The sacral spinal nerve 3 (S3) is a

spinal nerve A spinal nerve is a mixed nerve, which carries Motor neuron, motor, Sensory neuron, sensory, and Autonomic nervous system, autonomic signals between the spinal cord and the body. In the human body there are 31 pairs of spinal nerves, one on each s ...

of the sacral segment.American Medical Association
Nervous System -- Groups of Nerves It originates from the

spinal column The spinal column, also known as the vertebral column, spine or backbone, is the core part of the axial skeleton in vertebrates. The vertebral column is the defining and eponymous characteristic of the vertebrate. The spinal column is a segmen ...

from below the 3rd body of the

sacrum The sacrum (: sacra or sacrums), in human anatomy, is a triangular bone at the base of the spine that forms by the fusing of the sacral vertebrae (S1S5) between ages 18 and 30. The sacrum situates at the upper, back part of the pelvic cavity, ...

Muscles

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 The levator ani is a broad, thin muscle group, situated on either side of the pelvis. It is formed from three muscle components: the pubococcygeus, the iliococcygeus, and the puborectalis. It is attached to the inner surface of each side of the ...

* coccygeus * sphincter urethrae membranaceae * superior gemellus

Additional images

File:Slide20y.JPG, Sacral spinal nerve 3

References

Spinal nerves {{neuroanatomy-stub