Muscle Name: semimembranosus

AKA:  musculus semimembranosus

Abbreviation: SM

Spinal Nerve Roots:
    L4
    L5
    S1
Plexus:
    lumbosacral plexus

Named Nerves:
    sciatic nerve (tibial division)

Proximal Attachment:  Ischial tuberosity

Distal Attachment:  Medail tibia

Action: Hip extension and knee flexion

Needle Insertion: With the patient lying on their side the needle is inerted medial to the medial quadriceps tendon approximately one third the length of the thigh proximal to the knee.

Activation for EMG:   Have the patient flex the knee.

Pitfalls:  Too lateral insertion will lead to the long head of the biceps femoris or the semitendinous being sampled, too medially and the adductor longus will be sampled.

Notes: