Changes

'''''Semimembranosus'''''

'''''Semimembranosus'''''

:'''Innervation'''

: Most medial muscle in the 'hamstring' group, it unites with the semitendinosus to form the caudal contour of the thigh. In the horse it has two heads, a '''vertebral head''' and stronger '''pelvic head'''.

:'''Origin'''

:'''Innervation''': Caudal gluteal n., Tibial n.

:'''Insertion'''

:'''Origin''':

:'''Action'''

::Pelvic Head - Ventral aspect of the ischial tuberosity

The semimembranous also originates from various points including the vertebral head (sacrotuberous ligament), 1st caudal vertebrae, pelvic head and the ventral aspect of ischial tuberosity. The two bellies of the muscle then unite and insert at three places; the medial femoral condyle via a short tendon, the medial collateral ligament of the femerotibial joint and to the medial condyle of the tibia via an aponeurosis.  

::Vertebral head - Sacrotuberous ligament, 1st caudal vertebra

:'''Insertion''': The two bellies of the muscle unite to insert at three places; the medial femoral condyle via a short tendon, the medial collateral ligament of the femerotibial joint and to the medial condyle of the tibia via an aponeurosis.

:'''Action''': Extends the hop and stifle during weightbearing, facillitating propulsion. When non-weightbearing, adducts and retracts the limb.

'''''Sartorius'''''

'''''Sartorius'''''