Semimembranosus muscle
3042881
222654698
2008-06-30T13:28:42Z
Vedran12
7322109
interwiki hr
{{Muscle infobox |
Name = Semimembranosus muscle |
Latin = musculus semimembranosus |
GraySubject = 128 |
GrayPage = 479 |
Image = Semimembranosus muscle.PNG |
Caption = Muscles of the gluteal and posterior femoral regions. Semimembranosus labeled at bottom left. |
Image2 = Gray432 color.png |
Caption2 = Semimembranosus labeled at bottom right. |
Origin = [[Ischial tuberosity]] |
Insertion = Medial surface of [[tibia]] |
Action = [[Hip]] [[Extension (kinesiology)|extension]], [[Knee]] [[flexion]] |
Antagonist = [[Quadriceps muscle]] |
Blood = [[profunda femoris]], [[gluteal artery]] |
Nerve = [[sciatic nerve]] |
MeshName = |
MeshNumber = |
DorlandsPre = m_22 |
DorlandsSuf = 12550673 |
}}
The '''semimembranosus''' is a [[muscle]] in the back of the [[thigh]]. It is the most medial of the three [[hamstring]] muscles.
==Structure==
The semimembranosus, so called from its membranous tendon of origin, is situated at the back and medial side of the [[thigh]].
It arises by a thick tendon from the upper and outer impression on the tuberosity of the ischium, above and lateral to the [[biceps femoris]] and [[semitendinosus]].
The tendon of origin expands into an [[aponeurosis]], which covers the upper part of the anterior surface of the muscle; from this aponeurosis muscular fibers arise, and converge to another aponeurosis which covers the lower part of the posterior surface of the muscle and contracts into the tendon of insertion.
It is inserted mainly into the horizontal groove on the posterior medial aspect of the medial condyle of the [[tibia]].
The tendon of insertion gives off certain fibrous expansions: one, of considerable size, passes upward and lateralward to be inserted into the back part of the lateral condyle of the femur, forming part of the oblique popliteal ligament of the [[knee-joint]]; a second is continued downward to the fascia which covers the [[Popliteus muscle]]; while a few fibers join the tibial collateral ligament of the joint and the fascia of the leg.
The muscle overlaps the upper part of the popliteal vessels.
==Innervation==
The semimembranosus is innervated by the tibial part of the [[sciatic nerve]].
==Actions==
The semimembranosus helps to extend (straighten) the [[hip joint]] and flex (bend) the [[knee joint]]. It also helps [[medially rotate]] the knee.
==Variations==
It may be reduced or absent, or double, arising mainly from the [[sacrotuberous ligament]] and giving a slip to the femur or [[adductor magnus]].
==Additional images==
<gallery>
Image:Gray235.png|Right hip bone. External surface.
Image:Gray259.png|Bones of the right leg. Posterior surface.
Image:Gray551.png|The popliteal, posterior tibial, and peroneal arteries.
Image:Gray1239.png|Back of left lower extremity.
</gallery>
==See also==
* [[Semitendinosus]]
* [[Biceps femoris]]
==External links==
* {{MuscleLoyola|semm}}
* {{SUNYAnatomyLabs|14|st|04|08}}
* {{SUNYAnatomyFigs|14|01|07}} - "Muscles (hamstrings) of the [[posterior compartment]] of the [[thigh]]."
* {{SUNYAnatomyFigs|14|02|06}} - "Muscles that form the superficial boundaries of the [[popliteal fossa]]."
* {{DartmouthAnatomy|knee/surface/surface4}}
* [http://www.ptcentral.com/muscles/musclelegs.html#semimembranosus PTCentral]
{{Gray's}}
{{Muscles_of_lower_limb}}
[[Category:Thigh muscles]]
[[de:Musculus semimembranosus]]
[[fr:Muscle semi-membraneux]]
[[he:השריר החצי קרומי]]
[[hr:Poluopnasti mišić]]
[[it:Muscolo semimembranoso]]
[[pl:Mięsień półbłoniasty]]
[[fi:Puolikalvoinen lihas]]
[[sl:Polopnasta mišica]]