Perineal membrane
Encyclopedia
The perineal membrane is an anatomical term for a fibrous membrane
in the perineum
. The term "inferior fascia of urogenital diaphragm
", 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
.
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, above the crus penis.
Its base is directed toward the rectum
, and connected to the central tendinous point
of the perineum
.The base is fused with both the pelvic fascia and Colle's fascia.
behind the Transversus perinæi superficialis, and with the inferior layer of the diaphragmatic part of the pelvic fascia.
, by the urethra
, 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 close to the urethral orifice
; by the deep arteries of the penis, one on either side close to the pubic arch
, 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 and nerves, while between its apex and the arcuate pubic ligament the deep dorsal vein of the penis
passes upward into the pelvis.
. It also attaches to the perineal body
.
Biological membrane
A biological membrane or biomembrane is an enclosing or separatingmembrane that acts as a selective barrier, within or around a cell. It consists of a lipid bilayer with embedded proteins that may constitute close to 50% of membrane content...
in the perineum
Perineum
In human anatomy, the perineum is a region of the body including the perineal body and surrounding structures...
. The term "inferior fascia of urogenital diaphragm
Urogenital diaphragm
Older texts have asserted the existence of an 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 the urogenital diaphragm and superior fascia of the...
", used in older texts, is considered equivalent to the perineal membrane.
It is the superior border of the superficial perineal pouch
Superficial perineal pouch
The superficial perineal pouch is a compartment of the perineum.-Structure:The superficial perineal pouch is a fully enclosed compartment:* its inferior border is the perineal fascia...
, and the inferior border of the deep perineal pouch
Deep perineal pouch
The deep perineal pouch is a human anatomical term that refers to the space enclosed in part by the perineum, and located superior to the perineal membrane.-Structure:...
.
Shape and boundaries
It is triangular in shape, and about 4 cm. in depth.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
Deep dorsal vein of the penis
The deep dorsal vein of the penis lies beneath the deep fascia of the penis; it receives the blood from the glans penis and corpora cavernosa penis and courses backward in the middle line between the dorsal arteries; near the root of the penis it passes between the two parts of the suspensory...
.
Its lateral margins are attached on either side to the inferior rami
Inferior pubic ramus
The inferior pubic ramus is a part of the pelvis and is thin and flat. It passes laterally and downward from the medial end of the superior ramus; it becomes narrower as it descends and joins with the inferior ramus of the ischium below the obturator foramen....
of the pubis
Pubis (bone)
In vertebrates, the pubic bone is the ventral and anterior of the three principal bones composing either half of the pelvis.It is covered by a layer of fat, which is covered by the mons pubis....
and ischium, above the crus penis.
Its base is directed toward the rectum
Rectum
The rectum is the final straight portion of the large intestine in some mammals, and the gut in others, terminating in the anus. The human rectum is about 12 cm long...
, and connected to the central tendinous point
Perineal body
The perineal body is a pyramidal fibromuscular mass in the middle line of the perineum at the junction between the urogenital triangle and the anal triangle . It is found in both males and females...
of the perineum
Perineum
In human anatomy, the perineum is a region of the body including the perineal body and surrounding structures...
.The base is fused with both the pelvic fascia and Colle's fascia.
Relations
It is continuous with the deep layer of the superficial fasciaSuperficial fascia
Superficial fascia is found in the subcutis in most regions of the body, blending with the reticular layer of the dermis. It is present on the face, over the upper portion of the sternocleidomastoid, at the nape of the neck, and overlying the sternum. It is mainly loose areolar connective tissue...
behind the Transversus perinæi superficialis, and with the inferior layer of the diaphragmatic part of the pelvic fascia.
Perforations
It is perforated, about 2.5 cm. below the pubic symphysisPubic symphysis
The pubic symphysis or symphysis pubis is the midline cartilaginous joint uniting the superior rami of the left and right pubic bones. It is located anterior to the urinary bladder and superior to the external genitalia; for females it is above the vulva and for males it is above the penis...
, by the urethra
Urethra
In anatomy, the urethra is a tube that connects the urinary bladder to the genitals for the removal of fluids out of the body. In males, the urethra travels through the penis, and carries semen as well as urine...
, 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 close to the urethral orifice
Internal urethral orifice
The internal urethral orifice is the opening of the urinary bladder into the urethra. It is placed at the apex of the trigonum vesicae, in the most dependent part of the bladder, and is usually somewhat crescent-shaped; the mucous membrane immediately behind it presents a slight elevation in males,...
; by the deep arteries of the penis, one on either side close to the pubic arch
Pubic arch
The eminences of the lower circumference of the true pelvis are separated by three notches: one in front, the pubic arch, formed by the convergence of the inferior rami of the ischium and pubis on either side. The angle at which they converge is known as the subpubic angle.-External links:* *...
, 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 and nerves, while between its apex and the arcuate pubic ligament the deep dorsal vein of the penis
Deep dorsal vein of the penis
The deep dorsal vein of the penis lies beneath the deep fascia of the penis; it receives the blood from the glans penis and corpora cavernosa penis and courses backward in the middle line between the dorsal arteries; near the root of the penis it passes between the two parts of the suspensory...
passes upward into the pelvis.
Contents
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 penisDeep dorsal vein of the penisThe deep dorsal vein of the penis lies beneath the deep fascia of the penis; it receives the blood from the glans penis and corpora cavernosa penis and courses backward in the middle line between the dorsal arteries; near the root of the penis it passes between the two parts of the suspensory...
- the membranous portion of the urethra
- the Transversus perinæi profundus and Sphincter urethræ membranaceæ muscles
- the bulbourethral glands and their ducts
- the pudendal vesselsPudendal vesselsPudendal vessels can refer to:* Internal pudendal artery* Deep external pudendal artery...
and dorsal nerves of the penis - the arteries and nerves of the urethral bulb
- a plexusPlexusA plexus is a part of nervous system. Plexus has a slightly different definition in vertebrates and in invertebrates.- In vertebrates :In vertebrates, a plexus is an area where nerves branch and rejoin. The electrical signals do not mix; rather, the fibres travel together with their electrical...
of veins
Structure
The perineal membrane is triangular in shape. It attaches to both ischiopubic rami of the pelvisPelvis
In human anatomy, the pelvis is the lower part of the trunk, between the abdomen and the lower limbs .The pelvis includes several structures:...
. It also attaches to the perineal body
Perineal body
The perineal body is a pyramidal fibromuscular mass in the middle line of the perineum at the junction between the urogenital triangle and the anal triangle . It is found in both males and females...
.