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Perineal raphe
Perineal raphe
Perineal raphe
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Perineal raphe
Details
PrecursorUrogenital folds
Identifiers
Latinraphe perinei
TA98A09.5.00.002
A09.4.01.013
A09.4.03.002
TA23698
FMA20244
Anatomical terminology

The perineal raphe (/ˈrā-fē/) is a visible line or ridge of tissue on the body that extends from the anus through the perineum to the scrotum (male) or the vulva (female). It is found in both males and females, arises from the fusion of the urogenital folds, and is visible running medial through anteroposterior, to the anus where it resolves in a small knot of skin of varying size.

In males, this structure continues through the midline of the scrotum (the so-called scrotal raphe or Vesling line) and upwards through the posterior midline aspect of the penis (penile raphe). It also exists deeper through the scrotum where it is called the scrotal septum. It is the result of a fetal developmental phenomenon whereby the scrotum and penis close toward the midline and fuse.[1]

In females, the raphe consists in most cases of normal skin and is not clearly visible. In around 10% of the population the raphe is present as a ridge of skin; in around 25% of the population the raphe has rough patches of skin or diagonal ridges on one or both sides of the midline.[2]

See also

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Images

[edit]
  • Stages in the development of the external sexual organs in the male and female
    Stages in the development of the external sexual organs in the male and female
  • Perineal and scrotal raphe
    Perineal and scrotal raphe
  • Perineal raphe in female
    Perineal raphe in female
  • Another example of the perineal raphe in an adult human male.
    Another example of the perineal raphe in an adult human male.

References

[edit]
Revisions and contributorsEdit on WikipediaRead on Wikipedia

Perineal raphe

View on Grokipedia
from Grokipedia
The perineal raphe is a midline of skin and subcutaneous fibrous tissue in the , representing the line of embryonic fusion between the bilateral urogenital folds and extending posteriorly from the posterior aspect of the external genitalia to the . It serves as an anatomical landmark dividing the into left and right halves and is underlain by a fibrous reinforced by intermuscular fibers, particularly from the in males. In males, the structure is more prominent and continuous anteriorly with the scrotal raphe—a vertical crease dividing the into two compartments, each housing a testis and associated structures—and further with the along the ventral penile shaft. In females, the perineal raphe is typically less conspicuous, extending from the to the of the or the fourchette, with fusion occurring between the raphe and the vestibular wall during fetal development. Embryologically, the perineal raphe develops during the fusion of the bilateral urogenital folds around weeks 9–12 of , with the midline epithelial seam eventually differentiating into the mature ridge; incomplete fusion can lead to anomalies such as perineal grooves or median raphe cysts. Histologically, it consists of dense collagenous tissue attaching posteriorly to the , providing structural support to the perineal body and contributing to the integrity of the . Clinically, the perineal raphe is relevant in surgical procedures like or perineal reconstruction, where its midline position guides incision placement to minimize damage to surrounding neurovascular structures, and it may be involved in congenital conditions affecting urogenital development.

Anatomy

Structure and composition

The perineal raphe appears as a visible midline line or ridge on the perineal skin, resulting from the fusion of the urogenital folds. It is composed primarily of covering a layer of . It is underlain by a subcutaneous fibrous plate or , reinforced by intermuscular fibers, particularly from the in males. Histologically, the structure features a superficial keratinized , beneath which lies the rich in fibers; notable is the absence of significant glandular structures within the raphe itself. The raphe lies superficially adjacent to the perineal body, aligning with its midline and underlain by a fibrous reinforced by intermuscular fibers.

Location and extent

The perineal raphe is a visible midline ridge of tissue that originates at the anal verge and extends anteriorly through the along the midsagittal plane. In males, it proceeds to the posterior aspect of the , where it aligns with the midline of the and continues superiorly as the continuous . In females, the raphe runs anteriorly to the posterior , terminating at the fourchette, the posterior junction of the . The posterior boundary of the perineal raphe is defined by the anal verge, while its anterior limit reaches the scrotal-perineal junction in males or the fourchette in females. This structure is situated primarily within the of the , traversing the midline without extending posteriorly into the beyond the .

