Rigi10™ Malleable Penile Prosthesis
Also Known As
Perineal membrane, Triangular ligament
Definition
The term “Urogenital Diaphragm” has historically been used to describe a musculofascial structure in the anterior part of the perineum, specifically within the urogenital triangle.¹ However, contemporary anatomical understanding often favors the term “Perineal Membrane” to more accurately describe the key fascial component of this region.² The perineal membrane is a strong, dense, triangular sheet of fibromuscular tissue that stretches across the anterior half of the pelvic outlet, attaching laterally to the ischiopubic rami and posteriorly to the perineal body.¹ Its primary purpose is to provide structural support to the pelvic viscera, particularly the urethra and, in females, the vagina as they pass through it.² It effectively separates the deep perineal pouch (located superiorly) from the superficial perineal pouch (located inferiorly).¹ The “urogenital diaphragm” was traditionally considered to consist of the perineal membrane (as its inferior fascia) along with the muscles of the deep perineal pouch, such as the deep transverse perineal muscle and the external urethral sphincter (sphincter urethrae).¹ Some sources describe the superior fascia of the urogenital diaphragm as a continuation of the fascia covering the pelvic diaphragm (levator ani).¹ The perineal membrane and associated muscular structures play a crucial role in urethral support, urinary continence, and overall pelvic floor stability.²
Clinical Context
The perineal membrane (historically referred to as part of the urogenital diaphragm) is clinically significant due to its structural role in the pelvic floor and its proximity to vital urogenital structures. Its integrity and function are important in several contexts:
Pelvic Organ Prolapse (POP): The perineal membrane contributes to the support of pelvic organs, particularly the urethra and vagina in females.² Weakness or damage to the perineal membrane and associated structures can contribute to the development of POP, where pelvic organs descend from their normal anatomical positions.²
Urinary Incontinence: The perineal membrane provides support to the urethra and is closely associated with the external urethral sphincter.¹² Damage during childbirth or other trauma can impair urethral support and sphincter function, leading to stress urinary incontinence.
Childbirth Trauma: The perineal membrane is susceptible to injury during vaginal childbirth, including tears or episiotomy.² Such trauma can affect its structural integrity and contribute to postpartum pelvic floor dysfunction, including pain, incontinence, and prolapse. Understanding its anatomy is crucial for managing and repairing perineal injuries.²
Surgical Procedures: Surgeons operating in the perineal region (e.g., for urological, gynecological, or colorectal conditions) must have a thorough understanding of the perineal membrane’s anatomy to avoid iatrogenic injury and to effectively repair pelvic floor defects.¹² Procedures for POP or incontinence often involve structures related to the perineal membrane.
Perineal Pain Syndromes: Chronic perineal pain can sometimes be related to issues involving the perineal membrane or the nerves and muscles in its vicinity, although this is a complex area often involving multiple factors.
Diagnostic Imaging: Imaging modalities like MRI can be used to visualize the perineal membrane and surrounding structures, aiding in the diagnosis of pelvic floor disorders and guiding surgical planning.²
Anatomical Terminology: The shift in terminology from “urogenital diaphragm” to “perineal membrane” reflects a more accurate anatomical understanding, which is important for clear communication among healthcare professionals and researchers.²&sup5; While “urogenital diaphragm” is still encountered, especially in older texts, “perineal membrane” is preferred for the specific fascial layer