Knee Surgery, Sports Traumatology, Arthroscopy https://doi.org/10.1007/s00167-018-5265-z HIP Anatomy of proximal attachment, course, and innervation of hamstring muscles: a pictorial essay Karolina Stępień1 · Robert Śmigielski2,3 · Caroline Mouton4 · Bogdan Ciszek5,6 · Martin Engelhardt7 · Romain Seil4,8 Received: 12 July 2018 / Accepted: 23 October 2018 © European Society of Sports Traumatology, Knee Surgery, Arthroscopy (ESSKA) 2018 Abstract Hamstring injuries are very common in sports medicine. Knowing their anatomy, morphology, innervation, and function is important to provide a proper diagnosis, treatment as well as appropriate prevention strategies. In this pictorial essay, based on anatomical dissection, the detailed anatomy of muscle–tendon complex is reviewed, including their proximal attachment, muscle course, and innervation. To illustrate hamstrings’ role in the rotational control of the tibia, the essay also includes the analysis of their biomechanical function. Level of evidence V (expert opinion based on laboratory study). Keywords Hamstring · Hamstring anatomy · Hamstring injury · Muscle · Biceps femoris · Semimembranosus · Semitendinosus · Posterior thigh · Sciatic nerve Introduction and skiing [3, 4], but can be observed in the general non- sporting population as well [50]. Males and professional Hamstring injuries are one of the most common prob- football players are particularly at risk of hamstring inju- lems in sports medicine. Their prevalence is estimated to ries [4, 50], which cause on average more than 14 days reach 12–15% among professional football players [22, of time loss from sports participation (range 1–128 days) 28, 87] and increases by 4% annually in this group [31]. It [29]. Although different prevention programs have been is also a major problem of track and field sports, dancing developed, the reinjury risk remains unacceptably high (12–63%). The majority of reinjuries occur at the same location of the hamstrings complex than the primary Electronic supplementary material The online version of this article (https ://doi.org/10.1007/s0016 7-018-5265-z) contains supplementary material, which is available to authorized users. * Karolina Stępień 3 MIBO Foundation-The International Institute for Orthopaedic [email protected] Research, Twarda 4, 00-105 Warsaw, Poland Robert Śmigielski 4 Department of Orthopaedic Surgery, Centre Hospitalier [email protected] Luxembourg, Clinique d’Eich. 78, rue d’Eich, 1460 Luxembourg, Luxembourg Caroline Mouton [email protected] 5 Department of Descriptive and Clinical Anatomy, Centre of Biostructure Research, Medical University of Warsaw, Bogdan Ciszek Chałubińskiego 5, 02-004 Warsaw, Poland [email protected] 6 Department of Neurosurgery, Prof. Bogdanowicz Children Martin Engelhardt Hospital, Niekłańska 4/24, 03-924 Warsaw, Poland [email protected] 7 Department of Orthopaedics, Trauma and Hand Surgery, Romain Seil Osnabrück Clinic, Am Finkenhügel 1, 49076 Osnabrück, [email protected] Germany 1 Department of Orthopedics, Carolina Medical Center, Pory 8 Sports Medicine Research Laboratory, Luxembourg Institute 78, 02-757 Warsaw, Poland of Health, 78 rue d’Eich, 1460 Luxembourg, Luxembourg 2 Mirai Institute, Wolska 96, 01-126 Warsaw, Poland Vol.:(0123456789)1 3 Knee Surgery, Sports Traumatology, Arthroscopy injury [33, 52, 81, 85]. The common mechanisms of injury the complex was also analysed to bring a fresh perspective are indirect trauma, running and stretching [34]. on this problematic anatomic entity of lower leg. Most of the injuries in football and athletics occur in the midportion of the hamstring muscle–tendon complex [21, The proximal attachment of the hamstrings 30]. Avulsions of the proximal attachment area differ from the above. They have a different injury mechanism and are The semitendinosus (ST), long head of the biceps femo- often caused by a forced hyperextension [7, 8, 16, 20]. ris (long head, lhBF) and semimembranosus (SM) muscles Hamstring tendons are also among the most frequently originate from the ischial tuberosity (Fig. 1a, b). The ST and harvested grafts for ligament reconstructions. Even though lhBF have a common origin on the posteromedial aspect of they have a high capacity for regeneration [73], functional the ischial tuberosity, over its top. Tendons of the ST and deficits after hamstring tendon harvesting remain common. lhBF are conjoined at a distance of 9.1–10 cm [35, 37, 58, It may induce a reduction of knee flexion, extension and 81]. The SM origin is separate from the previous one and internal rotation [44, 74]. it is located anterolaterally from the ST/lhBF attachment. Recent biomechanical investigations have suggested Fibres of the proximal SM attachment are twisted before that the hamstring muscle–tendon complex plays an forming a proper tendon (Figs. 2a, b, 3a, b, 4). important role in controlling the rotational stability of the A majority of authors agree with the presence of a con- knee. Ultimately, they also play a role in the prevention of joined