The pubic symphysis is a secondary
cartilaginous joint between the left and right
superior rami of the pubis of the
hip bones. It is in front of and below the
urinary 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 ...
. In males, the
suspensory ligament of the penis attaches to the pubic symphysis. In females, the pubic symphysis is close to the
clitoris
The clitoris ( or ) is a female sex organ present in mammals, ostriches and a limited number of other animals. In humans, the visible portion – the glans – is at the front junction of the labia minora (inner lips), above the ope ...
. In most adults it can be moved roughly 2 mm and with 1 degree rotation. This increases for women at the time of childbirth.
The name comes from the Greek word ''symphysis'', meaning 'growing together'.
Structure
![Blausen 0723 Pelvis](https://upload.wikimedia.org/wikipedia/commons/2/26/Blausen_0723_Pelvis.png)
The pubic symphysis is a
nonsynovial amphiarthrodial joint. The width of the pubic symphysis at the front is 3–5 mm greater than its width at the back. This joint is connected by
fibrocartilage
Fibrocartilage consists of a mixture of white fibrous tissue and cartilaginous tissue in various proportions. It owes its inflexibility and toughness to the former of these constituents, and its elasticity to the latter. It is the only type of ...
and may contain a fluid-filled cavity; the center is
avascular
The blood vessels are the components of the circulatory system that transport blood throughout the human body. These vessels transport blood cells, nutrients, and oxygen to the tissues of the body. They also take waste and carbon dioxide away f ...
, possibly due to the nature of the compressive forces passing through this joint, which may lead to harmful vascular disease. The ends of both pubic bones are covered by a thin layer of
hyaline cartilage
Hyaline cartilage is the glass-like (hyaline) and translucent cartilage found on many joint surfaces. It is also most commonly found in the ribs, nose, larynx, and trachea. Hyaline cartilage is pearl-gray in color, with a firm consistency and has ...
attached to the fibrocartilage. The fibrocartilaginous disk is reinforced by a series of ligaments. These ligaments cling to the fibrocartilaginous disk to the point that fibers intermix with it.
Two such ligaments are the superior pubic ligament and the inferior pubic ligament, which provide the most stability; the anterior and posterior ligaments are weaker. The strong and thicker superior ligament is reinforced by the tendons of the
rectus abdominis muscle
The rectus abdominis muscle, ( la, straight abdominal) also known as the "abdominal muscle" or simply the "abs", is a paired straight muscle. It is a paired muscle, separated by a midline band of connective tissue called the linea alba. It exte ...
, the
abdominal external oblique muscle
The abdominal external oblique muscle (also external oblique muscle, or exterior oblique) is the largest and outermost of the three flat abdominal muscles of the lateral anterior abdomen.
Structure
The external oblique is situated on the lateral ...
, the
gracilis muscle
The gracilis muscle (; Latin for "slender") is the most superficial muscle on the medial side of the thigh. It is thin and flattened, broad above, narrow and tapering below.
Structure
It arises by a thin aponeurosis from the anterior margins o ...
, and by
muscles of the hip
In human anatomy, the muscles of the hip joint are those muscles that cause movement in the hip. Most modern anatomists define 17 of these muscles, although some additional muscles may sometimes be considered. These are often divided into fou ...
. The superior pubic ligament connects together the two pubic bones superiorly, extending laterally as far as the pubic tubercles. The inferior ligament in the pubic arch is also known as the arcuate pubic ligament or subpubic ligament; it is a thick, triangular arch of ligamentous fibers, connecting together the two pubic bones below, and forming the upper boundary of the
pubic arch. Above, it is blended with the interpubic fibrocartilaginous lamina; laterally, it is attached to the inferior rami of the
pubic bones; below, it is free, and is separated from the fascia of the
urogenital diaphragm by an opening through which the
deep dorsal vein of the penis
Deep or The Deep may refer to:
Places United States
* Deep Creek (Appomattox River tributary), Virginia
* Deep Creek (Great Salt Lake), Idaho and Utah
* Deep Creek (Mahantango Creek tributary), Pennsylvania
* Deep Creek (Mojave River tributary), C ...
passes into the
pelvis
The pelvis (plural pelves or pelvises) is the lower part of the trunk, between the abdomen and the thighs (sometimes also called pelvic region), together with its embedded skeleton (sometimes also called bony pelvis, or pelvic skeleton).
