[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Anatomy](https://durgical.com/en/anatomy/) › [Lower limb](https://durgical.com/en/anatomy/region/lower-limb/) › Semimembranosus tendon [Muscular system](https://durgical.com/en/anatomy/system/muscular-system/) · [Lower limb](https://durgical.com/en/anatomy/region/lower-limb/) # Semimembranosus tendon The semimembranosus tendon is the hamstring tendon that wraps the back inner corner of the [tibia](https://durgical.com/en/anatomy/tibia/) and tightens the back of the knee capsule. Official name: Tendon of semimembranosus [See in 3D →](https://durgical.app/?from=durgipedia&lang=en#region=lower_limb&select=semimembranosus_tendon&side=r) Opens in the Durgical app, no sign-up needed. ## What it is The broad hamstring tendon wrapping the back inner corner of the tibia. ## What it does Helps bend the knee and turn the shin inward; supports the knee from the inner side. ## Key points - Its tendon divides into several arms (often described as five) that tension the posteromedial capsule and pull the [medial meniscus](https://durgical.com/en/anatomy/medial-meniscus/) backward as the knee bends - Baker's cyst: joint fluid escapes through a slit between this tendon and the tendon of the medial head of gastrocnemius; on ultrasound, a cyst neck between the two tendons confirms it - Tendinopathy at its insertion on the back of the medial tibial condyle is an under-recognised cause of pain at the back of the inner knee ## Key facts **Attaches** Main insertion in the posterior groove of the medial tibial condyle; expansions to the oblique popliteal ligament, posterior capsule, medial meniscus and [popliteus](https://durgical.com/en/anatomy/popliteus-muscle/) fascia **Function** Knee flexion and medial rotation; hip extension; stabilizes the posteromedial corner; the semimembranosus–gastrocnemius bursa between it and the medial gastrocnemius is where a Baker cyst forms **Tight in** Hip flexion with the knee extended ## Relations **Superficial** [Semitendinosus tendon](https://durgical.com/en/anatomy/tendon-of-semitendinosus/), which lies on it **Lateral** [Medial head of gastrocnemius](https://durgical.com/en/anatomy/medial-head-of-gastrocnemius/), with the [semimembranosus](https://durgical.com/en/anatomy/semimembranosus-muscle/) –gastrocnemius bursa between them; further out, the [popliteal artery](https://durgical.com/en/anatomy/popliteal-artery/), [popliteal vein](https://durgical.com/en/anatomy/popliteal-vein/) and [tibial nerve](https://durgical.com/en/anatomy/tibial-nerve/) **Deep** Posterior knee [joint capsule](https://durgical.com/en/anatomy/articular-capsule-of-knee-joint/) and the [oblique popliteal ligament](https://durgical.com/en/anatomy/oblique-popliteal-ligament/) **Medial** Superficial MCL, under which its anterior (tibial) arm passes ## How to find it Prone with the knee bent against resistance, it is felt as the broad tendon on either side of and deep to the [semitendinosus](https://durgical.com/en/anatomy/semitendinosus-muscle/) cord; its insertion is felt just below the joint line on the back of the medial tibial condyle. ## On imaging MRI shows its arms around the posteromedial corner, and insertional tendinopathy as thickening, high signal or bone oedema; axial images show a Baker's cyst between it and the medial gastrocnemius tendon. ## Common problems - Strains or tendinitis, mostly in sports with sprinting or kicking. ## How it is diagnosed Physical exam; ultrasound or MRI if needed. ## Treatment - Rest, ice and progressive physical therapy. ## Clinical notes - Posteromedial corner injuries often accompany ACL tears; ramp lesions of the medial meniscus lie close to where its capsular arm attaches - A separate [semimembranosus bursa](https://durgical.com/en/anatomy/semimembranosus-bursa/), between the tendon and the tibia, can also swell and mimic a Baker's cyst ## Related conditions - [Baker's (Popliteal) Cyst](https://durgical.com/en/conditions/baker-s-cyst/) - [Hamstring Strain](https://durgical.com/en/conditions/hamstring-strain/) ## Test yourself Think of the answer, then tap the question to see it. ## Where is the main insertion of the semimembranosus tendon? In the posterior groove of the medial tibial condyle, with expansions to the oblique popliteal ligament, posterior capsule and medial meniscus. ## Through which gap does a Baker's cyst communicate with the knee joint? Between the semimembranosus tendon and the tendon of the medial head of gastrocnemius. ## What does the semimembranosus do to the medial meniscus as the knee bends? Its arms tension the posteromedial capsule and pull the medial meniscus backward. [Add to my cards (3)](https://durgical.app/estudiar/?add=/en/anatomy/tendon-of-semimembranosus/) Educational information, not medical advice. For any symptom, see a health professional. ## Its names **Official Latin (TA2)** musculus semimembranosus TA2 2642 **Official Spanish (DeCS)** Tendón del semimembranoso DeCS D013710 **English (TA2)** Tendon of semimembranosus **Also called** musculus semimembranaceus ## Related - [MCL](https://durgical.com/en/anatomy/tibial-collateral-ligament/) - [Semimembranosus](https://durgical.com/en/anatomy/semimembranosus-muscle/) - [Femur](https://durgical.com/en/anatomy/femur/) - [Tibia](https://durgical.com/en/anatomy/tibia/) Sources: Terminologia Anatomica (TA2); [DeCS](https://decs.bvsalud.org/es/ths/resource/?id=14088); [Anatomy, Bony Pelvis and Lower Limb, Hamstring Muscle](https://www.ncbi.nlm.nih.gov/books/NBK546688/); [Anatomy, Bony Pelvis and Lower Limb: Posterior Thigh Muscles](https://www.ncbi.nlm.nih.gov/books/NBK542215/). ## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake Representative model, for educational purposes only. --- Source: https://durgical.com/en/anatomy/tendon-of-semimembranosus/ License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/anatomy/tendon-of-semimembranosus/