Penile Nerve Block Targets the Dorsal Nerve of the Penis
A penile nerve block anesthetizes the dorsal nerve of the penis, which is a terminal branch of the pudendal nerve that travels beneath Buck's fascia along the dorsolateral aspect of the penile shaft.
Anatomical Basis
The dorsal nerve of the penis (DNP) consists of two distinct populations of axons 1, 2:
- Shaft and urethral innervation: Lateral arcading branches radiate from the dorsal midline toward the ventral surface, providing sensory innervation to the lateral and ventral penile shaft 3
- Glanular innervation: Axons remain in a constant dorsal midline location along the penile shaft before branching abundantly within the glans 3
Clinical Technique Implications
The block is performed by infiltrating local anesthetic at the base of the penis beneath the pubic symphysis, where the paired dorsal nerves run in a predictable dorsolateral position beneath Buck's fascia. This location is proximal to where the nerve branches extensively.
Expected Anesthetic Coverage
When properly performed, dorsal nerve block produces 1:
- Complete anesthesia of the dorsal, lateral, and glanular aspects of the penis
- Incomplete coverage of the ventral surface and frenulum, which receive additional innervation from branches of the perineal nerve
Important Caveats
The ventral penis and frenulum have dual innervation - both from DNP branches and from the perineal nerve 4, 1. This explains why some patients may retain sensation ventrally despite adequate dorsal nerve blockade. The perineal nerve travels along the ventral penis covering the corpus spongiosum and communicates with DNP branches at the junction of the corpora cavernosa and spongiosum 4.
Additionally, communicating branches exist between the cavernous nerves and the dorsal nerve at the penile hilum 5, though this is less clinically relevant for superficial nerve blocks.