The perineal membrane is an

anatomical Anatomy () is the branch of biology concerned with the study of the structure of organisms and their parts. Anatomy is a branch of natural science that deals with the structural organization of living things. It is an old science, having it ...

term for a fibrous

membrane A membrane is a selective barrier; it allows some things to pass through but stops others. Such things may be molecules, ions, or other small particles. Membranes can be generally classified into synthetic membranes and biological membranes. B ...

in the

perineum The perineum in humans is the space between the anus and scrotum in the male, or between the anus and the vulva in the female. The perineum is the region of the body between the pubic symphysis (pubic arch) and the coccyx (tail bone), includi ...

. The term "inferior fascia of

urogenital diaphragm Older texts have asserted the existence of a urogenital diaphragm, also called the triangular ligament, which was described as a layer of the pelvis that separates the deep perineal sac from the upper pelvis, lying between the inferior fascia of t ...

", used in older texts, is considered equivalent to the perineal membrane. It is the superior border of the superficial perineal pouch, and the inferior border of the

deep perineal pouch The deep perineal pouch (also deep perineal space) is the anatomic space enclosed in part by the perineum, and located superior to the perineal membrane. Structure The deep perineal pouch is bordered inferiorly by the perineal membrane, also kno ...

Structure

The perineal membrane is triangular in shape. It attaches to both ischiopubic rami of the

pelvis The pelvis (plural pelves or pelvises) is the lower part of the trunk, between the abdomen and the thighs (sometimes also called pelvic region), together with its embedded skeleton (sometimes also called bony pelvis, or pelvic skeleton). The ...

. It also attaches to the

perineal body The perineum in humans is the space between the anus and scrotum in the male, or between the anus and the vulva in the female. The perineum is the region of the body between the pubic symphysis (pubic arch) and the coccyx (tail bone), includi ...

. It is about 4 cm. in depth. Its apex is directed forward, and is separated from the

arcuate pubic ligament The pubic symphysis is a secondary cartilaginous joint between the left and right superior rami of the pubis of the hip bones. It is in front of and below the urinary bladder. In males, the suspensory ligament of the penis attaches to the pubic ...

by an oval opening for the transmission of the

deep dorsal vein of the penis Deep or The Deep may refer to: Places United States * Deep Creek (Appomattox River tributary), Virginia * Deep Creek (Great Salt Lake), Idaho and Utah * Deep Creek (Mahantango Creek tributary), Pennsylvania * Deep Creek (Mojave River tributary), C ...

or the deep dorsal vein of the clitoris. Its lateral margins are attached on either side to the inferior rami of the pubis and

ischium The ischium () form ...

, above the

crus penis For their anterior three-fourths the corpora cavernosa penis lie in intimate apposition with one another, but behind they diverge in the form of two tapering processes, known as the crura, which are firmly connected to the ischial rami. Traced ...

. Its base is directed toward the

rectum The rectum is the final straight portion of the large intestine in humans and some other mammals, and the Gastrointestinal tract, gut in others. The adult human rectum is about long, and begins at the rectosigmoid junction (the end of the s ...

, and connected to the central tendinous point of the

. The base is fused with both the pelvic fascia and Colle's fascia.

Relations

It is continuous with the deep layer of the

superficial fascia A fascia (; plural fasciae or fascias; adjective fascial; from Latin: "band") is a band or sheet of connective tissue, primarily collagen, beneath the skin that attaches to, stabilizes, encloses, and separates muscles and other internal orga ...

behind the

superficial transverse perineal muscle The transverse perineal muscles (transversus perinei) are the superficial and the deep transverse perineal muscles. Superficial transverse perineal ...

, and with the inferior layer of the diaphragmatic part of the pelvic fascia.

Perforations

It is perforated, about 2.5 cm. below the

pubic symphysis The pubic symphysis is a secondary cartilaginous joint between the left and right superior rami of the pubis of the hip bones. It is in front of and below the urinary bladder. In males, the suspensory ligament of the penis attaches to the pubic ...

, by the

urethra The urethra (from Greek οὐρήθρα – ''ourḗthrā'') is a tube that connects the urinary bladder to the urinary meatus for the removal of urine from the body of both females and males. In human females and other primates, the urethra con ...

, the aperture for which is circular and about 6 mm. in diameter, by the arteries to the bulb, and the ducts of the

bulbourethral glands The bulbourethral glands or Cowper's glands (named for English anatomist William Cowper) are two small exocrine glands in the reproductive system of many male mammals (of all domesticated animals, they are absent only in dogs). They are homologo ...

close to the urethral orifice; by the

deep arteries of the penis The deep artery of the penis (artery to the corpus cavernosum), one of the terminal branches of the internal pudendal, arises from that vessel while it is situated between the two fasciæ of the urogenital diaphragm Older texts have asserted the ...

, one on either side close to the

pubic arch The pubic arch, also referred to as the ''ischiopubic arch'', is part of the pelvis. It is formed by the convergence of the inferior rami of the ischium and pubis on either side, below the pubic symphysis. The angle at which they converge is kno ...

, and about halfway along the attached margin of the fascia; by the dorsal arteries and nerves of the penis near the apex of the fascia. Its base is also perforated by the

perineal vessels The perineal artery (superficial perineal artery) arises from the internal pudendal artery, and turns upward, crossing either over or under the superficial transverse perineal muscle, and runs forward, parallel to the pubic arch, in the interspac ...

and nerves, while between its apex and the

the

passes upward into the pelvis.

If the inferior fascia of the urogenital diaphragm is detached on either side, the following structures will be seen between it and the superior fascia: * the

* the

membranous portion of the urethra The membranous urethra or intermediate part of male urethra is the shortest, least dilatable, and, with the exception of the urinary meatus, the narrowest part of the urethra. It extends downward and forward, with a slight anterior concavity, b ...

* the

deep transverse perineal muscle The transverse perineal muscles (transversus perinei) are the superficial and the deep transverse perineal muscles. Superficial transverse perineal ...

and the

urethral sphincter The urethral sphincters are two muscles used to control the exit of urine in the urinary bladder through the urethra. The two muscles are either the male or female external urethral sphincter and the internal urethral sphincter. When either of th ...

muscles * the

and their ducts * the

pudendal arteries The pudendal arteries are a group of arteries which supply many of the muscles and organs of the pelvic cavity. The arteries include the internal pudendal artery, the superficial external pudendal artery, and the deep external pudendal artery. ...

and dorsal nerves of the penis * the arteries and nerves of the

urethral bulb Just before each crus of the penis meets its fellow, it presents a slight enlargement, which Georg Ludwig Kobelt named the bulb of the corpus cavernosum penis. The bulb of penis is also known as the urethral bulb. The bulb is homologous to the ...

* a

plexus In neuroanatomy, a plexus (from the Latin term for "braid") is a branching network of vessels or nerves. The vessels may be blood vessels (veins, capillaries) or lymphatic vessels. The nerves are typically axons outside the central nervous syste ...

veins Veins are blood vessels in humans and most other animals that carry blood towards the heart. Most veins carry deoxygenated blood from the tissues back to the heart; exceptions are the pulmonary and umbilical veins, both of which carry oxygenated b ...

Structure

Relations

Perforations

Contents

Additional images

References

External links