the median nerve compression and should be also considered during FDS surgery

Klimek-Piotrowska, Wiesława

Koziej, Mateusz

Lis, Maciej

Solewski, Bernard

Walocha, Ewa

Walocha, Jerzy

English

Jagiellonian Univeristy Repository

FOLIA MEDICA CRACOVIENSIAVol. LVIII, 1, 2018: 107–111PL ISSN 0015-5616Th e median nerve penetrating through the radial head of the fl exor digitorum superfi cialis muscle: Case reportMaciej Lis1, Bernard Solewski1, Mateusz Koziej1, Ewa Walocha2, Jerzy A. Walocha1, Wiesława Klimek-Piotrowska11Department of Anatomy, Jagiellonian University Medical College, Kraków, Poland2Department of Clinical Nursing, Institute of Nursing and Obstetrics, Jagiellonian University Medical CollegeKraków, PolandCorresponding author: Maciej LisDepartment of Anatomy, Jagiellonian University Medical Collegeul. Kopernika 12, 31-034 Kraków, Poland Phone/Fax: +48 12 422 95 11; E-mail: maciej97.lis@gmail.comAbstract: Th e forearm is a body region of numerous anatomical variations. Due to its favorable anatomy fl exor digitorum superfi cialis muscle (FDS) is commonly used in tendon transfer surgeries. In this study a unique combination of abnormalities was found in a single forearm: the fl exor digitorum superfi cialis muscle penetrated by the median nerve, one of the fl exor digitorum superfi cialis tendons early division and absence of the palmaris longus muscle. Described variation potentially may lead to the clinical mani-festation of the median nerve compression and should be also considered during FDS surgery. Key words: anatomic variation, fl exor digitorum superfi cialis, median nerve; palmaris longus; tendon transfer. IntroductionTh e median nerve originates from a fusion of medial (C8–T1) and lateral (C5–C7) roots in the axillary fossa. It travels distally in medial bicipital sulcus of the arm together with the brachial artery as a neurovascular bundle. It descends to the cubital fossa and then traverses three consecutive structures — the bicipital aponeurosis, Y  — shaped convergence formed by heads of pronator teres muscle and second Y  —  shaped 108 Maciej Lis, Bernard Solewski, et al.convergence, but now formed by the heads of fl exor digitorum superfi cialis (FDS). Th en it situates between the fl exor digitorum profundus and fl exor digitorum superfi cialis muscles [1]. In the lower part of the forearm, the median nerve lies more superfi cially, due to FDS muscle turning into separate tendons. Just before entering the hand the median nerve is covered anteriorly by fascia of forearm and partially by the palmaris longus muscle tendon. Laterally it goes with the fl exor pollicis longus tendon which lies near the tendon of fl exor carpi radialis [2].Th e aim of this report is to present a  rare anatomical variation in which the median nerve travels through the forearm piercing a belly of FDS muscle. Although the median nerve variations are described in the literature, the cases of the forearm variations are fairly uncommon. Case reportDuring a  routine anatomical dissection in Department of Anatomy in Jagiellonian University Medical College (Kraków, Poland), an unusual variation on the course of the median nerve was found in a male’s right upper limb (Fig. 1). Th e nerve typically Fig. 1. Discovered course of the median nerve — scheme. Th e median nerve penetrating through the radial head of the fl exor digitorum superfi cialis muscle… 109passed between two heads of pronator teres and then entered the space between the fl exor digitorum superfi cialis and profundus with the ulnar artery in accordance with its typical path. Its following course was, however, unusual. Instead of a  classic path, in which it lies under the dorsal surface of the fl exor digitorum superfi cialis, the median nerve entered this muscle and passed through its radial head (Fig. 2). It pierced muscle tissue over a distance of 11.2 cm. It left  the muscle on the radial side, heading towards the radial artery.Fig. 2. Unusual course of the median nerve through the forearm. A — Medial view on the right forearm. (FDP) fl exor digitorum profundus, (UA) Ulnar artery, (UN) Ulnar nerve, (FDS) fl exor digitorum superfi cialis. Arrowheads indicate the normal pathway of the median nerve (MN). B — Magnifi ed area marked with white rectangle depicted in A. Early division of separate tendon (ST) from the FDS is shown. (MN) Median nerve.Other unusual anatomical features were also noticed in the examined forearm: an absence of palmaris longus muscle as well as an early division of one of the tendons of the fl exor digitorum superfi cialis, which in the carpal tunnel joined a  bundle of tendons of the fl exor digitorum profundus.DiscussionAs to the authors knowledge, a case of the median nerve penetrating muscle tissue of the fl exor digitorum superfi cialis has been described just once previously [3, 4].110 Maciej Lis, Bernard Solewski, et al.Th e muscles of the upper limb including the fl exor digitorum superfi cialis develop from somites and are identifi able by 7th week of embryonic development. Th e nerves enter the limb by the 5th week of embryonic development. Th e median nerve arises from the cubital fossa between the two heads of the pronator teres muscle. Its branch, going to the flexor digitorum superficialis muscle goes off before passing under the tendinous arch of the fl exor digitorum superfi cialis [5]. In this case, the above mentioned branch was not separated from the median trunk, but all median nerve fi bres have entered muscle tissue of the fl exor digitorum superfi cialis muscle.Interestingly, there has been an inverse situation reported by Skie and Ciocanel [6], that means the fl exor digitorum superfi cialis pierced the median nerve. In