Embryological development

Formation process

The formation of the perineal raphe commences around the seventh week of , coinciding with the differentiation of the cloacal membrane into distinct urogenital and anal components through the caudal migration of the urorectal , which divides the . At this juncture, urethral folds arise bilaterally along the margins of the urethral groove on the surface of the urogenital membrane; these folds originate from mesenchymal proliferations adjacent to the endodermal lining of the . By the eighth to ninth week, the urethral folds begin to migrate toward the midline, with initial approximation occurring posteriorly near the cloacal terminus. This fusion proceeds in a zipper-like manner, starting from the posterior perineal region and advancing anteriorly, thereby obliterating the urethral groove and creating a seamless midline union. The perineal raphe emerges as the visible scar or ridge along this line of closure in the perineal area, extending from the posterior or toward the . The mechanistic basis of this closure involves directed mesenchymal ingrowth that bridges the apposing epithelial surfaces of the urethral folds, followed by and fusion of the ectodermal and endodermal layers, which leaves a residual thickened due to partial tissue remodeling rather than full resorption. At approximately 10 weeks, the raphe appears thin and undulating, aligning continuously with the inferior aspect of the developing penile or vulvar . By 12 to 13 weeks, it thickens and establishes continuity with the anal margin. Fusion of the urethral folds is generally completed by 14 to 16 weeks of , solidifying the perineal raphe as a permanent embryological remnant that delineates the midline of the in the mature structure.

Sexual dimorphism

The of the perineal raphe arises primarily during embryological development, driven by the presence or absence of androgens such as testosterone and its metabolite (DHT). In male fetuses, testosterone produced by the testes beginning around the 7th week of promotes the masculinization of external genitalia, including the fusion of the urethral folds and labioscrotal swellings. This process results in a prominent perineal raphe that extends continuously from the through the , , and to the base of the , forming the and as visible ridges along the line of fusion. In contrast, female fetuses lack significant exposure, allowing the urethral folds to develop into the and the labioscrotal swellings into the without midline fusion beyond the . Consequently, the perineal raphe in females is subtler, confined to the perineal region and posterior , with minimal ridge formation and often fading or becoming imperceptible distally toward the vulvar vestibule. This androgen-independent development emphasizes the raphe's role as a remnant of the indifferent stage, where the absence of hormonal signaling prevents the extensive midline reinforcement seen in males. A key structural difference involves the reinforcement of the raphe by a muscular . Fetal studies demonstrate that in males, the bilateral bulbospongiosus muscles form a midline intermuscular beginning around 10 weeks and thickening by 14-15 weeks, straightening the raphe while supporting the and enhancing its prominence. This muscular support is absent in females, leading to a thinner, less defined raphe that relies solely on epithelial fusion without additional structural reinforcement.

Variations and anomalies

Normal variations

The perineal raphe exhibits benign variations in visibility among individuals, primarily influenced by sex and skin characteristics. In males, the raphe is typically more pronounced, forming a distinct midline accentuated by distribution and skin pigmentation along the and . In females, it is generally subtler, often appearing as unremarkable skin without a clear in the majority of cases, though it may be faintly discernible in some. Length and prominence of the perineal raphe also show minor individual differences within the normal range. The raphe usually extends from the posterior (in males) or labial commissure (in females) toward the , but slight shortenings or incomplete extensions to the anal margin occur in some adults without clinical implications. Prominence varies from a subtly elevated fibrous line to a more defined ridge, reflecting natural differences in thickness. Approximately 10-20% of individuals display mild in the raphe, such as slight deviation from the midline, which is considered a normal without requiring intervention.

