somite 34 form cloacal muscles solely. Within pelvic girdle develop-
root of the umbilical artery passing to the placenta, and continues into
ment, myoblasts do not attain their position by somitic hypaxial
the limb bud as the axial artery. The arterial supply to the developing
domain extension; all myoblasts migrate into the region. Interestingly,
lower limb is thus far less oxygenated than the arterial supply to the
the population of myoblasts giving rise to perineal muscles are inner-
upper limb, which receives blood directly from the heart via the sub-
vated by axons derived from neurones located in Onuf’s nucleus,
clavian artery. It is possible that the development of several arteries,
whereas those that remain in the limb bud gain innervation from ante-
some of which subsequently regress, in the distal part of the leg in the
rior horn cells (Valasek et al 2005).
embryonic period, is a reflection of the lower oxygenation of these
The bony pelvis forms from two hemipelves, each of which develops
tissues. During development, the lower limb undergoes medial rotation
from one cartilaginous focus. Ossification of the pelvis starts with the
and extension, so that the original dorsal (extensor) portion of the limb
ilium, which undergoes endochondral ossification at 9.5 weeks. Devel-
becomes directed ventrally. This relative movement suggests that very
opment of trabecular bone in the ilium is evident from about 22 weeks’
different patterning mechanisms operate in the lower limb compared
gestation and a mature trabecular morphology is present at birth (Cun-
to those in the upper limb: an early, complex vasculature may be a
ningham and Black 2009a, Cunningham and Black 2009b). It is sug-
product of that difference.
gested that the trabecular pattern, previously assumed to develop
There have been relatively few studies on the early development of
consequent to weight bearing and bipedal gait, is initiated through
the vasculature of the lower limb (Senior 1991a,b, Mandell et al 1985,
genetic patterning plus intrauterine muscular movements which confer
Levinsohn et al 1991). The terminology used to describe the developing
biomechanical loading onto the ilium and pelvis.


vessels is specific and will be used here: descriptions of developmental
The development of the superior pubic rami is related to the normal
vascular anomalies retain the original terminology. Table 79.1 describes
development of the cloacal membrane. In cases of bladder exstrophy
and illustrates the changes to the axial artery, the new vessels that arise
(see Fig. 72.11), the superior pubic rami are shortened and do not meet
and the vessels that regress, during stages 13–19 (corresponding to
at the pubic symphysis. There is a 4 cm pubic diastasis at birth, which
weeks 5–7 of development). The mature vascular pattern is established
increases to 8 cm at age 10 years, compared with a mean normal width
by the end of the embryonic period.
of the pubic symphysis of 0.6 cm at all ages (Wild et al 2011). The
ischiopubic segment of the pelvis is 30% shorter, the iliac wings are
Veins
externally rotated and the acetabuli are retroverted (Wild et al 2011).
The mechanisms suggested for this are premature rupture of an abnor-
mally cranially placed cloacal membrane, obstruction of medial migra- The superficial veins of the lower limb are derived from the marginal
tion of somatopleuric mesenchyme, and local apoptosis of ventral vein which runs along the periphery of the extending limb bud beneath
mesenchyme (Stec 2011). It is thought that some combination of the the pre- and post-axial limb borders. The preaxial vein becomes the long
three is likely. saphenous vein, which drains into the femoral vein at the saphenous
The sacroiliac joint can be recognized from 7 weeks; its development opening. The postaxial vein becomes the short saphenous vein, which
is slightly different from that of other synovial joints in that the devel- passes deep and joins the popliteal vein. The earliest valves in the short
opment of the ilium is ahead of that of the sacrum. Reconsideration of saphenous vein are noted at 13 weeks’ gestation. The number of valves


the role of the sacroiliac joint in the transfer of load from axial to increases from 1 to 8 between 13 and 18 weeks’ gestation; there are
appendicular skeleton has been prompted by study of the relative more valves present in the upper than in the lower portion of the short
growth of regional surface areas of the ilium from birth to adulthood saphenous vein (Czarniawska-Grzesińska and Bruska 2002).
(Yusof et al 2013). Cavitation of the hip joint has been reported at
7–8 weeks.
ULTRASOUND ANTENATAL IMAGING
LOWER LIMB DEVELOPMENT
Femur length is routinely measured to assess growth velocity (along
with head circumference and abdominal circumference) and to predict
The lower limb is first recognizable as a laterally projecting thickening the expected date of delivery. The longest axis of the ossified diaphysis
in the body wall opposite somites 24–29 at stage 13 (28 days); by stage is identified with soft tissue noted beyond both ends. The distal
14, it is closely associated with the wide umbilical cord. During stages epiphysis is excluded (Fig. 79.1). Fetal femur length is related to ethnic-
15–17, the limb projects laterally and outgrowth is fairly symmetrical. ity, and appropriate fetal biometry comparison charts are necessary for
The core of mesenchymal cells is derived from both somatopleuric and accurate evaluation; whether such data can be extrapolated to mixed
1334 paraxial mesenchyme. ethnicity fetal populations has been questioned (Ogasawara 2009).


Neonatal lower limb
1335
97
RETPAHC
Table 79.1 The development of the arteries of the lower limb during stages 13–19 (corresponding to weeks 5–7 of development), showing the changes to the axial artery, the
new vessels that arise and the vessels that regress
Stage of Axial artery Developing arteries Regressing Arterial status
development arteries
11–12 First appearance of the lower
limb bud. The lower limb
axial artery arises from the
fifth lumbar intersegmental
branch of the aorta.
13–16 The axial artery courses Aorta Umbilical
through the lower limb bud
to the developing digital
plate where it branches into
Common
a terminal plexus (future
iliac
dorsal and plantar networks). Axial
16–17 The axial artery is now The external iliac artery, which arises Femoral RCS
described as ischiadic just proximal to the origin of the
proximally and popliteal ischiadic artery, extends distally towards
profunda (PP) and interossea the knee as the femoral artery. A branch,
(I) as it progresses distally. the ramus communicans superior (RCS),
passes dorsally to join the ischiadic
artery. Perforating branches of the Ischiadic PP I
profunda femoris artery initially
anastomose with the proximal part of the
ischiadic artery. Parts of the
axial artery
18 Elongation of the axial artery Two new vessels arise from the popliteal The proximal portion Femoral I
forms the popliteal superficialis artery. These are the tibialis of the ischiadic artery
superficialis (PS) between posterior superficialis (TPS) and the starts to regress. RCS
the popliteal profunda and peronea posterior superficialis (PPS). Parts persist in the
interossea arteries. Both vessels join the plantar network. adult as the inferior Ischiadic
There are now three arteries in the leg. gluteal artery and the
arteria comitans nervi
ischiadici.
PP PS TPS PPS
19 Two further vessels arise. They are the TApd
tibialis anterior pars distalis (TApd) from I
the interossea artery and the ramus
communicans inferior (RCI) from the


peronea posterior superficialis. The
original plantar network is remodelled
into a medial plantar artery (from the
distal part of tibialis posterior
superficialis) and a lateral plantar artery
(from the distal continuation of the
PP PS TPS PPS RCI
confluence of the interossea, ramus
communicans inferior and the peronea
posterior superficialis) which together
form the plantar arch.
There are now five arteries in the leg.
20 The arteries in the leg at this stage are Popliteal profunda, PP
the tibilalis anterior (TA), tibialis posterior interossea artery and TA
and the ramus communicans inferior. peronea posterior
The latter is confluent with the peronea superficialis arteries.
posterior superficialis in the tarsal region
and becomes the fibular (peroneal)
artery. The plantar arch is now supplied
solely by the tibialis posterior.
There are now three arteries in the leg.
PS TP RCI PPS
Identification of short femur length is associated with a higher risk of
chromosomal abnormalities (Mathiesen et al 2014) and a significantly
higher likelihood of the fetus being small for gestational age and at risk
of early preterm delivery (Mathiesen et al 2014, Özlü and Ozcan 2013).
It has been estimated that identification of isolated short femur length
below the tenth or fifth percentile at mid-gestation is associated with
more than a three-fold risk of the development of fetal growth retarda-
tion and increased risk of early preterm birth before 37 and 34 weeks
(Goetzinger et al 2012). Although the cause of this relationship must
be multifactorial, it is suggested that changes in placentation and
chronic fetal hypoxia may lead to a fetal adaptive response in which
highly oxygenated blood is diverted to the brain and heart at the
expense of the extremities.
NEONATAL LOWER LIMB
Fig. 79.1 An ultrasound image showing femur length. (With permission In the neonate, the pelvis is cone-shaped. The transverse diameter of
from To M, Pereira S 2015 Routine fetal anomaly scan, in Coady AM (ed) the true pelvis is 2.2 cm, its anteroposterior diameter is 2.8 cm, and the


Twining’s Textbook of Fetal Abnormalities, 3rd edition, Churchill length between the inlet and outlet is 2 cm. The sacrum is proportion-
Livingstone.) ately larger than in the adult and the sacral promontory is higher. When
walking begins, the sacrum descends between the ilia and the promon-
tory develops. The ilia, ischia and pubic bones are variably ossified at


DEvEloPmENT of THE PElviC giRDlE AND lowER limb
1336
9
NoiTCES
birth; they meet at the acetabulum, which in the neonate is cartilagi- sia of the hip; magnetic resonance imaging (MRI) may be beneficial in
nous, relatively large and shallow. identifying the underlying bony and soft tissue anatomy.
The lower limbs are underdeveloped in the neonate when compared The collodiaphysial angle (CDA; neck–shaft angle, Mikulicz angle)
to the upper limbs. They are retained in a flexed position and the lower is the angle between the long axis of the femoral shaft and the head
leg is proportionately shorter than the thigh. Although the legs appear and neck of the femur; the normal range varies between 125° and 140°
to be bowed, the tibia and fibula are straight; the illusion of bow legs (see Fig. 81.10). Where the CDA is enhanced, usually above 135°, a
is caused by the shape of the soft tissues and the slightly more advanced coxa valga deformity occurs. Where CDA is decreased (usually defined
development of the lateral head of gastrocnemius compared to its as less than 120°), a coxa vara deformity occurs; the mechanism is
medial head. The femoral neck is much shorter and forms an acute thought to be a failure of medial growth of the physial plate. The result-
angle with the shaft. The latter is quite straight because the adult cur- ing lower limb is shortened and abduction is restricted. In both coxa
vature is acquired with walking. The head of the femur is larger than valga and coxa vara, the long-term unequal weight distribution may
the acetabular fossa and nearly one-third remains external, which result in excessive wear of articular cartilage.
means that the ligament of head of femur is relatively very long. Dislo- The femur normally aligns on the tibia obliquely, creating an angle
cation of the hip joint is relatively easy; the femoral head can be of 174° facing laterally. A medial angulation of the leg in relation to
removed from the acetabular fossa laterally but not posteriorly. The the thigh is a deformity called genu varum, whereas a lateral angulation