tendon of the ST/lhBF, but the precise description of the valgus collapse observed in severe knee injuries such its attachment area varies amongst authors. Most of authors as the anterior cruciate ligament (ACL) injuries. Indeed, observed the attachment on the posteromedial aspect of the hamstrings turn out to be the main ACL agonists and pro- ischial tuberosity as in our dissection [61, 68, 82], whereas tectors of the ACL [89, 90]. others indicated it to be directly medial [10, 58] or lateral on A better understanding of the anatomy of the hamstring the ischial tuberosity [35, 60]. Consequently, the SM attach- muscle complex may help to provide a better diagnosis, ment is also described in different ways: on the anterolateral treatment as well as appropriate prevention strategies. The aspect of the ischial tuberosity as in our dissection [61, 68, aim of this article, based on anatomical dissection, was to 82, 84], but also anteriorly [35] or purely lateral [58]. provide a detailed review of the anatomy of muscle–ten- We observed the shape of the ST/lhBF attachment as don complex, including their proximal attachment, muscle being oval and of the SM footprint as a crescent-shaped course, and innervation. This kind of essay with clear and being wider than the ST/lhBF—similar to most of the useful photographic documentation has not been reported authors [58, 61, 68, 82]. in the literature previously. The biomechanical function of The ischial tuberosity is also the area of the distal attach- ment of a sacrotuberous ligament (STL)—an elastic and Fig. 1 a, b Posterior view of the gluteal region and the proximal part of the posterior thigh of a right lower extremity. (1) Gluteus maximus muscle; (2) semitendinosus muscle; (3) ischial tuberosity; (4) sciatic nerve; (5) perineal branches of the posterior femoral cutaneous nerve 1 3 Knee Surgery, Sports Traumatology, Arthroscopy dynamic structure [40, 83]. Fibres of the STL are descend- ing from the sacrum to the ischial tuberosity in continuity with fibres of the lhBF [12, 58, 68] (Fig. 5). In the proximal hamstring attachment area, two main bur- sas can be identified. The bursa of the ischial tuberosity cov- ers a prominent part of the ischiatic bone [24, 38, 57]. The bursa of the proximal biceps femoris can be found between the common attachment of the ST/lhBF and the SM fill- ing the space between proximal tendons close to their bony attachment [14](Figs. 6, 7a–c). The proximal attachment of short head of biceps femo- ris (shBF) arises on the middle third of femur. Its origin is located on the lateral lip of the linea aspera, descending distally and laterally [17]. Course of the muscles Semitendinosus muscle The semitendinosus muscle (ST) lies in the posteromedial area of the thigh. It runs distally and medially from its proxi- mal insertion on the ischial tuberosity and lies directly on the SM. From its origin, the ST creates a conjoined tendon with the lhBF forming an aponeurosis. The muscle belly of the ST is fusiform (from external aspect) and has a characteristic oblique or V-shaped raphe (tendinous inscription) [41, 43, Fig. 2 a, b Posterolateral view of the area of the proximal attach- 51, 82, 86]. The distal tendon starts below the mid-thigh ment of the hamstring muscles (right lower extremity). (1) Area of and runs around the medial condyle of the tibia to its distal the attachment of the conjoined tendon of the semitendinosus and the insertion as a part of pes anserinus (Fig. 8). long head of the biceps femoris; (2) the proximal attachment area of the conjoined tendon; (3) conjoined tendon of the semitendinosus and Semimembranosus muscle the long head of the biceps femoris—cut and rotated 180°; (4) proxi- mal tendon of the semimembranosus muscle; (5) area of the attach- ment of the semimembranosus muscle; arrowheads—shape of the The semimembranosus muscle (SM) lies posteromedially in semimembranosus attachment the thigh and has a similar location as the ST. It starts on the Fig. 3 Proximal tendons of the hamstring muscles—dorsal (a) and abdominal (b) view with indicated direction of the fibres (lines: ST—blue, lhBF—red, SM—white). (1) The conjoined tendon of the semitendinosus and the long head of the biceps femoris; (2) the proximal tendon of the semimembranosus muscle 1 3 Knee Surgery, Sports Traumatology, Arthroscopy Fig. 4 Posterolateral view on the area of the proximal attachment of Fig. 6 Lateral view of the area of the ischial tuberosity (right lower the hamstring muscles. (1) Area of the attachment of conjoined ten- extremity). (1) Sacrotuberous ligament; (2) superficial bursa of the don of the semitendinosus and the long head of the biceps femoris; ischial tuberosity; (3) tendon of the long head of the biceps femoris; (2) area of the attachment of the semimembranosus muscle; (3) quad- (4) sciatic nerve; (5) perineal branches of the posterior femoral cuta- ratus femoris muscle neous nerve; (6) nerve branch to the bursa of the ischial tuberosity and distal tendons of the lhBF are overlapping [82].