pudendal nerve is the main nerve of the perineum. This brings the sensation of external genitalia of both sex and skin around the anus and perineum, as well as motor supply to various pelvic muscles, including male or female external urethral sphincter and external anal sphincter. If damaged, most often through labor, the lesion may cause sensory loss or fecal incontinence. The nerves may be temporarily blocked as part of the anesthesia procedure.
The pudendal canal that carries the pudendal nerve is also known as the eponymous "Alcock channel", after Benjamin Alcock, an Irish anatomist who documented the canals in 1836.
Video Pudendal nerve
Structure
Pudendus nerve paired, meaning there are two nerves, one on the left and one on the right side of the body. Each is formed as three roots immediately gathered over the upper border of the sacrotuberous ligament and coccygeus muscle. The three roots become two ropes when the middle and lower roots join to form the bottom wires, and this in turn unite to form the right pudendal nerve just proximal to the sacrospinous ligament. The three roots come from the second, third, and fourth spinal ventral spinal nerves, with the major contribution coming from the fourth.
The pudendal nerve crosses between the piriformis muscle and the coccygeus muscle (ischiococcygeus) and leaves the pelvis through the lower part of the larger sciatic foramen. Across the lateral portion of the sacrospinous ligament and pelvic reenters through the lower sciatic foramen. Upon reentering the pelvis, it accompanies the internal pudendal artery and internal pudendal vein upward and forward along the lateral wall of the ischiorectal fossa, which is contained in the obturator fascial sheath called the pudendal canal, together with the internal pudendal blood vessels.
In the pudendal canal, the nerve splits into branches, first releasing the inferior rectal nerve, then the perineal nerve, before proceeding as the penis dorsal nerve (in the male) or the dorsal nerve clitoris (in the female).
Nucleus
The nerves are the main branches of the sacral plexus, with fibers originating from the Onuf nucleus in the sacral region of the spinal cord.
Variations
The pudendal nerve may vary in its origin. For example, the pudendal nerve may be derived from the sciatic nerve. As a result, the damage to the sciatic nerve may affect the pudendal nerve as well. Sometimes dorsal flax from the first sacral nerve contributes fiber to the pudendal nerve, and even rarer S5 .
Maps Pudendal nerve
Function
The pudendal nerve has motor and sensory functions. It does not carry parasympathetic fibers but carries the sympathetic fibers.
The pudendal nerve provides a sensation to the penis in males, and in the clitoris in women, which travels through the branches of both the dorsal nerve of the penis and the dorsal nerve of the clitoris. The posterior scrotum in men and labia in women is also given, via the posterior (posterior) scrotum nerve or the posterior (female) labial nerve. The pudendal nerve is one of the few nerves that supply sensations to these areas. The branches also supply sensations to the anal canal. By giving sensation to the penis and clitoris, the pudendal nerve is responsible for the afferent component of erectile penis and clitoral erection. It is also responsible for ejaculation.
The branches also infect the perineal muscles and pelvic floor; namely, bulbospongiosus and muscle ischiocavernosus respectively, levator ani muscle (including Iliococcygeus, pubococcygeus, puborectalis and either pubovaginalis in women or puboprostaticus in men) external anal sphincter (via inferior anal branch), and external urethra of male or female sphincter.
Because it serves to mengtertervasi external urethral sphincter, he is responsible for the tone of the sphincter is mediated through the release of acetylcholine. This means that during the period of increased acetylcholine, release the skeletal muscle in the external urethral sphincter contract, leading to urinary retention. While in the period of decreased acetylcholine, loose skeletal muscle in the external urethral sphincter will relax, allowing the occurrence of urinary bladder. (Clarification: Unlike internal sphincter muscles, the external sphincters are made of skeletal muscle, therefore under the voluntary control of the somatic nervous system.)
Clinical interests
Anesthesia
The pudendal neural block, also known as a saddle nerve block, is a local anesthetic technique used in obstetric procedures to anesthetize the perineum during labor. In this procedure, an anesthetic agent such as lidocaine is injected through the inner wall of the vagina regarding the pudendal nerve.
Damage
The pudendal nerve can be compressed or stretched, resulting in temporary or permanent neuropathy. Irreversible nerve injuries can occur when nerves are stretched by 12% or more of their normal length. If the pelvic floor is too stretched, acute (eg prolonged or difficult) or chronic (eg, chronic tension during bowel movements caused by constipation), the pudendal nerve is susceptible to induced stretching neuropathy. Pudendal nerves, also known as Alcock channel syndrome, are very rare and associated with professional cycling. Systemic diseases such as diabetes and multiple sclerosis can damage the pudendal nerves through demyelination or other mechanisms. Pelvic tumors (especially large sacrococcygeal teratomas), or surgery to remove tumors, can also cause permanent damage.
Unilateral pudendar nerve neuropathy inconsistently causes fecal incontinence in some patients, but not others. This is because the innervation of crosses from external anal sphincters occurs in some individuals.
Imaging
The pudendal nerve is difficult to visualize in routine CT or MR imaging, but under CT guidance, the needle may be placed adjacent to the pudendal neurovascular bundle. Iscia spina, easily identifiable CT structure, is used as an injection level. The spinal needle progresses through the gluteal muscle and progresses within a few millimeters of the iscone spine. Contrast (X-ray dye) is then injected, highlighting the nerves in the channel and allowing confirmation of correct needle placement. The nerves can then be injected with local cortisone and anesthesia to confirm and also treat chronic pain from external genitalia (known as vulvodynia in women), pelvic and anorectal pain.
Test nerve delays
The time required for the muscles provided by the pudendal nerve to contract in response to the electrical stimuli applied to the sensors and motor fibers can be quantified. Increased conduction time (terminal motor latency) indicates damage to the nerve. 2 stimulating electrodes and 2 measuring electrodes mounted on the gloved finger of the examiner ("St Mark electrode").
History
The pudendal term is derived from the Latin pudenda , which means external genital, derived from pudendum , which means" part to be ashamed ". The pudendal canal is also known as the eponymous "Alcock channel", after Benjamin Alcock, an Irish anatomist who documented the canals in 1836. Alcock documents the existence of canals and pudendal nerves in contributions to the iliac artery in Robert Bentley Todd "The Cyclopaedia of Anatomy and Physiology".
Additional images
See also
- Neurogenic bladder
References
External links
- Anatomical figure: 41: 04-11 in Human Anatomy Online, SUNY Downstate Medical Center - "Inferior view of the female perineum, branch of the internal pudendal artery."
- number/bab_32/32-2.HTM: Basic Human Anatomy at Dartmouth Medical School
- number/bab_32/32-3.HTM: Basic Human Anatomy at Dartmouth Medical School
- Cross-section image: pelvis-pelvis-female-17 - Plastination Laboratory at Medical University of Vienna
- Diagnosis and treatment at www.nervemed.com
- www.pudendal.com
- Pudendal nerves at chronicprostatitis.com
- The CT sequence shows the pudendal neural block.
Source of the article : Wikipedia
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