The pelvic floor or pelvic diaphragm is composed of muscle fibers of the

levator ani The levator ani is a broad, thin muscle group, situated on either side of the pelvis. It is formed from three muscle components: the pubococcygeus, the iliococcygeus, and the puborectalis. It is attached to the inner surface of each side of the ...

, the

coccygeus muscle The coccygeus muscle or ischiococcygeus is a muscle of the pelvic floor, located posterior to levator ani and anterior to the sacrospinous ligament. Structure The coccygeus muscle is posterior to levator ani and anterior to the sacrospino ...

, and associated connective tissue which span the area underneath the pelvis. The pelvic diaphragm is a muscular partition formed by the levatores ani and coccygei, with which may be included the parietal pelvic fascia on their upper and lower aspects. The pelvic floor separates the

pelvic cavity The pelvic cavity is a body cavity that is bounded by the bones of the pelvis. Its oblique roof is the pelvic inlet (the superior opening of the pelvis). Its lower boundary is the pelvic floor. The pelvic cavity primarily contains the reproduc ...

above from the perineal region (including

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 ...

) below. Both males and females have a pelvic floor. To accommodate the birth canal, a female's pelvic cavity is larger than a male's.

Structure

The right and left levator ani lie almost horizontally in the floor of the pelvis, separated by a narrow gap that transmits the urethra, vagina, and anal canal. The levator ani is usually considered in three parts: pubococcygeus,

puborectalis The levator ani is a broad, thin muscle group, situated on either side of the pelvis. It is formed from three muscle components: the pubococcygeus, the iliococcygeus, and the puborectalis. It is attached to the inner surface of each side of the ...

, and iliococcygeus. The pubococcygeus, the main part of the levator, runs backward from the body of the pubis toward the coccyx and may be damaged during

birth Birth is the act or process of bearing or bringing forth offspring, also referred to in technical contexts as parturition. In mammals, the process is initiated by hormones which cause the muscular walls of the uterus to contract, expelling the f ...

. Some fibers are inserted into the prostate, urethra, and vagina. The right and left puborectalis unite behind the anorectal junction to form a muscular sling. Some regard them as a part of the

external anal sphincter The external anal sphincter (or sphincter ani externus ) is a flat plane of skeletal muscle fibers, elliptical in shape and intimately adherent to the skin surrounding the margin of the anus. Anatomy The external anal sphincter measures about 8 ...

. The iliococcygeus, the most posterior part of the levator ani, is often poorly developed. The coccygeus, situated behind the levator ani and frequently tendinous as much as muscular, extends from the ischial spine to the lateral margin of the sacrum and coccyx. The

of the

true pelvis The pelvic cavity is a body cavity that is bounded by the bones of the pelvis. Its oblique roof is the pelvic inlet (the superior opening of the pelvis). Its lower boundary is the pelvic floor. The pelvic cavity primarily contains the reproduc ...

has the pelvic floor as its inferior border (and the

pelvic brim The pelvic brim is the edge of the pelvic inlet. It is an approximately Mickey Mouse head-shaped line passing through the prominence of the sacrum, the arcuate and pectineal lines, and the upper margin of the pubic symphysis. Structure The pel ...

as its superior border). The

has the pelvic floor as its superior border. Some sources do not consider "pelvic floor" and "pelvic diaphragm" to be identical, with the "diaphragm" consisting of only the levator ani and coccygeus, while the "floor" also includes the

perineal membrane 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 su ...

and deep perineal pouch. However, other sources include the fascia as part of the diaphragm. In practice, the two terms are often used interchangeably. Posteriorly, the pelvic floor extends into the anal triangle. The pelvic floor has two hiatuses (gaps): Anteriorly urogenital hiatus through which

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 c ...

and

vagina In mammals, the vagina is the elastic, muscular part of the female genital tract. In humans, it extends from the vestibule to the cervix. The outer vaginal opening is normally partly covered by a thin layer of mucosal tissue called the hymen ...

pass through and posteriorly

rectal hiatus The rectum is the final straight portion of the large intestine in humans and some other mammals, and the gut in others. The adult human rectum is about long, and begins at the rectosigmoid junction (the end of the sigmoid colon) at the le ...

through which

anal canal The anal canal is the part that connects the rectum to the anus, located below the level of the pelvic diaphragm. It is located within the anal triangle of the perineum, between the right and left ischioanal fossa. As the final functional seg ...

passes.

Function

It is important in providing support for pelvic

viscera In biology, an organ is a collection of tissues joined in a structural unit to serve a common function. In the hierarchy of life, an organ lies between tissue and an organ system. Tissues are formed from same type cells to act together in a f ...

(organs), e.g. the

bladder The urinary bladder, or simply bladder, is a hollow organ in humans and other vertebrates that stores urine from the kidneys before disposal by urination. In humans the bladder is a distensible organ that sits on the pelvic floor. Urine enters ...

, intestines, the

uterus The uterus (from Latin ''uterus'', plural ''uteri'') or womb () is the organ in the reproductive system of most female mammals, including humans that accommodates the embryonic and fetal development of one or more embryos until birth. The ...

(in females), and in maintenance of

continence Continence may refer to: *Fecal continence, the ability to control defecation, see Fecal incontinence *Urinary continence, the ability to control urination, see Urinary incontinence, the involuntary excretion of urine *Sexual continence, a synony ...

as part of the

urinary The urinary system, also known as the urinary tract or renal system, consists of the kidneys, ureters, bladder, and the urethra. The purpose of the urinary system is to eliminate waste from the body, regulate blood volume and blood pressure, co ...

and

anal Anal may refer to: Related to the anus *Related to the anus of animals: ** Anal fin, in fish anatomy ** Anal vein, in insect anatomy ** Anal scale, in reptile anatomy *Related to the human anus: ** Anal sex, a type of sexual activity involving s ...

sphincters. It facilitates birth by resisting the descent of the presenting part, causing the fetus to rotate forwards to navigate through the pelvic girdle. It helps maintain optimal intra-abdominal pressure.

