The sacral spinal nerve 3 (S3) is a spinal nerve of the sacral segment.

It originates from the spinal column from below the 3rd body of the sacrum.

S3 supplies many muscles, either directly or through nerves originating from S3. They are not innervated with S3 as single origin, but partly by S3 and partly by other spinal nerves. The muscles are:

iliococcygeus

puborectalis

coccygeus

sphincter urethrae membranaceae

superior gemellus

Patients who had preservation of only one S3 nerve root had more severe incontinence (1.99 ± 0.79 versus 2.60 ± 0.63, p = 0.01) and more sensory loss (1.88 ± 0.82 versus 2.31 ± 0.59, p = 0.02) than those patients with preservation of bilateral S3 nerve roots ¹⁾.

Laparoscopic implantation of neuromodulation electrodes allows simultaneous stimulation of S3 and pudendal nerves, providing more programming options and possibly increasing success rates in complex pelvic floor dysfunction cases ²⁾.