calcaneus and the talus have an ossification centre at birth, and a centre is called genu valgum. The hip–knee (femoral–tibial) angle in children
is present in the cuboid in half of neonates. is +3.6° (varum) between the ages of 1 and 2 years, and −2.5° (valgum)
The muscles of the lower limb are much less developed than those between the ages of 2 and 3 years. The prevalence of lower limb deform-
in the upper limb. The fetal position often assumed by postnatal babies ities physiologically decreases after 5 years of age; the angle is +0.3° after
keeps the thighs in continuous abduction, stretching the adductors. The the age of 7 years, which is within 1° of adult reference values (Sabhar-
muscles that will be used for walking are weak; the lack of gluteal wal and Zhao 2009). Both deformities cause unequal weight distribu-
development, in particular, gives the typically diminutive buttocks of tion that hastens destruction of knee cartilages; persistence of genu
the neonate. varum/valgum until late childhood may require correction in order to
In neonates, the feet are usually inverted and they have a greater prevent arthrosis. (For further reading, see Goldman and Green (2010).)
degree of dorsiflexion, caused by the relatively greater area of the tro- The patella may be absent or hyoplastic, a malformation that may be
chlea of the talus. Plantar flexion is limited, in part reflecting the short- isolated or may be associated with other defects (Mizobuchi et al 2007).
ness of the extensor muscles of the foot. At birth, the footprint outlines Congenital talipes equinovarus, or club foot, derives its name from
the whole plantar surface, reflecting the deposition of subcutaneous fat a combination of talus and pes, together with terms describing an ele-
beneath the longitudinal and transverse arches, and so most babies vated heel resembling that of a horse (equino), which is also turned
appear flat-footed. inwards (varus). It is a common neonatal anomaly and occurs in
approximately 1 per 1000 live births, with males affected twice as often


as females. There is some degree of inheritance, so it is not entirely an
DEVELOPMENTAL ANOMALIES OF THE
effect of intrauterine positioning or of oligohydramnios (abnormally
LOWER LIMB
little amniotic fluid). Both bones and soft tissues are affected and it is
difficult to tell which are primary effects and which are secondary. A
The categories of limb defects described by Swanson (1976) are given number of theories have been proposed to explain the underlying
on page 796. Although devised for the upper limb, they similarly apply pathogenetic mechanism(s), including abnormal tendon and ligament
to the lower limb. attachments, defective development of the talus and delayed muscle
Developmental dysplasia of the hip (previously known as congenital maturation. One theory is that the talus undergoes defective develop-
dislocation of the hip) refers to an abnormal configuration of, or rela- ment and that all the other deformities arise as a consequence of this
tionship between, the femoral head and the acetabulum that occurs initial defect. The talus is decreased in size by up to 25%. It has a fore-
either before or after birth in approximately 1 in 100 live births with a shortened neck and decreased body/neck angle, and the subtalar facets
female : male ratio of 6 : 1. (In 2% of cases, hip dislocation is not evident are medially rotated. The navicular is small and medially deviated rela-
at birth but manifests in the first few months of the life.) It covers a tive to the talus. The calcaneus is also small and shows varus displace-
continuum of disorders that ranges from shallowness of the acetabulum ment and equinus tilt; the anterior facets correspond to those of the
to instability and subluxation of the femoral head and, ultimately, to talus (Barlow and Clarke 1994). The entire affected foot and calf are
frank dislocation. Acetabular anteversion may occur (Li et al 2009). The smaller than their normal counterparts. The foot is inverted and supi-
aetiology is considered to be multifactorial and is associated with first nated, and the forefoot is adducted. The heel is small, rotated inwards


pregnancies, suggesting that both maternal and uterine musculature and elevated. The calcaneus is inverted beneath the talus. MRI analysis
restricts fetal movement and puts postural strain on the fetal hips. of the lower legs of patients who had been treated for idiopathic con-
Developmental dysplasia of the hip is seen more frequently in genital talipes equinovarus showed that leg muscle volume was consist-
breech delivery, especially if the child’s knees are extended. The inci- ently reduced (Duce et al 2013). Treatment varies between splintage
dence is similar in preterm and term infants born in the breech position and repeated complex surgery, which reflects the highly variable severity
(Quan et al 2013). The left hip is more frequently affected than the of the condition and individual response to therapy.
right, possibly because, in breech presentation, the fetus lies with the ‘Flat feet’ are common in childhood. The majority are ‘flexible’ and
right shoulder anterior and the left thigh closest to the maternal sacrum. simply related to posture, whereas ‘rigid’ flat feet are caused by structural
The physiological effects that cause the maternal ligaments to become abnormalities. The description of ‘rocker bottom’ foot is associated with
temporarily lax prior to delivery are also considered to affect the fetus many congenital syndromes. The foot is flat and rigid, and the plantar
and to contribute to laxity of the hip capsule. Risk factors are breech surface appears curved with the apex of the curve at the mid-tarsal joint.
delivery, female sex, a positive family history and clicking hips at clini- The condition shows an equinus position of the hindfoot. The talus
cal examination (de Hundt et al 2012). Ultrasound is beneficial in the may be vertical and palpable on the plantar surface. A majority of
early detection and assessment of children with developmental dyspla- infants with this condition have neurological abnormalities.
KEY REFERENCES
Cunningham CA, Black SM 2009a Development of the fetal ilium – chal- Senior HD 1991a The development of the arteries of the human lower
lenging concepts of bipedality. J Anat 214:91–9. extremity. 25:54–95.
Cunningham CA, Black SM 2009b Anticipating bipedalism: trabecular Senior HD 1991b An interpretation of the recorded arterial anomalies of


organization in the newborn ilium J Anat 214:897–29. the human leg and foot. J Anat 53:130–71.
Levinsohn EM, Hootnick DR, Packard DS 1991 Consistent arterial abnor- Swanson AB 1976 A classification for congenital limb malformations.
malities associated with a variety of congenital malformations of the J Hand Surg Am 1:8–22.
human lower limb. Invest Radiol 26:364–73. Details of an accepted classification for congenital limb malformations.
Mandell VS, Jaques PF, Delany DJ et al 1985 Persistent sciatic artery: Clinical, Yusof N, Soames RW, Cunningham CA, Black SM 2013 Growth of the
embryologic, and angiographic features. AJR 144:245–9. Human Ilium: the anomalous sacroiliac junction. Anat Rec 296:
O’Rahilly R, Gardner E 1975 The timing and sequence of events in the 1688–94.
development of the limbs in the human embryo. Anat Embryol (Berl)
148:1–23.
A description of the stages in human limb development.


Development of the pelvic girdle and lower limb
1336.e1
97
RETPAHC
REFERENCES
Barlow I, Clarke NM 1994 Congenital talipes equinovarus. Surgery 12: Ogasawara KK 2009 Variation in fetal ultrasound biometry based on differ-
211–15. ences in fetal ethnicity. Am J Obstet Gynecol 200:676–8.
Cunningham CA, Black SM 2009a Development of the fetal ilium – chal- O’Rahilly R, Gardner E 1975 The timing and sequence of events in the
lenging concepts of bipedality. J Anat 214:91–9. development of the limbs in the human embryo. Anat Embryol (Berl)
Cunningham CA, Black SM 2009b Anticipating bipedalism: trabecular 148:1–23.
organization in the newborn ilium J Anat 214:897–29. A description of the stages in human limb development.
Czarniawska-Grzesińska M, Bruska M 2002 Development of valves in the Özlü T, Ozcan T 2013 Fetal isolated short femur in the second trimester and
small saphenous vein in human fetuses. Folia Morphol (Warsz) 61: adverse pregnancy outcomes. Prenat Diagn 33:1063–9.
37–42. Quan T, Kent AL, Carlisle H 2013 Breech preterm infants are at risk of
de Hundt M, Vlemmix F, Bais JM et al 2012 Risk factors for developmental developmental dysplasia of the hip. J Paediatr Child Health 49:
dysplasia of the hip: a meta-analysis. Eur J Obstet Gynecol Reprod Biol 658–63.
165:8–17. Sabharwal S, Zhao C 2009 The hip-knee-ankle angle in children: reference
Duce SL, D’Alessandro M, Du Y et al 2013 3D MRI analysis of the lower legs values based on a full-length standing radiograph. J Bone Joint Surg Am
of treated idiopathic congenital talipes equinovarus (clubfoot). PLoS 91:2461–8.
One 8:e54100. Senior HD 1991a The development of the arteries of the human lower


Goetzinger KR, Cahill AG, Macones GA et al 2012 Isolated short femur extremity. 25:54–95.
length on mid-trimester ultrasound: a marker for fetal growth restriction Senior HD 1991b An interpretation of the recorded arterial anomalies of
and other adverse perinatal outcomes. J Ultrasound Med 31:1935–41. the human leg and foot. J Anat 53:130–71.
Goldman V, Green DW 2010 Advances in growth plate modulation for lower Stec AA 2011 Embryology and bony and pelvic floor anatomy in the bladder
extremity malalignment (knock knees and bow legs). Curr Opin Pediatr exstrophy-epispadias complex. Semin Pediatr Surg 20:66–70.
22:47–53. Swanson AB 1976 A classification for congenital limb malformations.
Levinsohn EM, Hootnick DR, Packard DS 1991 Consistent arterial abnor- J Hand Surg Am 1:8–22.
malities associated with a variety of congenital malformations of the Details of an accepted classification for congenital limb malformations.
human lower limb. Invest Radiol 26:364–73. Valasek P, Evans DJ, Maina F et al 2005 A dual fate of the hindlimb muscle
Li LY, Zhang LJ, Zhao Q et al 2009 Measurement of acetabular anteversion mass: cloacal/perineal musculature develops from leg muscle cells.
in developmental dysplasia of the hip in children by two- and three- Development 132:447–58.
dimensional computed tomography. J Int Med Res 37:567–75. Wild AT, Sponseller PD, Stec AA et al 2011 The role of osteotomy in surgical
Mandell VS, Jaques PF, Delany DJ, Oberheu V 1985 Persistent sciatic artery: repair of bladder exstrophy. Semin Pediatr Surg 20:71–8.
Clinical, embryologic, and angiographic features. AJR 144:245–9. Yusof N, Soames RW, Cunningham CA, Black SM 2013 Growth of the
Mathiesen JM, Aksglaede L, Skibsted L et al 2014 Outcome of fetuses with Human Ilium: the anomalous sacroiliac junction. Anat Rec 296:


short femur length detected at second-trimester anomaly scan: a national 1688–94.
survey. Ultrasound Obstet Gynecol 44:160–5.
Mizobuchi RR, Galbiatti JA, Quirici Neto F et al 2007 Ultrasonographic
study of the femoropatellar joint and its attachments in normal infants
from birth to 24 months of age: part I. J Pediatr Orthop 16:262–5.


