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The coccygeal plexus is formed by the anterior rami of S4-S5 in combination with the coccygeal nerve and is described as supplying the skin of the post-anal region.
The plexus consists of a minute network of nerve fibers contributed by the anterior rami of S4, S5 and the coccygeal nerve 1.
The coccygeal nerves emerge from the conus medullaris before descending within the cauda equina and exiting at the sacral hiatus with the S5 roots 3. S5 travels superior to the transverse process of the first coccygeal vertebra while the coccygeal nerve travels inferior. A small branch from S4 also joints to form the coccygeal plexus upon the pelvic surface of coccygeus 2,3.
One cadaveric study found that unlike standard descriptions of the coccygeal plexus, however, the plexus formed within the coccygeus muscle rather on the surface in a manner more similar to that of the lumbar plexus and the psoas muscle 4.
Anococcygeal nerve branches of the coccygeal plexus have a variable description of supply 4. Typically they are described as supplying the post-anal skin between the tip of the coccyx and the anus 1. Some authors also describe these nerves as supplying the coccygeus muscle, part of the levator ani, the posterior extremity of the external anal sphincter, and the sacrococcygeal joint 2,3.
- 1. Chummy S. Sinnatamby. Last's Anatomy e-Book. (2011) ISBN: 9780702048395
- 2. Keith L. Moore, Anne M. R. Agur, Arthur F. Dalley, II. Clinically Oriented Anatomy. (2017) ISBN: 9781496347213
- 3. Woon JT, Stringer MD. Clinical anatomy of the coccyx: A systematic review. (2012) Clinical anatomy (New York, N.Y.). 25 (2): 158-67. doi:10.1002/ca.21216 - Pubmed
- 4. Woon JT, Stringer MD. Redefining the coccygeal plexus. (2014) Clinical anatomy (New York, N.Y.). 27 (2): 254-60. doi:10.1002/ca.22242 - Pubmed