Pudendal nerve 1

Pudendal nerve

Nerve: Pudendal nerve

Pudendal nerve, course and branches in a male.

Latin Nervus pudendus

Gray's p.967 [1]

From Sacral nerves S2, S3, S4

To Inferior rectal nervesperineal nervedorsal nerve of the penis

The pudendal nerve is the main nerve of the perineum.:274 It carries sensation from the external genitalia of bothsexes and the skin around the anus and perineum, as well the motor supply to various pelvic muscles, including theexternal urethral sphincter and the external anal sphincter.

Pudendal nerve 2

Structure

Image showing the greater sciatic foramen (largeforamen), and the lesser sciatic foramen,

separated by the sacrospinous ligament. Thepudendal nerve exits the pelvis through the

greater sciatic foramen, passes over the ligament,and then reenters the pelvis through the lesser

sciatic foramen.

The pudendal nerve is a paired structure, with one on either side,termed the left and right pudendal nerves respectively. Each is formedas three roots immediately above the upper border of the sacrotuberousligament and the ischiococcygeus muscle. The three roots become twocords when the middle and lower root join to form the lower cord, andthese in turn unite to form the pudendal nerve proper just proximal tothe sacrospinous ligament. The three roots are derived from the ventralrami of the second, third, and fourth sacral spinal nerves, with theprimary contribution coming from the fourth.:215:157

The pudendal nerve passes between the piriformis muscle andischiococcygeus muscles and leaves the pelvis through the lower partof the greater sciatic foramen. It crosses over the lateral part of thesacrospinous ligament and reenters the pelvis through the lesser sciaticforamen. After reentering the pelvis, it accompanies the internalpudendal artery and internal pudendal vein upwards and forwardsalong the lateral wall of the ischiorectal fossa, being contained in asheath of the obturator fascia termed the pudendal canal, along with theinternal pudendal blood vessels.:8

Inside the pudendal canal, the nerve divides into branches, first givingoff the inferior anal nerve, then the perineal nerve, before continuing asthe dorsal nerve of the penis (in males) or the dorsal nerve of the clitoris (in females).:34

Nucleus

The nerve is a major branch of the sacral plexus,:950 with fibres originating in Onuf's nucleus in the sacral region ofthe spinal cord.

VariationThe pudendal nerve may vary in its origins. For example, the pudendal nerve may actually originate off of the sciaticnerve. Consequently, damage to the sciatic nerve can affect the pudendal nerve as well. Sometimes dorsal rami of thefirst sacral nerve contribute fibers to the pudendal nerve, and even more rarely S5.

FunctionThe pudendal nerve has both motor and sensory functions. It does not carry parasympathetic fibres.:1738

The pudendal nerve supplies sensation to the penis in males and the clitoris in females, through the branches dorsalnerve of penis and dorsal nerve of clitoris.:422 The posterior scrotum in males and the labia in females are alsosupplied, via the posterior scrotal nerves (males) or posterior labial nerves (females). The pudendal nerve is one ofseveral nerves supplying sensation to these areas.[2] Branches also supply sensation to the anal canal.:8 By providingsensation to the penis, the pudendal nerve is responsible for the afferent component of penile erection. :147

Branches also innervate muscles of the perineum and pelvic floor; namely the bulbospongiosus and ischiocavernosusmuscles, the levator ani muscle (including the Iliococcygeus, pubococcygeus, puborectalis and either pubovaginalisin females or pubourethralis in males),:422 the external anal sphincter (via the inferior anal branch),:7 and externalurethral sphincter.:424425

Pudendal nerve 3

Clinical significance

AnesthesiaA pudendal nerve block, also known as a saddle nerve block, is a local anaesthesia technique used in a obstetricprocedure to anesthetize the perineum during labor. In this procedure, an anaesthetic agent such as lidocaine isinjected through the inner wall of the vagina into the pudendal nerve.

DamageThe pudendal nerve can compressed or stretched, resulting in temporary or permanent neuropathy. Irreversible nerveinjury may occur when nerves are stretched by 12% or more of their normal length.:655 If the pelvic floor isover-stretched, acutely (e.g. prolonged or difficult childbirth) or chronically (e.g. chronic straining during defecationcaused by constipation), the pudendal nerve is vulnerable to stretch-induced neuropathy.:655 Pudendal nerveentrapment, also known as Alcock canal syndrome, is very rare and is associated with professional cycling. Systemicdiseases such as diabetes and multiple sclerosis can damage the pudendal nerve via demyelination or othermechanisms.:37 A pelvic tumor (most notably a large sacrococcygeal teratoma), or surgery to remove the tumor, canalso cause permanent damage.Unilateral pudendal nerve neuropathy inconsistently causes fecal incontinence in some, but not others. This isbecause crossover innervation of the external anal sphincter occurs in some individuals.:34

Imaging

The pudendal nerve is difficult to visualize on routine CT or MR imaging, however under CT guidance, a needlemay be placed adjacent to the pudendal neurovascular bundle. The ischial spine, an easily identifiable structure onCT, is used as the level of injection. A spinal needle is advanced via the gluteal muscles and advanced within severalmillimeters of the ischial spine. Contrast (X-ray dye) is then injected, highlighting the nerve in the canal, confirmingcorrect needle placement. The nerve may then be injected with cortisone and local anaesthetic to confirm and alsotreat chronic pain of the external genitalia (known as vulvodynia in females), pelvic and anorectal pain In rare cases,the nerve may be destroyed with either alcoholic or radiofrequency ablation.