CHAPTER
80
Pelvic girdle, gluteal region and thigh
The pelvic girdle consists of the paired hip bones (each composed of Innervation
the ilium, ischium and pubis) and the sacrum. The two pubic bones
articulate anteriorly at the pubic symphysis and the sacrum articulates
For the dermatomes and cutaneous nerves, see Figures 78.12B, 78.13,
posteriorly with the two iliac bones at the sacroiliac joint; the bones are
78.14.
virtually incapable of independent movement, except in the female
during parturition or as a result of pathological change. The pelvic girdle
is massively constructed and serves as a weight-bearing and protective SOFT TISSUES
structure, as an attachment for trunk and lower limb muscles, and as
the skeletal framework of a birth canal capable of accommodating Subcutaneous tissue
passage of the fetus.
The subcutaneous tissue (tela subcutanea) of the thigh and buttock
The gluteal region or buttock is an area demarcated by the gluteal
consists, as elsewhere in the limbs, of loose areolar tissue containing a
fold inferiorly, a line joining the greater trochanter and the anterior
variable quantity of fat. In some regions, particularly near the inguinal
superior iliac spine laterally, the iliac crest superiorly and the midline
ligament, it splits into recognizable layers, between which may be found
medially. It contains a large bulk of skeletal muscle that covers several
the branches of superficial vessels and nerves. It is thick in the inguinal
vulnerable neurovascular structures, and incorporates junctional zones
region, where its two layers enclose the superficial inguinal lymph
between the lower limb, pelvis and perineum at the sciatic foramina.
nodes, long saphenous vein and other smaller vessels. Here, the super-
Direct and indirect musculoskeletal injuries in this region may damage
ficial layer is continuous with that of the abdominal fascia. The deep
the sciatic nerve and gluteal vessels.
layer, a thin fibroelastic stratum, is most marked medial to the long
The thigh consists of a cylinder of compact bone, the femoral shaft,
saphenous vein and inferior to the inguinal ligament, and is interposed


surrounded by muscle groups traversed by important neurovascular
between the subcutaneous vessels and nerves and the deep fascia, fusing
structures. The muscles are grouped according to function and lie
with the latter a little below the ligament. This membranous layer of
within osteofascial compartments that are defined by fascial septa
subcutaneous tissue overlies the saphenous opening, blending with its
running between the femur and an enveloping tube of thick fascia, the
circumference and with the femoral sheath. Over the opening, it is
fascia lata. The femoral artery gives off its major branch, the profunda
perforated by the long saphenous vein, by the superficial branches of
femoris artery (deep artery of the thigh), in the anterior compartment,
the femoral artery other than the superficial circumflex iliac branch
and the sciatic nerve usually divides into its main branches, the tibial
(which perforates the fascia lata separately), and lymphatic vessels;
and common fibular nerves, as it passes through the posterior compart-
hence the term cribriform fascia. The subcutaneous tissue of the buttock
ment of the thigh. The femoral nerve divides soon after entering the
is continuous superiorly with that over the low back and contains a
anterior compartment of the thigh beneath the inguinal ligament; the
variable quantity of fat.
obturator nerve enters the medial thigh proximally and medially from
the pelvis and divides into its main branches, which run anterior and Deep fascia
posterior to adductor brevis.
The deep fascia (fascia musculorum) covering the gluteal muscles varies
in thickness. Over gluteus maximus it is thin, but over the anterior two-
SKIN AND SOFT TISSUES thirds of gluteus medius it forms the thick, strong gluteal aponeurosis.
This is attached to the lateral border of the iliac crest superiorly, and
splits anteriorly to enclose tensor fasciae latae and posteriorly to enclose
SKIN
gluteus maximus.
See also Chapter 78 (p. 1316). Fascia lata
The fascia lata, the wide, deep fascia of the thigh, is thicker in the proxi-
Cutaneous vascular supply
mal and lateral parts of the thigh where tensor fasciae latae and an
and lymphatic drainage


expansion from gluteus maximus are attached to it. It is thin posteriorly
and over the adductor muscles, but thicker around the knee, where it
Buttock is strengthened by expansions from the tendon of biceps femoris lat-
Most of the skin of the buttock is supplied by musculocutaneous per- erally, sartorius medially and quadriceps femoris anteriorly. The fascia
forating vessels from the superior and inferior gluteal arteries. There lata is attached superiorly and posteriorly to the back of the sacrum and
are also small peripheral contributions from similar branches of the coccyx, laterally to the outer margin of the iliac crest, anteriorly to the
internal pudendal, iliolumbar and lateral sacral arteries. inguinal ligament and superior ramus of the pubis, and medially to the
Cutaneous veins are tributaries of vessels that correspond to the inferior ramus of the pubis, the ramus and tuberosity of the ischium,
named arteries. Cutaneous lymphatic drainage is to the superficial and the lower border of the sacrotuberous ligament. From the iliac crest,
inguinal nodes. it descends as a dense layer over gluteus medius to the upper border of
gluteus maximus, where it splits into two layers, one passing superficial
Thigh and the other deep to the muscle, the layers reuniting at the lower
The skin of the thigh distal to the inguinal ligament and gluteal fold is border of the muscle.
supplied mainly by branches of the femoral and profunda femoris
arteries. There is some contribution from the obturator, inferior gluteal Iliotibial tract
and popliteal arteries, and from direct cutaneous, musculocutaneous Over the flattened lateral surface of the thigh, the fascia lata thickens to
and fasciocutaneous vessels. For further details, consult Cormack and form a strong band, the iliotibial tract. The upper end of the tract splits
Lamberty (1994). into two layers, where it encloses and anchors tensor fasciae latae and
Cutaneous veins are tributaries of vessels that correspond to the receives, posteriorly, most of the tendon of gluteus maximus. The super-


named arteries. Cutaneous lymphatic drainage is to the superficial ficial layer ascends lateral to tensor fasciae latae to the iliac crest; the
inguinal nodes, mainly via collecting trunks accompanying the long deeper layer passes up and medially, deep to the muscle, and blends
saphenous vein. with the lateral part of the capsule of the hip joint. Distally, the iliotibial 1337


Pelvic girdle, gluteal region and thigh
1338
9 noitceS
tract is attached to a smooth, triangular facet (Gerdy’s tubercle) on the Fascial compartments
anterolateral aspect of the lateral condyle of the tibia, where it is super-
There are three functional groups of muscle in the thigh: namely, ant-
ficial to, and blends with, an aponeurotic expansion from vastus latera-
erior (extensor), posterior (flexor) and medial (adductor). The anterior
lis. When the knee is extended against resistance, it stands out as a
and posterior groups occupy separate osteofascial compartments that
strong, visible ridge on the anterolateral aspect of the thigh and knee.
are limited peripherally by the fascia lata and separated from each other
Distally, the fascia lata is attached to all exposed bony points around
by the femur and the medial and lateral intermuscular septa (Fig. 80.2).
the knee joint, such as the condyles of the femur and tibia, and the
The adductor muscles do not possess a separate compartment limited
head of the fibula. On each side of the patella, the deep fascia is re-
by fascial planes. Nevertheless, it is customary to speak of three com-
inforced by transverse fibres, which receive contributions from the
partments: anterior, posterior and medial. The muscles of the three
lateral and medial vasti. The stronger lateral fibres are continuous with
compartments are described below. Adductor magnus, adductor longus
the iliotibial tract.
and pectineus could each be considered to be constituents of two com-
partments, i.e. adductor magnus in the posterior and the medial com-
Intermuscular septa
partments, and adductor longus and pectineus in the anterior and the
The deep surface of the fascia lata yields two intermuscular septa, which
medial compartments.
are attached to the whole of the linea aspera and to its proximal and
The nerve supply to the compartments of the thigh mainly follows
distal prolongations. The lateral septum, thicker and stronger than the
the ‘one compartment – one nerve’ principle. Thus, the femoral nerve
medial one, extends from the attachment of gluteus maximus to the


supplies the anterior compartment muscles, the obturator nerve sup-
lateral femoral condyle; it lies between vastus lateralis in front and
plies the medial compartment muscles, and the sciatic nerve supplies
the short head of biceps femoris behind, and provides partial attach-
those in the posterior compartment. The dual functional and compart-
ment for them. The medial, thinner and weaker septum lies between
mental attribution of adductor magnus, adductor longus and pectineus
vastus medialis and the adductors and pectineus. Numerous smaller
are reflected in their dual nerve supplies.
septa, such as that separating the thigh adductors and flexors, pass
In contrast to the motor innervation, the arterial supply to the com-
between the individual muscles, ensheathing them and sometimes
partmental muscle groups does not exhibit such a direct relationship.
providing partial attachment for their fibres.
All groups receive a supply from the femoral system, particularly from
the profunda femoris artery and its branches. The adductors receive a
Saphenous opening
contribution from the obturator artery, and the hamstrings receive a
The saphenous opening is an aperture in the deep fascia, inferolateral
proximal supply from the inferior gluteal artery. Further details are
to the medial end of the inguinal ligament, which allows passage for
given in the descriptions of the individual muscles.
the long saphenous vein and other smaller vessels (Fig. 80.1). The
cribriform fascia, which is pierced by these structures, fills in the aper- Femoral sheath
ture and must be removed to reveal it. Adjacent subsidiary openings
The femoral sheath is a funnel-shaped distal prolongation of extraperi-
may exist to transmit venous tributaries. In the adult, the approximate
toneal fascia, formed of transversalis fascia anterior to the femoral
centre of the saphenous opening is 3 cm lateral to a point just distal to
vessels, and of the iliac fascia posteriorly. It is wider proximally and its
the pubic tubercle. The length and width of the opening vary consider-
tapered distal end fuses with the vascular adventitia 3 or 4 cm distal to
ably. The fascia lata in this part of the thigh displays superficial and


the inguinal ligament. At birth the sheath is shorter; it elongates when
deep strata (not to be confused with the superficial and deep layers of
extension at the hips becomes habitual. The femoral branch of the
the subcutaneous tissue described above). They lie, respectively, anterior
genitofemoral nerve perforates its lateral wall. The medial wall slopes
and posterior to the femoral sheath, with the saphenous opening situ-
laterally and is pierced by the long saphenous vein and lymphatic
ated where the two layers are in continuity. This serves to explain the
vessels. Like the carotid sheath, the femoral sheath encloses a mass of
somewhat oblique and spiral configuration of the saphenous opening.
connective tissue in which the vessels are embedded. Three compart-
The superficial layer, lateral and superior to the saphenous opening,
ments are described: a lateral one containing the femoral artery; an
is attached, in continuity, to the crest and anterior superior spine of the
intermediate one for the femoral vein; and a medial compartment, the
ilium, to the whole length of the inguinal ligament, and to the pecten
femoral canal, which contains lymph vessels and an occasional lymph
pubis and lacunar ligament. It is reflected inferolaterally from the pubic
node embedded in areolar tissue. The presence of this canal allows the
tubercle as the arched falciform margin, which forms the superior,
femoral vein to distend. The canal is conical and approximately 1.25 cm
lateral and inferior boundaries of the saphenous opening; this margin
in length. Its proximal (wider) end, termed the femoral ring, is bounded
adheres to the anterior layer of the femoral sheath, and the cribriform
in front by the inguinal ligament, behind by pectineus and its fascia
fascia is attached to it. The falciform margin is considered to have
and the pectineal ligament, medially by the crescentic, lateral edge of
superior and inferior horns. The inferior horn is well defined, and is
the lacunar ligament and laterally by the femoral vein. The spermatic
continuous behind the long saphenous vein with the deep stratum of


