Regional anatomy of the perineum

Perineum (perineum) is a structure that covers the exit from the pelvic cavity. It has a rhomboid shape and has the following borders: the pubic symphysis anteriorly, the apex of the coccyx inferiorly, the lower branches of the pubis and ischium bones, as well as ischial tuberosities bilaterally.

In the center of the perineum, the so-called central tendon of the perineum (centrum tendineum) is located.

Central tendon (centrum tendineum) - male — Central tendon (centrum tendineum) – male

Central tendon (centrum tendineum) - female — Central tendon (centrum tendineum) – female

Median perineal raphe (raphe perinei) runs along the perineum in the anteroposterior direction.

Median perineal raphe (raphe perinei) - male — Median perineal raphe (raphe perinei) – male

Median perineal raphe (raphe perinei) - female — Median perineal raphe (raphe perinei) – female

The line that connects the ischial tuberosities divides the perineum into two important zones:

Urogenital diaphragm (regio urogenitalis)
Pelvic diaphragm / anal triangle (regio analis)

The perineal muscles are covered with several fasciae.

The superficial investing fascia of the perineum (fascia perinei superficialis) covers the superficial perineal muscles.

Superficial investing fascia (fascia perinei superficialis)

In men, it continues into the so-called superficial fascia of the penis.

In the posterior portion of the urogenital diaphragm, there is the inferior fascia of the pelvic diaphragm (fascia inferior diaphragmatis pelvis).

Inferior fascia of the pelvic diaphragm (fascia inferior diaphragmatis pelvis)

It fuses with the superior fascia of the pelvic diaphragm (fascia superior diaphragmatis pelvis), forming a thickening, the so-called tendinous arch of the levator ani muscle.

Deeper is the endopelvic fascia (fascia endopelvica), which has two sheaths: parietal and visceral.

The visceral sheath forms several thickenings or ligaments:

In men, these are the puboprostatic ligament (lig. puboprostaticum);

and the transverse ligament of the perineum (lig. transversum perinei). The deep dorsal vein of the penis passes through the latter.

In women, the fascia forms the pubovesical ligament (lig. pubovesicale).

Between the prostate gland and the bladder in front and the rectum in the back, men have a rectovesical septum (septum rectovesicale).

In women, such a septum is located between the rectum and the vagina and is called the rectovaginal septum (septum rectovaginale).

On the sides of the anus there is an ischiorectal (or anal) fossa (fossa ischiorectalis).

It is filled with fatty tissue, in which blood vessels pass. During defecation, it provides mobility of the pelvic diaphragm.

From above, it is delimited by the already mentioned tendinous arch. The lateral wall is formed by the obturator internus muscle and the ischial tuberosity.

The medial wall is formed by the levator ani muscle and the external anal sphincter

The posterior wall is formed by the posterior cords of the levator ani muscle and the ischiococcygeus muscle.

The ischiorectal fossa may be the site of inflammation.

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