Pathological anomalies

Pathological anomalies of the perineal raphe primarily consist of congenital malformations resulting from disruptions in the normal embryological fusion processes of the genital structures. These anomalies can manifest as structural defects along the midline raphe, potentially leading to functional or aesthetic concerns, though many are benign and asymptomatic. Unlike normal variations, which are minor and non-disruptive, pathological anomalies often stem from incomplete or aberrant development and may require clinical to rule out associated conditions. Common anomalies include the bifid or split raphe, which arises from a failure of complete fusion of the urethral folds, resulting in a notched or divided midline seam extending from the to the penile or scrotal region. This defect is typically identified in infants during routine examination and has been reported in case series with an overall incidence of genital raphe anomalies around 2% in screened newborns. Raphe cysts represent another frequent type, formed by trapped epithelial remnants from incomplete fusion, presenting as benign, fluid-filled lesions along the raphe from the urethral to the perianal area. These cysts are lined by various epithelia, including stratified squamous or pseudostratified ciliated types, and are congenital in origin due to defects in urethral fold merging. The groove, a persistent midline defect appearing as a moist, erythematous sulcus from the to the vaginal fourchette or perineal body, is also common among these anomalies and is characterized by a thin epithelial layer over . Rarer manifestations involve deviation of the raphe, where the midline seam shifts laterally, often signaling underlying urethral abnormalities such as , with studies showing associations in up to 30% of cases with raphe anomalies. along the raphe may occasionally indicate associated developmental issues, though it is less commonly documented as a primary pathological feature. Median raphe anomalies in infants, encompassing cysts, splits, or canals, are typically detected neonatally and can extend to the , sometimes mimicking infectious lesions but confirmed histologically as embryologic remnants. Most perineal raphe anomalies link embryologically to incomplete fusion of the urethral folds, which normally merge in the midline to form the raphe during weeks 9 to 12 of , corresponding to a of approximately 38 to 55 mm. This process transforms the into the tubular , with basal portions of the folds uniting ventrally; disruptions during this critical window lead to persistent defects like grooves or cysts. The perineal groove specifically occurs with a low incidence, estimated as rare among congenital perineal malformations, though exact rates remain unknown due to underdiagnosis; it is more prevalent in females and often self-resolves through epithelialization by age 2 years without intervention. While usually isolated, it may associate with anorectal malformations in a minority of cases, necessitating screening for coexisting anomalies.

Clinical significance

Surgical applications

The perineal raphe serves as a critical anatomical landmark in various surgical procedures involving the perineum, guiding midline incisions to minimize damage to surrounding nerves and muscles. In obstetric surgery, midline episiotomies are vertical incisions made in the midline of the perineum from the posterior vaginal fourchette toward the anus, facilitating vaginal delivery while preserving the integrity of the perineal body. Post-childbirth perineal repairs align suturing of lacerations or episiotomy sites to ensure proper approximation of tissues and reduce the risk of complications such as incontinence. Similarly, in anorectal tumor resection, the perineal body helps delineate surgical margins, aiding in achieving clear margins and lowering recurrence rates. In male patients, the perineal raphe aligns with the , making it a preferred site for incisions in procedures like orchidopexy for undescended testes. Single median raphe scrotal incisions allow for safe mobilization and fixation of the testis while avoiding disruption of the vasculature. This approach is particularly useful in low-lying palpable undescended testes, offering a cosmetically favorable outcome with low complication rates. In patients, the perineal raphe marks the posterior boundary for vulvar surgeries, such as excisions for benign or malignant lesions, ensuring precise and preservation of continence mechanisms. During fistula repairs, such as rectovaginal or urethroperineal s, incisions along the raphe facilitate access to the defect while minimizing trauma to adjacent sphincters. In abdominoperineal resection for rectal cancer, the perineal body assists in identifying the plane, contributing to oncologically sound margins and reduced local recurrence risk.