cord, or the round ligament of the uterus, is just above its anterior
the fascia lata.
margin, while the inferior epigastric vessels are near its anterolateral
The deep layer is medial to the saphenous opening and is continu-
rim. It is larger in women than in men: this is due partly to the relatively
ous with the superficial stratum at its lower margin. Traced upwards,
greater width of the female pelvis and partly to the smaller size of the
it covers pectineus, adductor longus and gracilis, passes behind the
femoral vessels in women. The ring is filled by condensed extraperito-
femoral sheath, with which it blends, and continues to the pecten pubis.
neal tissue, the femoral septum, which is covered on its proximal aspect
by the parietal peritoneum. Numerous lymph vessels that connect the
deep inguinal to the external iliac lymph nodes traverse the femoral
Psoas major Iliacus
septum (Fig. 80.3).
Femoral nerve
Psoas minor tendon Femoral hernia
Inguinal ligament Femoral hernia is described with other groin hernias on page 1081.
Iliopectineal arch
Deep inguinal iliac fascia
lymph node
The iliac fascia covers psoas and iliacus. It is thin above but thickens
Fascia lata
Superficial circumflex progressively towards the inguinal ligament. The part covering psoas is
iliac vein thickened above as the medial arcuate ligament. Medially, the fascia
Superficial Saphenous over psoas is attached by a series of fibrous arches to the intervertebral
epigastric vein opening discs, the margins of vertebral bodies, and the upper part of the sacrum.
Laterally, it blends with the fascia anterior to quadratus lumborum
E pux dte er nn da al l veins Femoral vein above the iliac crest, and with the fascia covering iliacus below the crest.
The iliac part is connected laterally to the whole of the inner lip of
Long saphenous the iliac crest and medially to the pelvic brim, where it blends with the
vein periosteum. It is attached to the iliopubic ramus, where it receives a slip


from the tendon of psoas minor, when this muscle is present. The
external iliac vessels are anterior to the fascia but the branches of the
Fig. 80.1 The saphenous opening following removal of the cribriform lumbar plexus are posterior to it. The fascia is separated from the peri-
fascia. (With permission from Waschke J, Paulsen F (eds), Sobotta Atlas toneum by loose extraperitoneal tissue. Lateral to the femoral vessels,
of Human Anatomy, 15th ed, Elsevier, Urban & Fischer. Copyright 2013.) the iliac fascia is continuous with the posterior margin of the inguinal


Bones
1339
08
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A Fig. 80.2 A transverse (axial)
section through the thigh.
A, At the level of the apex of
Rectus femoris the femoral triangle. B, At
the level of the mid-thigh.
Sartorius Vastus lateralis
Branches of femoral nerve
Long saphenous vein
Vastus intermedius
Femoral artery Femur
Femoral vein
Adductor longus Vastus medialis
Profunda femoris artery and veins
Adductor brevis
Obturator nerve Adductor magnus
Gracilis
Sciatic nerve
Semimembranosus Gluteus maximus
Biceps femoris (long head)
and semitendinosus
B
Rectus femoris Vastus lateralis
Vastus medialis
Vastus intermedius
Nerve to vastus medialis
Saphenous nerve
Femur
Femoral artery in adductor canal
Sartorius
Profunda femoris artery
Femoral vein
Long saphenous vein Biceps femoris (short head)
Gracilis
Sciatic nerve
Biceps femoris (long head)
Adductor longus
Semitendinosus
Adductor magnus
Semimembranosus Posterior femoral cutaneous nerve
ligament and the transversalis fascia. Medially, it passes behind the
BONES
femoral vessels to become the pectineal ligament, attached to the pecten
pubis. At the junction of its lateral and medial parts, it is attached to
the iliopubic ramus and the capsule of the hip joint. It thus forms a The pelvic girdle is an entity consisting of the two hip bones and the
septum between the inguinal ligament and the hip bone, dividing the sacrum (strictly speaking, the sacrum is part of the vertebral column).
space here into a lateral part, the muscular space, containing psoas The pelvic girdle is massively constructed and serves as a weight-bearing
major, iliacus and the femoral nerve, and a medial part, the vascular and protective structure, an attachment for trunk and limb muscles, and
space, transmitting the femoral vessels (see Fig. 80.3). The iliac fascia as the skeletal framework of the birth canal.
continues downwards to form the posterior wall of the femoral sheath.


obturator membrane HIP BONE
The obturator membrane (Fig. 80.4) is a thin aponeurosis that closes
(obturates) most of the obturator foramen, leaving a superolateral aper- The hip bone is large, irregular, constricted centrally and expanded
ture, the obturator canal, through which the obturator vessels and nerve above and below (Fig. 80.5). Its lateral surface has a deep, cup-shaped
leave the pelvis and enter the thigh. The membrane is attached to the acetabulum, articulating with the femoral head, anteroinferior to which
sharp margin of the obturator foramen except at its inferolateral angle, is the large, oval or triangular obturator foramen. Above the acetabu-
where it is fixed to the pelvic surface of the ischial ramus, i.e. internal lum, the bone widens into an undulant plate surmounted by a sinu-
to the foramen. Its fibres are arranged mainly transversely in interlacing ously curved iliac crest.
bundles; the uppermost bundle, which is attached to the obturator The bone articulates in front with its fellow and posteriorly with the
tubercles, completes the obturator canal. The outer and inner surfaces side of the sacrum to form the pelvic girdle. Each hip bone has three
of the obturator membrane provide attachment for the obturator exter- parts – ilium, ischium and pubis, connected to each other by cartilage
nus and internus, respectively. Some fibres of the pubofemoral ligament in youth but united as one bone in adults. The principal union is in
of the hip joint are attached to the outer surface. the acetabulum. The ilium includes the upper acetabulum and expanded


Pelvic girdle, gluteal region and thigh
1340
9
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Fig. 80.3 Structures
passing beneath the
inguinal ligament. (With
Femoral branch of genitofemoral nerve Lateral femoral cutaneous nerve permission from Waschke
J, Paulsen F (eds),
Femoral artery and vein Anterior superior iliac spine Sobotta Atlas of Human
Anatomy, 15th ed,
Inguinal ligament
Elsevier, Urban & Fischer.
Deep inguinal lymph node
Iliopsoas Copyright 2013.)
Femoral nerve
Lacunar ligament
Iliopectineal arch
Spermatic cord (cut)
Pectineal ligament
Pubic tubercle
Pectineus
Pubic symphysis
Obturator membrane
Obturator artery and vein
Obturator canal
Obturator nerve
obturator foramen
The obturator foramen lies below and slightly anterior to the acetabu-
Pectineal ligament Inguinal ligament
lum, between the pubis and ischium. It is bordered above by the
Lacunar ligament grooved obturator surface of the superior pubic ramus, medially by the
pubic body and its inferior ramus, below by the ischial ramus, and later-
Interpubic disc ally by the anterior border of the ischial body, including the margin of
the acetabulum. The foramen is almost closed by the obturator mem-
Cavity in interpubic disc
brane (see above), which is attached to its margins, except superolat-
erally, where a communication remains between the pelvis and thigh.
This free edge of the membrane is attached to an anterior obturator
tubercle at the anterior end of the inferior border of the superior pubic
Acetabular labrum ramus, and a posterior obturator tubercle on the anterior border of
the acetabular notch; these tubercles are sometimes indistinct. Since
the tubercles lie in different planes and the obturator groove crosses the
upper border of the foramen, the acetabular margin is in fact a spiral.
The foramen is large and oval in males, but smaller and nearly triangu-
Transverse acetabular
ligament lar in females.
Structure


The thicker parts of the hip bone are trabecular, encased by two layers
of compact bone, while the thinner parts, as in the acetabulum and
Obturator canal central iliac fossa, are often translucent and consist of a single lamina
of compact bone. In the upper acetabulum and along the arcuate line,
Obturator membrane
i.e. the route of weight transmission from the sacrum to the femur, the
amount of compact bone is increased and the subjacent trabecular bone
Fig. 80.4 An anterolateral view of left bony pelvis, showing associated displays two sets of pressure lamellae. These start together near the
ligaments and the obturator membrane. upper auricular surface and diverge to meet two strong buttresses of
compact bone, from which two similar sets of lamellar arches start and
converge on the acetabulum. The anterior part of the iliac crest has been
much studied with regard to distribution of cortical and trabecular
area above it; the ischium includes the posteroinferior acetabulum and bone. Whitehouse (1977) described the cortical bone as very porous,
bone posteroinferior to it; the pubis forms the anteroinferior being only 75% bone, decreasing to 35% near the anterior superior iliac
acetabulum. spine.
Studies of the internal stresses within the hip bone have revealed a
acetabulum
pattern of trabeculae that corresponds well with the theoretically
The acetabulum (Fig. 80.5A,C) is an approximately hemispherical expected patterns of stress trajectories (Holm 1980). These patterns
cavity situated about the centre of the lateral aspect of the hip bone. It are considerably more complex than in any other major bone. Stresses
faces anteroinferiorly and is circumscribed by an irregular margin defi- are higher in the acetabular than in the iliac region. In the ilium, the
cient inferiorly at the acetabular notch. The acetabular fossa forms the pelvic surface is subjected to considerably less stress than is the gluteal
central floor and is rough and non-articular. The articular lunate surface surface.
is widest above (the ‘dome’), where weight is transmitted to the femur.
Consequently, fractures through this region tend to be associated with Muscle attachments


unsatisfactory outcomes. All three components of the hip bone contrib- See individual bones.
ute to the acetabulum, although unequally. The pubis forms the antero-
superior fifth of the articular surface, the ischium forms the floor of the vascular supply
fossa and rather more than the posteroinferior two-fifths of the articular In the infant, nutrient arteries are clearly demonstrable for each com-
surface, and the ilium forms the remainder. Occasionally, a linear defect ponent of the hip bone. Each nutrient artery branches in a fan-like
may be seen to cross the acetabular surface from the superior border to fashion within its bone of supply (Crock 1996). Later, a periosteal art-
the acetabular fossa. This does not correspond to any junction between erial network develops, with contributions from numerous local arteries
the main morphological parts of the hip bone. (see under individual bones).


Bones
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A
Inner lip
Intermediate zone
Iliac crest
Outer lip
Ala of ilium
Tubercle of iliac crest
Anterior gluteal line
Ala of ilium Inferior gluteal line Gluteal surface
Anterior superior iliac spine
Posterior gluteal line
Posterior superior iliac spine
Body of ilium
Anterior inferior iliac spine
Posterior inferior iliac spine
Supra-acetabular groove
Greater sciatic notch
Lunate surface
Acetabular margin
Acetabular fossa
Pecten pubis Acetabular notch
(pectineal line)
Ischial spine
Pubic tubercle Lesser sciatic notch
Oburator crest
Body of ischium
Inferior pubic ramus
Anterior obturator tubercle
Ischial tuberosity
Obturator foramen
B
Ramus of ischium
Iliac crest
Intermediate zone
Ala of ilium
Inner lip
Sacropelvic
surface
Iliac fossa
Iliac tuberosity Anterior superior
iliac spine
Auricular surface
Posterior superior
iliac spine
Anterior inferior
Posterior inferior iliac spine
iliac spine
Arcuate line
Greater sciatic notch
Iliopubic ramus
Body of ischium Obturator groove
Superior pubic ramus,
Ischial spine pecten pubis (pectineal line)
C Lesser sciatic notch
Obturator foramen
Ischial tuberosity
Symphysial surface
Inner lip
Ramus of ischium
Intermediate zone
Iliac tuberosity Iliac crest Inferior pubic ramus
Ala of ilium
Outer lip
Sacropelvic surface
Iliac fossa
Anterior superior iliac spine
Auricular surface
Body of ilium
Iliopubic ramus Supra-acetabular groove
Body of pubis Anterior inferior iliac spine
Superior pubic ramus
Obturator crest
Pecten pubis Acetabular margin
(pectineal line) Lunate surface
Acetabulum
Pubic tubercle Acetabular fossa
Acetabular notch
Pubic crest
Symphysial Body of ischium
surface


Obturator foramen
Inferior pubic ramus
Ramus of ischium Ischial tuberosity
Fig. 80.5 The left hip bone. A, Outer aspect. B, Inner aspect. C, Anterosuperior view. (With permission from Waschke J, Paulsen F (eds), Sobotta Atlas
of Human Anatomy, 15th ed, Elsevier, Urban & Fischer. Copyright 2013.)


