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157
Lower Limb55
C H A P T E R
The primary func tion of the lower limb is to suppo rt the
weight of the bo dy and to provide a stable foundation when
standing, walking, or running. Each lower limb may be d i-
vided into the gluteal region, the thigh, the knee , the leg, the
ankle, and the foot.
It is suggested that the lower limb be reviewed in the
following order:
1. A brief overview of the bo nes and the major joints, prefer-
ably with use o f an articulated skeleton.
2. A consideration of the more important muscles, concen-
trating on their actions and their nerve supply.3. A brief review of the b lood supply and the lymphatic
drainage.
4. A detailed overview of the nerves and their distribution.
To assist students, tables are used extensively in this
chapter.
BONES
Bones o f the Pelvic Girdle
The pelvic girdle consists of four b ones: the two hip bones,
the sacrum, and the coccyx (see Fig. 3-1). The pelvic girdle
pro vides a stron g co nn ec tion be tween the trun k an d the
lower limbs.
HIP BONE
In ch ildren, ea ch h ip bone co nsists of the ilium, the ischium,
and the pub is (Fig. 5-1). At pub erty, these three bones fuse
together to form one large, irregular bon e. The acetabulum
is a cup-shaped depression on the outer surface of the hip
bo ne , and it articulates with the head of the femur. The ar-
ticular surface of the acetabulum is limited to a horseshoe-
shaped area and is covered with hyaline cartilage. The ac-
etabular fossa is the floor of the acetabulum, which is
nonarticular. The acetabular notch is situated on the
inferior margin of the acetabu lum.
The iliac crest runs between the anterior and poste-
rior superior iliac spines. Below these spines are the cor-
responding inferior iliac spines.
The ischium possesses an ischial spine and an ischial
tuberosity (Fig. 5-1).
The pubis has a body and a superior and an inferior
pubic rami. The b ody of the pubis has the pubic crest an dthe pubic tubercle, and it articulates with the pubic bone
of the oppo site side at the symphysis pubis.
The obturator foramen is a large opening that is
bo unde d b y the p arts of the isch ium an d pub is (Fig. 5-1).
Bones o f the Thigh
The b one s of the thigh consist of the femu r and the pa tella
(Fig. 5-2).
FEMUR
The head of the femur is hemispheric in sha pe and fits intothe acetabulum to form the hip joint. The fovea capitis is
a small depression in the center of the head for the attach-
ment of the ligament of the head. Part of the blood sup-
ply to the head of the femur from the ob tura tor artery is
conveyed along this ligament and enters the bone at the
fovea.
The neck connects the head to the shaft (Fig. 5-2). The
greater and the lesse r trochanters are large e minences at
the junction of the neck and the shaft. Connecting the two
trochanters are the intertrochanteric line anteriorly
(where the iliofemoral ligament is attached) and a promi-
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158 CHAPTER5 Lower Limb
iliac crestrough surface for attachment of interosseous ligament
posterior superior iliac spine
auricular surface
posterior inferior iliac spine
greater sciatic notch
ischial spine
lesser s ciatic notch
obturator membrane
ischial tuberosity
ischial ramusinferior ramus of pubis
obturator canal
pubic crest
pubic tubercle
body of pubis
superior ramus of pubis
iliopectineal line
anterior inferior iliac spine
anterior superior iliac spine
iliac fossa
ilium tubercle of ilium
line of fusion of bones
acetabulum
obturator foramen
ischium
A
B
pubis
Figure 5-1 Right h ip bone . A. Medial surface. B. Lateral surface. Note the lines of fusion b etwee nthe ilium, the ischium , and the pub is.
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nent intertrochanteric crest posteriorly (on which is thequadrate tubercle) .
The shaft is smooth on its anterior surface but has a
ridge posteriorly (the linea aspera) to which are attached
muscles and intermuscular septa. The medial margin of
the linea aspera continues below (as the medial supra-
condylar ridge) to the adductor tubercle (Fig. 5-2) on
the medial condyle. The lateral margin becomes continu-
ous below with the lateral supracondy lar ridge. On the
posterior surface of the sha ft below the greater trochante r
is the gluteal tuberosity for the insertion of the gluteus
maximus muscle. A flat, triangular area on the posterior surface of the lower end of the shaft is called the popliteal
surface.
The lower end of the femur has a lateral and a medial
condyle, which are separated posteriorly by the inter-
condylar notch. The anterior surface s of the con dyles are
join ed by an ar ticula r surfac e for the patella. The two
condyles take p art in the formation of the knee joint. Above
the condyles are the medial and the lateral epicondyles.
