pro cessus vaginalis in hernial sacs excised from babies with indirect (15% affected). It is also seen in myelomeningocoele affecting the
inguinal hernia. upper lumbar spinal cord (>30% affected), although in these latter cases
At birth, the processus vaginalis is narrowed and collapsed, but not it is not clear whether low abdominal pressure or genitofemoral nucleus
necessarily completely obliterated. It remains patent for 2 weeks in dysplasia is the cause (Hutson 2012). Cryptorchidism used to be con
nearly 70% of male infants but, by 3 weeks after birth, it is at least sidered a relatively minor birth defect that was corrected surgically
partially obliterated in 80% of male infants, the left side before the sometime during childhood. It is now considered to be a symptom of
right. testicular dysgenesis syndrome, a spectrum that includes hypospadias,
Persistent patency of the processus vaginalis leads to indirect inguinal impaired semen quality and testicular germ cell cancer (Toppari et al
hernia (widely patent and allowing prolapse of bowel), or hydrocele 2014). Since germ cell numbers decrease rapidly in undescended testes,
(narrow patency permitting only intraperitoneal fluid to trickle down orchipexy is now undertaken between 6–9 months of postnatal life.
into the tunica vaginalis). During obliteration, fluid may trickle only Further delay results in impaired testicular catchup growth in boys:
part of the way down the processus vaginalis to produce an encysted even with early orchipexy, men with bilateral undescended testes are
hydrocele of the cord. This is a relatively common but transient state six times more likely to be infertile (Lee and Shortliffe 2014).
and usually resolves completely within a few weeks by further oblitera
tion. Because of perinatal androgen exposure, the spermatic cord and Descent of the ovary
scrotum are relatively large in the neonate, as are the seminal vesicles The relative movements of the ovary are less extensive than those of the
and adjacent ampullae of the vas deferens. testis and are not hormonally regulated. Like the testis, the ovary ulti


In aberrant testicular descent, the testis may remain in the abdomen, mately reaches a lower level than it occupies in the early months of fetal
although this is thought to be uncommon because the hormonal and life, but it does not leave the pelvis to enter the inguinal canal, except
morphological features of the transabdominal phase are relatively in certain anomalies. The ovary is connected to the medial aspect of the
simple. By contrast, the indirect endocrine regulation and complex mesonephric fold by the mesovarium (homologous with the mesor
migratory process of the gubernaculum during the inguinoscrotal phase chium), and to the ventral abdominal wall by the inguinal fold (see
is frequently abnormal, leading to the testis lying in the inguinal or Fig. 72.13; Fig. 72.18). A mesenchymatous gubernaculum develops in
pubic region in 2–5% of neonates. Rarely, the testis may lie in the this fold but, as it traverses the mesonephric fold, it acquires an addi
perineum, in the upper part of the thigh or at the root of the penis. The tional attachment to the lateral margin of the uterus near the entrance
cause for these aberrant locations is unknown but is most likely to be of the uterine tube. Its lower part, caudal to this uterine attachment,
secondary to aberrant migration of the gubernaculum, perhaps caused becomes the round ligament of the uterus, and the part cranial to this
by a mislocated genitofemoral nerve. becomes the ovarian ligament. Collectively, these structures are homo
Testes that have descended may not remain within the scrotum if logous with the gubernaculum testis in the male (Fig. 72.19). This new
the spermatic cord does not double its length between birth and puberty uterine attachment may be correlated with the restricted ovarian
(Hutson 2013). It is thought that the aetiology of such acquired unde descent. At first, the ovary is attached to the medial side of the mesone
scended testes is also linked to that of hydrocele and hernia. Causes phric fold but, in accordance with the manner in which the two mes


may be deficient prenatal and postnatal androgens and inadequate onephric folds form the genital cord, it is finally connected to the
CGRP from the genitofemoral nerve. posterior layer of the broad ligament of the uterus. The gubernacula
Cryptorchidism is common in infants with abdominal wall defects thus develop in the female, unlike the male, as bilateral fibrous bands
such as bladder exstrophy, exomphalos (30% affected) and gastroschisis or ligaments in the absence of Insl3. They do not extend into the labia


DeveloPment of the urogenital system
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noitCes
A B
Ovary
Degenerating
mesonephros Ovarian ligament Mesovarium
Mesosalpinx
Uterine tube
Uterine tube
Uterus
Broad ligament
of uterus
Gubernaculum
ovarii
Uterus
C D
Uterine tube
Mesosalpinx
Ovarian ligament Mesovarium
Mesovarium Broad ligament
Mesosalpinx Round ligament
Broad ligament
Round ligament
Fig. 72.18 The descent of the ovary. A, An early developing left ovary and uterine tube. B, The start of posterior movement of the ovary. C, The left
ovary in its definitive posterior position. D, A sagittal section of the ligaments associated with the ovary, viewed from a left lateral position. (Based on
Tuchmann-Duplessis H, Haegel P 1972 Illustrated Human Embryology, Vol 2 Organogenesis. London: Chapman and Hall. With kind permission of
Springer Science+Business Media.)
majora, but end in the connective tissue just external to the external the enteric hindgut, and ventrocaudally is in contact with overlying
ring of the inguinal canal because, in the absence of androgens, there ectoderm at the cloacal membrane. Proliferation of mesenchyme at the
is no migratory phase analogous to inguinoscrotal migration in the angle of the junction of the hindgut and allantois produces a urorectal
male. The saccus vaginalis is present in the female. Its prolongation into septum (intercloacal mesenchyme), which grows caudally, promoting
the inguinal canal (sometimes termed the canal of Nuck) is normally the movement, but not the fusion, of the endodermal epithelium
completely obliterated, but may remain patent and form the sac of a towards the cloacal membrane (Fig. 72.20). The cloaca becomes sepa
potential indirect inguinal hernia. rated into a presumptive rectum and anal canal dorsally, and a pre


In the neonate, the ovaries lie in the lower part of the iliac fossae. sumptive urinary bladder and urogenital sinus ventrally; the cloacal
The long axis of the ovary is almost vertical. It becomes temporarily membrane is divided into anal and urogenital parts, respectively.
horizontal during descent, but regains the vertical when it reaches The nodal centre of division is the site of the future perineal body.
the ovarian fossa. The ovaries complete their descent into the ovarian The urogenital sinus receives the mesonephric and paramesonephric
fossae in early childhood. Thus, at birth, the ovary and the lateral ducts.
end of the corresponding uterine tube lie above the pelvic brim. They Anomalies of cloacal development may result in a range of defects.
do not sink into the lesser pelvis until the latter enlarges sufficiently In extroversion of the cloaca (ectopia cloacae), the urorectal septum
to contain both of them and the other pelvic viscera, including the does not develop and there is failure of mesenchymal migration around
bladder. Neonatal ovaries are 1–3.6 mm long (Stranzinger and Strouse the ventral body wall to support the umbilical cord; this results in a
2008) and their combined weight at birth is 0.3 g, which is relatively large abdominal defect with a central colonic portion and bilateral
large, and much larger than the combined weight of the testes (see bladder components. With only partial development of the urorectal
Figs 72.9, 14.6C). The ovaries double in weight during the first 6 septum, the urogenital sinus may remain with a high confluence of
postnatal weeks. They bear surface furrows, which disappear during bladder, vagina and rectum. The cloacal membrane may be abnormally
the second and third postnatal months. All of the primary oocytes for elongated and prematurely ruptured throughout its whole extent, prior
the reproductive life of a female are present in her ovaries by the end to the formation of the urorectal septum, or, in some cases, there may
of the first trimester of pregnancy. Of the 7 million primary oocytes be only a small sinus opening externally at the skin. The anal muscu


estimated to be present at the fifth month of gestation, 1 million lature is often present but not associated with the anal canal.
remain at birth and 40,000 by puberty; only 400 are ovulated during
reproductive life. Pelvic floor
The pelvic floor consists of the ligamentous supports of the cervix, and
Cloaca and external genitalia
the pelvic and urogenital diaphragms, and constitutes another partition
The cloaca is that region at the end of the primitive hindgut that is that traverses the body cavity. Little is known about pelvic floor devel
continuous with the allantois (see Figs 72.4, 72.7). The allantois, a opment in the human. The striated muscle is derived from the dermo
ventral diverticulum, passes into the connecting stalk of the early myotomes in a similar manner to the muscles of the ventrolateral body
embryo prior to tailfolding and is then drawn into the body cavity after wall. Puborectalis appears in 20–30 mm embryos, following opening
stage 10. It retains an extension into the connecting stalk, and later into of the anal membrane, and striated muscle fibres can be seen at
the umbilicus, throughout embryonic life. The cloaca is a slightly 15 weeks. The smooth muscle of the urethral sphincter is also present
dilated cavity lined with endoderm. It is initially connected cranially to at this time.


