ISSN: 2595-7651 Acta Sci Anat. 2019;1(3):190-194. A rare variation of the longest striated muscle in humans Istemihan Coban1, Ozge Topkul1, Lokman Ozturk1 ABSTRACT Sartorius muscle is the longest skeletal muscle of the body. The muscle starts from the anterior superior iliac spine. Its tendon is attached to the anteromedial part of the proximal tibia bone and ends around the tuberosity of the tibia, together with the tendon of the gracilis and semitendinosus muscle and forms the pes anserinus (goose foot). In short, this muscle extends downward from the outer surface of the os coxae (usually similar to the letter s), from the ASIS towards the leg, as such it passes over the hip and knee joints and acts on two of the largest joints of the body. We observed an unusual biventeric variation of this muscle in routine dissection program of assistant education programme. In this biventeric variation we observed that there were two separate muscle bundles starting around anterior superior iliac spine. The lateral muscle bundle extended more linearly towards the medial edge of the patella and terminated around the tibial tuberosity. The distal tendon portion of this lateral part was closely associated with the patellofemoral ligament and medial collateral ligament before ending in the anterior margin of tibia. The medial muscle bundle also started from the anterior superior iliac spine but the extension of this bundle was similar to the classical sartorius muscle extension. The medial part was mainly associated with pes anserinus. Keywords: sartorius muscle, variation, duplication INTRODUCTION CASE REPORT The name of the muscle originates from the During routine cadaver dissection performed Latin word 'sartor' which means 'tailor' [1]. The in the Department of Anatomy, Department of muscle extends obliquely from proximal to distal, Macroscopy, Ege University School of Medicine, it lateral to medial. The tendon of the muscle joins the was observed that a cadaver’s (fixed with %10 pes anserinus along with the tendon of the gracilis formalin solution) left sartorius muscle was and semitendinosus muscles and terminates composed of two portions (Figure 1). medially in the anterior edge of the tibia [1]. These two bundles of muscle fibers, namely It is innervated by the femoral nerve and a medial and a lateral part, started from the anterior supplied by the femoral artery. It acts on the hip and superior iliac spine (ASIS) and its periphery. Both knee joints. This muscle plays a role in thigh flexion, were extending medially. The lateral part was abduction and external rotation. It also plays a role shorter and narrower than the other. It was attached in the internal rotation and flexion of the leg as it to the medial aspect of the tibial head. The crosses the knee joint and is attachs to the tibia [2]. morphometric aspects are shown in Table 1. The tendon of this lateral part was in close relationship with the patellar ligament, patellofemoral ligament and medial collateral ligament of knee (Figure 1). The medial portion was adjacent to the 1Department of Anatomy, School of Medicine, Ege University, Turkey. Corresponding author: Istemihan Coban, MsC - [email protected] 191 Sartorius muscle variation lateral and started on the medial side of ASIS. The DISCUSSION muscle extended obliquely to the medial region. The tendon of the medial part of the sartorius, gracilis Sartorius muscle variation was researched and semitendinosus muscle formed the pes by Macalister in 1871 [3]. There are more recent anserinus. studies reporting sartorius variation in the literature There were no variations in the right side of [4-7]. the same cadaver (Figure 2). Figure 1: Medial aspect of left thigh, illustration (A) and dissection (B) (R: Rectus femoris muscle, P: Tendon of quadriceps femoris muscle, T: Tuberosity of tibia, L: Lateral part of sartorius muscle, M: Medial part of sartorius muscle, A: Adductor longus muscle, G: Gracilis muscle, PA: Pes anserinus/ goose foot, GA: Gastrocnemius muscle, medial head, Nf: Femoral nerve, Af: Femoral artery, Vf: Femoral vein). Table 1. Right and left sartorius muscle metric In 2011, Kedzia et al. divided the variations evaluation. Total muscle lengths were measured in into four groups in their study on fetuses. The first of centimeters. The widths of the muscles were these is the presence of accessory tendons proximal measured every three centimeters and averages of to the muscle, the second is the total duplication of these values were obtained. the muscle, the third is the double-headed distal part of the muscle, and the fourth is the presence of Right side Left Side discontinuous muscle [8]. Medial Lateral This study on fetuses suggests that the band band varying states of the muscle have a genetic Total 56.5 cm 56.5 cm 50.5 cm background. length In 2015, Moriyama et al stated that external Average 26.8 cm 23.97 cm 18.93 cm factors are effective in determining muscle width morphology, but the most powerful determinant is genetic background [9]. 