that case the anatomical anomaly was clinically manifested by the symptoms of median nerve compression. In our case, since the medical records were not available, we can only assume that activities requiring numerous repetitive or single prolonged and forced contractions of the flexor digitorum superficialis might have led to a  temporal occurrence of the symptoms of median nerve compression. Paresthesia and general disturbances of feeling on palmar side of the hand within the range of neuration of the median nerve, as well as disorders of muscles supplied by its motoric part might have occured.Due to its favorable anatomy [7], FDS is commonly used in tendon transfer surgeries. Th e middle fi nger portion of the muscle is independent, therefore it can be used in non-synergistic tendon transfers, as opposed to other fi nger tendons, which can be used for synergistic transfers. Since FDS tendon transfers require a division of tendons, the risk of damaging the median nerve which pierces muscle tissue might be increased. In non-synergistic transfers of the middle fi ngers tendon of FDS Boyes [8] recommended suturing tendons under maximum tension to provide better fi nger extension, however it entails more tension also in the rest of FDS. Th e postoperative complications seem to be even more convincing, as described by Chuinard et al.  [9] and Richer and Peimer [10], such a situation might cause compression of the median nerve because of increased intramuscular pressure during contraction of FDS muscle. In our case, the occurrence of such condition would be probably significantly increased.Th e agenesis of the palmaris longus muscle is the most common variation of that muscle [11] with a  prevalenve of 10.3% (95% CI: 6.4–15.0) measured in cadaveric studies and 15.6% (95% CI: 11.5–20.3) measured in functional studies [12]. Th e palmaris longus muscle is also used as a  landmark for the median nerve localization during surgery [13]. Anomaly described in this case consisted of an absence of the palmaris longus muscle combined with such an unusual course of the median nerve that may cause some confusion during surgery.Cumul ative variations of the palmaris longus and the fl exor digitorum superfi cialis have been previously reported [11], however, a  pattern of the flexor digitorum  Th e median nerve penetrating through the radial head of the fl exor digitorum superfi cialis muscle… 111superfi cialis tendon joining the fl exor digitorum profundus tendons in the carpal tunnel described in this report contributes to exceptionality of the case.Confl ict of interestNo declared.References 1. Savastano L., Yang L.J.: Anatomy of the Median Nerve and Its Branches. Elsevier Ltd., 2014. 2. Mizia E., Tomaszewski K., Depukat P., et al.: Median nerve (anatomical variations) and carpal tunel syndrome — revisited. Folia Med Cracov. 2013; 53: 37–46. 3. Th ompson I.M.: Anomaly of median nerve and fl exor digitorum sublimis muscle. J Anat Physiol. 1923; 23: 375–379. 4. Tubbs R.S., Shoja M.M., Loukas M.: Human anatomic variations. Wiley Blackwell, 2016; 1085. 5. Elliot D., Khandwala A.R., Kulkarni M.: Anomalies of the fl exor digitorum superfi cialis muscle. J Hand Surg J Br Soc Surg Hand. 1999; 24: 570–574. doi: 10.1054/jhsb.1999.0237. 6. Skie M., Ciocanel D., Hedayat I., et al.: Anomaly of Flexor Digitorum Superfi cialis Penetrating Through the Median Nerve: Case Report. J Hand Surg Am. 2010; 35: 27–29. doi: 10.1016/j.jhsa.2009.09.010. 7. Agee J., McCarroll H.R., Hollister A.: Th e anatomy of the fl exor digitorum superfi cialis relevant to tendon transfers. J Hand Surg Br. 1991; 16: 68–69. 8. Boyes J.: Tendon Transfers for Radial Palsy. Bull Hosp Joint Dis. 1960; 21: 97–105. 9. Chuinard R.G., Boyes J.H., Stark H.H., Ashworth C.R.: Tendon transfers for radial nerve palsy: use of superfi cialis tendons for digital extension. J Hand Surg Am. 1978; 3: 560–570.10. Richer R.J., Peimer C.A.: Flexor superfi cialis abductor transfer with carpal tunnel release for thenar palsy. J Hand Surg Am. 2005; 30: 506–512. doi: 10.1016/j.jhsa.2004.12.010.11. Yammine K.: Clinical prevalence of palmaris longus agenesis: A systematic review and meta-analysis. Clin Anat. 2013; 26: 709–718. doi: 10.1002/ca.22289.12. Pękala P.A., Henry B.M., Pękala J.R., Skinningsrud B., Walocha J.A., Bonczar M., Tomaszewski K.A.: Congenital absence of the palmaris longus muscle: A meta-analysis comparing cadaveric and functional studies. J Plast Reconstr Aesthet Surg. 2017 Dec; 70 (12): 1715–1724. doi: 10.1016/j.bjps.2017.08.002.13. Bernardes A., Melo C., Pinheiro S.: A combined variation of Palmaris longus and Flexor digitorum superfi cialis: Case report and review of literature. Morphologie. 2016; 100: 245–249. doi: 10.1016/j.morpho.2016.03.002.

The median nerve penetrating through the radial head of the flexor digitorum superficialis muscle : case report

Walocha, Jerzy A.

Biblioteka Nauki - repozytorium artykuÅÃ³w

The median nerve penetrating through the radial head of the flexor digitorum superficialis muscle: Case report

https://ruj.uj.edu.pl/xmlui/bitstream/handle/item/143483/koziej_et-al_the_median_nerve_penetrating_2018.pdf?sequence=1&isAllowed=y

The median nerve penetrating through the radial head of the flexor digitorum superficialis muscle : case report

Abstract

Similar works

Full text

Available Versions

Jagiellonian Univeristy Repository

Biblioteka Nauki - repozytorium artykuÅÃ³w

The median nerve penetrating through the radial head of the flexor digitorum superficialis muscle : case report

Abstract

Similar works

Full text

Available Versions

Jagiellonian Univeristy Repository

Biblioteka Nauki - repozytorium artykuÅÃ³w

Biblioteka Nauki - repozytorium artykuÅÃ³w