reproductive system
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Indifferent stage
Mesonephric (Wolffian) duct
Mesonephric tubules
Paramesonephric (Müllerian) duct
Gonad
Mesonephros
Urachus Gubernaculum
Metanephros
Primitive bladder
Trigone
Sinus (Müllerian) tubercle
Ureter
Rectum
Anal canal
Female Male
Urachus Paroophoron Vas deferens Seminal vesicle
Trigone Ovary Ureter
Fimbriae
Epoophoron
Ligament of ovary
Uterine tube
Round ligament of uterus
Ureter
Urachus
Prostatic utricle
Prostate
Bulbourethral gland
Superior aberrant ductules
Paradidymis
Appendix epididymis
Appendix testis
Efferent ductules
Epididymis
Line of degenerate Müllerian duct
Line of Gartner’s duct
Testis Inferior aberrant ductule
Vagina Fossa terminalis Gubernaculum
Fig. 72.19 The development of the urogenital system from the indifferent stage to the definitive male and female states. (Modified with permission from
Williams PL, Wendell-Smith CP, Treadgold S 1969 Basic Human Embryology, 2nd edn. London, Pitman Medical & Scientific.)
urethra believed that these regions are invaded by ectoderm because they are
The urethra is derived from endoderm, as are the prostate gland and innervated by somatic nerves.
vagina (both outgrowths of the lower urogenital sinus), and the other Urethral defects caused by anomalous development are not uncom
small glandular structures that develop around the caudal body mon in the male. In epispadias, the urethra opens on the dorsal aspect
orifices. of the penis at its junction with the anterior abdominal wall. This
In the male, the prostatic urethra proximal to the orifice of the pro anomaly is considered to be a less severe form of exstrophy of the
static utricle is derived from the vesicourethral part of the cloaca and bladder. In the simplest form of hypospadias, related to incomplete


the incorporated caudal ends of the mesonephric ducts. The remainder canalization of the urethral plate, the urethra may open on the ventral
of the prostatic part, the membranous part, and probably the part (perineal) aspect of the penis at the base of the glans, and the part of
within the bulb, are all derived from the urogenital sinus. The anterior the urethra that is normally within the glans is absent. In more severe
urethra, as far as the glans, is formed by canalization of the urethral cases, the genital folds fail to fuse, and the urethra opens on the ventral
plate (see below). Secondary ingrowth of mesenchyme fuses the genital aspect of a malformed penis just in front of the scrotum. A still greater
folds over the urethra (see Fig. 72.20). The short section within the glans degree of this anomaly is accompanied by failure of the genital swell
may be formed from ectoderm, which invaginates into the glans. ings to unite with each other. In these cases, the scrotum is divided and,
In the female, the urethra is derived entirely from the vesicourethral since the testes are also frequently undescended, the resemblance to the
region of the cloaca, including the dorsal region derived from the meso labia majora is very striking, leading to genital ambiguity. In such cases,
nephric ducts. It is homologous with the part of the prostatic urethra it is important to determine at the earliest time not only the chromo
proximal to the orifices of the prostatic utricle and the ejaculatory ducts. somal status of the infant but also the internal anatomy and state of
The region of the early urethra remains open to form the vestibule, into development of the internal genital tract. Sex assignment and rearing
which the definitive urethra and vagina open (see Fig. 72.20). It is will depend on these factors.


DeveloPment of the urogenital system
1218
8
noitCes
The urethral sphincter first forms as a mesenchymal condensation
Umbilical cord around the urethra in 12–15 mm (stage 18) embryos, after division of
Early bladder
Allantoic duct the cloaca. The mesenchyme proliferates and becomes defined at the
bladder neck in 31 mm embryos, and along the anterior part of the
urethra by 69 mm. The muscle fibres differentiate after 15 weeks’ devel
opment, at which time both smooth and striated fibres are present. In
females, there is continuity between the smooth muscle of the urethral
Genital tubercle
Endodermal cloaca wall and of the bladder. In males, the muscle fibres are less abundant
Cloacal because of the local development of the prostate. Striated muscle fibres
membrane form around the smooth muscle, initially in the anterior wall of the
urethra, and later encircle the smooth muscle layer. The origin of the
striated muscle is not known; it could be derived from the myogenic
cells that give rise to puborectalis. The smooth and striated components
of the urethral sphincter are closely related, but there is no mixing of
fibres as occurs in the anorectal sphincter.
Prostate gland
The prostate gland arises during the third month from interactions
Urogenital sinus Hindgut between the urogenital sinus mesenchyme – mesenchyme that was
associated with the mesonephric and paramesonephric ducts and the
endoderm of the proximal part of the urethra. This region has been
Genital tubercle
termed the Müllerian duct–urogenital sinus junction (Cai 2008). Early
Genital fold
outgrowths, some 14–20 in number, arise from the endoderm around
Urogenital orifice the whole circumference of the tube, but mainly on its lateral aspects
and excluding the dorsal wall above the utricular plate. They give rise
Anal orifice
to the outer glandular zone of the prostate. Later outgrowths from
and tubercles
the dorsal wall above the mesonephric ducts arise from the epithelium


of mixed urogenital, mesonephric and, possibly, paramesonephric
origin that covers the cranial end of the sinus tubercle. They produce
the internal zone of glandular tissue that appears to be patterned by
the mesenchyme that surrounded the lower end of the mesonephric
Labioscrotal and paramesonephric ducts. The developing gland is affected by the
swelling
local hormonal environment, as, in response to increased androgens,
recombination of female vaginal mesenchyme can direct endodermal
epithelium to form prostate gland (Cai 2008). The outgrowths, which
are at first solid, branch, become tubular and invade the surrounding
Male Female
mesenchyme. The latter differentiates into smooth muscle, associated
blood and lymphatic vessels and connective tissue, and is invaded
by autonomic nerves. An early surge in androgens at 8–10 weeks is
associated with endodermal growth, with mesenchymal proliferation
occurring later at 12 weeks, when maternal oestrogen levels increase
Glans penis Glans clitoridis
(Cai 2008).
Urethral groove Similar outgrowths occur in the female but remain rudimentary in
the absence of androgenic stimulation. The urethral glands correspond
Urethral orifice
to the mucosal glands around the upper part of the prostatic urethra,
and the paraurethral glands correspond to the true prostatic glands of
Genital fold the external zone.
Vagina The bulbourethral glands in the male, and the greater vestibular
glands in the female, arise as diverticula from the epithelial lining of
the urogenital sinus.
Scrotal Labial
swelling swelling
external genitalia
Patterning of the external genitalia may be achieved by mechanisms
Anus similar to those that pattern the face and limb. In the cranial region,
neural crest mesenchyme makes an important contribution to the
organization of the pharyngeal arches and the regions around the upper
sphincters. Neural crest also arises from the tailbud region, specifically
from a population of cells termed the caudoneural hinge, which share
the same molecular markers as the primitive node. The neural tube at
Glans penis this level is derived from a mesenchymal–epithelial transformation of


Glans clitoridis caudoneural hinge cells, which form a cylinder. Neural crest cells de
laminate from the dorsal surface of the cylinder in a rostrocaudal direc
Urethral orifice tion. It is not known whether neuronal neural crest arising from
Fused genital folds secondary neurulation processes contributes to the caudal interface
between endoderm and ectoderm. Many of the genes controlling exter
nal genital development have been identified (Kojima et al 2010, Blas
Vestibule
chko et al 2012).
Labium majus The external genitalia, like the gonads, pass through an indifferent
Labium minus state before distinguishing sexual characters appear (see Fig. 72.20).
Scrotum From stage 13, primordia of the external genitalia, composed of under
lying proliferating mesenchyme covered with ectoderm, arise around
Median raphe the cloacal membrane, between the primitive umbilical cord and the
caudal limit of the embryo. During stage 15, the cloacal membrane is
Anus divided by the urorectal septum into a cranial urogenital membrane
and a caudal anal membrane (see Fig. 72.4). Local ectodermal–
Fig. 72.20 The development of the external genitalia from the indifferent mesenchymal interactions give rise to the anal sphincter, which will
stage to the definitive male and female states. develop even without the presence of the anal canal. A surface elevation,
produced by underlying pericloacal mesenchyme, the genital tubercle,
appears at the cranial end of the urogenital membrane and two lateral


reproductive system
1219
27
retPahC
A B C
Fig. 72.21 Scanning electron micrographs of early human external genitalia. A, The indifferent stage in a human embryo, estimated as 42 postovulatory
days. B, A human female embryo at 12 weeks’ development. The genital folds are not fused. C, A human male embryo at 12 weeks. Fusion of the genital
folds has occurred. (Photographs by P Collins.)
ridges, the genital or urethral folds, form each side of the membrane wards to become continuous with the genital folds at the margins of
(see Fig. 72.20). The genital tubercle forms a distinct primordium, the urethral orifice. As the urethral folds meet to form the terminal part
which will become the glans of either the penis or the clitoris. Elonga of the urethra, the ventral horns of the ridge fuse to form the frenulum.
tion of the genital folds and urogenital membrane produces a primitive The epithelial lamella breaks down over the dorsum and sides of the
phallus. As this structure grows, it is described as having a cranial surface glans to form the preputial sac, and thus free the prepuce from the
analogous to the dorsum of the penis, and a caudal surface analogous surface of the glans. Thereafter, the prepuce grows as a free fold of skin,
to the perineal surface of both sexes. The urogenital sinus, contiguous which covers the terminal part of the glans. Although the prepuce and
with the internal aspect of the urogenital membrane, becomes attenu glans begin to separate from the fifth month in utero, they may still be
ated within the elongating phallus, forming the primitive urethra. The joined at birth. The preputial sac may not be complete until 6–12 months
urogenital membrane breaks down at about stage 19, allowing com or more after birth and, even then, the presence of some connecting
munication of ectoderm and endoderm at the edges of the disrupted strands may still interfere with the retractability of the prepuce.
membrane and continuity of the urogenital sinus with the amniotic The mesenchymal core of the phallus is comparatively undifferenti


cavity. Urine can escape from the urinary tract from this time. The ated in the first 2 months, but the blastemata of the corpora cavernosa
endodermal layer of the attenuated distal portion of the urogenital become defined during the third month. Nerves are present in the dif
sinus, which is now displayed on the caudal aspect of the phallus, is ferentiating mesenchyme from the seventh week. Despite containing
termed the urethral plate. As mesenchyme proliferates within the genital less smooth muscle and elastic tissue than the adult, the neonatal penis
folds, the urethral plate sinks into the body of the phallus, forming a is capable of erection.
primary urethral groove. The genital folds meet proximally in a trans The scrotum is formed by proliferation of the genital swellings. The
verse ridge immediately ventral to the anal membrane. genital swellings fuse across the midline covering the base of the penis.
While these changes are in progress, two labioscrotal (genital) swell The testes descend into the scrotum prior to birth. The gelatinous matrix
ings appear, one on each side of the base of the phallus, and extend of the gubernaculum is then resorbed and the tunica vaginalis becomes
caudally, separated from the genital folds by distinct grooves (see Fig. adherent to the connective tissue of the scrotum. In the neonate, the
72.20; Fig. 72.21). penis and scrotum are relatively large. The scrotum has a broad base
As a general rule, epithelium, which can be touched easily and has that does not narrow until after the first year. Both the septum (i.e. the
a somatic innervation, is derived from ectoderm. In the buccal cavity mesenchyme remaining between the tunica vaginalis on each side) and
and pharynx, the ectoderm/endoderm zone is towards the posterior the walls of the scrotum are relatively thicker than in adults.
third of the tongue; touch here usually elicits the gag reflex. In the anal
canal, the outer portion, distal to the anal valves, is derived from ecto Female genitalia