Pelvic girdle, gluteal region and thigh
1342
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innervation conjoined ischial and pubic rami, and continues to the pubic symphy-
Periosteal innervation is by a network of nerves derived from branches sial surface and along the pubic crest to the pubic tubercle.
of local nerves. These nerves also supply muscles attaching to the peri- The ossifying ischium and pubis fuse to form a continuous ischio-
osteum and the joints involving the hip bone. Autonomic nerves pubic ramus at the seventh or eighth year. Secondary centres, other than
accompany nutrient arteries and branch within the bone. for the acetabulum, appear at about puberty and fuse between the fif-
teenth and twenty-fifth years. There are usually two for the iliac crest
ossification (which fuse early), and single centres for the ischial tuberosity (in car-
Ossification (Figs 80.6–80.7) is by three primary centres: one each for tilage close to the inferior acetabular margin and spreading forwards),
the ilium, ischium and pubis. The iliac centre appears above the greater anterior inferior iliac spine (although it may ossify from the triradiate
sciatic notch prenatally at about the ninth week; the ischial centre in cartilage) and symphysial surface of the pubis (the pubic tubercle and
its body in the fourth month; and the pubic centre in its superior ramus crest may have separate centres). Progression of ossification of the iliac
between the fourth and fifth months. The pubis is often not recovered crest in girls is an index of skeletal maturity and is useful in determining
from prenatal remains due to its size and fragility and because it is the the optimal timing of surgery for spinal deformity.
last of the hip bones to begin ossification (Scheuer and Black 2004). At Between the ages of 8 and 9 years, three major centres of ossification
birth the whole iliac crest, the acetabular floor and the inferior margin appear in the acetabular cartilage. The largest appears in the anterior
are cartilaginous. Gradual ossification of the three components of the wall of the acetabulum and fuses with the pubis, the second in the iliac


acetabulum results in a triradiate cartilaginous stem extending medially acetabular cartilage superiorly, fusing with the ilium, and the third in
to the pelvic surface as a Y-shaped epiphysial plate between the ilium, the ischial acetabular cartilage posteriorly, fusing with the ischium. At
ischium and pubis, and including the anterior inferior iliac spine. Car- puberty, these epiphyses expand towards the periphery of the acetabu-
tilage along the inferior margin also covers the ischial tuberosity, forms lum and contribute to its depth (Ponseti 1978). Fusion between the
three bones within the acetabulum occurs between the sixteenth and
eighteenth years. Delaere et al (1992) have suggested that ossification
A B of the ilium is similar to that of a long bone, possessing three cartilagi-
nous epiphyses and one cartilaginous process, although it tends to
Ilium
undergo osteoclastic resorption comparable with that of cranial bones.
During development, the acetabulum increases in breadth at a faster
rate than it does in depth.
Avulsion fractures of pelvic apophyses may occur from excessive pull
on tendons, usually in athletic adolescents. The most frequent examples
of such injuries are those to the ischial tuberosity (hamstrings) and
anterior inferior iliac spine (rectus femoris).
Iliac crest Pubis
Acetabulum
The pubis (see Figs 80.5–80.6) is the ventral part of the hip bone and
Pubis forms a median cartilaginous pubic symphysis with its fellow. The body
of the pubis occupies the anteromedial part of the bone, and from the
body a superior ramus passes up and back to the acetabulum and an
inferior ramus passes back, down and laterally to join the ischial ramus
inferomedial to the obturator foramen.
Body
Ischial The body, anteroposteriorly compressed, has anterior, posterior and
tuberosity symphysial (medial) surfaces and an upper border, the pubic crest. The
Ischium anterior surface also faces inferolaterally; it is rough superomedially and


smooth elsewhere, giving attachment to medial thigh muscles. The
Unossified (cartilaginous) regions
smooth posterior surface faces upwards and backwards as the oblique
Fig. 80.6 The hip bone. A, At birth. B, In adolescence; more heavily anterior wall of the lesser pelvis and is related to the urinary bladder.
stippled areas indicate the secondary centres of ossification. The symphysial surface is elongated and oval, united by cartilage to its
fellow at the pubic symphysis. Denuded of cartilage, it has an irregular
surface of small ridges and furrows or nodular elevations, varying con-
siderably with age, features that are of forensic interest. The pubic crest
is the rounded upper border of the body and overhangs the anterior
surface; the pubic tubercle is a small rounded eminence on its lateral
end. Both crest and tubercle are palpable; the latter partly is obscured
1 in males by the spermatic cord that crosses above it from the scrotum
to the anterior abdominal wall. The pubic rami diverge posterolaterally
from the superolateral corners of the body.
The anterior surface of the pubic body faces the adductor region. The
2
anterior pubic ligament attaches to its medial part along a rough strip,
3 which is wider in females. The posterior surface is separated from the
urinary bladder by retropubic fat. The puboprostatic ligaments are
4
attached to this surface medial to levator ani.
5 Superior pubic ramus
4 7 The superior pubic ramus passes upwards, backwards and laterally from
the body, superolateral to the obturator foramen, to reach the acetabu-
8
6 lum. It is triangular in section and has three surfaces and borders. Its
anterior, pectineal surface, tilted slightly up, is triangular in outline and
extends from the pubic tubercle to the iliopubic ramus. It is bounded
in front by the rounded obturator crest and behind by the sharp pecten
pubis (pectineal line), which, with the crest, is the pubic part of the
linea terminalis (i.e. anterior part of the pelvic brim). The posterosupe-
rior, pelvic surface, medially inclined, is smooth and narrows into the


Fig. 80.7 An anteroposterior radiograph of the pelvis of a boy aged posterior surface of the body, which is bounded above by the pecten
7 years. Key: 1, ilium; 2, part of triradiate growth cartilage; 3, superior pubis and below by a sharp inferior border. The obturator surface,
femoral epiphysis; 4, cartilaginous growth plates; 5, ossifying greater directed down and back, is crossed by the obturator groove sloping
trochanter; 6, ischium; 7, pubis; 8, cartilage between inferior pubic and down and forwards. Its anterior limit is the obturator crest and its pos-
ischial rami. terior limit is the inferior border.


Bones
1343
08
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inferior pubic ramus sacropelvic and iliac (internal) surfaces. The posterolateral gluteal
The inferior pubic ramus, an inferolateral process of the body, descends surface is an extensive rough area; the anteromedial iliac fossa is smooth
inferolaterally to join the ischial ramus medial to, and below, the obtu- and concave; and the sacropelvic surface is medial and posteroinferior
rator foramen. The union may be locally thickened, but not obviously to the fossa, from which it is separated by the medial border.
so in adults. The ramus has two surfaces and borders. The anterolateral
iliac crest
surface, continuous above with that of the pubic body, faces the thigh
and is marked by muscles. It is limited laterally by the margin of the The iliac crest is the superior border of the ilium. It is convex upwards
obturator foramen, and medially by the rough anterior border. The but sinuous from side to side, being internally concave in front and
posteromedial surface is continuous above with that of the body and convex behind. Its ends project as anterior and posterior superior iliac
is transversely convex; its medial part is often everted in males and gives spines. The anterior superior iliac spine is palpable at the lateral end of
attachment to the crus of the penis. This surface faces the perineum the inguinal fold; the lateral end of the inguinal ligament is attached
medially, its smooth lateral part tilted up towards the pelvic cavity. to the anterior superior iliac spine. The posterior superior iliac spine is
The internal surface is indistinctly divided into medial, intermediate not palpable but is often indicated by a dimple, approximately 4 cm
and lateral areas. The medial area faces inferomedially in direct contact lateral to the second sacral spinous process, above the medial gluteal
with the crus of the penis or clitoris and is limited above and behind region.
by an indistinct ridge for attachment of the fascia overlying the super- The iliac crest has ventral and dorsal segments. The ventral segment


ficial perineal muscles. The medial margin of the ramus, strongly occupies slightly more than the anterior two-thirds of the iliac crest and
everted in males, provides attachment for the fascia lata and the stratum its prominence is associated with changes in iliac form as a result of the
membranosum perinei. emergence of the upright posture. It has internal and external lips and
a rough intermediate zone that is narrowest centrally. The dorsal
Pubic tubercle segment, which occupies approximately the posterior one-third in
The pubic tubercle provides attachment to the medial end of the humans, is a feature of all land vertebrates. It has two sloping surfaces
inguinal ligament. It forms part of the floor of the superficial inguinal separated by a longitudinal ridge ending at the posterior superior spine.
ring and is crossed by the spermatic cord. The interosseous and posterior sacroiliac ligaments arise from the
medial margin of the dorsal segment. The tubercle of the iliac crest
Pecten pubis projects outwards from the outer lip approximately 5 cm posterosupe-
The pecten pubis is the sharp, superior edge of the pectineal surface. rior to the anterior superior spine. The summit of the iliac crest, a little
The conjoint tendon (inguinal falx) and lacunar ligament are attached behind its midpoint, is level with the fourth lumbar vertebral body in
at its medial end and a strong, fibrous pectineal ligament is attached adults and with the fifth lumbar vertebral body in children aged 10 years
along the rest of its surface. The smooth pelvic surface is separated from or less (Tame and Burstal 2003).
parietal peritoneum only by areolar tissue, in which the lateral umbili-
anterior border
cal ligament descends forwards across the ramus and, laterally, the vas
deferens (ductus deferens) passes backwards. The obturator groove, The anterior border descends to the acetabulum from the anterior
which is converted to a canal by the upper borders of the obturator superior spine. Superiorly it is concave forwards. Inferiorly, immediately
membrane and obturator muscles, transmits the obturator vessels and above the acetabulum, is a rough anterior inferior iliac spine, which is


