Journal of the Anatomical Society of India 67 (2018) 130–132 Contents lists available at ScienceDirect Journal of the Anatomical Society of India journal homepage: www.elsevier.com/locate/jasi Original Article The effects of the communicating branch between medial and lateral plantar nerves on the innervations of the foot lumbrical muscles a b a a b, Cüneyt Bozer , Deniz Uzmansel , Didem Dönmez , Muhammed Parlak , Orhan Beger *, b Özlem Elvan a Trakya University, Faculty of Medicine, Department of Anatomy, Edirne, Turkey b Mersin University, Faculty of Medicine, Department of Anatomy, Mersin, Turkey A R T I C L E I N F O A B S T R A C T Article history: Introduction: The communicating branches between the medial (MPN) and lateral (LPN) plantar nerves Received 1 November 2017 aren’t frequently observed in relation to the innervation of the foot muscles in previous studies. In this Accepted 6 November 2018 study, the number and localization of the communicating branch on the innervations of foot muscles Available online 13 November 2018 were evaluated to open a new sight considering the innervations of lumbrical muscles. Material and methods: 30 formalin-fixed feet (15 right – 15 left feet), with an average age of 76 from the Keywords: inventory of Trakya and Mersin University Anatomy Departments in 2015 were dissected. The Lateral plantar nerve innervations of the lumbricals and the communicating branches were revealed and then photographed. Medial plantar nerve Results: In all feet, first lumbricals were observed to be innervated by MPN, while the remaining muscles Lumbrical muscles were innervated by deep branches of LPN. In four cadaveric feet, communicating branches of MPN, LPN Deep branch of lateral plantar nerve Communicating branch and deep branch of LPN were appeared but, in one of them, proximal to the branches of MPN and LPN to Foot lumbricals, a communicating branch between MPN and deep branch of LPN were observed. Discussion: Data about the innervations of the lumbricals were found to be consistent with the previous studies. Taking into account the localization of the communicating branches between the MPN and LPN, it should be considered that nerve injuries during surgical procedures such as flexor tendon transfers, island flap surgery, treatment of hallux valgus or lesser toes deformity in the foot and ankle region may unexpectedly lead to different functional failures. © 2018 Anatomical Society of India. Published by Elsevier, a division of RELX India, Pvt. Ltd. All rights reserved. 1. Introduction According to the standard text books of anatomy and previous research reports, the first lumbrical is innervated by the medial plantar Lumbrical muscles in the hands and feet were taken from the nerve(MPN)andtheremainderthreelumbricalsareinnervatedbythe 2,4–6 lumbricus, which is reffered to the meaning of worm in Latin, due to deep branch of the lateral plantar nerve (LPN) The variations of 1 4,6 the similarity in shape. The four lumbricals in foot, named by this innervations were reported rarely in the literature. Although numbering from the medial to the lateral, begin at tendons of flexor there are many studies evaluating the branching patterns of MPN and 5–8 digitorum longus and end to the dorsal digital expansions of LPN and communicating branches between plantar nerves, a direct 2 proximal phalanges of lesser toes. They provide extension of the relationship between lumbricals innervation and communicating 6 proximal and distal interphalangeal joint and flexion of the branches were reported only in the study of Akita et al. 2,3 metatarsophalangeal joint. However, due to the decrease in In the current study, considering the communicating branches muscle size and the increase in muscle spindles, it has been reported between MPN and LPN, it is planned to determine the innervations 3 that lumbricals perform a sensory function more than a motor. As a of the foot lumbricals and to interpret our data with a new sight. result, the lumbricals, the sensory and motor connection between 2. Materials and methods the flexor and extensor tendons are known to be contributing to the 2 3 movement of the feet during walking and stance. , In order to increase the number of dissected specimens, the study was performed in two different anatomy departments in Turkey from June to September 2015. With the collaboration of * Corresponding author at: Mersin University Faculty of Medicine, Department of Anatomy Departments of Trakya and Mersin Universities,11 and 19 Anatomy, Ciftlikkoy Campus, 33343, Mersin, Turkey. E-mail address: [email protected] (O. Beger). cadaveric feet were dissected under dissection microscope, https://doi.org/10.1016/j.jasi.2018.11.006 0003-2778/© 2018 Anatomical Society of India. Published by Elsevier, a division of RELX India, Pvt. Ltd. All rights reserved. C. Bozer et al. / Journal