derm and has a somatic innervation, whereas the epithelium proximal The female phallus, which exceeds the male in length in the early stages,
to the valves is derived from endoderm and has an autonomic becomes the clitoris. The genital swellings remain separate as the labia
innervation. majora and the genital folds also remain separate, forming the labia
Homologies of the parts of the urogenital system are shown in minora (see Fig. 72.20). The perineal orifice of the urogenital sinus is
Table 72.1. retained as the cleft between the labia minora, above which the urethra
and vagina open. The prepuce of the clitoris develops in the same way
Male genitalia as its male homologue. By the fourth month, the female external geni
The growth of male external characteristics is stimulated by androgens talia can no longer be masculinized by androgens.
regardless of the genetic sex. The male phallus enlarges to form the At birth, neonatal females have relatively enlarged labia minora,
penis. The genital swellings meet each other ventral to the anus and clitoris and labia majora. The labia majora are united by a posterior
unite to form the scrotum (see Fig. 72.20). The genital folds fuse with labial commissure. The distal end of the round ligament of the
each other from behind forwards, enclosing the phallic part of the uterus, the gubernaculum ovarii, ends just outside the external inguinal
urogenital sinus behind to form the bulb of the urethra, and closing ring.
the definitive urethral groove in front to form the greater part of the There is evidence that in certain tissues, e.g. urogenital sinus and
spongiose urethra. Fusion of the folds results in the formation of a genital swellings, testosterone is converted into 5αdihydrotestosterone.
median raphe and occurs in such a way that the lining of the postglan In XY individuals with a genetic deficiency of the enzyme responsible
dular urethra is mainly, perhaps wholly, endodermal in origin, formed for this conversion, not only functioning testes but also female external


by canalization of the urethral plate. Thus, as the phallus lengthens, the genitalia, with an enlarged clitoris and a small vaginal pouch, are
urogenital orifice is carried onwards until it reaches the base of the glans present, suggesting that external genital development is under the
at the apex of the penis. From the tip of the phallus, an ingrowth of control of 5αdihydrotestosterone (Kang et al 2014). Such individuals
surface ectoderm occurs within the glans to meet and fuse with the are often raised as girls; however, at puberty the external genitalia
penile urethra. Subsequent canalization of the ectoderm permits a con become responsive to testosterone, which causes masculinization at this
tinuation of the urethra within the glans. time.
The glans and shaft of the penis are recognizable by the third month.
Disorders of sex development
The prepuce also begins to develop in the third month, when the
primary external orifice of the urethra is still at the base of the glans. A The acquisition of appropriate gonads, reproductive ducts, external
ridge consisting of a mesenchymal core covered by epithelium appears genital structures and matching gender identity occurs through a myriad
proximal to the neck of the penis and extends forwards over the glans. of complex processes, both local and systemic. Anomalous develop
A solid lamella of epithelium deep to this ridge extends backwards to mental processes, leading to differences in sex chromosomes, gonadal
the base of the glans. The ventral extremities of the ridge curve back structure and position, retention of ductal homologues, androgen


DeveloPment of the urogenital system
1220
8
noitCes
insensitivity, androgen excess, and ambivalent external genitalia requir
ing gender assignment, were previously described as intersexual condi Average girl
tions or hermaphrodism. Such terminology is nonspecific, confusing
and perceived as potentially pejorative by affected individuals. Advances
in the identification of molecular genetic causes of such conditions have
Height spurt
led to proposed changes to describe them as ‘disorders of sex develop 9½–14½
ment’ (DSD): congenital conditions in which development of chromo
somal, gonadal or anatomical sex is atypical (Lee et al 2006). The range Menarche
of anomalous development and its management by multidisciplinary Bud 10–16½
teams, as well as by the affected family, are comprehensively covered Breast 2 3 4 5
by Arboleda and Vilain (2014). 8–13
Pubic hair 2 3 4 5
Maturation of the reproductive organs 8–14
at puberty
Until the adolescent growth spurt, the reproductive organs grow very
8 9 10 11 12 13 14 15 16 17 18
slowly. Generally, the changes occur over a time period termed puberty.
The sequence of these events is much less variable than the age at which Average boy Apex strength spurt
they take place. The sequence of puberty in girls and boys is shown in
Figure 72.22.
In girls, the appearance of the breast bud is usually the first sign of
Height spurt
puberty. The uterus and vagina develop simultaneously with the breast.
10½–16 13–17½
Menarche occurs after the peak of the height spurt; onset is more closely
related to radiological than to chronological age. It has been suggested Penis
that the menarche occurs as a critical weight of 50 kg is attained, and 11–14½ 13½–17
certainly sports and excessive restriction of diet, which may reduce Testis
weight below this level, can cause amenorrhoea in women who were 10–13½ 14½–18
previously menstruating normally. Tall girls reach sexual maturity
Pubic hair 2 3 4 5


earlier than short ones, but girls with a late adolescent growth spurt and
10–15 14–18
later puberty are ultimately taller on the average than those who pass
through the menarche early, for they have longer to grow. A girl who
has begun to menstruate can be predicted to grow a further 7.5 cm at
8 9 10 11 12 13 14 15 16 17 18
most. Menarche marks a definitive stage of uterine development but
Age (years)
does not mean attainment of full reproductive function. Many of the
Fig. 72.22 The average ages at which maturation events occur in
early menstrual cycles may not involve ovulation.
adolescent girls and boys. The figures beneath the bars indicate the
The earliest sign of puberty in boys is the growth of the testes and
range of ages within which each event may begin and end. Figures within
scrotum. The volume of the testes may be estimated: the average adult
the bars indicate the developmental stage. The velocity of the strength
volume is 20 ml, and a volume of 6 ml indicates that puberty has
spurt peaks later than the height spurt in boys, associated with
started. Later, the penis, prostate and seminal vesicles begin to enlarge.
testosterone and growth hormone levels. It is appreciated that the
Increased testosterone levels produced by the Leydig cells of the testes assessment and interpretation of the strength spurt during puberty is
promote changes in the larynx, skin and distribution of bodily hair. complex (De Ste Croix 2007). (Adapted with permission from Tanner JM
1962 Growth at Adolescence, 2nd edn. Oxford: Blackwell Publishing.)
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Arboleda VA, Vilain E 2014 Disorders of sex development. In: Strauss JF, Sharpe RM, McKinnell C, Kivlin C et al 2003 Proliferation and functional
Barbieri RL (eds) Yen & Jaffe’s Reproductive Endocrinology, 7th ed. maturation of Sertoli cells, and the relevance to disorders of testis func
Philadelphia: Elsevier, Saunders; Ch. 17. tion in adulthood. Reproduction 125:769–84.
This chapter considers the complexities of disorders of sex development and This paper considers the importance of Sertoli cell development and the


their management. future sperm count of adult males.
Barteczko KJ, Jacob MI 2000 The testicular descent in human. Origin, devel Tanaka ST, Ishii K, Demarco RT et al 2010 Endodermal origin of bladder
opment and fate of the gubernaculum Hunteri, processus vaginalis trigone inferred from mesenchymalepithelial interaction. J Urol 183:
peritonei and gonadal ligaments. Adv Anat Embryol Cell Biol 156:III–X, 386–91.
1–98. This paper presents the molecular evidence for the origin of the bladder
This paper presents excellent images of early human testis and its descent trigone mucosa.
into the scrotum. Wang C, Wang JY, Borer JG et al 2013 Embryonic origin and remodelling of
Chai O, Song C, Park S et al 2013 Molecular regulation of kidney develop the urinary and digestive outlets. PLoS One 8:e55587.
ment. Anat Cell Biol 46:19–31. This paper considers the development of the cloacal region and its separation
This paper examines the molecular processes behind some of the into enteric and urogenital parts.
epithelial:mesenchymal interactions occurring in the developing kidney. White SL, Perkovic V, Cass A et al 2009 Is low birth weight an antecedent
Hutson JM 2013 Undescended testis: the underlying mechanisms and the of CKD in later life? A systematic review of observational studies. Am J
effects on germ cells that cause infertility and cancer. J Pediatr Surg Kidney Dis 54:248–61.
48:903–8. This paper considers the evidence that impaired nephrogenesis caused by low
This paper considers the relationships between testicular development and birth weight may give rise to chronic kidney disease.
final testis maturity.
Lee PA, Houk CP, Ahmed SF et al 2006 Consensus statement on manage
ment of intersex disorders. International Consensus Conference on
Intersex. Paediatrics 118:e488–500.
This paper presents the recommendations in intersex disorder management.


Development of the urogenital system
1220.e1
27
retPahC
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Kidney Dis 54:248–61.