The ...
.
Fibrocartilage
Fibrocartilage
Fibrocartilage consists of a mixture of white fibrous tissue and cartilaginous tissue in various proportions. It owes its inflexibility and toughness to the former of these constituents, and its elasticity to the latter. It is the only type of ...
is composed of small, chained bundles of thick, clearly defined, type I
collagen
Collagen () is the main structural protein in the extracellular matrix found in the body's various connective tissues. As the main component of connective tissue, it is the most abundant protein in mammals, making up from 25% to 35% of the whole ...
fibers. This fibrous
connective tissue
Connective tissue is one of the four primary types of animal tissue, along with epithelial tissue, muscle tissue, and nervous tissue. It develops from the mesenchyme derived from the mesoderm the middle embryonic germ layer. Connective tiss ...
bundles have cartilage cells between them; these cells to a certain extent resemble
tendon cells. The collagenous fibers are usually placed in an orderly arrangement parallel to tension on the tissue. It has a low content of
glycosaminoglycans
Glycosaminoglycans (GAGs) or mucopolysaccharides are long, linear polysaccharides consisting of repeating disaccharide units (i.e. two-sugar units). The repeating two-sugar unit consists of a uronic sugar and an amino sugar, except in the case ...
(2% of dry weight). Glycosaminoglycans are long, unbranched
polysaccharides (relatively complex carbohydrates) consisting of repeating
disaccharide units. Fibrocartilage does not have a surrounding
perichondrium
The perichondrium (from Greek el, περί, peri, around, label=none and el, χόνδρος, chondros, cartilage, label=none) is a layer of dense irregular connective tissue that surrounds the cartilage of developing bone. It consists of two sep ...
. Perichondrium surrounds the cartilage of developing bone; it has a layer of dense, irregular connective tissue and functions in the growth and repair of cartilage.
Hyaline cartilage
Hyaline cartilage
Hyaline cartilage is the glass-like (hyaline) and translucent cartilage found on many joint surfaces. It is also most commonly found in the ribs, nose, larynx, and trachea. Hyaline cartilage is pearl-gray in color, with a firm consistency and has ...
is the white, shiny gristle at the end of long bones. This cartilage has poor healing potential, and efforts to induce it to repair itself frequently end up with a similar, but poorer fibrocartilage.
Development
In the newborn, the symphysis pubis is 9–10 mm in width, with thick cartilaginous end-plates. By mid-adolescence the adult size is achieved. During adulthood the end-plates decrease in width to a thinner layer. Degeneration of the symphysis pubis accompanies aging and
postpartum. Women have a greater thickness of this pubic disc which allows more mobility of the pelvic bones, hence providing a greater diameter of pelvic cavity during
childbirth
Childbirth, also known as labour and delivery, is the ending of pregnancy where one or more babies exits the internal environment of the mother via vaginal delivery or caesarean section. In 2019, there were about 140.11 million births globall ...
.
Function
Analysis of the pelvis shows the skinny regions function as arches, transferring the weight of the upright trunk from the sacrum to the hips. The symphysis pubis connects these two weight-bearing arches, and the ligaments that surround this pelvic region maintain the mechanical integrity.
The main motions of the symphysis pubis are superior/inferior glide and separation/compression. The functions of the joint are to absorb shock during walking and allow delivery of a baby.
Clinical significance
Injury
The pubic symphysis widens slightly when the legs are stretched far apart. In sports where these movements are often performed, the risk of a pubic symphysis blockage is high, in which case, after completion of the movement, the bones at the symphysis do not realign correctly and can get jammed in a
dislocated position. The resulting pain can be severe, especially when further strain is put upon the affected joint. In most cases, the joint can only be successfully reduced into its normal position by a trained medical professional.
Disease
Metabolic diseases, such as
renal osteodystrophy, produce widening, while
ochronosis results in calcific deposits in the symphysis. Inflammatory diseases, such as
ankylosing spondylitis
Ankylosing spondylitis (AS) is a type of arthritis characterized by long-term inflammation of the joints of the spine typically where the spine joins the pelvis. Occasionally areas affected may include other joints such as the shoulders or hip ...
