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SemimembranosusMusculus semimembranosus

Broad, flat inner hamstring muscle lying under semitendinosus that bends the knee, extends the hip and turns the leg inwards.

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LatinMusculus semimembranosus
Origin
  • Upper, outer part of the ischial tuberosity, by a thick flat tendon
Insertion
  • Back of the medial condyle of the tibia
  • Medial margin of the tibia
  • Expansions to the back of the knee joint capsule (oblique popliteal ligament), the fascia over popliteus and the medial collateral ligament
Action
  • Flexes the knee
  • Extends the hip
  • Medially rotates the leg when the knee is bent
  • Medially rotates the thigh when the hip is extended
NerveSciatic nerve (tibial part) (L5–S2)
GroupHamstrings
NameLatin semi, 'half', and membranosus, 'membranous' — named for its flat, sheet-like tendon of origin.

Palpation

  1. Client prone with the knee bent to about 90° and the foot supported; stand beside the thigh.
  2. Find the pencil-like semitendinosus tendon on the inner side of the back of the knee.
  3. Place your fingers just either side of that tendon, slightly higher up; the broader, softer mass here is semimembranosus.
  4. Ask the client to bend the knee against light resistance; feel the wide muscle firm around the semitendinosus tendon.

Landmarks: Ischial tuberosity

Semimembranosus is the deepest and most medial of the Hamstrings. It lies under Semitendinosus but is wider, so its edges can be felt on either side of the semitendinosus tendon above the knee. Its tendon spreads out at the back of the knee into several expansions, one of which helps form the ligament across the back of the joint capsule.

Wikipedia lists the root levels as L5–S2 in its summary box, but describes the whole sciatic nerve as coming from L4–S3. The narrower L5–S2 range is the one usually given for this muscle.

Treat it together with semitendinosus in a routine. Near the back of the knee, keep your pressure broad and avoid the centre of the hollow, where the main nerve and blood vessels run.

Techniques

  • Effleurage — Long, gliding strokes with the whole palm that spread the medium, warm the tissue and link the other strokes together.
  • Petrissage — Kneading strokes that compress, lift and squeeze the muscle away from the bone, working the tissue between the hands.
  • Compression — Pressing straight down into a muscle with the palm, fist or forearm, holding briefly, then releasing and moving on.
  • Stripping — A slow, deep, narrow glide along the length of a single muscle with the thumb, knuckle or elbow, pausing over tight bands on the way.
  • PNF stretching — Assisted stretching that combines a passive stretch with an isometric contraction of the stretched muscle, and sometimes of the opposite muscle, before stretching further.

Works with

  • Semitendinosus — Inner hamstring muscle with a long, cord-like lower tendon that bends the knee, extends the hip and turns the leg inwards.
  • Biceps femoris — Two-headed hamstring muscle on the outer back of the thigh that bends the knee, and with its long head also extends the hip.
  • Gluteus maximus — The largest and most superficial buttock muscle, and the main extensor of the hip.
  • Popliteus — Small, flat, triangular muscle deep behind the knee that rotates the tibia or femur to "unlock" the straightened knee so it can bend.

Opposes

  • Quadriceps — Group of four large muscles on the front of the thigh that join into one tendon over the kneecap and are the only muscles that straighten the knee.
  • Rectus femoris — Spindle-shaped muscle down the middle of the front of the thigh, the only quadriceps muscle that crosses the hip, so it both flexes the hip and straightens the knee.

Same group

  • Biceps femoris — Two-headed hamstring muscle on the outer back of the thigh that bends the knee, and with its long head also extends the hip.
  • Semitendinosus — Inner hamstring muscle with a long, cord-like lower tendon that bends the knee, extends the hip and turns the leg inwards.

Used in routines

Sources

  1. Wikipedia: Semimembranosus muscle
  2. Wikipedia: Hamstring