The perineal membrane is an

anatomical Anatomy () is the branch of morphology concerned with the study of the internal 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 scien ...

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. Bi ...

in the

perineum The perineum (: perineums or perinea) in placentalia, placental mammals is the space between the anus and the genitals. The human perineum is between the anus and scrotum in the male or between the anus and vulva in the female. The perineum is ...

. 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 ...

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

superficial perineal pouch The superficial perineal pouch (also superficial perineal compartment/space/sac) is a compartment of the perineum. Structure The superficial perineal pouch is an open compartment, due to the fact that anteriorly, the space communicates freely wi ...

, 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 (: pelves or pelvises) is the lower part of an Anatomy, anatomical Trunk (anatomy), trunk, between the human abdomen, abdomen and the thighs (sometimes also called pelvic region), together with its embedded skeleton (sometimes also c ...

. It also attaches to the

perineal body The perineum (: perineums or perinea) in placental mammals is the space between the anus and the genitals. The human perineum is between the anus and scrotum in the male or between the anus and vulva in the female. The perineum is the regio ...

Female

The perineal membrane has two distinct portions that span the opening of the anterior pelvic outlet. The ''ventral'' (anterior) portion is associated with the compressor urethra and urethrovaginal sphincter muscles (previously called deep transverse perineal muscles), and is continuous with the insertion of the arcus tendineus fascia pelvis. The apex is separated from the arcuate pubic ligament by an oval opening for the transmission of the deep dorsal vein of the clitoris. The ''dorsal'' (posterior) portion consists of a sheet of dense fibrous tissue that attaches laterally to the ishiopubic rami and medially to the distal third of the vagina and to the perineal body. The perineal membrane provides support to the distal vagina and urethra by attaching these structures to the bony pelvis.

Male

Its apex is directed forward, and is separated from the arcuate pubic ligament by an oval opening for the transmission of the deep dorsal vein of the penis Its lateral margins are attached on either side to the inferior rami of the pubis and

ischium The ischium (; : is ...

, above the crus penis. Its base is directed toward the

rectum The rectum (: rectums or recta) is the final straight portion of the large intestine in humans and some other mammals, and the gut in others. Before expulsion through the anus or cloaca, the rectum stores the feces temporarily. The adult ...

, 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 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

Females

The vagina, including the opening of the urethra, divides the perineal membrane into two halves. The artery to the bulb of the vestibule originates from the perineal artery and pierces the perineal membrane to travel towards the vestibule of the vagina. The deep and dorsal artery of clitoris are the two terminal branches of the internal pudendal artery which pierce the perineal membrane to supply the clitoris.

Males

In males, it is perforated, about 2-3 cm below the pubic symphysis, by the

urethra The urethra (: urethras or urethrae) is the tube that connects the urinary bladder to the urinary meatus, through which Placentalia, placental mammals Urination, urinate and Ejaculation, ejaculate. The external urethral sphincter is a striated ...

. The bulbourethral glands are present on either side of the membranous urethra and their ducts pierce the perineal membrane posterolateral to the urethra. The deep and dorsal artery of the penis arises from the internal pudendal artery and penetrates the perineal membrane to enter the corpora cavernosa in the crus of the penis.

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 deep dorsal vein of the penis and deep dorsal vein of the clitoris * the urethra ( membranous portion in males) * the deep transverse perineal muscle 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 external sphincter muscle of male urethra, male or external sphincter muscle of female urethra, fe ...

muscles * the bulbourethral glands and their ducts * the pudendal arteries, dorsal nerves of the penis, dorsal nerves of the clitoris * the arteries and nerves of the

vestibular bulbs In female anatomy, the vestibular bulbs, bulbs of the vestibule or clitoral bulbs are two elongated masses of erectile tissue typically described as being situated on either side of the vaginal opening. They are united to each other in front by a ...

and urethral bulb * a plexus of veins

Additional images

Image:Gray1154.png, The constituent cavernous cylinders of the penis.

References

External links

* (, ) {{Authority control Perineum