Which peripheral nerves carry genital sensation to the brain and how do they differ (pudendal vs pelvic vs vagus)?

1. Pudendal nerve — the somatic highway for external genital touch and reflexes

The pudendal nerve is the principal somatic nerve of the perineum, formed from sacral ventral rami S2–S4, and it carries the bulk of tactile and proprioceptive information from the external genitalia, perineal skin and anus to the spinal cord while also supplying motor fibers to pelvic floor and sphincter muscles ^{[2] [4]}; because it is mixed (sensory + motor), pudendal afferents mediate fast, localized sensations and reflex arcs important for erection, orgasm-related muscle contractions, and sphincter control ^{[4] [5]}.

2. Pelvic nerves — parasympathetic visceral afferents that modulate arousal and internal genital sensation

The pelvic nerves (pelvic splanchnic/pelvic plexus and associated cavernous nerves) are primarily parasympathetic and provide proerectile innervation to penile and clitoral vascular tissues and visceral pelvic organs, carrying visceral afferent information from internal genital structures back to the lumbosacral spinal cord and modulating tumescence via neurotransmitters like nitric oxide ^{[6] [3]}; these fibers convey slower, diffuse visceral sensations (arousal, fullness, visceral pain) and integrate with spinal centers for reflexogenic sexual responses ^{[3] [6]}.

3. Vagus nerve — a brainstem route for some pelvic visceral sensations

Emerging functional imaging and review literature report that vagal fibers can transmit pelvic visceral sensations directly to brainstem nuclei, providing a non-spinal pathway for certain internal genital signals to reach central autonomic and affective centers ^[3]; this vagal contribution appears to channel visceral, affect-laden signals rather than discrete somatic touch, and its prominence helps explain residual genital sensation reported by some people after spinal cord injury—though exact territory and clinical limits are still under study ^[3].

4. Practical differences: what each nerve “feels” and why that matters clinically

Pudendal afferents mediate sharp, well-localized tactile input and reflexes (hence nerve blocks anesthetize the posterior perineum, penis, vulva and anus but not anterior perineum supplied by other spinal nerves) and damage causes focal sensory loss, pain syndromes and motor deficits of sphincters ^{[5] [2] [7]}; pelvic nerves carry parasympathetic proerectile signals and visceral sensations important for engorgement and internal organ sensation rather than fine touch ^{[6] [3]}; vagal pelvic afferents project to the brainstem and likely carry diffuse visceral and affective signals rather than precise somatosensory detail, making them important for central autonomic responses and for some preserved sensation after spinal lesions ^[3].

5. Clinical and research caveats — overlapping maps and unresolved boundaries

Anatomy is not tidy: multiple nerves overlap or contribute to genital innervation (genitofemoral, ilioinguinal, hypogastric and sympathetic fibers alongside pudendal and pelvic nerves), pudendal blocks do not anesthetize all genital territories, and neuropathic pain can arise from several pelvic nerves, so attributing a symptom to a single nerve requires careful assessment ^{[5] [8] [9]}; likewise, the vagal role—documented in PET and review literature—is accepted as real but not fully mapped to precise genital regions, so interpretations about its clinical reach must remain cautious ^[3].

6. Bottom line — three complementary routes with distinct roles

Synthesis of the literature shows a triad: the pudendal nerve supplies fast, local somatic sensation and motor reflexes from external genitalia (S2–S4) ^{[2] [4]}, pelvic nerves supply parasympathetic proerectile signals and visceral afference for internal genital structures ^[6], and the vagus provides a brainstem-bound visceral channel that can carry pelvic sensations to central autonomic centers—each pathway carries different qualities of sensation and has distinct clinical implications ^{[3] [6] [2]}.