Nerves of the Pelvis

Pelvic Nerve Supply and Nursing Considerations

 Nerves of the Pelvis Nerve supply of the vulva and perineum, Nerve supply of the pelvic viscera Anatomical Description of other related Structure Genital Systems. 

Nerve supply of the vulva and perineum

    The pudendal nerve arises from the second, third and fourth sacral nerves. As it passes along the outer wall of the ischiorectal fossa, it gives off an inferior rectal branch and divides into the perineal nerve and the dorsal nerve of the clitoris. The perineal nerve gives the sensory supply to the vulva; it also innervates the anterior part of the external anal sphincter and levatorani, and the superficial perineal muscles. The dorsal nerve of the clitoris is sensory.

    Sensory fibers from the mons and labia also pass, in the ilioinguinal and genitofemoral nerves, to the first lumbar root. The posterior femoral cutaneous nerve carries sensation from the perineum to the small sciatic nerve, and thus to the first, second and third sacral nerves.The main nerve supply of the levatorani muscles comes from the third and fourth sacral nerves.

Nerve supply of the pelvic viscera

    To describe what can be seen dissection of the extensive autonomic nerve supply of the pelvic organs is one thing to determine the physiological functions of the various parts of the system is another.

    Nerve fibers of the pre-aortic plexus of the sympathetic nervous system are continuous with those of the superior hypogastric plexes, which lies in front of the last lumbar vertebra and is wrongly called the pre sacral nerve. Below, the superior hypogastric plexus divides, and on each side its fibers are continuous with films passing beside the rectum hi join the uterovaginal plexus inferior hypogastric plexus Plexus of Frankenhauser). 

    This plexus lies in the loose cellular to posterolateral to the cervix below the uterosacral folds of peritoneum

    Parasympathetic fibers from the second, third and fourth sacral nerves join the uterovaginal plexus Fibers from (or to) the bladder, uterus, vagina and rectum join the plexus. The uterovaginal plexus.contains a few ganglion cells, so it is likely that a few motor nerves have their relay stations there and then pass onwards with the blood vessels to the viscera       

    The ovary is not innervated by the nerves already described but from the ovarian plexus, which sur rounds the ovarian vessels and joins the pre-aortic plexes high up.

    This description thus avoided any conjecture as to the particular function of the sympathetic and parasympathetic nerves, and no opinion has been expressed as to whether the various nerves carry senssory or motor impulses Clinical facts are few. It is evident that afferent sensory impulses are often carried in the superior hypogastric plexus. If this is divided during presacral neurectomy, pain from the bladder and uterus can often be blocked. 

    Apart from a transient pelvic hyperaemia, there is no change in the motor fanction of either bladder or uterus. At an ordinary by sterectomy, the uterinvaginal plexus is not disturbed, but after a more extensive Wertheim operation, there may be painless atony and distension of the bladder, which is attributes to loss of bladder sensation because the sacral connections of the uterovaginal plexus have been divided

    The motor effects are even less certain than the sensory: Stimulation of the cut lower end of the hypogastric plexus seems to have no effect on the bladder the uterus Although it has boot stated that the parasympathetic nerves are excitatory to the musculature of the body of the uterus and inhibitory to that of the cervix, and that the sympathetic nerves have the opposite effect, there is not general agreement about this.

    The myometrium contains both a and ẞ adrenergic receptors and also cholinergic receptors. In the non-pregnant uterus, the balance of their action is uncertain, but during pregnancy, strong stimulation of B-receptors with B-mimetic drugs such as isoxsuprine will inhibit myometrial activity.

Anatomical Description of other related Structure Genital Systems 

The nephrogenic card develops from the mesoderm and forms the urogenital ridge and the mesonephric duct. The paramesonephric duct, which later forms the Mullenan system, is the precursor of female genital development

The lower ends of the Müllerian ducts come together in the midline, fuse and develop into uterus and cervix

Most of the upper vagina is of Müllerian origin. The lower vagina forms from the sinovaginal bulbs.

The primitive gonad is first evident at 5 weeks of embryonic life and forms on the medial aspect of the mesonephric ridge. The size and ratio of the cervix to uterus change with age and parity.

Vaginal pH is normally acidic and has a protective role for decreasing the growth of pathogenic organisms

An adult uterus weighs about 70g and consists of three layers: the peritoneum, the myometrium and the endometrium

The cervix is narrower than the body of the uterus and is approximately 2.5 cm in length. The ureter runs about 1 cm lateral to the supravaginal cervix

The epithelium of the cervix in its lower third is stratified squamous epithelium and the junction between this and the columnar epithelium is where most cervical carcinoma arises.

The ovary is the only intraperitoneal structure not covered by peritoneum

The main supports to the pelvic floor are the connective tissue and levatorani muscles. The main supports of the uterus are the uterosacral ligaments, which are condensations of connective tissue.

The ovarian arteries rise from the aorta. The right ovarian vein drains into the vena cava, the left ovarian vein usually drains into the left renal vein.

The major nerve supply of the pelvis comes from the pudendal nerves, which arise from the second, third and fourth sacral nerves.