The neuroanatomy of the human scrotum: surgical ramifications

To define the scrotal nerve origin and distribution with respect to surrounding structures in male human fetuses, by using neuronal-specific markers and three-dimensional (3D) imaging techniques, as the developmental neuroanatomy of the human scrotum has not been studied in detail and an explicit description of nerve derivation and distribution in the human scrotum is germane to genital reconstructive surgery.

Sixteen normal human fetal penile specimens at 17.5-38 weeks of gestation were studied. Specimens were fixed in formalin, embedded in paraffin wax, serially sectioned at 6 micro m and stained with the neuronal marker S-100. All of the specimens contained the whole penis and scrotum from glans to anal verge. The gestational age of the fetuses was determined by fetal heel-to-toe length. 3D-computer reconstruction of serial sections allowed a detailed analysis of the neuroanatomy of the fetal penis and scrotum.

The nerves innervating the ventral side of the proximal penis and scrotum originated mainly from the perineal nerves arising from pudendal nerves. The nerves travelling along the ventral side of penis coalesced at the penoscrotal area to be directed into the interscrotal septum. At the penoscrotal junction, nerves on both sides of the ventral penis shifted to the interscrotal septum in a triangular fashion. The interscrotal septum was densely occupied by nerve fibres. Nerves were distributed horizontally to both hemiscrotal walls through this interscrotal septum. Both hemiscrota seem primarily to be innervated separately.

The interscrotal septum has a dense innervation. Both hemiscrota were innervated mainly by horizontally distributed nerve fibres arising from the interscrotal septum. Any procedure violating the penoscrotal and interscrotal septal area may jeopardize scrotal innervation.