Nerve latency testing

The time taken for a muscle supplied by the pudendal nerve to contract in response to an electrical stimulus appliedto the sensory and motor fibers can be quantified. Increased conduction time (terminal motor latency) signifiesdamage to the nerve.:46 2 stimulating electrodes and 2 measuring electrodes are mounted on the examiner's glovedfinger ("St Mark's electrode").:46 Prolonged motor latency can be an indicator of the extent of idiopathic or obstetricneurological damage, and can provide some indication regarding potential recovery or response to surgery.

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HistoryThe term pudendal comes from Latin pudenda, meaning external genitals, derived from pudendum, meaning "partsto be ashamed of". The pudendal canal is also known by the eponymous term "Alcock's canal", after BenjaminAlcock, an Irish anatomist who documented the canal in 1836. Alcock documented the existence of the canal andpudendal nerve in a contribution about iliac arteries in Robert Bentley Todd's "The Cyclopaedia of Anatomy andPhysiology".

Additional images

The male pelvis, showing thepudendal nerve (centre right).

Schematic showing thestructures innervated by the

pudendal nerve.

Diagram of the course of the pudendal nervein the male pelvis

Notes[1] http:/ / archive. org/ stream/ anatomyofhumanbo1918gray#page/ 967/ mode/ 2up[2][2] |page=Neurovascular Bundles of the Perineum

References

External links SUNY Figs 41:04-11 (http:/ / ect. downstate. edu/ courseware/ haonline/ figs/ l41/ 410411. htm) - "Inferior view

of female perineum, branches of the internal pudendal artery." figures/chapter_32/32-2.HTM (http:/ / www. dartmouth. edu/ ~humananatomy/ figures/ chapter_32/ 32-2. HTM) -

Basic Human Anatomy at Dartmouth Medical School figures/chapter_32/32-3.HTM (http:/ / www. dartmouth. edu/ ~humananatomy/ figures/ chapter_32/ 32-3. HTM) -

Basic Human Anatomy at Dartmouth Medical School Cross section at UV pelvis/pelvis-female-17 (http:/ / www. univie. ac. at/ anatomie2/ pelvis/

pelvis-female-17-text. html) Diagnosis and treatment at www.nervemed.com (http:/ / www. nervemed. com/ nerve-pudendal. html) www.pudendal.com (http:/ / www. pudendal. com) Pudendal nerve entrapment at chronicprostatitis.com (http:/ / www. chronicprostatitis. com/ pne. html) CT sequence showing a pudendal nerve block. (http:/ / www. melbourneradiology. com. au/

interventional-radiology/ nerve-blocks. html)

Article Sources and Contributors 5

Article Sources and ContributorsPudendal nerve Source: http://en.wikipedia.org/w/index.php?oldid=603886348 Contributors: Achantihari, Afiller, Anupam, Aoidh, Arcadian, Arjayay, Avb, Beland, Brimcmike,Captain-n00dle, Colonies Chris, Dough34, Dr Chamms, Filip em, Flyer22, GhostGirl, GinaD50, Grook Da Oger, Heybuddysup, IceCreamAntisocial, Iztwoz, Jacquesbeco, JakobSteenberg,Jarble, Jfdwolff, Karada, Kernsters, Kyinaire, LT910001, Lesion, Looie496, Malcolm Farmer, Mauvila, Mcstrother, Mikael Hggstrm, Mr Stephen, Pearle, Phenomic69, Pmakker, Prissi,Pudendal1, RDBrown, Rjwilmsi, Scottalter, Sonjaaa, Symbic, Tristanb, Una Smith, Wisdom89, Zephalis, 38 anonymous edits

Image Sources, Licenses and ContributorsFile:Pudendal nerve.svg Source: http://en.wikipedia.org/w/index.php?title=File:Pudendal_nerve.svg License: Public Domain Contributors: Made, for the sake of free knowledge to allmankind, by Mikael Hggstrm (User:Mikael Hggstrm)File:Gray320.png Source: http://en.wikipedia.org/w/index.php?title=File:Gray320.png License: Public Domain Contributors: Gray's Anatomy (Quain) (uploaded by Phyzome)Image:Gray829.png Source: http://en.wikipedia.org/w/index.php?title=File:Gray829.png License: Public Domain Contributors: Arcadian, Jmarchn, Magnus ManskeFile:Grant 1962 214.png Source: http://en.wikipedia.org/w/index.php?title=File:Grant_1962_214.png License: Public Domain Contributors: CFCFFile:Grant 1962 215.png Source: http://en.wikipedia.org/w/index.php?title=File:Grant_1962_215.png License: Public Domain Contributors: CFCF

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Pudendal nerveStructureNucleusVariation

FunctionClinical significanceAnesthesiaDamageImagingNerve latency testing

HistoryAdditional imagesNotesReferencesExternal links

License