nerve from the pelvis to the thigh. Some fibres of the pubofemoral liga- divided indistinctly into an upper area for the straight head of rectus
ment are attached to the lateral end of the obturator crest. femoris and a lower area extending laterally along the upper acetabular
margin to form a triangular impression for the proximal end of the
Muscle attachments iliofemoral ligament.
The tendon of adductor longus is attached on the anterior (external)
surface of the body, below the pubic crest. Below adductor longus, Posterior border
gracilis is attached to a line near the lower margin extending down on The posterior border is irregularly curved and descends from the pos-
to the inferior ramus. Above gracilis, adductor brevis is attached to the terior superior spine, at first forwards, with a posterior concavity forming
body and inferior ramus. Above again, obturator externus is attached a small notch. At the lower end of the notch is a wide, low projection:
to the anterior surface, spreading on to inferior pubic and ischial rami. the posterior inferior iliac spine. Here the border turns almost horizont-
Adductor magnus usually extends from the ischial ramus on to the ally forwards for approximately 3 cm, then down and back to join the
lower part of the inferior pubic ramus between adductor brevis and posterior ischial border. Together these borders form a deep notch, the
obturator externus. Pectineus is attached to the pectineal surface of the greater sciatic notch, which is bounded above by the ilium and below
superior ramus along its upper part. Ascending loops of cremaster are by the ilium and ischium. The upper fibres of the sacrotuberous liga-
attached to the pubic tubercle. The lateral part of rectus abdominis and, ment are attached to the upper part of the posterior border. The superior
inferiorly, pyramidalis, are attached lateral to the tubercle, on the pubic rim of the notch is related to the superior gluteal vessels and nerve. The
crest. Medially, the crest is crossed by the medial part of rectus abdominis, lower margin of the greater sciatic notch is covered by piriformis and


ascending from ligamentous fibres that interlace in front of the pubic is related to the sciatic nerve.
symphysis. Anterior fibres of levator ani are attached on the posterior
(internal) surface of the body near its centre. More laterally, obturator Medial border
internus is attached on this surface, extending on to both rami. Psoas The medial border separates the iliac fossa and the sacropelvic surface.
minor, when present, is attached near the centre of the pecten pubis. It is indistinct near the crest, rough in its upper part, then sharp where
it bounds an articular surface for the sacrum, and finally rounded.
vascular supply The latter part is the arcuate line, which inferiorly reaches the poste-
The pubis is supplied by a periosteal anastomosis of branches from the rior part of the iliopubic ramus, marking the union of the ilium and
obturator, inferior epigastric and medial circumflex femoral arteries. pubis.
The superficial and deep external pudendal arteries may also contribute.
Multiple vascular foramina are present, mainly at the lateral (acetabu- gluteal surface
lar) end of the bone, but there is no consistently placed nutrient The gluteal surface, facing inferiorly in its posterior part and laterally
foramen. and slightly downwards in front, is bounded above by the iliac crest,
and below by the upper acetabular border and by the anterior and
innervation
posterior borders. It is rough and curved, convex in front, concave
The pubic periosteum is innervated by branches of the nerves that behind, and marked by three gluteal lines. The posterior gluteal line is
supply muscles attached to the bone, the hip joint and the symphysis shortest, descending from the external lip of the crest approximately
pubis. 5 cm in front of its posterior limit and ending in front of the posterior
inferior iliac spine. Above, it is usually distinct, but inferiorly it is poorly
ossification defined and frequently absent. The anterior gluteal line, the longest,
Ossification of the pubis is described on page 1342. begins near the midpoint of the superior margin of the greater sciatic
notch and ascends forwards into the outer lip of the crest, a little anter-
Ilium


ior to its tubercle. The inferior gluteal line, seldom well marked, begins
posterosuperior to the anterior inferior iliac spine, curving posteroinfe-
The ilium has upper and lower parts and three surfaces (see Figs 80.5, riorly to end near the apex of the greater sciatic notch. Between the
80.6). The smaller, lower part forms a little less than the upper two-fifths inferior gluteal line and the acetabular margin is a rough, shallow
of the acetabulum. The upper part is much expanded, and has gluteal, groove. Behind the acetabulum, the lower gluteal surface is continuous


Pelvic girdle, gluteal region and thigh
1344
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with the posterior ischial surface, the conjunction marked by a low upper fibres of gluteus maximus and the lower, smooth region to part
elevation. of the sacrotuberous ligament and iliac head of piriformis. Gluteus
The articular capsule is attached to an area adjoining the acetabular medius is attached between the posterior and anterior lines, below the
margin, most of which is covered by gluteus minimus. Posteroinferiorly, iliac crest, and gluteus minimus is attached between the anterior and
near the union of the ilium and ischium, the bone is related to inferior lines. The fourth area, below the inferior line, contains vascular
piriformis. foramina.
The reflected head of rectus femoris attaches to a curved groove
iliac fossa above the acetabulum. Iliacus is attached to the upper two-thirds of the
The iliac fossa, the internal concavity of the ilium, faces anterosuperi- iliac fossa and is related to its lower one-third. The medial part of
orly. It is limited above by the iliac crest, in front by the anterior border quadratus lumborum is attached to the anterior part of the sacropelvic
and behind by the medial border, separating it from the sacropelvic surface, above the iliolumbar ligament. Piriformis is sometimes partly
surface. It forms the smooth and gently concave posterolateral wall of attached lateral to the pre-auricular sulcus, and part of obturator int-
the greater pelvis. Below it is continuous with a wide shallow groove, ernus is attached to the more extensive remainder of the pelvic surface.
bounded laterally by the anterior inferior iliac spine and medially by
the iliopubic ramus. vascular supply
The converging fibres of iliacus occupy the wide groove between Branches of the iliolumbar artery run between iliacus and the ilium;
the anterior inferior iliac spine and the iliopubic ramus laterally and one or more enter large nutrient foramina lying posteroinferiorly in the
the tendon of psoas major medially; the tendon is separated from the iliac fossa. The superior gluteal, obturator and superficial circumflex


underlying bone by a bursa. The right iliac fossa contains the caecum, iliac arteries contribute to the periosteal supply. The obturator artery
and often the vermiform appendix and terminal ileum. The left iliac may supply a nutrient branch. Vascular foramina on the ilium underly-
fossa houses the terminal part of the descending colon and the proxi- ing the gluteal muscles may lead into large vascular canals in the bone.
mal sigmoid colon.
innervation
Sacropelvic surface The periosteum is innervated by branches of nerves that supply muscles
The sacropelvic surface, the posteroinferior part of the medial iliac attached to the bone, the hip joint and the sacroiliac joint.
surface, is bounded posteroinferiorly by the posterior border, antero-
ossification
superiorly by the medial border, posterosuperiorly by the iliac crest and
anteroinferiorly by the line of fusion of the ilium and ischium. It is Ossification of the ilium is described on page 1342.
divided into iliac tuberosity and auricular and pelvic surfaces. The iliac
tuberosity, a large, rough area below the dorsal segment of the iliac crest, Ischium
shows cranial and caudal areas separated by an oblique ridge and con-
nected to the sacrum by the interosseous sacroiliac ligament. The sac- The ischium, the inferoposterior part of the hip bone, has a body and
ropelvic surface gives attachment to the posterior sacroiliac ligaments ramus. The body has upper and lower ends and femoral, posterior and
and, behind the auricular surface, to the interosseous sacroiliac liga- pelvic surfaces (see Figs 80.5–80.7). Above, it forms the posteroinferior
ment. The iliolumbar ligament is attached to its anterior part. The part of the acetabulum; below, its ramus ascends anteromedially at an
auricular surface, immediately anteroinferior to the tuberosity, articu- acute angle to meet the inferior pubic ramus, thereby completing the


lates with the lateral sacral mass. Shaped like an ear, its widest part is boundary of the obturator foramen. The ischiofemoral ligament is
anterosuperior, and its ‘lobule’ posteroinferior and on the medial aspect attached to the lateral border below the acetabulum (Fuss and Bacher
of the posterior inferior spine. Its edges are well defined but the surface, 1991).
though articular, is rough and irregular. It articulates with the sacrum The femoral surface faces downwards, forwards and laterally towards
and is reciprocally shaped. The anterior sacroiliac ligament is attached the thigh. It is bounded in front by the margin of the obturator foramen.
to its sharp anterior and inferior borders. The narrow part of the pelvic The lateral border, indistinct above but well defined below, forms the
surface, between the auricular surface and the upper rim of the greater lateral limit of the ischial tuberosity. At a higher level, the femoral
sciatic notch, often shows a rough pre-auricular sulcus (that is usually surface is covered by piriformis, from which it is partially separated by
better defined in females) for the lower fibres of the anterior sacroiliac the sciatic nerve and the nerve to quadratus femoris. The posterior
ligament. For the reliability of this feature as a sex discriminant, refer surface, facing superolaterally, is continuous above with the iliac gluteal
to Finnegan (1978) and Brothwell and Pollard (2001). The pelvic surface, and here a low convexity follows the acetabular curvature.
surface is anteroinferior to the acutely curved part of the auricular Inferiorly, this surface forms the upper part of the ischial tuberosity,
surface, and contributes to the lateral wall of the lesser pelvis. Its upper above which is a wide, shallow groove on its lateral and medial aspects.
part, facing down, is between the auricular surface and the upper limb Above the ischial tuberosity, the posterior surface is crossed by the
of the greater sciatic notch. Its lower part faces medially and is separated tendon of obturator internus and the gemelli. The nerve to quadratus


from the iliac fossa by the arcuate line. Anteroinferiorly, it extends to femoris lies between these structures and the ischium. The ischial tuber-
the line of union between the ilium and ischium. Though usually osity is a large, rough area on the lower posterior surface and inferior
obliterated, it passes from the depth of the acetabulum to approxi- extremity of the ischium. Though obscured by gluteus maximus in hip
mately the middle of the inferior limb of the greater sciatic notch. extension, it is palpable in hip flexion. It is 5 cm from the midline and
about the same distance above the gluteal fold. It is elongated and
Muscle attachments widest above, and tapers inferiorly. The ischial posterior aspect lies
The attachment of sartorius extends down the anterior border below the between the lateral and posterior borders. The posterior border blends
anterior superior iliac spine. The iliac crest gives attachment to the ant- above with that of the ilium, helping to complete the inferior rim of
erolateral and dorsal abdominal muscles, and to the fasciae and muscles the greater sciatic foramen, the posterior end of which has a conspicu-
of the lower limb. The fascia lata and iliotibial tract are attached to the ous ischial spine. Below this, the rounded border forms the floor of the
outer lip and tubercle of its ventral segment. Tensor fasciae latae is lesser sciatic foramen, between the ischial spine and tuberosity. The
attached anterior to the tubercle. The lower fibres of external oblique pelvic surface is smooth and faces the pelvic cavity; inferiorly, it forms
and, just behind the summit of the crest, the lowest fibres of latissimus part of the lateral wall of the ischio-anal fossa.
dorsi are attached to its anterior two-thirds. A variable interval exists
between the most posterior attachment of external oblique and the most ischial ramus
anterior attachment of latissimus dorsi, and here the crest forms the base The ischial ramus has anteroinferior and posterior surfaces continuous
of the lumbar triangle through which herniation of abdominal contents with the corresponding surfaces of the inferior pubic ramus. The antero-


may rarely occur. Internal oblique is attached to the intermediate area of inferior surface is roughened by the attachment of the medial thigh
the crest. Transversus abdominis is attached to the anterior two-thirds of muscles. The smooth posterior surface is partly divided into perineal
the inner lip of the crest, and behind this to the thoracolumbar fascia and pelvic areas, like the inferior pubic ramus. The upper border com-
and quadratus lumborum. The highest fibres of gluteus maximus are pletes the obturator foramen; the rough lower border, together with the
attached to the dorsal segment of the crest on its lateral slope. Erector medial border of the inferior pubic ramus, contributes to the pubic
spinae arises from the medial slope of the dorsal segment. The straight arch. The fascia overlying the superficial muscles of the perineum is
head of rectus femoris is attached to the upper area of the anterior infe- attached below the ridge between the perineal and pelvic areas of the
rior spine. Some fibres of piriformis are attached in front of the posterior posterior surface of the ischial ramus. Above the ridge, areas give attach-
inferior spine on the upper border of the greater sciatic foramen. ment to the crus of the penis or clitoris and the external urethral
The gluteal surface is divided by three gluteal lines into four areas. sphincter. The lower border of the ramus provides an attachment for
Behind the posterior line, the upper rough part gives attachment to the the fascia lata and the stratum membranosum perinei.


