perineum n : the general region between the anus and the genital organs [also: perinea (pl)]

English

Alternative spellings

• perinaeum

Etymology

From post-classical perineum, perineos, from περίνεος, from περι- + ἰνᾶν + adjectival suffix -ιος.

Pronunciation

/pɛɹɪˈniːəm/

Noun

1. The region between the genital area and the anus in both sexes

Synonyms

See

Translations

Derived terms

• perineal

In human anatomy, the perineum is generally defined as the surface region in both males and females between the pubic symphysis and the coccyx. The perineum is the region of the body inferior to the pelvic diaphragm and between the legs.

A diamond-shaped area on the inferior surface of the trunk which includes the anus and, in females, the vagina. Its definition varies: it can refer to only the superficial structures in this region, or it can be used to include both superficial and deep structures.

The perineum corresponds to the outlet of the pelvis.

The anogenital distance is a measure of male feminisation measuring the distance between the anus and the base of the penis. Studies show that the perineum is twice as long in males as in females. Validity of anogenital distance as a marker of in utero phthalate exposure. PMID 16393642 Measuring the anogenital distance in neonatal humans has been suggested as a noninvasive method to predict neonatal and adult reproductive disorders.

Boundaries

Its deep boundaries are as follows:

• in front: the pubic arch and the arcuate ligament of the pubis
• behind: the tip of the coccyx
• on either side: the inferior rami of the pubis and Ischium, and the sacrotuberous ligament

In Alfred Kinsey's 1967 report, he concluded that the perineum was one of the 6 key erogenous zones for males.

Triangles

A line drawn transversely across in front of the ischial tuberosities divides the space into two triangles:

Perineal fascia

The terminology of the perineal fascia can be confusing, and there is some controversy over the nomenclature. This stems from the fact that there are two parts to the fascia, the superficial and deep parts, and each of these can be subdivided into superficial and deep parts.

The layers and contents are as follows, from superficial to deep:

• 1) Skin

• 2) superficial perineal fascia: Subcutaneous tissue divided into two layers: (a) A superficial fatty layer, and (b) Colles' fascia, a deeper, membranous layer.

• 3) deep perineal fascia and muscles:

• 4) fascia and muscles of pelvic floor (levator ani, coccygeus)

Areas of the perineum

The region of the perineum can be considered a distinct area from pelvic cavity, with the two regions separated by the pelvic diaphragm. The following areas are thus classified as parts of the perineal region:

• perineal pouches: superficial and deep (see above for details)
• Ischioanal fossa - a fat filled space at the lateral sides of anal canal. It is bounded laterally by obturator internus muscle, medially by pelvic diaphragm and anal canal. Its base is the skin.
  • Anal canal
  • Pudendal canal - contains internal pudendal artery and the pudendal nerve.

Additional images

References

See also

• Pelvic floor
• Deep perineal pouch

External links