Bilateral Tensor Fasciae Suralis Muscles in a Cadaver with Unilateral Accessory Flexor Digitorum Longus Muscle

Abstract

Muscle variants are routinely encountered in the dissection laboratory and in clinical practice and therefore anatomists and clinicians need to be aware of their existence. Here we describe two different accessory muscles identified while performing educational dissection of a 51-year-old male cadaver. Tensor fasciae suralis, a rare muscle variant, was identified bilaterally and accessory flexor digitorum longus, a more common muscle variant, was present unilaterally. Tensor fasciae suralis and accessory flexor digitorum longus are clinically relevant muscle variants. To our knowledge, the coexistence of tensor fasciae suralis and accessory flexor digitorum longus in the same individual has not been reported in either cadaveric or imaging studies.

“Popliteofascial muscle” or rare variant of the tensor fasciae suralis?

“…In contrast, the TFS is one of the least frequently observed muscles in the lower limb. It has been identified using both sonograpy and MRI [4,9,12] and during anatomical studies [1,2,6,22,24,26,29], and its origin and insertion are morphologically highly variable (Table 1; Fig. 3).…”

“…AMs are usually asymptomatic and encountered as incidental findings; however, some have been implicated as potential sources of clinical symptoms [17]. When it occurs, the TFS is clinically significant because it can cause swelling in the popliteal fossa [1,12]. In addition, its location between the hamstring tendons in the popliteal region can mimic a Baker's cyst on physical examination [4,12].…”

“…In addition, its location between the hamstring tendons in the popliteal region can mimic a Baker's cyst on physical examination [4,12]. Moreover, as the TFS is located close to the neurovascular bundle, it can compress the popliteal vein, popliteal artery, sciatic nerve, tibialis or sural nerve [1,9,26,27]; this can be mistaken for soft tissue tumors or aneurysms of the popliteal artery or abscesses [12]. Although no electrostimulation research has been carried out, it has been suggested that the TFS assists in flexion of the leg and places tension on the fascia of the posterior leg [29].…”

An online catalog of muscle variants: Student perceptions of a new opportunity for self-directed learning

“…Indeed, 2 case reports that were first created for inclusion within our online catalog have been published in anatomical journals. 53,61 As exemplified as early as the works of Vesalius, the desire to document unique anatomical variations has existed among anatomists for centuries. 62 Digital preservation of cadaveric material is a natural manifest of this same spirit, as it serves as a more modern means of documenting variation.…”

Accessory Muscles of the Extremities

“…Accessory muscles of the lower limb Insertion: Variable, either posterior fasciae of the leg, medial head of the gastrocnemius, or superficial part of the Achilles tendon25 • Potential symptoms: Palpable popliteal mass, mimicking soft tissue tumor or Baker's cyst,24 potential vascular compression of the popliteal vein or artery, and nerve compression of the sciatic, tibial, and sural nerves was also suggested26 …”