Peculiarities of the Female Genitals' Sensory Innervation
Dr. Nelson Soucasaux , Brazilian gynecologist
The purpose of this article is to introduce and comment on some peculiarities
of the female genitals' sensibility and some of its implications for women
and gynecologic practice. The female genitals basically possess two different
kinds of innervation and, consequently, of sensibility: the "somatic"
and the visceral (vegetative) ones.
Sensations originating in parts of the body whose innervation is of
the "somatic" type are perceived in a very accurate, precise and
well-localized form (see Note below). Conversely,
sensations originated in the visceral organs (whose innervation is of the
visceral or vegetative type) usually are extremely imprecise, diffuse and
very difficult to be exactly "localized." Visceral pain often
has, for instance, the characteristic of projecting itself on areas of the
body that do not correspond to the exact origin of the painful stimulus,
and this happens due to extremely intricate reflex pathways of metameric
origin. (Metameric: related to the embryonic development of the nervous
system.)
In women, the external genitals (vulva), the lower part of the vagina
(basically the vaginal entrance) and the perineal muscles possess the "somatic"
type of innervation and, as areas directly related to the sexual response,
they have an extremely precise and localized sensitivity for all kinds of
stimuli. Conversely, the vaginal inner or upper two-thirds (that is, most
of the vagina), the uterus, Fallopian tubes, ovaries and respective ligaments
and surrounding structures possess the visceral (vegetative) type of innervation.
These facts have several implications in gynecologic practice, in the female
sexual response and in the ways through which women experience their sexual
organs.
We can therefore understand why the vagina is an organ of sexual expression
whose greatest part (the inner or upper two-thirds) presents a relatively
small sexual sensitivity, behaving more as a visceral organ than as a sensory
one. Sensations that come from the vaginal inner part present the diffuse,
imprecise and vaguely localized features typical of the visceral kind of
sensibility. Only the external third of this organ (next to the vulva) possesses
a great sexual sensibility, as well as the other characteristics of the
"somatic" type of sensibility.
The inner or upper two-thirds of the vagina have a restricted sexual
sensitivity and the sensations originating there are vague and imprecise.
For all these reasons, in repose conditions (that is, in the absence of
sexual intercourse and other forms of vaginal stimulation), the greater
part of the vagina almost does not send any kind of information to women.
(That's the reason why the existence of her vagina may not be known to a
child, because it is not sensed.)
The aforementioned peculiarities of the kind of sensitivity of most
of the vagina and all the woman's internal genitals perhaps may contribute
to the creation, in the female psychology, of many mysterious fantasies
regarding these organs. There is, for instance, the idea of the vagina as
an "obscure and mysterious tunnel that leads to the intimacy of the
female body." It is obvious that a great part of these fantasies are
also due to the action of mythological and archetypal elements, and also
to an extremely rich symbology.
These features of the innervation of the woman's sexual organs also
have consequences in the routine of gynecologic consultations, mostly in
anxious patients. During the gynecological examination, the dislike and
discomfort that many women demonstrate even in procedures that, in normal
circumstances, do not cause pain - procedures such as the intravaginal introduction
and movement of the speculum, the taking of smears for vaginal and ectocervical
cytology - make evident this peculiarity of the female anatomy and physiology.
As women have well-defined and correctly localized sensations only at
the vulva and vaginal entrance, it is probable that, regarding the examination
procedures performed at the inner part of the vagina and the uterine cervix,
the sensations that reach their consciousness are very imprecise, diffuse
and confused. The patient feels that "something" is being done
inside her genitals, but she is not able to evaluate exactly what
we are doing, and this can generate anxiety even when we explain in detail
all that is being done.
Obviously the psychological features of this group of women aggravate
the situation (mostly if they exhibit neurotic attitudes concerning the
gynecologic examination), transforming the smaller stimuli originating from
the examination into pain and discomfort. On the other hand, with regard
to the taking of smears for endocervical cytology, the occurrence of some
pain and uterine cramps is normal because the painful sensitivity of the
cervical canal to mechanical stimulation is often great.
During the bimanual palpation of the uterus, Fallopian tubes and ovaries,
the occurrence of some pain or discomfort even in the absence of pathology
is also normal, because we need to press these organs through the vagina
and the abdominal wall in order to perform the examination. The ovaries
possess an especially great sensitivity to compression.
Considering that the purpose of this article was to analyse some clinical
aspects of the sensitive innervation of the female genitals, all the other
functions of the visceral (vegetative) and "somatic" innervation
of these organs were not discussed here. For a detailed study of the innervation
of the female pelvic organs, see my article "Fundamentos para o Estudo
das Influências Neurovegetativas em Ginecologia."*(after
the article) An introductory discussion about the still obscure functions
of the vegetative innervation of these organs (that is, their sympathetic
and parasympathetic innervation) can be found in this article.
Note: The "somatic" type of innervation
is that of the skin, skeletal muscles and joints, also including most of
the structures close to the surface of the body.
*Soucasaux, Nelson "Fundamentos para
o Estudo das Influências Neurovegetativas em Ginecologia" ("Basis
for the Study of the Neurovegetative Influences in Gynecology") in:
Jornal Brasileiro de Medicina, Vol 57, nº 4, October 1989, Rio de Janeiro.
The article above is an adapted excerpt from my book "Novas
Perspectivas em Ginecologia" ("New Perspectives in Gynecology").
For information on the book, see page http://www.nelsonginecologia.med.br/novas.htm,
from my Web site www.nelsonginecologia.med.br
.
Copyright Nelson Soucasaux 1990, 2003
_______________________________________________
Nelson Soucasaux is a gynecologist dedicated to clinical, preventive
and psychosomatic gynecology. Graduated in 1974 by Faculdade de Medicina
da Universidade Federal do Rio de Janeiro, he is the author of several articles
published in medical journals and of the books "Novas Perspectivas
em Ginecologia" ("New Perspectives in Gynecology") and "Os
Órgãos Sexuais Femininos: Forma, Função, Símbolo
e Arquétipo" ("The Female Sexual Organs: Shape, Function,
Symbol and Archetype"), published by Imago Editora, Rio de Janeiro,
1990, 1993.
Website (Portuguese-English): http://www.nelsonginecologia.med.br
Email: nelsons@nelsonginecologia.med.br