Musculus semimembranosus
The semimembranosus has two heads. The vertebral head originates from the first caudal vertebra and sacrosciatic ligament; the pelvic head originates from the ventromedial aspect of the ischial tuberosity. It inserts on the medial condyles of the femur and tibia. Its actions depend on limb position: in the weight-bearing limb it extends the hip and stifle joints; in the non-weight-bearing limb it retracts, adducts, and rotates the limb inward. It blends with the adductor. It is innervated by the caudal gluteal and sciatic nerves (tibial branch, roughly L6-S2).
Origin: Ischial tuberosity (ventral surface)
Insertion: Medial femoral condyle and medial tibial condyle
Action: Extends the hip; adducts the hindlimb; may assist stifle flexion
Innervation: Sciatic nerve — tibial branch (L6-S2)
Strain can cause hindlimb lameness and reduced propulsion. Relevant in evaluations of caudal thigh trauma or after overexertion. Diagnosis is clinical and with ultrasound.
## Overview Semimembranosus strain is injury to one of the hamstring muscles on the medial caudal thigh. It occurs from overexertion during collection, steep hill work, or slipping. Signs include hin
## Overview Injury to the hamstring complex (semitendinosus, semimembranosus, biceps femoris) produces severe hind-limb lameness, swelling, and pain in the caudal thigh. Bruising may be visible on th
Sudden hindlimb lameness with swelling or pain in the caudal thigh after work should be evaluated. Rest and controlled rehabilitation are important.
## Overview Semimembranosus strain is injury to one of the hamstring muscles on the medial caudal thigh. It occurs from overexertion during collection, steep hill work, or slipping. Signs include hind-limb lameness, swelling, pain on palpation, and a shortened stride. It can be difficult to distinguish from semitendinosus strain. ## Causes Acute overload. ## Diagnosis Palpation and ultrasound. ## Treatment Rest and rehabilitation. ## Recovery and Prognosis Good. ## Prevention Conditioning and safe footing. Signs include: hind-limb lameness; swelling on the medial caudal thigh; pain on palpation; reluctance to engage the hindquarters; shortened stride
## Overview Injury to the hamstring complex (semitendinosus, semimembranosus, biceps femoris) produces severe hind-limb lameness, swelling, and pain in the caudal thigh. Bruising may be visible on the inner thigh. Recovery is prolonged. ## Causes Overstretching, slips, kicks, or acute overload. ## Diagnosis Palpation of pain and swelling, ultrasound of the muscle bellies, and exclusion of fracture. ## Treatment Rest, anti-inflammatories, cold therapy initially, then controlled rehabilitation and physiotherapy. Severe tears may leave residual fibrosis. ## Recovery and Prognosis Fair to good with time. Fibrotic myopathy can develop as a sequela. ## Prevention Conditioning and safe footing. Signs include: severe hind-limb lameness; swollen painful caudal thigh; reluctance to move; possible bruising on the inner thigh
Strain can cause hindlimb lameness and reduced propulsion. Relevant in evaluations of caudal thigh trauma or after overexertion. Diagnosis is clinical and with ultrasound.
Sudden hindlimb lameness with swelling or pain in the caudal thigh after work should be evaluated. Rest and controlled rehabilitation are important.
See the Semimembranosus on our interactive 3D horse model. Open 3D Model