Clinical significance

The pelvic floor is subject to clinically relevant changes that can result in: * Anterior vaginal wall prolapse ** Cystocele (bladder into vagina) **

Urethrocele A urethrocele is the prolapse of the female urethra into the vagina. Weakening of the tissues that hold the urethra in place may cause it to protrude into the vagina. Urethroceles often occur with cystoceles (involving the urinary bladder as well ...

(urethra into vagina) ** Cystourethrocele (both bladder and urethra) * Posterior vaginal wall prolapse **

Enterocele An enterocele is a protrusion of the small intestines and peritoneum into the vaginal canal. It may be treated transvaginally or by laparoscopy. An enterocele may also obstruct the rectum, leading to symptoms of obstructed defecation. Enteroceles ...

(small intestine into vagina) **

Rectocele In gynecology, a rectocele ( ) or posterior vaginal wall prolapse results when the rectum bulges ( herniates) into the vagina. Two common causes of this defect are childbirth and hysterectomy. Rectocele also tends to occur with other forms of pe ...

(rectum into vagina) * Apical vaginal prolapse **

Uterine prolapse Uterine prolapse is when the uterus descends towards or through the opening of the vagina. Symptoms may include vaginal fullness, pain with sex, trouble urinating, urinary incontinence, and constipation. Often it gets worse over time. Low back ...

(uterus into vagina) **

Vaginal vault The vaginal vault is the expanded region of the vaginal canal at the internal end of the vagina. Prolapse The vaginal vault may prolapse after a hysterectomy, as there is no uterus supporting the interior end of the vagina. ''Colposacropexy'' i ...

prolapse (roof of vagina) - after hysterectomy Pelvic floor dysfunction can result after treatment for gynecological cancers. Damage to the pelvic floor not only contributes to urinary incontinence but can lead to pelvic organ

prolapse In medicine, prolapse is a condition in which organs fall down or slip out of place. It is used for organs protruding through the vagina, rectum, or for the misalignment of the valves of the heart. A spinal disc herniation is also sometimes ca ...

. Pelvic organ prolapse occurs in women when pelvic organs (e.g. the vagina, bladder, rectum, or uterus) protrude into or outside of the vagina. The causes of pelvic organ prolapse are not unlike those that also contribute to urinary incontinence. These include inappropriate (asymmetrical, excessive, insufficient) muscle tone and asymmetries caused by trauma to the pelvis. Age, pregnancy, family history, and hormonal status all contribute to the development of pelvic organ prolapse. The vagina is suspended by attachments to the perineum, pelvic side wall and sacrum via attachments that include collagen, elastin, and smooth muscle. Surgery can be performed to repair pelvic floor muscles. The pelvic floor muscles can be strengthened with

Kegel exercise Kegel exercise, also known as pelvic-floor exercise, involves repeatedly contracting and relaxing the muscles that form part of the pelvic floor, now sometimes colloquially referred to as the "Kegel muscles". The exercise can be performed many t ...

s. Disorders of the posterior pelvic floor include

rectal prolapse A rectal prolapse occurs when walls of the rectum have prolapsed to such a degree that they protrude out of the anus and are visible outside the body. However, most researchers agree that there are 3 to 5 different types of rectal prolapse, depen ...

rectocele In gynecology, a rectocele ( ) or posterior vaginal wall prolapse results when the rectum bulges ( herniates) into the vagina. Two common causes of this defect are childbirth and hysterectomy. Rectocele also tends to occur with other forms of pe ...

perineal hernia Perineal hernia is a hernia involving the perineum ( pelvic floor). The hernia may contain fluid, fat, any part of the intestine, the rectum, or the bladder. It is known to occur in humans, dogs, and other mammals, and often appears as a sudden ...

, and a number of functional disorders including

anismus Anismus or dyssynergic defecation is the failure of normal relaxation of pelvic floor muscles during attempted defecation. It can occur in both children and adults, and in both men and women (although it is more common in women). It can be caused ...

Constipation Constipation is a bowel dysfunction that makes bowel movements infrequent or hard to pass. The stool is often hard and dry. Other symptoms may include abdominal pain, bloating, and feeling as if one has not completely passed the bowel movement ...

due to any of these disorders is called "functional constipation" and is identifiable by clinical diagnostic criteria. Pelvic floor exercise (PFE), also known as Kegel exercises, may improve the tone and function of the pelvic floor muscles, which is of particular benefit for women (and less commonly men) who experience stress urinary incontinence. However, compliance with PFE programs often is poor, PFE generally is ineffective for urinary incontinence unless performed with biofeedback and trained supervision, and in severe cases it may have no benefit. Pelvic floor muscle tone may be estimated using a perineometer, which measures the pressure within the vagina. Medication may also be used to improve continence. In severe cases, surgery may be used to repair or even to reconstruct the pelvic floor.

Perineology Perineology is a speciality dealing with the functional troubles of the three axes (urological, gynaecological and coloproctological) of the female perineum. The perineologist takes a holistic approach, using defect-specific and mini-invasive tr ...

or pelviperineology is a speciality dealing with the functional troubles of the three axes (urological, gynaecological and coloproctological) of the pelvic floor.

Additional images

Gray404.png, The pelvic floor muscles span the bottom of the pelvis. This image shows the left

from within. Gray241.png Gray242.png

References

External links