, result in bony fusion of the symphysis.
Osteitis pubis, the most common inflammatory disease in this area, is treated with anti-inflammatory medication and rest. Degenerative joint disease of the symphysis, which can cause groin pain, results from instability or from abnormal pelvic mechanics.
''
Symphysiolysis'' is separation or slipping of the symphysis. It has been estimated to occur in 0.2% of pregnancies.
Pregnancy
During
pregnancy
Pregnancy is the time during which one or more offspring develops ( gestates) inside a woman's uterus (womb). A multiple pregnancy involves more than one offspring, such as with twins.
Pregnancy usually occurs by sexual intercourse, but ca ...
in the human, hormones such as
relaxin
Relaxin is a protein hormone of about 6000 Da first described in 1926 by Frederick Hisaw.
The relaxin family peptide hormones belong to the insulin superfamily and consists of seven peptides of high structural but low sequence similarity; rela ...
remodel this ligamentous capsule allowing the pelvic bones to be more flexible for delivery. The gap of the symphysis pubis, normally is 4–5 mm but during pregnancy there will be an increase of at least 2–3 mm, therefore, it is considered that a total width of up to 9 mm between the two bones is normal for a pregnant woman. The symphysis pubis separates to some degree during
childbirth
Childbirth, also known as labour and delivery, is the ending of pregnancy where one or more babies exits the internal environment of the mother via vaginal delivery or caesarean section. In 2019, there were about 140.11 million births globall ...
. In some women this separation can become a
diastasis of the symphysis pubis. The
diastasis could be the result of a rapid birth, or a
forceps delivery, or may be a
prenatal
Prenatal development () includes the development of the embryo and of the fetus during a viviparous animal's gestation. Prenatal development starts with fertilization, in the germinal stage of embryonic development, and continues in fetal devel ...
condition. A diastasis of the symphysis pubis is a cause of
pelvic girdle pain (PGP). Overall, about 45% of all pregnant women and 25% of all women postpartum suffer from PGP.
Symphysiotomy
Symphysiotomy
Symphysiotomy is an outdated surgical procedure in which the cartilage of the pubic symphysis is divided to widen the pelvis allowing childbirth when there is a mechanical problem. It is also known as pelviotomy, synchondrotomy.
Introduction
Sym ...
is a surgical procedure in which the cartilage of the pubic symphysis is divided to widen the pelvis allowing childbirth when there is a mechanical problem. It allows the safe delivery of the fetus where
Caesarean section
Caesarean section, also known as C-section or caesarean delivery, is the surgical procedure by which one or more babies are delivered through an incision in the mother's abdomen, often performed because vaginal delivery would put the baby or mo ...
is not an option. Symphysiotomy is suggested for woman in isolated areas experiencing
obstructed labor
Obstructed labour, also known as labour dystocia, is the baby not exiting the pelvis because it is physically block during childbirth although the uterus contracts normally. Complications for the baby include not getting enough oxygen which may ...
where other medical intervention is unavailable.
This practice was carried out in Europe before the introduction of the Caesarean section. Historically, during obstructed labor, the skull of the fetus was also, at least occasionally, crushed in order to further facilitate the delivery.
Society and culture
Use in forensic anthropology
Pubic symphyses have importance in the field of
forensic anthropology, as they can be used to estimate the age of adult skeletons. Throughout life, the surfaces are worn at a fairly predictable rate. By examining the wear of the pubic symphysis, it is possible to estimate the age of the person at death.
Additional images
File:Gray1228.png, Median sagittal section of male pelvis
File:Gray1230.png, Median sagittal section of female pelvis
File:Slide3ADA.JPG, Anterior view of the body pelvis from a dissection. Pubic symphysis anteriorly.
See also
References
External links
Pelvic Instability Network Support (PINS)* – "Major Joints of the Lower Extremity – hip and sacrum (anterior view)"
* – "The Male Pelvis: Hemisection of the Male Pelvis"
*
{{DEFAULTSORT:Pubic Symphysis
Pelvis
Joints