Associated conditions

Abnormalities of the perineal raphe are frequently associated with urogenital malformations in males, serving as indicators for underlying conditions such as , where deviation of the median raphe from the midline shows a significant , observed in up to 32% of cases among infants with genital median raphe anomalies. Similarly, prominent or deviated raphe features often signal megameatus intact prepuce, a concealed urethral anomaly, with such raphe irregularities acting as key diagnostic clues in neonates undergoing routine examination. may also coexist with perineal raphe defects, particularly in syndromes involving scrotal or bifid structures, highlighting the need for comprehensive genital assessment. In the anorectal region, perineal groove—a wet, midline sulcus disrupting the raphe—represents a rare congenital malformation. It has been associated with other anorectal anomalies such as ectopic or imperforate anus. Other associations include rare elevations in maternal serum alpha-fetoprotein levels linked to perineal groove, which may prompt evaluation for neural tube defects or other fetal anomalies, though direct chromosomal ties remain uncommon. Untreated median raphe cysts along the perineal area can predispose to secondary infections, manifesting as painful abscesses or purulent discharge, necessitating prompt intervention to prevent complications. In neonates, median raphe deviation warrants imaging to rule out concealed urethral anomalies, given the notable co-occurrence rate approaching 30% in affected cohorts.

References

  1. https://www.sciencedirect.com/science/article/abs/pii/S147751311200294X
  2. https://pmc.ncbi.nlm.nih.gov/articles/PMC4927426/
  3. https://my.clevelandclinic.org/health/body/scrotum
  4. https://abdominalkey.com/penis-and-male-urethra/
  5. https://medicine.uodiyala.edu.iq/wp-content/uploads/2022/11/scrotum-p-p-2022-talib-jawad.pdf
  6. https://pmc.ncbi.nlm.nih.gov/articles/PMC4737640/
  7. https://journals.lww.com/ijpd/fulltext/2023/24020/a_case_of_multiple_median_raphe_cysts_with.27.aspx
  8. https://www.researchgate.net/publication/272517938_Perineal_groove_in_pediatric_gynecology_A_report_of_2_cases
  9. https://teachmeanatomy.info/pelvis/areas/perineum/
  10. https://www.ncbi.nlm.nih.gov/books/NBK557601/
  11. https://www.ncbi.nlm.nih.gov/books/NBK560572/
  12. https://pmc.ncbi.nlm.nih.gov/articles/PMC11737307/
  13. https://www.ncbi.nlm.nih.gov/books/NBK526128/
  14. https://pubmed.ncbi.nlm.nih.gov/20882767/
  15. https://pmc.ncbi.nlm.nih.gov/articles/PMC4440541/
  16. https://pmc.ncbi.nlm.nih.gov/articles/PMC4075225/
  17. https://pmc.ncbi.nlm.nih.gov/articles/PMC4352436/
  18. https://pubmed.ncbi.nlm.nih.gov/25236772/
  19. https://www.pediatricurologycasereports.com/articles/median-raphe-deviation-association-with-hypospadias-and-clinical-significance-a-case-report-and-literature-review.pdf
  20. https://adc.bmj.com/content/97/Suppl_2/A452.1
  21. https://embryology.med.unsw.edu.au/embryology/index.php/Penis_Development
  22. https://pmc.ncbi.nlm.nih.gov/articles/PMC8396188/
  23. https://www.frontiersin.org/journals/pediatrics/articles/10.3389/fped.2018.00227/full
  24. https://www.glowm.com/resources/glowm/cd/pages/v2/v2c069.html
  25. https://www.ncbi.nlm.nih.gov/books/NBK537345/
  26. https://pubmed.ncbi.nlm.nih.gov/34912420/
  27. https://pubmed.ncbi.nlm.nih.gov/23333249/
  28. https://pubmed.ncbi.nlm.nih.gov/30096348/
  29. https://www.orpha.net/en/disease/detail/495879
  30. https://www.scientificliterature.org/Clinicalmedicine/Clinicalmedicine-24-128.pdf
  31. https://www.theijcp.org/index.php/ijcp/article/view/383
  32. https://pmc.ncbi.nlm.nih.gov/articles/PMC8896147/
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