CHAPTER
73
True pelvis, pelvic floor and perineum
ischiococcygeus form the pelvic diaphragm and delineate the lower
TRUE PELVIS AND PELVIC FLOOR
limit of the true pelvis (Fig. 73.2). The fasciae investing the muscles are
continuous with visceral pelvic fascia above, perineal fascia below, and
The true pelvis is a bowl-shaped structure formed from the sacrum, obturator fascia laterally.
pubis, ilium, ischium, the ligaments that interconnect these bones, and
the muscles that line their inner surfaces. The true pelvis is considered Piriformis
to start at the level of the plane passing through the promontory of the Piriformis forms part of the posterolateral wall of the true pelvis and is
sacrum, the arcuate line on the ilium, the iliopectineal line and the attached to the anterior surface of the sacrum, the gluteal surface of the
posterior surface of the pubic crest. This plane, or ‘inlet’, lies at an angle ilium near the posterior inferior iliac spine, the capsule of the adjacent
of between 35° and 50° up from the horizontal; above this plane, the sacroiliac joint and, sometimes, to the upper part of the pelvic surface
bony structures are sometimes referred to as the false pelvis. They form of the sacrotuberous ligament. It passes out of the pelvis through the
part of the walls of the lower abdomen. In children, the width of the greater sciatic foramen above the sacrospinous ligament. Within the
pelvic inlet is an age-independent predictor of chest width and thoracic pelvis, the posterior surface of the muscle lies against the sacrum, and
dimensions (Emans et al 2005). The ‘outlet’ of the true pelvis is formed the anterior surface is related to the rectum (especially on the left), the
by the ischiopubic rami, ischial tuberosities, sacrotuberous ligaments sacral plexus of nerves and branches of the internal iliac vessels. Piri-
and distal sacrum. The bones surround a central pelvic canal that forms formis is described in more detail in Chapter 80.
a ventrally concave curve (the curve of Carus); in the female, it consti-


tutes the birth canal. The details of the topography of the bony and Obturator internus
ligamentous pelvis are considered fully in Chapter 80. Obturator internus and the fascia over its upper, inner (pelvic), surface
form part of the anterolateral wall of the true pelvis. It is attached to
the structures surrounding the obturator foramen, ischio-pubic ramus,
MUSCLES AND FASCIAE OF THE PELVIS
the pelvic surface of the hip bone below and behind the pelvic brim,
and the upper part of the greater sciatic foramen. It is also attached to
Pelvic muscles
the medial part of the pelvic surface of the obturator membrane. The
muscle is covered by a fascial layer, and the muscle fibres can be seen
The muscles arising within the pelvis form two groups. Piriformis and through this semi-transparent membrane from within the pelvis. Spe-
obturator internus form part of the walls of the pelvis, and are consid- cialized portions of the fascia give attachment to some of the fibres of
ered primarily as muscles of the lower limb (Fig. 73.1). Levator ani and levator ani (tendinous arch of levator ani), so that only the upper
Greater sciatic foramen
Sacral promontory
Piriformis
Ischiococcygeus
Ischium
Ischial spine
Obturator Obturator fascia
canal
Tendinous arch
Superior of levator ani
pubic ramus Sacrospinous Anococcygeal
ligament
ligament
Lesser sciatic
foramen Iliococcygeus
Inferior pubic
(ischiopubic) ramus Sacrotuberous
ligament
Obturator internus Ischial tuberosity Pubococcygeus Pubovaginalis
Fig. 73.1 Piriformis, obturator internus and the ligaments of the pelvis. Fig. 73.2 Muscles of the female pelvis. The superior gluteal and obturator
Those muscles relating only to the pelvis or perineum have been omitted vessels and nerves, as well as the pelvic viscera, have been omitted for


for clarity. (Adapted with permission from Drake RL, Vogl AW, Mitchell A clarity. (Adapted with permission from Drake RL, Vogl AW, Mitchell A
(eds), Gray’s Anatomy for Students, 2nd ed, Elsevier, Churchill (eds), Gray’s Anatomy for Students, 2nd ed, Elsevier, Churchill
Livingstone. Copyright 2010.) Livingstone. Copyright 2010.) 1221


True pelvis, pelvic floor and perineum
1222
8
noiTces
Pubic symphysis Fig. 73.3 Muscles of the female pelvis viewed
from above. The sacral nerve roots have been
Endopelvic fascia lining superior
Pubis divided close to the sacral foramina. The anorectal
aspect of deep perineal
junction, vagina and urethra have been divided at
space/pouch
the level of the pelvic floor.
Urethra
Vagina
Tendinous arch of
levator ani
Pubococcygeus
Fascia over
obturator internus
Iliococcygeus
Rectum
Ischium
Ischiococcygeus
Third and fourth
sacral foramina
Piriformis
Anococcygeal ligament
Iliac wing
Sacrum
portion of obturator internus can be seen from above. The lower portion Iliococcygeus Iliococcygeus is attached to the inner surface of the
forms part of the boundaries of the ischio-anal fossa. In the male, the ischial spine below and anterior to the attachment of ischiococcygeus,
upper portion lies lateral to the bladder, the obturator and vesical and also to the tendinous arch as far forwards as the obturator canal
vessels, and the obturator nerve. In the female, the attachments of the (see Fig. 73.2). The most posterior fibres are attached to the tip of the
broad ligament of the uterus, the ovarian end of the uterine tubes and sacrum and coccyx, but the majority join fibres from the contralateral
the uterine vessels also lie medial to obturator internus and its fascia. side to form a raphe that is effectively continuous with the fibroelastic
anococcygeal ligament, which is closely applied to its inferior surface;
Levator ani (pubococcygeus, iliococcygeus
some muscle fibres may attach into the ligament. The raphe provides a
and puborectalis) strong attachment for the pelvic floor posteriorly and must be divided
Levator ani is a broad muscular sheet of variable thickness attached to to allow wide excisions of the anorectal canal during abdominoperineal


the internal surface of the pelvis. It forms a large portion of the pelvic excisions for malignancy. An accessory slip may arise from the most
floor (Fig. 73.3) (Lawson 1974a, Roberts et al 1988, Wendell-Smith posterior part and is sometimes referred to as iliosacralis.
and Wilson 1991). The muscle is subdivided into named portions
according to their attachments and the pelvic viscera to which they are Puborectalis Puborectalis lies lateral to pubococcygeus and cannot
related (pubococcygeus, iliococcygeus and puborectalis). These parts been seen from inside the pelvis. It originates from the inner surface of
are often referred to as separate muscles but the boundaries between the ischiopubic rami immediately adjacent to, and sometimes arising
each part cannot be easily distinguished and, moreover, they perform in part from, the perineal membrane. Its fibres pass lateral to those of
many similar physiological functions. Ischiococcygeus (coccygeus) lies iliococcygeus and pubococcygeus to decussate posterior to the rectum
immediately cranial to levator ani and is contiguous with it. Pubococcy- at the anorectal junction. The border between puborectalis and some
geus is often subdivided into separate parts according to the pelvic fibres of the external anal sphincter is indistinct.
viscera to which each part relates (puboperinealis, puboprostaticus or
pubovaginalis, puboanalis, puborectalis). Levator ani arises from each Ischiococcygeus Ischiococcygeus may be referred to as a separate
side of the walls of the pelvis along the condensation of the obturator muscle, sometimes named coccygeus. It lies as the most posterosuperior
fascia (the tendinous arch of levator ani). Fibres from ischiococcygeus portion of levator ani, and arises as a triangular musculotendinous
attach to the sacrum and coccyx but the remaining parts of the muscle sheet with its apex attached to the pelvic surface and tip of the ischial


converge in the midline. Fibres from iliococcygeus join by a partly spine, and base attached to the lateral margins of the coccyx and the
fibrous intersection and form the iliococcygeal raphe posterior to the fifth sacral segment. Ischiococcygeus is rarely absent, but may be almost
anorectal junction. Closer to the anorectal junction, and elsewhere completely tendinous rather than muscular. It lies on the pelvic aspect
in the pelvic floor, the fibres are more nearly continuous with those of of the sacrospinous ligament and may be fused with it, particularly if
the opposite side, such that the muscle forms a sling (iliococcygeus, it is mostly tendinous. The sacrospinous ligament may represent either
puborectalis). a degenerate part or an aponeurosis of the muscle, since muscle and
ligament are coextensive.
Attachments The attachments for pubococcygeus, iliococcygeus and
puborectalis are as follows. Relations The superior, pelvic, surface of levator ani is separated only
by fascia (superior pelvic diaphragmatic, visceral and extraperitoneal)
Pubococcygeus Pubococcygeus originates from the posterior aspect from the urinary bladder, prostate or uterus and vagina, rectum and
of the body of the pubis and passes back almost horizontally. The most peritoneum. Its inferior, perineal, surface forms the medial wall of the
medial fibres run directly lateral to the urethra and its sphincter as it ischio-anal fossa and the superior wall of the anterior recess of the fossa,
passes through the pelvic floor; here, the muscle is correctly called both being covered by inferior pelvic diaphragmatic fascia. The poste-
puboperinealis, although, because of its close relationship to the upper rior border is separated from the coccyx by areolar tissue. The medial
half of the urethra in both sexes, it is often referred to as pubourethralis; borders of the two levator muscles and the inferior ischiopubic rami
despite this, no direct connection with the urethra is present. In males, border the levator hiatus, through which pass the urethra, vagina (in


some of these fibres lie lateral and inferior to the prostate and are the female) and anus. In the female, that portion of the hiatus that lies
referred to as puboprostaticus (levator prostatae). In females, fibres run anterior to the perineal body is referred to as the urogenital hiatus.
further back and attach to the lateral walls of the vagina, where they are
referred to as pubovaginalis. In both sexes, fibres from this part of Vascular supply Levator ani is supplied by branches of the inferior
pubococcygeus attach to the perineal body; a few elements also attach gluteal, inferior vesical and pudendal arteries.
to the anorectal junction. Some fibres, sometimes called puboanalis,
decussate and blend with the longitudinal rectal muscle and fascial Innervation The nerves to levator ani originate mainly from the third
elements to contribute to the conjoint longitudinal coat of the anal and fourth sacral spinal segments, with lesser contributions from the
canal. Behind the rectum, other fibres of pubococcygeus form a tendi- second segment. These nerves enter the pelvis just above, and some-
nous intersection as part of the levator raphe. Elements of pubococcy- times pierce, ischiococcygeus to pass along the ventral surface of ischio-
geus (puboperineus, pubovaginalis/puboprostaticus and puboanalis) coccygeus and pubococcygeus, supplying these muscles and sending
may collectively be referred to as ‘pubovisceralis’. fibres to puborectalis (Sato 1980, Roberts and Krishingner 1967). The


True pelvis and pelvic floor
1223
37
reTpaHc
pudendal nerve also may supply pubococcygeus from its lateral surface ated upper portion of the attachment of levator ani. It is connected to
through its inferior rectal and perineal branches. the posterior part of the arcuate line of the ilium and is continuous
with iliac fascia. Anterior to this, as it follows the line of origin of obtu-
Actions Pubococcygeus and puborectalis pull the pelvic and perineal rator internus, it is gradually separated from the attachment of the iliac
structures ventrally and cranially, occluding the levator hiatus. In the fascia, and a portion of the periosteum of the ilium and pubis spans
female, this action occludes the vaginal canal and prevents prolapse of between them. It arches below the obturator vessels and nerve, investing
the pelvic organs through the urogenital hiatus. The constant baseline the obturator canal, and is attached anteriorly to the back of the pubis.
activity of the levator muscles is similar to that of the anal sphincter, Behind the obturator canal, the fascia is markedly aponeurotic and gives
modulated to adjust to the loads placed on them. The action of pubo- a firm attachment to the iliococcygeal portion of levator ani, usually
rectalis and pubococcygeus also reinforces the external anal sphincter called the tendinous arch of levator ani (arcus tendineus musculi leva-
and helps to create the anorectal angle. Iliococcygeus and, to a lesser toris ani) (see Figs 73.3, 73.14, 73.15). Above the attachment of levator
extent, the less muscular ischiococcygeus form a relatively horizontal ani, the fascia is thin and is effectively composed only of the epimysium
diaphragm, especially in the dorsal half of the pelvis, that assists pubo- of the muscle and overlying connective tissue; posteriorly, it forms part
rectalis in achieving anorectal and urinary continence. of the lateral wall of the ischio-anal fossa in the perineum, and anteri-


