Lumbar paraspinal muscles examination is an interesting part of the electrodiagnostic evaluation of patients with suspected lumbosacral radiculopathy. However, many electromyographers hesitate to routinely include that technique in their study of lower limbs. The purpose of this paper is to specify the anatomy and electrophysiologic data of multifidus lumbar paraspinal muscle. Previous anatomic studies indicate that the medial lumbar multifidus and lumbar interspinalis muscles share unisegmental innervation by the dorsal ram of the spinal nerve. Electromyography of these muscles can improve the sensitivity of lumbosacral radiculopathy detection. Multi-MUP analysis of quantitative electromyographic parameters in lumbar paraspinal muscles, in a population of 75 healthy subjects without back pain, allowed to set up normal values for the L5 myotome.