192 Sartorius muscle variation Figure 2: Photograph of right and left thigh of the cadáver (S: Sartorius muscle, G: Gracilis muscle, R: Rectus femoris muscle, VM: Medial vastus muscle, M: Medial part of variative sartorius muscle, L: Lateral part of variative sartorius muscle). 193 Sartorius muscle variation In 1999, Garbelotti et al. reported that there rotation and extension limitation of the hip joint may be a relationship between accessory sartorius and/or knee joint and this variative condition should muscle and atrophic remains of pelvic bundle in be investigated. lower mammals. [10]. In 2019, Kim and Lee presented a case of variant sartorius in their study. They divided the variations of muscle into three CONFLICTS OF INTEREST types; sartorius bicaudatus, biceps sartorius and the combination of these two types [7]. The authors declare no conflicts of interest. In our case, the sartorius muscle was extending from proximal to distal as two separate ACKNOWLEDGMENTS bundles of fibers. This suggests that the muscle is leaned to the medial and lateral part during None. development. The two parts of the muscle started adjacent but separately. The locations where the lateral part and the medial part end were clearly REFERENCES different. In this respect, our case is similar to the combination of sartorius bicaudatus and biceps 1. Moore K, Dalley A, Agur A. Clinically oriented sartorius. anatomy. Lippincott Williams & Wilkins; 2013. However, there are some differences from 2. Standring S, Gray H. Gray's anatomy. 41st ed. those previously reported. In our case, the medial Edinburgh: Churchill Livingstone; 2015. and lateral parts were completely isolated. The 3. Macalister A. Observations on muscular tendinous part of the lateral part is wide and flat, it anomalies in the human anatomy. Trans R Ir Acad supports the knee joint like a kinesio tape. The Sci. 1871;25(1):130. tendinous part of the lateral bundle is flat and 4. El-Badawi M. An anomalous bifurcation of the supports the knee joint. It attaches to the medial sartorius muscle. Anatomischer Anzeiger. epicondyle of the femur, the medial condyle of the 1987;163(1):79-82. tibia and the external medial ligaments of the joint 5. Melling M, Zweymueller K. Musculus sartorius (also adheres to the patellar ligament). The medial bicaudatus. Cells Tissues Organs. 1996;155(3):215- bundle joined the pes anserinus. In this respect we 218. can call the medial bundle a true sartorius and the 6. Patil J, Kumar N, Swamy R, Guru A, Rao K, Aithal lateral bundle as an accessory muscle. The A. Unilateral accessory Sartorius muscle: A case accessory may assist in knee joint stability as well report on its functional and clinical implications. as knee joint movement. Saudi Journal of Sports Medicine. 2015;15(3):285. Sartorius muscle variations are clinically 7. Kim J, Lee J. A unique case of an accessory important. There may be changes in hip and knee sartorius muscle. Surgical and Radiologic Anatomy. joint movements in the presence of accessory 2019;41(3):323-325. sartorius muscle [7]. Long-term and unresponsive 8. Kedzia A, Walek E, Podleśny K, Dudek K. therapies may be continued if this variant is not Musculus sartorius metrology in the fetal period. Adv recognized. The sartorius muscle is also important Clin Exp Med. 2011;20(5):567-574. for reconstructive surgery. The use of the distal third 9. Moriyama H, Amano K, Itoh M, Matsumura G, of the sartorius muscle as an alternative for popliteal Otsuka N. Morphometric aspects of the facial and reconstructions has been proposed [11]. skeletal muscles in fetuses. International journal of In this case, the accessory muscle can be pediatric otorhinolaryngology. 2015;79(7):998-1002. used without leaving a significant defect. The effects 10. Garbelotti J, Rodrigues C, Nobeschi L, Seiji F, of this variation, which makes the joint appear Olave E. Anatomical variation of the Sartorius stronger against unhappy triad, should be muscle. Rev Chil Anat. 1999;17:95-97. investigated and kinesiologic evaluations should be 11. Manjunath K, Venkatesh M, Shivaprasad A. performed. The relationship between external Distal major pedicle of sartorius muscle flap: 194 Sartorius muscle variation Anatomical study and its clinical implications. Indian Association of Plastic Surgeons of India. journal of plastic surgery: official publication of the 2018;51(1):40. RESUMO Uma variação rara do mais longo músculo em humanos O músculo sartório é o músculo esquelético mais longo do corpo. O músculo começa na espinha ilíaca ântero-superior. Seu tendão é preso à parte ântero-medial do osso proximal da tíbia e termina ao redor da tuberosidade da tíbia, junto com o tendão do músculo grácil e semitendinoso e forma a pata de ganso. Em suma, este músculo se estende para baixo a partir da superfície externa do osso do quadril (geralmente semelhante à letra s), da espinha ilíaca ântero-superior para a perna, como tal, passa sobre as articulações do quadril e joelho e atua em duas das maiores articulações de o corpo.