The distal semimembranosus complex: normal MR anatomy, variants, biomechanics and pathology.
OBJECTIVE
To describe the normal MR anatomy and variations of the distal semimembranosus tendinous arms and the posterior oblique ligament as seen in the three orthogonal planes, to review the biomechanics of this complex and to illustrate pathologic examples.


CONCLUSIONS
The distal semimembranosus tendon divides into five tendinous arms named the anterior, direct, capsular, inferior and the oblique popliteal ligament. These arms intertwine with the branches of the posterior oblique ligament in the posterior medial aspect of the knee, providing stability. This tendon-ligamentous complex also acts synergistically with the popliteus muscle and actively pulls the posterior horn of the medial meniscus during knee flexion. Pathologic conditions involving this complex include complete and partial tears, insertional tendinosis, avulsion fractures and bursitis.
Beltran
Javier
J
Department of Radiology, Maimonides Medical Center, 4802 Tenth Avenue, Brooklyn, NY 11219, USA. jbeltran46@msn.com
Matityahu
Amir
A
Hwang
Ki
K
Jbara
Marlena
M
Maimon
Ron
R
Padron
Mario
M
Mota
Javier
J
Beltran
Luis
L
Sundaram
Murali
M
D001696:Biomechanical Phenomena; D006801:Humans; D007717:Knee / Q000033:anatomy & histology*; D007718:Knee Injuries / Q000175:diagnosis; D007719:Knee Joint / Q000502:physiology; D008279:Magnetic Resonance Imaging; D018482:Muscle, Skeletal / Q000033:anatomy & histology* / Q000293:injuries; D013710:Tendons / Q000033:anatomy & histology