Bones
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ischial tuberosity
The ischial tuberosity is divided nearly transversely into upper and L4 vertebra
lower areas. The upper area is subdivided by an oblique line into Sacroiliac
superolateral and inferomedial parts. The lower area, narrowing as it joint
curves on to the inferior ischial aspect, is subdivided by an irregular
vertical ridge into lateral and medial areas. The medial area is covered Ala of the
sacrum
by fibroadipose tissue that usually contains the sciatic bursa of gluteus
maximus, which supports the body in sitting. Medially, the tuberosity
Anterior
is limited by a curved ridge that passes on to the ramus and which gives
superior
attachment to the sacrotuberous ligament and its falciform process. iliac spine
ischial spine Coccyx
The ischial spine projects downwards and a little medially (see Fig.
Superior
80.5A,B). The sacrospinous ligament is attached to its margins, separat-
pubic ramus
ing the greater from the lesser sciatic foramen. The ligament is crossed
Obturator
posteriorly by the internal pudendal vessels, pudendal nerve and the
foramen
nerve to obturator internus.
Lesser
Muscle attachments trochanter
Part of obturator externus is attached to the lower femoral surface of
the ischial body. Part of obturator externus, the anterior fibres of adduc-
tor magnus and, near the lower border, gracilis are all attached to the
anterior surface of the ischial ramus. Between adductor magnus and A
gracilis, the attachment of adductor brevis may descend from the infe-
rior pubic ramus. The posterior surface is divided into pelvic and peri-
neal areas. The pelvic area, facing back, has part of obturator internus
attached to it. The perineal area faces medially; its upper part is related
to the crus of the penis or clitoris, and its lower part gives attachment
Spinous process
to sphincter urethrae, ischiocavernosus and the superficial transverse of L5
perineal muscle.
Posterior superior


The ischial tuberosity gives attachment to the posterior thigh iliac spine
muscles. Quadratus femoris is attached along the upper part of its
lateral border. The upper area of the tuberosity is subdivided by an
Sacral hiatus
oblique line into a superolateral part for semimembranosus and an
inferomedial part for the long head of biceps femoris and semitendi-
nosus. The lower area is subdivided by an irregular vertical ridge into
Head of femur
lateral and medial areas. The larger lateral area is for part of adductor
magnus. Superomedial to the tuberosity, the posterior surface has a
wide, shallow groove, usually covered by hyaline cartilage, with a bursa
between it and the tendon of obturator internus. Gemellus inferior is Ischial tuberosity
attached to the lower margin of the groove, near the tuberosity. Gemel-
lus superior is attached to the upper margin, near the ischial spine.
Forceful contraction of the hamstrings can result in an avulsion fracture
of the ischial tuberosity.
The pelvic surface of the ischial spine gives attachment to coccygeus
and to the most posterior fibres of levator ani. Obturator internus is
attached to the upper part of the smooth pelvic ischial surface and B
converges on the bony part of the lesser sciatic foramen, covering the
rest of this surface other than the pelvic aspect of the ischial spine; the Fig. 80.8 Anterior (A) and posterior (B) views of the female pelvis, upper
muscle and its fascia separate the bone from the ischio-anal fossa. femur and lower lumbar spine, using three-dimensional computed
tomography. (Courtesy of Dr Yoginder Vaid and Mr Jon C Betts, Jr.)
vascular supply
There are multiple vascular foramina at the acetabular margins and a
few are usually present on the pelvic surface. Branches of the obturator, region where the trunk and lower limbs meet (Fig. 80.8). It is used here
medial circumflex femoral and inferior gluteal arteries supply the in the skeletal sense, to describe the irregular osseous girdle between
ischium. the femoral heads and fifth lumbar vertebra. It is large because its


primary function is to withstand the forces of body weight and muscu-
innervation
lature. In this section, its obstetric, forensic and anthropological signifi-
The periosteum is innervated by branches of nerves that supply the hip cance will be considered.
joint and muscles attached to the bone. The pelvis can be regarded as having greater and lesser segments, the
true and false pelves. The segments are arbitrarily divided by an oblique
ossification
plane passing through the sacral promontory posteriorly and the lineae
Ossification of the ischium is described on page 1342. terminales elsewhere. Each linea terminalis includes the iliac arcuate
line, pectineal line (pecten pubis) and pubic crest.
SACRUM Greater pelvis
The greater pelvis consists of the ilium and pubis above the lineae
See page 726. terminales and the base of the sacrum. This junctional zone is structur-
ally massive and forms powerful arches from the acetabular fossae to
the vertebral column around the visceral cavity, which is part of the
COCCYX
abdomen. It has little anterior wall because of the pelvic inclination.
Pelvic inlet (superior pelvic aperture)
See page 729.
The pelvic inlet or brim may be round or oval in shape, and is indented
posteriorly by the sacral promontory. The pelvic brim is obstetrically
BONY PELVIS AS A WHOLE important and has also long been measured for anthropological
reasons, as has the pelvic cavity.
The term pelvis (‘basin’) is applied variously to the skeletal ring formed By convention, the pelvic inlet is described in three dimensions. The
by the hip bones and the sacrum, the cavity therein, and even the entire anteroposterior diameter (true conjugate) is measured between the


Pelvic girdle, gluteal region and thigh
1346
9
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midpoints of the sacral promontory and upper border of the pubic the rectum, urinary bladder and parts of the reproductive organs. The
symphysis, and on average is 10 cm in the adult male and 11.2 cm in cavity in females must also permit passage of the fetus.
the adult female. The transverse diameter is the maximum distance The pelvic cavity diameters are measured at approximately the mid-
between similar points (assessed by eye) on opposite sides of the pelvic level. The anteroposterior diameter is measured between the midpoints
brim, and is on average 12.5 cm in the adult male and 13.1 cm in the of the third sacral segment and posterior surface of the pubic symphysis,
adult female. The oblique diameter is measured from the iliopubic and is about 10.5 cm in the adult male and 13 cm in the adult female.
ramus to the opposite sacroiliac joint, and is on average 12 cm in the The transverse diameter is the widest transverse distance between the
adult male and 12.5 cm in the adult female. These measurements vary side walls of the cavity, and often the greatest transverse dimension in
with the individual and with racial group. In children, dimensions of the whole cavity. It measures about 12 cm in the adult male and
the thorax and spine are significantly correlated with the width of the 12.5 cm in the adult female. The oblique diameter is the distance from
pelvic inlet, which are age-independent predictors of paediatric chest the lowest point of one sacroiliac joint to the midpoint of the contral-
width and may be useful in assessing growth of the thorax and spine ateral obturator membrane, and measures about 11 cm in the adult
in children with early-onset spinal deformity (Emans et al 2005). male and 13.1 cm in the adult female. All measurements vary with the
individual and with racial group.
Articulated bony pelvis
Pelvic outlet (inferior pelvic aperture)
The lesser pelvis encloses a true basin when soft tissues of the pelvic
floor are in place. Skeletally, it is a narrower continuation of the greater Less regular in outline than the pelvic inlet, the pelvic outlet is indented


pelvis, with irregular but more complete walls around its cavity. Of behind by the coccyx and sacrum, and bilaterally by the ischial tuberos-
obstetric importance, it has a curved median axis, and superior and ities. Its perimeter thus consists of three wide arcs. Anteriorly is the
inferior openings. The superior opening is occupied by viscera. The pubic arch, between the converging ischiopubic rami. Posteriorly and
pelvic floor, viscera and subjacent perineal sphincters close the inferior laterally on both sides are the sciatic notches between the sacrum and
opening. ischial tuberosities. The sciatic notches are divided by the sacrotuberous
and sacrospinous ligaments into greater and lesser sciatic foramina
Cavity of the lesser pelvis
(Fig. 80.9).
The cavity of the lesser pelvis is short, curved, and markedly longer in With ligaments included, the pelvic outlet is rhomboidal. Its anterior
its posterior wall. Anteroinferiorly, it is bounded by pubic bones, their limbs are the ischiopubic rami (joined by the inferior pubic ligament)
rami and symphysis. Posteriorly, it is bounded by the concave anterior and its posterior margins are the sacrotuberous ligaments, with the
sacral surface and coccyx. Laterally on each side, its margins are the coccyx in the midline. The outlet is thus not rigid in its posterior half,
smooth quadrangular pelvic aspect of the fused ilium and ischium. being limited by ligaments and the coccyx, all slightly yielding. Even
The region so enclosed is the pelvic cavity proper, through which pass with the sacrum taken as the posterior midline limit (more reliable for
A
L4 vertebra
Iliolumbar ligament
Sacroiliac joint, anterior sacroiliac ligament
Iliac crest
Greater sciatic foramen
Sacrospinous ligament
Anterior superior iliac spine
Sacrotuberous ligament Inguinal ligament
Lesser sciatic foramen
Muscular space
Straight head of rectus femoris Iliopectineal arch
Iliofemoral ligament Greater trochanter
Vascular space
Superior pubic ligament
Obturator foramen Pubic arch
B


Iliolumbar ligament
Supraspinous ligament
Posterior sacroiliac
ligament
Greater sciatic
Sacrotuberous foramen
ligament
Sacrospinous
ligament
Fig. 80.9 Joints and ligaments of the pelvis.
A, Anterior aspect. Note the arrows indicating vascular
and muscular spaces. B, Posterior aspect. (With
permission from Waschke J, Paulsen F (eds), Sobotta
Deep posterior Atlas of Human Anatomy, 15th ed, Elsevier, Urban &
sacrococcygeal ligament Fischer. Copyright 2013.)