Levator ani must relax appropriately to permit expulsion of urine orly, it merges with the fasciae of the muscles of the deep perineal space,
and, particularly, faeces; it contracts with the abdominal muscles and which is continuous with the ischio-anal fossa. The obturator fascia is
the abdominothoracic diaphragm to raise intra-abdominal pressure. It continuous with the pelvic periosteum and, thus, the fascia over
forms much of the muscular pelvic diaphragm, which supports the piriformis.
pelvic viscera. Like the abdominothoracic diaphragm, but unlike the
abdominal muscles, levator ani is also active in the inspiratory phase fascia over piriformis
of quiet respiration. In the pregnant female, the shape of the pelvic floor The fascia over the inner aspect of piriformis is very thin, and fuses with
may help to direct the fetal head into the anteroposterior diameter of the periosteum on the front of the sacrum at the margins of the anterior
the pelvic outlet. sacral foramina. It ensheathes the anterior primary rami of the sacral
nerves that emerge from these foramina; the nerves are often described
Pelvic fasciae as lying behind the fascia. The internal iliac vessels lie in front of
the fascia over piriformis; their branches draw out sheaths of the fascia
The pelvic fasciae may be conveniently divided into the parietal pelvic and extraperitoneal tissue into the gluteal region, above and below
fascia, which forms the coverings of the pelvic muscles, and the visceral piriformis.
pelvic fascia, which forms the coverings of the pelvic organs and their
fascia over levator ani (pelvic diaphragm)
neurovascular supply (Fig. 73.4).
Both surfaces of levator ani have a fascial covering; the combination of
Parietal pelvic fascia the two fascial layers and the intervening muscle is called the pelvic
The parietal pelvic fascia consists of the obturator fascia, the fasciae over diaphragm. On the inferior surface, the thin fascia is continuous with
piriformis, and over levator ani (the pelvic diaphragm) and the presac- the obturator fascia below the tendinous arch of levator ani laterally. It
ral fascia. covers the medial wall of the ischio-anal fossa and blends below with


fasciae on the urethral sphincter and the external anal sphincter. The
obturator fascia superior fascia of the pelvic diaphragm is markedly thicker than the
The parietal pelvic fascia on the pelvic (medial) surface of obturator inferior fascia and is attached anteriorly to the posterior aspect of
internus is well differentiated. In humans, ventral to the lateral attach- the body of the pubis, approximately 2 cm above its lower border. It
ment of the pelvic organs, a portion of it is derived from the degener- extends laterally across the superior pubic ramus, blending with the
Superficial abdominal fascia
Peritoneum Presacral fascia
Posterior mesorectal fascia
Anterior mesorectal fascia
Anococcygeal ligament
Suspensory ligament of the penis
Deep transverse perineal muscle
Endopelvic fascia
Perineal body
Perineal membrane
External anal sphincter
Superficial perineal fascia
Deep perineal fascia
Fig. 73.4 Fasciae of the pelvis and perineum: median sagittal section in the male. The visceral parietal fasciae have been omitted for clarity.


True pelvis, pelvic floor and perineum
1224
8
noiTces
obturator fascia and continuing along an irregular line to the spine of cervix, together with some of the pelvic autonomic nerves. A similar
the ischium. It is continuous posteriorly with the fascia over piriformis vesicosacral fold is present in the male.
and the anterior sacrococcygeal ligament. Medially, the superior fascia Approximately 1 cm above the inferior border of the pubic bone and
of the pelvic diaphragm blends with the visceral pelvic fascia to con- 1 cm lateral to the midline, a band of dense pelvic connective tissue
tribute to the endopelvic fascia. – the anterior end of the tendinous arch of the pelvic fascia – attaches
to the paravaginal tissues in the female and the prostatic tissues in the
Tendinous arch of the pelvic fascia/white line of the male. This band extends on the inner surface of levator ani and joins
parietal pelvic fascia the tendinous arch of levator ani to the ischium, just above the spine.
Low on the superomedial aspect of the upper fascia over levator ani, a The attachment of the paravaginal tissue to the pubic bones is some-
thick, white band of condensed connective tissue extends from the times called the pubourethral ligament, which is a misnomer since it
lower part of the pubic symphysis to the superior margin of the ischial is not attached to the urethra. The attachment of the anterior vaginal
spine. It provides attachment for the condensations of visceral pelvic wall to the tendinous arch of the pelvic fascia, the paravaginal attach-
fascia that provide support to the urethra and bladder, and to the vagina ment, helps to provide support to the vagina, urethra and bladder.
in females (see below). There is much less condensation of connective tissue around the
rectum. A layer presumed to be a peritoneal fusion fascia is described
presacral fascia between the rectum and either the seminal vesicles in the male or the
The presacral fascia forms a hammock-like structure behind the poste- vagina in the female (the rectovesical septum or rectovaginal septum,


rior portion of the mesorectal fascia. Laterally, it extends to the origin respectively); it does not connect to the rectum itself. The connective
of the fascia over piriformis and the fascia over levator ani (superior tissue over the longitudinal muscles of the rectum is thickened just
pelvic diaphragmatic fascia), with which it blends; more inferiorly, it above the anal hiatus in levator ani and fuses with the endopelvic fascia
extends between the white line of the parietal pelvic fascia on either and the anococcygeal ligament, forming a structure that is sometimes
side. Inferiorly, it extends to the anorectal junction, where it fuses with referred to as a rectosacral ligament.
the posterior aspect of the mesorectal fascia and the iliococcygeal raphe
at the level of the anorectal junction. Superiorly, it can be traced to the
origin of the superior hypogastric plexus, where it becomes progres- VASCULAR SUPPLY AND LYMPHATIC
sively thinner over the sacral promontory and becomes continuous with DRAINAGE OF THE PELVIS
the retroperitoneal tissues. The right and left hypogastric nerves and
inferior hypogastric plexuses lie on its surface, and the presacral veins The true pelvis contains the internal iliac arteries and veins, and the
lie immediately posterior to it. It forms a distinct layer that can be seen lymphatics that drain the majority of the pelvic viscera. The common
both on magnetic resonance images of the pelvis and during surgery. and external iliac vessels and the lymphatics that drain the lower limb
The presacral fascia provides an important landmark because extension lie along the pelvic brim and in the lower retroperitoneum, but are
of rectal tumours through it significantly reduces the possibility of cura- conveniently discussed together with the vessels of the true pelvis.
tive resectional surgery. Dissection in the plane posterior to the fascia Remarkable variation exists in the terminal branching pattern for the
may result in bleeding from the presacral veins; because the adventitia iliac vessels and no two individuals have quite the same anatomy.
of the veins is partly attached to the posterior surface of the fascia, the General patterns do, however, exist and this description will consider


haemorrhage may be severe (as the veins are unable to contract prop- the common pattern.
erly). The presacral fascia is a useful structure to which the rectum may
be sutured during rectopexy for rectal prolapse in children.
Arteries of the pelvis
Visceral pelvic fascia
Common iliac arteries
The urogenital organs in both sexes are connected bilaterally to the
pelvic walls by neurovascular mesenteric condensations ensheathed by The abdominal aorta bifurcates into the right and left common iliac
a meshwork of loose connective and adipose tissue and lying above the arteries anterolateral to the left side of the body of the fourth lumbar
perineal membrane (Roberts et al 1964, Ricci et al 1947, Reiffenstuhl vertebra (Roberts and Krishingner 1967). These arteries diverge as they
1982, Range and Woodburne 1964, Campbell 1950). The lateral attach- descend and they divide at the level of the sacroiliac joint into external
ments of the pelvic organs to the pelvic side walls are referred to as and internal iliac arteries. The external iliac artery is the principal artery
the endopelvic fascia. Considered as a unit, the connections provide a of the lower limb. The internal iliac artery provides the principal supply
conduit for conducting neurovascular elements from the pelvic side to the walls and viscera of the pelvis, the perineum and the gluteal
wall to the organs and attachments that help to retain the pelvic organs region.
in place; this factor is important in the female in preventing pelvic
organ prolapse (DeLancey 1992). The loose connective tissue associ- Right common iliac artery The right common iliac artery is
ated with these mesenteries extends to the midline, separating the approximately 5 cm long. It passes obliquely across part of the bodies
bladder from the vagina, and the vagina from the rectum, in the female; of the fourth and the fifth lumbar vertebrae, and is crossed anteriorly
it separates the bladder, prostate and seminal vesicles from the rectum by the sympathetic rami to the pelvic plexus and, at its division into


in the male. The fascial tissues contain varying amounts of connective internal and external iliac arteries, by the ureter. It is covered by the
tissue and smooth muscle; where they either are unusually dense or parietal peritoneum, which separates it from the coils of the small
form visible ridges, they are called ‘ligaments’ (e.g. cardinal ligament, intestine. Posteriorly, it is separated from the bodies of the fourth
uterosacral ligament). Clinically, these lateral attachments are often and fifth lumbar vertebrae and their intervening disc by the right sym-
referred to as visceral ‘ligaments’, but they are mesenteric in nature and, pathetic trunk, the terminal parts of the common iliac veins and the
therefore, quite unlike the bands of dense, regular, connective tissue start of the inferior vena cava, the obturator nerve, lumbosacral trunk
that typify skeletal ligaments. The lateral attachments of the mesenter- and iliolumbar artery. Laterally, the inferior vena cava and the right
ies sweep off the pelvic walls, arising from the superior fascia over common iliac vein lie superiorly and the right psoas major lies inferi-
levator ani and from part of the fascia over piriformis more superiorly orly. The left common iliac vein is medial to the upper part of the right
and posteriorly. The mesenteries passing to the bladder in the male, or common iliac artery.
the bladder and upper vagina and uterus in the female, are relatively
long, but these lateral connections become shorter towards the pelvic Left common iliac artery The left common iliac artery is shorter
outlet, until at the level of the perineal membrane, there is a direct than the right and is approximately 4 cm long. Lying anterior to it are
connection between the organs and the pelvic walls. the sympathetic rami to the pelvic plexus, the superior rectal artery and,
In the female, the cardinal ligament is the upper portion of this at its terminal bifurcation, the ureter. The sympathetic trunk, the bodies
mesentery. It surrounds the cervicovaginal junction and extends down of the fourth and fifth lumbar vertebrae and intervening disc, the obtu-