of the Anatomical Society of India 67 (2018) 130–132 131 respectively. Observations were made on 19 feet of 10 adult motor function, lumbricals should be considered as acting a 2,3 cadavers (8 males and 2 females, 9 right and 10 left feet) and 11 feet proprioceptive role due to the muscle spindles they possess. of 7 adult cadavers (6 males and 1 female, 6 right and 5 left feet) Thus, with this sensory and motor function, lumbricals provide an which were fixed by 10% formalin solution. Due to the deformation, important role in coordination of the movements of the foot 3 4 feet were excluded the study. during stance and gait. Lumbrical dysfunction, which occurs in In the dissection procedure, after careful removal of the tibial nerve injuries and hereditary motor-sensory neuropathies superficial part of the foot, including skin, subcutaneous fascia, such as Charcot-Marie-tooth disease, contributes to clawing of 2 9 10 plantar aponeurosis, flexor digitorum brevis muscle was cut from the toes. , , its origin. Then, abductor hallucis muscle was cut from its Although variations in innervation in the hand lumbricals are insertion. Starting from the muscular retinaculum, the detailed commonly seen, the innervation of the foot lumbricals is fairly 4 course of MPN and LPN were investigated. For the observation of constant. There are only two studies in the literature concerning 4,6 4 the dorsal surface of the muscles, quadratus plantae muscle was the variation of the innervations of the foot lumbricals. Brooks cut. The innervations of the lumbrical muscles and communicating reported a variation in innervation of the foot lumbricals only one branches between MPN and LPN were noted and then photo- case in 10. In that case, the first and second lumbricals were graphed. innervated by both MPN and the deep branch of LPN and also the third and fourth lumbricals were innervated by the deep branch of 4 3. Results LPN. In the same study, it was observed that for the lumbricals in 4 hand, there were 12 different innervations in 21 cases. In only one 6 In all thirty cadaveric feet, we could not find any variation of the 38 foot, Akita et al. reported a communicating branch different from the innervations of the lumbricals of the foot, between the deep branch of LPN and the branch of MPN that written in standard anatomical books. MPN innervated the first innervate the first lumbrical. We could not find any variation from lumbrical (Fig. 1a) and deep branch of LPN innervated the the innervations of the lumbricals of the foot, written in 2 11 remaining lumbricals (Fig. 1b). Communicating branches between anatomical text books. , However, communicating branches nerves were observed in 4 cases: between MPN, LPN and deep branch of LPN were detected in 4 cases. 1 case between MPN and MPN (between superficial branch of Data related to the incidence of communicating branches 7,8,12 MPN and the first common digital plantar nerve of MPN) between MPN and LPN is quite variable in the literature. 7 (Fig. 2a), Although Jones and Klenerman reported that there were 2 cases between the MPN and LPN (between the third common communicating branches between MPN and LPN in all 20 feet, 12 13 digital plantar nerve of MPN and the common digital plantar Levitsky et al. reported 19 of 71 feet (26.8%), Arakawa et al. 19 6 8 nerve of LPN) (Fig. 2b), and of 22 feet (86%), Akita et al. 2 of 38 feet (5.2%) and Govsa et al. 14 1 case between MPN and the deep branch of LPN (between first of 50 feet (28%). Although the vast majority of communicating common digital plantar nerve of MPN and deep branch of LPN) branches were usually superficial and distinct in previous 7,8,12 (Fig. 2c). studies, they were deeper and thinner fascicles in the study 6 13 8 of Akita et al. and Arakawa et al. In addition, Govsa et al. defined four types of communicating branches, based on the 4. Discussion course and anatomical features of the communicating branches between MPN and LPN. In our study, communicating branches The lumbricals function is described as extension of the between MPN and LPN were observed in 3 of 30 feet (10%). 8 proximal and distal interphalangeal joint and flexion of the Considering the classification of Govsa et al., two of them were 3 metatarsophalangeal joint. Compressing both metatarsophalan- interpreted as type 3 (Fig. 2b) where the communicating branch geal and interphalangeal joints provide a unique ability to the was between the third common digital plantar nerve of MPN and 9 lumbricals. In this way, the lumbricals, along with the other the fourth common digital plantar nerve of LPN. The other intrinsic muscles, may assist the control movements of the important communicating branch was between the first common 3 9 forefoot during stance and rear foot during gait. , In addition to digital plantar nerve of MPN and deep branch of LPN (Fig.