Sheath of Distal Tendon of Semimembranosus Muscle and it's Functional Significance

Abstract

Introduction: Semimembranosus (SM) muscle is important in maintaining the stability of knee joint, and the distal end of it's tendon is not only complex but has been described differently in the available literature, which is quite perplexing. How a muscle with such divergent attachments can efficiently perform it's functions? Hence a detailed study of the distal semimembranosus tendon unit was undertaken. Material and Methods: One hundred lower limbs (Rt-50; lt.-50) were utilized for the present study. The posterior surface of SM was exposed and as the main tendon could not be traced to its insertion hence a vertical incision was made on the posterior surface of this tendon and this lead to the splitting of the tendon-sheath which exposed the thick shining distal tendon of SM. Results: Surprisingly, it was found that the main tendon of the SM (SMT) was surrounded by a fibrous sheath which was derived from the main muscle mass in the lower part of the thigh and in the majority of cases it was separated from it by a synovial space. Traced inferiorly it was observed that it is the sheath that spreads out to various divergent destinations described in the literature, whereas the main tendon gets attached to the groove on the posterior aspect of the medial condyle of tibia and a rough triangular area below the groove. Discussion and Conclusion: It is the nature's ingenuity that a single muscle with such divergent distal attachments can still efficiently perform its functions due to the formation of a sheath of distal tendon of SM.

Variations in the branching pattern of tibial nerve in foot: a review of literature and relevant clinical anatomy

“…We also observed that the origin of the MCN was highly variable. The MCN has been reported to branch inside the TT [20,23,27,30,34,41,52,62,77], or proximal to it [18,20,57,73,77].…”

“…MPN and LPN) has also been noted if the origin of the MCN is very high or low [20,21,30,75]. Authors have classified the bifurcation of TN into five types, of which type I (bifurcation proximal to the MCA but in the TT) is most frequent [7,15,32,35,36,41,52,54,71,77,78]. Some have also measured the distance of the bifurcation from the MCA and found it usually to be within 2 cm proximal to the axis [7,18,52,77].…”

“…2): type I -the bifurcation is proximal to the axis and inside the TT; type II -the TN bifurcates at the axis; type III -the bifurcation is distal to the axis and inside the TT; type IV -the bifurcation is proximal to the axis and outside the TT; type V -the bifurcation is distal to the axis and outside the TT. We collected data on the prevalence of the different types of bifurcation described in several studies (Table 3) [7,15,20,27,31,32,35,36,41,52,54,62,71,73,78].…”

“…Many have also classified the bifurcation into types (Fig. 2) [7,15,20,27,32,35,36,41,52,54,62,73,78]. The TT is an osseo-fibrous tunnel that houses the aforesaid terminal branches of the TN, which frequently undergo compression, causing an entrapment neuropathy known as TT syndrome [25,49].…”

Transcutaneous medial plantar nerve stimulation in women with idiopathic overactive bladder

“…2 ). Correct positioning was determined by noting a hallux reaction (plantar flexion of the big toe or, rarely, fanning of the fingers) [ 14 15 16 17 18 ]. The stimulation protocol was applied at a continuous mode of 20 Hz and a pulse width of 200 µs [ 7 9 13 ].…”