to mid-vagina, where the vagina has a more direct lateral attachment at rator nerve, lumbosacral trunk and iliolumbar artery are all posterior.
the tendinous arch of the pelvic fascia. The portions that attach to the The left common iliac vein is posteromedial, and the left psoas major
uterus and vagina are sometimes called the parametrium and paracol- lateral, to the left common iliac artery.
pium, respectively. Further accounts of the paravisceral portions of the
visceral pelvic fascia are given in the chapters describing the organs to Branches In addition to the external iliac and internal iliac branches,
which the fascia relates. each common iliac artery also gives small branches to the peritoneum,
The uterosacral ligament is a visible fold of tissue flanking the psoas major, ureter, adjacent nerves and surrounding areolar tissue. The
rectum as it descends posterior to the cervix in the female. It contains common iliac artery occasionally gives rise to the iliolumbar artery and
a considerable amount of smooth muscle near its attachment to the accessory or replaced renal arteries if the kidney is low-lying.


True pelvis, pelvic floor and perineum
1224.e1
37
reTpaHc
The anteroposterior diameters of the common, external and internal
iliac arteries are strongly correlated to body surface area (BSA) in chil-
dren, in contrast to adults, in whom the relationship is inconsistent.
Vessel diameters measured by ultrasonography are significantly larger
in boys than in girls. The relationship between vessel diameters and BSA
is shown in Figure 73.7 (Munk et al 2002).
A Fig. 73.7 The relationship between
anteroposterior diameters of the right
Boys (1-16 years): common, internal and external iliac arteries
right common iliac artery
and body surface area (BSA) in boys and
(systolic phase)
girls between the ages of 1 and 16 years.
(With permission from Munk AL, Darge K,
Wiesel M, Troeger J, Diameter of the
infrarenal aorta and the iliac arteries in
children: ultrasound measurements.
Transplantation 2002;73:631–635.)
0
0.0 0.5 1.0
BSA (m2)
B
Boys (1-16 years):
right internal iliac artery
C
Boys (1-16 years):
right external iliac artery
D
Girls (1-16 years):
right common iliac artery
(systolic phase)
E
Girls (1-16 years):
right internal iliac artery
F
Girls (1-16 years):
right external iliac artery
)mm(
retemaiD
20
15
10
5
1.5 2.0
0
0.0 0.5 1.0
BSA (m2)
)mm(
retemaiD
20
15
10
5
1.5 2.0
0
0.0 0.5 1.0
BSA (m2)
)mm(
retemaiD
20
15
10
5
1.5 2.0
0
0.0 0.5 1.0
BSA (m2)
)mm(
retemaiD
0
0.0 0.5 1.0
BSA (m2)
20
15
10


5
1.5 2.0
)mm(
retemaiD
0
0.0 0.5 1.0
BSA (m2)
20
15
10
5
1.5 2.0
)mm(
retemaiD
20
15
10
5
1.5 2.0


True pelvis and pelvic floor
1225
37
reTpaHc
Internal iliac arteries
trunk and sacroiliac joint are posterior. Laterally are the external iliac
Each internal iliac artery, approximately 4 cm long, begins at the vein, between the artery and psoas major, and the obturator nerve lying
common iliac bifurcation, level with the lumbosacral intervertebral disc inferior to the vein. The parietal peritoneum is medial, separating it
and anterior to the sacroiliac joint (Figs 73.5, 73.6). It descends poste- from the terminal ileum on the right and the sigmoid colon on the left,
riorly to the superior margin of the greater sciatic foramen, where it and tributaries of the internal iliac vein. For details of the considerable
divides into an anterior trunk, which continues in the same line towards variation in the anatomy of the internal iliac artery, see Roberts and
the ischial spine, and a posterior trunk, which passes back to the greater Krishingner (1967).
sciatic foramen. The anterior trunk primarily supplies the pelvic organs, In the fetus, the internal iliac artery is twice the size of the external
while the posterior trunk primarily supplies muscles in the hip and iliac artery and is the direct continuation of the common iliac artery.
back. Anterior to the artery are the ureter and, in females, the ovary and The main trunk ascends on the anterior abdominal wall to the umbili-
fimbriated end of the uterine tube. The internal iliac vein, lumbosacral cus, converging on the contralateral artery, and the two arteries run
Fig. 73.5 Arteries of the male pelvis.
Internal iliac artery
Iliolumbar artery
Superior gluteal artery
Ureter
Posterior trunk
Anterior trunk
Superior
Lateral sacral artery
vesical artery
Pudendal artery
Inferior gluteal artery
Obturator artery
Middle rectal artery
Obliterated right
umbilical artery Inferior vesical artery
Fig. 73.6 Arteries of the female pelvis.
Internal iliac artery
Iliolumbar artery
Superior gluteal artery
Posterior trunk
Superior Anterior trunk
vesical artery Pudendal artery
Uterine artery


Lateral sacral artery
Obturator artery
Inferior gluteal artery
Obliterated right Vaginal artery
umbilical artery Inferior vesical artery
Middle rectal artery


True pelvis, pelvic floor and perineum
1226
8
noiTces
through the umbilicus to enter the umbilical cord as the umbilical the posterior surface of the pubis. It supplies the distal end of the ureter,
arteries. At birth, when placental circulation ceases, only the pelvic the bladder, the proximal end of the vas deferens and the seminal vesi-
segment remains patent as the internal iliac artery and part of the supe- cles. It also gives origin to the umbilical artery in the fetus, which
rior vesical artery; the remainder becomes a fibrous medial umbilical remains as a fibrous cord – the medial umbilical ligament – in the adult.
ligament. Persistence of the umbilical artery has been described and This vessel occasionally remains patent as a small artery supplying the
may cause extrinsic obstruction of the distal ureter (Gupta et al 1999). umbilicus.
In males, the patent part (commonly, the superior vesical artery) usually
gives off an artery to the vas (ductus) deferens. Inferior vesical artery The inferior vesical artery may arise as a
common branch with the middle rectal artery. It supplies the bladder,
posterior trunk branches prostate, seminal vesicles and vas deferens in the male, and the bladder
The branches of the posterior trunk of the internal iliac artery are the in the female, where it is often replaced by the vaginal artery.
iliolumbar, lateral sacral and superior gluteal arteries.
Middle rectal artery The middle rectal artery runs into the lateral
Iliolumbar artery The iliolumbar artery is the first branch of the fascial coverings of the mesorectum. It often consists of multiple
posterior trunk and ascends laterally anterior to the sacroiliac joint and branches, may be small, and occasionally arises either close to, or in
lumbosacral nerve trunk. It lies posterior to the obturator nerve and common with, the origin of the inferior vesical artery in males.
external iliac vessels, and reaches the medial border of psoas major,
dividing behind it into the lumbar and iliac branches. The lumbar Vaginal artery In females, the vaginal artery may replace the inferior


branch supplies psoas major and quadratus lumborum, and anastomo- vesical artery. It may arise from the uterine artery close to its origin and
ses with the fourth lumbar artery. It sends a small spinal branch through can be a single vessel or multiple branches.
the intervertebral foramen between the fifth lumbar and first sacral
vertebrae, to supply the cauda equina. The iliac branch supplies iliacus; Obturator artery The obturator artery runs anteroinferiorly from the
between the muscle and bone, it anastomoses with the iliac branches anterior trunk on the lateral pelvic wall to the upper part of the obtura-
of the obturator artery. A large nutrient branch enters an oblique canal tor foramen. In the pelvis, it is related laterally to the fascia over obtura-
in the ilium. Other branches run around the iliac crest, contribute to tor internus and is crossed on its medial aspect by the ureter and, in
the supply of the gluteal and abdominal muscles, and anastomose the male, by the vas deferens. The obturator nerve runs above the artery,
with the superior gluteal, circumflex iliac and lateral circumflex femoral the obturator vein below it. The artery provides iliac branches to the
arteries (see Fig. 80.18). iliac fossa that supply the bone and iliacus and anastomose with
the iliolumbar artery. It gives off a vesical branch that runs medially to
Lateral sacral arteries The lateral sacral arteries are usually double; the bladder and sometimes replaces the inferior vesical branch of the
if they are single, they divide rapidly into superior and inferior branches. internal iliac artery. In the female, the ovary lies medial to the obturator
The superior and larger artery passes medially into the first or second artery. A pubic branch usually arises just before the obturator artery
anterior sacral foramen, supplies the sacral vertebrae and contents of leaves the pelvis; it ascends over the pubis to anastomose with the
the sacral canal, and then leaves the sacrum via the corresponding contralateral artery and the pubic branch of the inferior epigastric
dorsal foramen to supply the skin and muscles dorsal to the sacrum. artery.