The adductor tubercle is continuous with the medial epi-
condyle.
CHAPTER5 Lower Limb 159
greater trochanter
intertrochanteric line
lateral condyle
patellar surface
head fovea capitis
neck
lesser trochanter
shaft
adductor tubercle
medial epicondyle
medial condyle
for attachment
of rectus femoris
for attachment
of vastus lateralis
for attachment
of vastus medialis
patella
for attachment of ligamentum patellae
lateral condyle
head of fibula
neck
shaft
lateral malleolus
medial malleolus
shaft of tibia
lateral border
anterior border
tibial tuberosity
medial condyle
intercondylar eminence
A
C
B
Figure 5-2 A. Anterior su rface of the right femu r. B. Anterior surface of the right patella. C.Anterior surface o f the righ t tibia an d fibu la.
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PATELLA
The pa tella is the largest sesamoid bo ne ( a bone that de vel-
ops within a tendon), and it lies within the tendon of the
quadriceps femoris muscle in front of the knee joint. It is tri-
angular in shape. Its apex lies inferiorly and is conne cted to
the tub erosity of the tibia b y the ligame ntum patellae. The
posterior surface articulates with the cond yles of the femu r.
Bones of the Leg
The bon es of the leg a re the tibia a nd the fibula (Fig. 5-2).
TIBIAThe tibia is the large, weight-bearing, med ial bone of the leg.
At the upper end are the lateral and medial condyles,
which articulate with the lateral and med ial condyles of the
femur with the lateral and medial menisci intervening.
Separating the upper articular surfaces of the tibial cond yles
is the intercondylar e minence. The lateral condyle pos-
sesses an oval articular facet for the h ead of the fibula
on its lateral aspect.
At the upper en d o f the anterior border of the shaft of the
tibia is the tuberosity (Fig. 5-2), which receives the attach-
men t of the ligamentum p atellae. The anterior border is pro-
longed downward and medially to form the medial malle-
olus below. The lateral border of the tib ia provide s
attachment to the interosseous me mbrane, which b inds to-
gether the tibia and the fibula. The lower end of the tibia
shows a wide, rough dep ression on its lateral surface for ar-
ticulation with the fibula.
FIBULA
The fibula provides attachmen t for muscles. It takes no pa rt
in articulation at the knee joint, but below, it forms part of
the an kle joint.
The head forms the upper end of the fibula (Fig. 5-2). It
has a styloid process, and it possesses an articular sur-
face for articula tion with the latera l cond yle of the tibia. The
shaft is attache d to the tibia by the interosseous memb rane.
The lower end of the fibula forms the lateral malleolus.
160 CHAPTER5 Lower Limb
BLOOD SUPPLY TO THE FEMORAL HEAD AND
FRACTURES OF THE FEMORAL NECK
In the young, the epiphysis of the he ad is supp lied bya small branch o f the obturator artery, which passes to
the head along the ligament to the femoral head. The
upper part of the neck of the femur rece ives a profuse
bloo d supp ly from the med ial femoral circum flex
artery. In the adu lt, after the epiphyseal cartilage dis-
appears, an anastomosis between the two sources of
blood supply is established . Frac tures o f the femo ral
neck interfere with or completely interrupt the main
blood supply from the root of the femora l neck to the
femo ral head . Avascular necrosis of the femoral head
is a commo n com plication of femoral neck fractures.
CLINICAL NOTES
FRACTURES OF THE NECK OF THE FIBULA ANDINJURY TO THE COMMON PERONEAL NERVE
The common peroneal nerve is in an exposed posi-
tion as it winds around the neck of the fibula. The
nerve can be injured in fractures of the neck of the
fibula an d b y pressure from casts or splints.
CLINICAL NOTES
Bones o f the Foot
The bones of the foot are the tarsal bones, the metatarsal
bone s, and the pha langes (Fig. 5-3).
TARSAL BONES
The tarsal bone s are the calcaneum, the talus, the navicular,
the cuboid, and the three cuneiform bones.
Calcaneum
The calcaneum is the largest bone of the foot. It articulates
abo ve with the talus and in front with the cuboid b one . The
po sterior surface forms the pro min en ce of the he el, an d
the med ial surface possesses a large, shelflike ridge (the
sustentaculum tali) that assists in supporting of the talus.
