Definition
The coccygeal plexus is a small peripheral nerve network formed by the ventral rami of the fourth and fifth sacral spinal nerves (S4, S5) and the coccygeal nerve (Co). It supplies motor and sensory innervation to structures of the coccygeal region, including skin over the coccyx and portions of the anal canal.
Overview
The plexus resides in the posterior pelvic floor, deep to the gluteus maximus and superficial to the coccygeal vertebrae. It lies inferior to the sacral plexus and is distinct from, although occasionally considered a continuation of, the lower sacral nerves. The plexus gives rise to several cutaneous and muscular branches, the most notable being the anococcygeal nerve, which innervates the skin around the coccyx and the posterior part of the anal canal. Due to its limited size, the coccygeal plexus plays a minor yet specific role in somatic sensation and voluntary control of the sphincteric muscles of the distal pelvic floor.
Etymology / Origin
- Coccygeal derives from the Greek kokkyx meaning “coconut” or “tail,” referring anatomically to the coccyx, the terminal vertebral segment of the vertebral column.
- Plexus comes from Latin plexus, meaning “braid” or “network,” used in anatomy to denote a tangled arrangement of nerves.
Thus, “coccygeal plexus” literally denotes the nerve network associated with the coccyx.
Characteristics
- Composition: Ventral rami of S4, S5, and Co (coccygeal) nerves.
- Major branches:
- Anococcygeal nerve: supplies skin over the coccyx and posterior anal canal.
- Perforating cutaneous nerve: provides cutaneous innervation to the inferior gluteal region.
- Function:
- Sensory: conveys cutaneous sensation from the skin overlying the coccyx and peri‑anal area.
- Motor: contributes to the innervation of the external anal sphincter and coccygeal muscles involved in tailbone movement (e.g., levator ani fibers).
- Clinical relevance:
- Injury or entrapment can lead to coccygeal pain (“coccydynia”) with sensory disturbances in the innervated skin region.
- Nerve blocks targeting the coccygeal plexus are occasionally employed in the management of chronic perineal or coccygeal pain.
Related Topics
- Sacral plexus
- Pudendal nerve
- Anococcygeal nerve
- Coccyx (tailbone)
- Pelvic floor musculature
- Coccydynia (coccygeal pain)
All presented information reflects established anatomical knowledge as of the latest medical literature.