The inferior or lateral sacral artery crosses obliquely anterior to piri- The obturator artery leaves the pelvis via the obturator canal and
formis and the sacral anterior spinal rami, and then descends lateral to divides into anterior and posterior branches that encircle the obturator
the sympathetic trunk to anastomose with its fellow and the median foramen between obturator externus and the obturator membrane. The
sacral artery anterior to the coccyx. Its branches enter the anterior sacral anterior branch curves anteriorly on the membrane and then inferiorly
foramina and are distributed in the same way as the branches of the along its anterior margin to supply branches to obturator externus,
superior artery. pectineus, the femoral adductors and gracilis. It anastomoses with the
posterior branch and the medial circumflex femoral artery. The poste-
Superior gluteal artery The superior gluteal artery is the largest rior branch follows the posterior margin of the foramen and turns
branch of the internal iliac artery and, effectively, forms the main con- anteriorly on the ischial part to anastomose with the anterior branch.
tinuation of its posterior trunk. It runs posteriorly between the lum- It supplies the muscles attached to the ischial tuberosity and anastomo-
bosacral trunk and the first sacral ramus, or between the first and second ses with the inferior gluteal artery. An acetabular branch enters the hip
rami, and then turns slightly inferiorly, leaving the pelvis by the greater joint at the acetabular notch, ramifies in the fat of the acetabular fossa
sciatic foramen above piriformis and dividing into superficial and deep and sends a branch along the ligament of the femoral head.
branches. In the pelvis, it supplies piriformis, obturator internus and a Occasionally, the obturator artery is replaced by an enlarged pubic
nutrient artery to the ilium. The superficial branch enters the deep branch of the inferior epigastric artery that descends almost vertically
surface of gluteus maximus. Its numerous branches supply the muscle to the obturator foramen. It usually lies near the external iliac vein,


and anastomose with the inferior gluteal branches (see Fig. 80.30), lateral to the femoral ring, and is rarely injured during inguinal or
while others perforate the tendinous medial attachment of the muscle femoral hernia surgery. Sometimes, it curves along the edge of the
to supply the skin over the sacrum, where they anastomose with the lacunar part of the inguinal ligament, partly encircling the neck of a
posterior branches of the lateral sacral arteries. The deep branch of the hernial sac, and may be inadvertently cut during enlargement of the
superior gluteal artery passes between gluteus medius and the bone, femoral ring in reducing a femoral hernia.
soon dividing into superior and inferior branches. The superior branch
skirts the superior border of gluteus minimus to the anterior superior Uterine artery The uterine artery is an additional branch in females.
iliac spine, and anastomoses with the deep circumflex iliac artery and It is a large artery that arises below the obturator artery on the lateral
the ascending branch of the lateral circumflex femoral artery. The infe- wall of the pelvis and runs inferomedially into the broad ligament of
rior branch runs through gluteus minimus obliquely, supplies it and the uterus (Ch. 77).
gluteus medius, and anastomoses with the lateral circumflex femoral
artery. A branch enters the trochanteric fossa to join the inferior gluteal Internal pudendal artery (pelvic portion) The internal pudendal
artery and ascending branch of the medial circumflex femoral artery; artery is the smaller terminal branch of the anterior division of the
other branches run through gluteus minimus to supply the hip joint. internal iliac artery. Close to its origin, it crosses anterior to piriformis,
The superior gluteal artery occasionally arises directly from the inter- the sacral plexus and the inferior gluteal artery. It descends laterally to
nal iliac artery with the inferior gluteal artery and sometimes from the the inferior rim of the greater sciatic foramen, where it leaves the pelvis
internal pudendal artery. between piriformis and ischiococcygeus, and enters the gluteal region


(see Fig. 77.3B). It next curves around the dorsum of the ischial spine
anterior trunk branches and enters the ischiorectal fossa via the lesser sciatic foramen. This
The branches of the anterior trunk of the internal iliac artery are the course effectively allows the nerve to wrap around the posterior limit
superior and inferior vesical, middle rectal, vaginal, obturator, uterine, of levator ani at its attachment to the ischial spine. Behind the ischial
internal pudendal and inferior gluteal arteries (see Fig. 73.6). Signifi- spine, the artery is covered by gluteus maximus, the pudendal nerve is
cant variation occurs in the branching patterns of the anterior trunk; medial, and the nerve to obturator internus is lateral. The artery traverses
the general principles will be considered here. the ischiorectal fossa in Alcock’s canal in the fascia covering obturator
internus; it gives off an inferior rectal branch early in its course through
Superior vesical artery The superior vesical artery is the first large the fossa (see Fig. 73.12). The internal pudendal artery gives off several
branch of the anterior trunk. It lies on the lateral wall of the pelvis, just muscular branches in the pelvis and gluteal region that supply adjacent
below the brim, and runs anteroinferiorly, medial to the periosteum of muscles and nerves.


True pelvis and pelvic floor
1227
37
reTpaHc
Inferior gluteal artery The inferior gluteal artery is the larger termi- ascends obliquely to end at the right side of the fifth lumbar vertebra,
nal branch of the anterior internal iliac trunk and principally supplies uniting at an acute angle with the contralateral vessel to form the infe-
the buttock and thigh. It descends posteriorly, anterior to the sacral rior vena cava. The right common iliac vein is shorter and more nearly
plexus and piriformis but posterior to the internal pudendal artery. It vertical, lying posterior, and then lateral, to its artery. The right obtura-
passes between either the first and second, or second and third, sacral tor nerve passes posteriorly. The left common iliac vein is longer and
ventral rami, then between piriformis and ischiococcygeus, before more oblique, and lies first medial, then posterior, to its artery. It is
running through the lower part of the greater sciatic foramen to reach crossed anteriorly by the attachment of the sigmoid mesocolon and
the gluteal region. The artery runs inferiorly between the greater tro- superior rectal vessels. Each vein receives iliolumbar and, sometimes,
chanter and ischial tuberosity, together with the sciatic and posterior lateral sacral veins. The left common iliac vein usually drains the
femoral cutaneous nerves, deep to gluteus maximus. It continues down median sacral vein. There are no valves in these veins.
the thigh, supplying the skin and anastomosing with branches of the The left common iliac vein occasionally ascends to the left of the
perforating arteries. The inferior gluteal and internal pudendal arteries aorta to the level of the kidney, where it receives the left renal vein and
often arise as a common stem from the internal iliac artery, sometimes crosses anterior to the aorta to join the inferior vena cava; this vessel
with the superior gluteal artery. In the pelvis, the inferior gluteal artery represents the persistent caudal half of the left postcardinal or supra-
gives branches to piriformis, ischiococcygeus and iliococcygeus, and cardinal vein.
occasionally contributes to the middle rectal arterial supply. In the


male, it may supply vessels to the seminal vesicles and prostate. Median sacral veins The right and left medial sacral veins accom-
pany the corresponding arteries anterior to the sacrum, where they unite
External iliac arteries
to form a single vein that usually ends in the left common iliac vein,
The external iliac arteries are of larger calibre than the internal iliac but which sometimes ends at the common iliac junction.
arteries (see Figs 73.5, 73.6). Each artery descends laterally along the
medial border of psoas major, from the common iliac bifurcation to a Internal pudendal veins The internal pudendal veins are venae
point midway between the anterior superior iliac spine and the pubic comitantes of the internal pudendal artery and unite as a single vessel
symphysis, and enters the thigh posterior to the inguinal ligament to that drains into the internal iliac vein. They receive veins from the
become the femoral artery. inferior rectal veins and either the penile bulb and scrotum (males), or
The parietal peritoneum and extraperitoneal tissue separate the right the clitoris and labia (females).
external iliac artery from the terminal ileum and, usually, the appendix,
and the left external iliac artery from the sigmoid colon and coils of Internal iliac vein
small intestine anteromedially. At its origin, the external iliac artery may The internal iliac vein is formed by the convergence of several veins
be crossed by the ureter; it is subsequently crossed by the gonadal above the greater sciatic foramen. It does not have the predictable
vessels, the genital branch of the genitofemoral nerve, the deep circum- trunks and branches of the internal iliac artery but its tributaries drain
flex iliac vein, and the vas deferens (male) or round ligament (female). the same territories. It ascends posteromedial to the internal iliac
Posteriorly, the artery is separated from the medial border of psoas artery to join the external iliac vein, forming the common iliac vein at
major by the iliac fascia. The external iliac vein lies partly posterior to the pelvic brim, anterior to the lower part of the sacroiliac joint. It is


its upper part but is more medial below. Laterally, it is related to psoas covered anteromedially by parietal peritoneum. Its tributaries are the
major, which is covered by the iliac and psoas fasciae. Numerous lymph gluteal, internal pudendal and obturator veins, which originate out-
vessels and nodes lie on its anterior and lateral aspects. side the pelvis; the lateral sacral veins, which run from the anterior
The external iliac artery is principally the artery of the lower limb surface of the sacrum; and the middle rectal, vesical, uterine and vagi-
and, as such, has few branches in the pelvis. Apart from giving off very nal veins, which originate in the venous plexuses of the pelvic viscera
small vessels to psoas major and neighbouring lymph nodes, the artery (Fig. 73.8).
has no branches until it gives off the deep circumflex iliac and inferior The venous drainage of the leg may be blocked by thrombosis
epigastric arteries, near to the point at which it passes under the inguinal involving the external iliac systems and the inferior vena cava. Under
ligament. these circumstances, the pelvic veins, particularly the internal iliac tribu-
taries, enlarge and provide a major avenue of venous return from the
Deep circumflex iliac artery The deep circumflex iliac artery femoral system. Surgical interference with these veins may seriously
branches laterally from the external iliac artery almost opposite the compromise venous drainage and precipitate oedema of one or
origin of the inferior epigastric artery (see Fig. 78.7A). It ascends and both legs.
runs laterally to the anterior superior iliac spine behind the inguinal
ligament in a sheath formed by the union of the transversalis and iliac Superior gluteal veins The superior gluteal veins are the venae
fasciae. There, it anastomoses with the ascending branch of the lateral comitantes of the superior gluteal artery. They receive tributaries that
circumflex femoral artery, pierces the transversalis fascia and skirts correspond to the branches of the superior gluteal artery and enter the