Bones
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measurement), there may be slight mobility at the sacroiliac joints. descends in the axis of the inlet as far as the level of the ischial spines;
Note also that a plane of the pelvic outlet is merely conceptual. The it is then directed forwards into the axis of the vagina at right angles to
anterior, ischiopubic part has a plane that is inclined down and back that axis. The form of this pelvic axis and the disparity in depth between
to a transverse line between the lower limits of the ischial tuberosities, the anterior and posterior contours of the cavity are prime factors in
and the posterior half has a plane approximating to the sacrotuberous the mechanism of fetal transit in the pelvic canal.
ligaments, sloping down and forwards to the same line. In the standing position, the pelvic canal curves obliquely backwards
Three measurements are made for the pelvic outlet. The anteropos- relative to the trunk and abdominal cavity. The whole pelvis is tilted
terior diameter is usually measured from the apex of the coccyx to the forwards, the plane of the pelvic brim making an angle of 50–60° with
midpoint of the lower rim of the pubic symphysis. The lowest sacral the horizontal. The plane of the pelvic outlet is tilted to about 15°.
point may also be used (on average: male 8 cm, female 12.5 cm). The Strictly, the pelvic outlet has two planes: an anterior passing backwards
transverse (bituberous) diameter is measured between the ischial tuber- from the pubic symphysis and a posterior passing forwards from the
osities at the lower borders of their medial surfaces (on average: male coccyx, both descending to meet at the intertuberous line. In standing,
8.5 cm, female 11.8 cm). The oblique diameter extends from the mid- the pelvic aspect of the pubic symphysis faces nearly as much upwards
point of the sacrotuberous ligament on one side to the contralateral as backwards and the sacral concavity is directed anteroinferiorly. The
ischiopubic junction (on average: male 10 cm, female 11.8 cm). All front of the pubic symphysis and anterior superior iliac spines are in


measurements vary among individuals and racial groups. the same vertical plane. While sitting, body weight is transmitted
through the inferomedial parts of the ischial tuberosities, with variable
Other measurements
soft tissues intervening. The anterior superior iliac spines are in a verti-
Apart from these main measurements, by consensus the basis of pelvic cal plane through the acetabular centres, and the whole pelvis is tilted
osteometry, other planes and measurements are used in obstetric prac- back with the lumbosacral angle somewhat diminished at the sacral
tice. The plane of greatest pelvic dimensions is an obstetric concept. It promontory.
represents the most capacious pelvic level, between the pelvic brim and
midlevel plane, and corresponds with the latter anteriorly at the middle Pelvic mechanism
part of the pubic symphysis and posteriorly at the level of the second The skeletal pelvis supports and protects the contained viscera but is
and third sacral segments. primarily part of the lower limbs, affording wide attachment for muscles
The plane of least dimensions is said to be at about mid-pelvic level. of the thigh, leg and trunk. It constitutes the major mechanism for
Its transverse diameter is between the apices of the ischial spines. This transmitting the weight of the head, trunk and upper limbs to the lower
measurement is about 9.5 cm in an adult female and is just wide limbs. It may be considered as two arches divided by a coronal trans-
enough to allow passage of the biparietal diameter of a fetal head acetabular plane. The posterior arch, chiefly concerned in transmitting
(about 9 cm). Not surprisingly, most difficulty in parturition occurs weight, consists of the upper three sacral vertebrae and strong pillars of
here. bone from the sacroiliac joints to the acetabular fossae. The anterior
The above measurements are sometimes made in clinical practice arch, formed by the pubic bones and their superior rami, connects these
using radiographs or magnetic resonance imaging (MRI) pelvimetry. lateral pillars as a tie beam to prevent separation; it also acts as a com-
Precise measurement is not possible without radiological techniques, pression strut against medial femoral thrust. The sacrum, as the summit


and even these do not take into account the adjacent soft tissues. In the of the posterior arch, is loaded at the lumbosacral joint. Theoretically,
past, measurements were made at physical (e.g. vaginal) examinations. this force has two components: one thrusting the sacrum downwards
However, these manual measurements have proved to be of little clini- and backwards between the iliac bones, the other thrusting its upper
cal value and are now more or less obsolete. end downwards and forwards. Sacral movements are regulated by
Morphological classification of pelves osseous shape and massive ligaments. The first component therefore
acts against the wedge, its tendency to separate iliac bones resisted by
the sacroiliac and iliolumbar ligaments and pubic symphysis.
Available with the Gray’s Anatomy e-book
Vertical coronal sections through the sacroiliac joints suggest divi-
sion of the (synovial) articular region of the sacrum into three segments.
Pelvic axes and inclination
In the anterosuperior segment, involving the first sacral vertebra, the
The axis of the superior pelvic aperture traverses its centre at right angles articular surfaces are slightly sinuous and almost parallel. In the middle
to its plane, directed down and backwards (Fig. 80.10). When pro- segment, the posterior width between the articular markings is greater
longed (projected), it passes through the umbilicus and mid-coccyx. An than the anterior, and centrally a sacral concavity fits a corresponding
axis is similarly established for the inferior aperture: projected upwards, iliac convexity, an interlocking mechanism relieving the strain on the
it impinges on the sacral promontory. Axes can likewise be constructed ligaments produced by body weight. In the posteroinferior segment, the
for any plane, and one for the whole cavity is a concatenation of an anterior sacral width is greater than the posterior and here its sacral
infinite series of such lines (see Fig. 80.10). The fetal head, however, surfaces are slightly concave. Anteroinferior sacral dislocation by the
second component (of force) is prevented, therefore, mainly by the
middle segment, owing to its cuneiform shape and interlocking mecha-


nism. However, some rotation occurs, in which the anterosuperior
segment tilts down and the posteroinferior segment up. ‘Superior’ seg-
mental movement is limited to a small degree by wedging but primarily
by tension in the sacrotuberous and sacrospinous ligaments. In all
movements, the sacroiliac and iliolumbar ligaments and pubic symphy-
sis resist separation of the iliac bones.
Sacral
promontory
SEXUAL DIFFERENCES IN THE PELVIS
The pelvis provides the most marked skeletal differences between male
Pelvic inlet and female. Distinction can be made even during fetal life, particularly
Axis of
pelvic outlet in the subpubic arch. In infancy, dimensions of the whole pelvis are
greater in males than in females, but the size of the pelvic cavity is
usually greater in females. This distinction prevails in childhood but
the difference is maximal at about 22 months. Sexual differences in
Axis of adults are divisible into metrical and non-metrical features; the range
Axis of cavity of most features overlaps between the sexes.
Pubic inlet plane of Differences are inevitably linked to function. While the primary
outlet
symphysis pelvic function in both sexes is locomotor, the pelvis, particularly the
lesser pelvis, is adapted to parturition in females, and these changes
variably affect the proportions and dimensions of the greater pelvis.
Horizontal plane Since males are distinctly more muscular and therefore more heavily
50–60º 15º built, overall pelvic dimensions, such as the intercristal distance (dis-
Fig. 80.10 A median sagittal section through the female pelvis, showing tance between the iliac crests), are greater, markings for muscles and
the planes of the inlet and outlet and the axis of the pelvic cavity. ligaments more pronounced, and general architecture more robust. The


08
retPahc
Pelvic girdle, gluteal region and thigh
Interest in the dimensions described above is primarily obstetric and,
less frequently, forensic. All pelvic measurements display individual
variation and the values quoted are means from limited surveys. These
measurements have been analysed by many anatomists, anthropolo-
gists, obstetricians and radiologists in attempts to classify human
pelves, especially female. The four most common terms used today are
gynaecoid, anthropoid, platypelloid and android. The gynaecoid pelvis
is the traditional Western female pelvis with a heart-shaped brim and
the range of measurements quoted above. An anthropoid pelvis has a
larger mid-cavity and a wide anteroposterior inlet, which is oval in
shape; it is more common in women of African origin and may be
associated with a ‘high-assimilation’ pelvis where there is an additional
lumbar vertebra. A platypelloid pelvis is flat and oval from side to side
at the brim; it is a contracted pelvis that is rarely seen nowadays, having
previously been associated with rickets. An android pelvis has a trian-
gular brim and is the shape of a male pelvis.
1347.e1


Pelvic girdle, gluteal region and thigh
1348
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noitceS
male iliac crest is more rugged and more medially inclined at its ant- strength with the weight and muscular forces it is required to withstand.
erior end; in females the iliac crests are less curved in all parts. The iliac Its shaft, almost cylindrical along most of its length, is bowed forwards.
alae are more vertical in females but do not ascend so far; the iliac fossae It has a proximal rounded, articular head projecting medially from its
are therefore shallower. These iliac peculiarities probably account for short neck, which, in turn, is a medial extension of the proximal shaft.
the greater prominence of female hips. The distal extremity is wider and more substantial, and presents a
The male is relatively and absolutely more heavily built above the double condyle that articulates with the tibia. In standing, the femoral
pelvis, with consequent differences at the lumbosacral and hip joints. shafts show an inclination upwards and outwards from their tibial
The sacral basal articular facet for the fifth lumbar vertebra and interven- articulations, with the femoral heads being separated by the pelvic
ing intervertebral disc is more than one-third of the total sacral basal width. Since the tibia and fibula descend vertically from the knees, the
width in males but less than one-third in females, in whom the sacrum ankles are also in the line of body weight in standing or walking. The
is also relatively broader, accentuating this difference. The female has degree of femoral obliquity varies between individuals but is generally
relatively broader sacral alae. The male acetabulum is absolutely larger, greater in women, reflecting the relatively greater pelvic breadth and
and its diameter is approximately equal to the distance between its shorter femora. Proximally, the femur consists of a head, neck and
anterior rim and pubic symphysis. In females, acetabular diameter is greater and lesser trochanters.
usually less than this distance, not only because it is absolutely smaller
but also because the anterolateral wall of the cavity is comparatively Femoral head
and often absolutely wider. The height of the female pubic symphysis The femoral head faces anterosuperomedially to articulate with the


and adjoining parts of the pubis and ischium, which form the anterior acetabulum (Fig. 80.13). The head, often described as rather more than
pelvic wall, are also absolutely less, producing a somewhat triangular half a ‘sphere’, is not part of a true sphere but is spheroidal. Its smooth-
obturator foramen, which is more ovoid in males. Differing pubic ness is interrupted posteroinferior to its centre by a small, rough fovea.
growth is also expressed in the pubic arch below the pubic symphysis The head is intracapsular and is encircled, distal to its equator, by the
and between the inferior pubic rami. It is more angular in males, being acetabular labrum. Its articular margin is distinct, except anteriorly,
50–60°; in females it is rounded, less easy to measure and usually where the articular surface extends on to the neck. The ligamentum teres
80–85°. A greater separation of the pubic tubercles in females contrib- is attached to the fovea. The anterior surface of the head is separated
utes to the pubic width. The ischiopubic rami are also much more inferomedially from the femoral artery by the tendon of psoas major,
lightly built and narrowed near the symphysis; in males they bear a the iliopectineal bursa and the articular capsule.
distinctly rough, everted area for attachment of the penile crura, the
corresponding attachment for the clitoris being poorly developed. The Femoral neck
ischial spines are closer in males and are more inturned. The greater The femoral neck (see Fig. 80.13) is approximately 5 cm long, narrow-
sciatic notch is usually wider in females: mean values for males and est in its mid part and widest laterally, and connects the head to the
females are 50.4° and 74.4°, respectively. The greater female values for shaft at an average angle of 127° (Gilligan et al 2013) (angle of incli-
angle and width are associated with increased backward sacral tilt and nation; neck–shaft angle): this facilitates movement at the hip joint,