Topics

Topic

design image
Distal semimembranosus tendon

The distal semimembranosus tendon is the terminal portion of the semimembranosus muscle, one of the three hamstring muscles. It plays an important role in stabilizing the posteromedial knee joint. The tendon expands into multiple slips that insert into the posteromedial tibia and joint capsule, providing both dynamic and static stabilization. Its broad insertion and close relationship to the posterior capsule and medial meniscus make it highly relevant in knee biomechanics and pathology.

Synonyms

  • Semimembranosus tendon (distal portion)

  • Posteromedial hamstring tendon

  • Distal hamstring attachment

Origin and Insertion

  • Origin: From the ischial tuberosity as part of the semimembranosus muscle belly (proximal origin)

  • Course: Distally, the tendon descends along the posteromedial aspect of the thigh, passing posterior to the medial femoral condyle and crossing the posteromedial knee joint

  • Insertion: Broad, complex distal insertions:

    • Posteromedial surface of the proximal tibia

    • Posterior oblique ligament of the knee

    • Joint capsule (capsular expansions)

    • Fascia over the popliteus muscle

    • Oblique popliteal ligament (key stabilizer of posterior knee)

Relations

  • Anteriorly: Posterior capsule of knee joint and medial tibial plateau

  • Posteriorly: Semitendinosus tendon and gracilis tendon

  • Laterally: Popliteus muscle and posterior cruciate ligament

  • Medially: Medial collateral ligament and medial meniscus

Nerve Supply

  • Tibial division of the sciatic nerve (L5–S2)

Arterial Supply

  • Perforating branches of the deep femoral artery

  • Inferior medial genicular artery (branch of popliteal artery)

Venous Drainage

  • Via corresponding genicular veins into the popliteal vein

Function

  • Provides posteromedial knee stability

  • Assists in knee flexion and hip extension (via semimembranosus muscle)

  • Reinforces posterior joint capsule via oblique popliteal ligament

  • Protects medial meniscus from excessive posterior translation

Clinical Significance

  • Tendinopathy and partial tears: common in athletes and older adults with degenerative changes

  • Medial meniscus pathology: due to close anatomic relation

  • Posteromedial corner injuries: tendon contributes to stability along with MCL and posterior oblique ligament

  • Surgical importance: Landmark in total knee arthroplasty and ACL/PCL reconstructions

  • Can mimic or be mistaken for cystic lesions when associated with bursitis (semimembranosus–gastrocnemius bursa)

MRI Appearance

T1-weighted images:

  • Distal tendon appears as a low-signal linear structure

  • Surrounded by bright fat, aiding contrast

  • Chronic tendinopathy shows focal thickening with low-to-intermediate signal

T2-weighted images:

  • Normal tendon: uniformly dark (low signal)

  • Pathology (edema, partial tear): focal or linear areas of bright signal intensity within or around the tendon

STIR (Short Tau Inversion Recovery):

  • Normal tendon: low signal

  • Pathology: bright hyperintensity indicating edema, tendinitis, or partial tear

Proton Density Fat-Saturated (PD FS):

  • Normal tendon: dark linear signal

  • Pathologic tendon: bright hyperintensity (tears, inflammation, bursitis)

T1 Fat-Sat Post-Contrast:

  • Normal tendon: minimal or no enhancement

  • Pathology: enhancement at tendon margins or insertion (tenosynovitis, enthesitis, post-traumatic changes)

  • Abscess or severe inflammation: rim enhancement

CT Appearance

Non-Contrast CT:

  • Tendon appears as a soft tissue density band inserting into posteromedial tibia

  • Calcification may be seen in chronic tendinopathy

  • Peritendinous fat helps delineation

Post-Contrast CT:

  • Normal tendon: no significant enhancement

  • Pathology: enhancing soft tissue thickening or peritendinous inflammatory changes

  • Chronic enthesopathy may show irregular calcifications and cortical bone changes at tibial insertion

MRI images

Distal semimembranosus tendon coronal cross sectional anatomy 3T MRI AI enhanced radiology anatomy image-img-00000-00000

MRI images

Distal semimembranosus tendon sag cross sectional anatomy 3T MRI AI enhanced radiology anatomy image-img-00000-00000

MRI images

Distal semimembranosus tendonaxial cross sectional anatomy 3T MRI AI enhanced radiology anatomy image-img-00000-00000

CT image

Distal semimembranosus tendon ct axial image

CT image

Distal semimembranosus tendon ct coronal image

CT image

Distal semimembranosus tendon ct sagittal image

MRI images

semimembranosus Tendon anatomy image 3t mri

MRI images

semimembranosus Tendon anatomy image