the internal lip of the iliac crest. About halfway along the iliac crest, it pelvis via the greater sciatic foramen, above piriformis. They join the
runs through transversus abdominis, and then between transversus internal iliac vein, frequently as a single trunk.
abdominis and internal oblique, to anastomose with the iliolumbar
and superior gluteal arteries. It gives off a large ascending branch at the Inferior gluteal veins The inferior gluteal veins are venae comitantes
anterior superior iliac spine that runs between internal oblique and of the inferior gluteal artery. They begin proximally and posterior in the
transversus abdominis, supplies both muscles, and anastomoses with thigh, where they anastomose with the medial circumflex femoral and
the lumbar and inferior epigastric arteries. first perforating veins, and they enter the pelvis low in the greater sciatic
foramen, joining to form a vessel that opens into the distal (lower) part
Inferior epigastric artery The inferior epigastric artery originates of the internal iliac vein. The inferior gluteal and superficial gluteal
from the external iliac artery posterior to the inguinal ligament. It curves veins connect by perforating veins (Doyle 1970) analogous to the sural
forwards in the anterior extraperitoneal tissue and ascends obliquely perforating veins. The gluteal veins probably have a venous ‘pumping’
along the medial margin of the deep inguinal ring; from here, it con- role, and provide collaterals between the femoral and internal iliac
tinues as an artery of the anterior abdominal wall. veins.
Veins of the pelvis Obturator vein The obturator vein begins in the proximal adductor
region and enters the pelvis via the obturator foramen. It runs posteri-
The true pelvis contains a large number of veins that drain the pelvic orly and superiorly on the lateral pelvic wall below the obturator artery
walls and most of the viscera contained within the pelvis, and also carry and between the ureter and internal iliac artery, and ends in the internal
venous blood from the gluteal region, hip and thigh. The external iliac iliac vein. It is sometimes replaced by an enlarged pubic vein, which


veins, which lie close to the brim of the pelvis, carry the venous drainage joins the external iliac vein.
from most of the lower limb. There is considerable variation in the
venous drainage of the pelvis: although the major veins frequently Lateral sacral veins The lateral sacral veins accompany the lateral
follow their named arterial counterparts, the small tributaries exhibit sacral arteries and are interconnected by a sacral venous plexus.
considerable inter-individual variation.
Middle rectal vein The middle rectal vein begins in the rectal venous
Common iliac veins plexus and drains the rectum and mesorectum. Variable in size, it runs
The common iliac vein is formed by the union of the external and laterally on the pelvic surface of levator ani to end in the internal iliac
internal iliac veins, anterior to the sacroiliac joints (see Fig. 78.8). It vein. The middle rectal vein often receives tributaries from the bladder


True pelvis, pelvic floor and perineum
1228
8
noiTces
Fig. 73.8 Veins of the female pelvis.
Internal iliac vein
Superior gluteal vein
Lateral sacral vein
Superior
vesical vein Pudendal vein
Obturator vein
Inferior gluteal
vein
Uterine vein
Middle rectal vein
Inferior vesical vein
and either the prostate and seminal vesicle (males) or the posterior They usually lie in medial, lateral and anterior chains around the
aspect of the vagina (females). common iliac artery, the lateral being the main route; one or two lie
inferior to the aortic bifurcation and anterior to the fifth lumbar verte-
External iliac vein
bra or sacral promontory. The common iliac nodes connect to the
The external iliac vein is the proximal continuation of the femoral vein lateral aortic nodes.
(see Figs 78.8, 80.33). It begins posterior to the inguinal ligament,
ascends along the pelvic brim, and ends anterior to the sacroiliac joint External iliac nodes
by joining the internal iliac vein to form the common iliac vein. On The external iliac nodes usually form three subgroups, which are lateral,
the right, it lies medial to the external iliac artery, gradually inclining medial and anterior to the external iliac vessels (see Fig. 77.3B). The
behind it as it ascends. On the left, it is wholly medial. Disease of the medial nodes are considered the main channel of drainage, collecting
external iliac artery may cause it to adhere closely to the vein at the lymph from the lower limb via the inguinal nodes, the deeper layers of
point where it is in contact, and, particularly on the right side, the walls the infra-umbilical abdominal wall, the adductor region of the thigh,
of the vessels may become fused, making dissection hazardous. The the glans penis or clitoris, the membranous urethra, prostate, fundus of
external iliac vein is crossed medially by the ureter and internal iliac the bladder, uterine cervix and upper vagina. Their efferents pass to the


artery. In males, it is crossed by the vas deferens, in females by the round common iliac nodes (see Fig. 78.10).
ligament and ovarian vessels. Psoas major lies laterally, except where
the artery intervenes. The vein is usually valveless but may contain a Inferior epigastric and circumflex iliac nodes The inferior
single valve. Its tributaries are the inferior epigastric, deep circumflex epigastric and circumflex iliac nodes are associated with their similarly
iliac and pubic veins. Agenesis of the external iliac vein has been named vessels and drain the corresponding areas to the external iliac
reported in association with Klippel–Trenaunay syndrome (Dogan et al nodes.
2003).
Internal iliac nodes
Inferior epigastric vein One or two inferior epigastric veins accom- The internal iliac nodes surround the branches of the internal iliac
pany the inferior epigastric artery and drain into the external iliac vein vessels. They receive afferents from most of the pelvic viscera (with the
a little above the inguinal ligament. exception of the gonads and the majority of the rectum), the deeper
parts of the perineum, and the gluteal and posterior femoral muscles,
Deep circumflex iliac vein The deep circumflex iliac vein is formed and drain to the common iliac nodes. The individual groups are con-
from venae comitantes of the corresponding artery. It joins the external sidered in the description of the viscera. There are frequent connections
iliac vein a little above the inferior epigastric vein, after crossing anterior between the right and left groups, particularly when they lie close to
to the external iliac artery. the anterior and posterior midlines (Fig. 73.9).
Pubic vein The pubic vein connects the external iliac and obturator
veins. It ascends on the pelvic surface of the pubis with the pubic branch INNERVATION OF THE PELVIS
of the inferior epigastric artery and sometimes replaces the normal
obturator vein. The pelvis contains the lumbosacral nerve trunk, the sacral and coccy-
geal plexuses, and the pelvic parts of the sympathetic and parasym-
Lymphatic drainage of the pelvis pathetic systems. Collectively, these nerves carry the somatic and


autonomic innervation to the majority of the pelvic visceral organs,
The lymph nodes in the pelvis are grouped around the common, and the muscles of the pelvic floor and perineum, the gluteal region
external iliac and internal iliac vessels, and are named accordingly and the lower limb.
(Nesselrod 1936). The ventral rami of the sacral and coccygeal spinal nerves form the
sacral and coccygeal plexuses (Fig. 73.10). The upper four sacral ventral
Common iliac nodes
rami enter the pelvis by the anterior sacral foramina, the fifth enters
The common iliac nodes receive the entire lymphatic drainage of the between the sacrum and coccyx, and the ventral ramus of the coccygeal
lower limb because they drain both internal and external iliac nodes. nerve curves forwards below the rudimentary transverse process of the


True pelvis and pelvic floor
1229
37
reTpaHc
first coccygeal segment. The first and second sacral ventral rami are of psoas major and descends over the pelvic brim, anterior to the sac-
large, the third to fifth diminish progressively in size, and the coccygeal roiliac joint, to join the first sacral ramus. The greater part of the second
ramus is the smallest. Each receives a grey ramus communicans from a and third sacral rami converge on the inferomedial aspect of the lum-
corresponding sympathetic ganglion. Visceral efferent rami leave the bosacral trunk in the greater sciatic foramen to form the sciatic nerve.
second to fourth sacral rami as the pelvic splanchnic nerves, containing The ventral and dorsal divisions of the nerves do not separate physically
preganglionic parasympathetic fibres to minute ganglia in the walls of from each other but their fibres remain separate within the rami; the
the pelvic viscera. ventral and dorsal divisions of each contributing root join within the
sciatic nerve. The fibres of the dorsal divisions will go on to form
Lumbosacral trunk and sacral plexus the common fibular nerve, and the fibres of the ventral division form
the tibial nerve. The sciatic nerve, occasionally, divides into common
fibular and tibial nerves inside the pelvis; when this occurs, the common
The sacral plexus is formed by the lumbosacral trunk, the first to third
fibular nerve usually runs through piriformis.
sacral ventral rami, and part of the fourth sacral ventral ramus
The sacral plexus lies against the posterior pelvic wall anterior to
(the remainder of the fourth sacral ventral ramus joins the coccygeal
piriformis, posterior to the internal iliac vessels and ureter, and behind
plexus).
the sigmoid colon on the left. The superior gluteal vessels run either
The lumbar part of the lumbosacral trunk contains part of the fourth
between the lumbosacral trunk and first sacral ventral ramus, or between
and all of the fifth lumbar ventral rami; it appears at the medial margin
the first and second sacral rami, while the inferior gluteal vessels


lie between either the first and second, or second and third, sacral
Common iliac nodes Posterior trunk nodes rami.
The sacral plexus is not commonly involved in malignant tumours
of the pelvis because it lies behind the relatively dense presacral fascia,
which resists all but locally very advanced malignant infiltration. When
it occurs, there is intractable pain in the distribution of the branches of
the plexus, which may be very difficult to treat. The plexus may also be
involved in the reticuloses or be affected by plexiform neuromas.
Branches of the sacral plexus
The branches of the sacral plexus are shown in Table 73.1.
The course and distribution of most of the branches of the sacral
plexus are covered fully in Section 9.
Table 73.1 Branches of the sacral plexus
Nerve Ventral divisions Dorsal divisions
Internal
iliac nodes Nerve to quadratus femoris and gemellus inferior L4, 5; S1
Nerve to obturator internus and gemellus superior L5; S1, 2
Superior Nerve to piriformis S2 (S1)
vesical nodes
Superior gluteal nerve L4, 5; S1
Middle Inferior gluteal nerve L5; S1, 2
rectal nodes Posterior femoral cutaneous nerve S2, 3 S1, 2
Tibial (sciatic) nerve L4, 5; S1, 2, 3
Obturator nodes
Common fibular (sciatic) nerve L4, 5; S1, 2
Uterine and lateral Perforating cutaneous nerve S2, 3
cervical nodes Vaginal nodes Pudendal nerve S2, 3, 4
Nerves to levator ani and external anal sphincter S4
Fig. 73.9 Lymphatic drainage of the female pelvis and urinary bladder.
Fig. 73.10 The lumbosacral plexus in the pelvis.
L4 root
L5 root
Lumbosacral trunk
S1 root
S2 root
Superior gluteal nerve S3 root
S4 root
Inferior gluteal nerve
Sciatic nerve
Nerve to piriformis
Obturator nerve
Perforating
cutaneous nerve