Talus
The talus articulates ab ove at the ankle joint with the tibia
and the fibula, be low with the calca neum, and in front with
the navicular bone (Fig. 5-3). It possesses a head, neck, an d
body. Nume rous important ligame nts are attach ed to the
talus, but no muscles are attached to this bone.
Navicular
The navicular lies between the head of the talus and the
three cuneiform bones (Fig. 5-3). The tuberosity lies in
front of and below the medial malleolus, and it attaches to
the ma in part of the tibialis posterior tend on.
Cuboid
The cuboid articulates with the anterior end of the calca-
neum ( Fig. 5-3). It has a dee p groove on its inferior aspec t for
the tendon of the peroneus longus muscle.
Cuneiform Bones
The three cuneiform bones are small, wedge-shaped bones
that articulate proximally with the navicular bone and dis-
tally with the first three metatarsal bon es. Their wedge shape
contributes to the formation and maintenance of the
transverse arch of the foot.
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METATARSAL BONES AND PHALANGES
The metatarsal bones and the phalanges resemble the
metacarpal bones and the phalanges of the hand; each pos-
sesses a distal head, shaft, and proximal base (Fig. 5-3).
There are five metatarsal bones, and they are numbered
from the med ial to the lateral side. The fifth metatarsal has
a prominent tubercle on its base, which can be easily pal-
pa ted along the la tera l borde r of the foot. The tub erc le pro-
vides attachment to the peroneus brevis tendon.
Except for the b ig toe, each toe h as three phalanges. The
big toe possesses only two.
JOINTS
Hip Joint
ARTICULATION
Articulation is between the head of the femur and the ac-
etabu lum of the hip bone (Fig. 5-4). The articular surface of
CHAPTER5 Lower Limb 161
extensor digitorum longus tendons
extensor hallucis longus
insertions of dorsal interossei
extensor digitorum brevis(extensor hallucis brevis)
second dorsal interosseous
first dorsal interosseous
first metatarsal bone
medial cuneiform
intermediate cuneiform
lateral cuneiform
navicular
talus
tendo calcaneus
calcaneum
extensor digitorum brevis
cuboid
peroneus brevis
peroneus tertius
fourth dorsal interosseous
third dorsal interosseous
Figure 5-3 Dorsal view o f the b one s of the right foot. Note the m uscle attachm ents.
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162 CHAPTER5 Lower Limb
acetabular labrum
capsule
head of femur
synovial membrane
acetabulum
acetabular fossa
pad of fat
ligamentof headof femur
epiphyseal line
synovial sheath
synovial membrane
articular surface
acetabular labrum
transverseacetabular ligament
obturator artery
small branchof obturator artery
ligamentof headof femur
synovial sheath
arterial supplyfrom circumflexfemoral arteries
arterial supplyfrom obturator artery
ligamentof headof femur
A
B
Figure 5-4 A. Corona l se ction o f the righ t hip joint. B. Articular su rfaces o f the righ t hip joint andthe arterial supply of the fem ur.
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the acetabulum is horseshoe shaped and is deficient inferi-
orly at the acetabular notch. The cavity of the ace tabulum
is deepened by the fibrocartilaginous rim called the ac-
etabular labrum. The labrum b ridges the ace tabular notch
and is called the transverse acetabular ligament.
TYPE
The hip is a synovial ball-and-socke t joint.
CAPSULE
The capsule encloses the joint and is attached medially to
the acetabular labrum (Fig. 5-4). It is attached late rally to the
intertrochanteric line of the femur in front of and halfway
along the posterior aspect of the neck of the bone be hind. It
is reinforced b y the iliofemo ral, the pub ofemoral, and the is-
chiofemoral ligaments.
LIGAMENTSIliofemoral Ligament
The iliofemoral ligament is the strongest and most important
ligament of the hip joint (Fig. 5-5). It is shaped like an in-
verted Y. Its base is attached to the anteroinferior iliac spine
abo ve, and the two limbs of the Y are attached to the up per
and the lower parts of the intertrochanteric line o f the femur
CHAPTER5 Lower Limb 163
anterior inferior iliac s pineopening for bursa
superior ramus of pubis
pubofemoral ligament
intertrochanteric line
iliofemoral ligament
capsule
A
ischiumiliofemoral ligament
ischiofemoral ligament
intertrochanteric crest
area of loose attachment
of capsule
B
Figure 5-5 Anterior (A) and poste rior (B) views of the right hip joint.
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below. This ligamen t resists hype rextension and latera l
rotation of the hip joint.
Pubofemoral Ligament
The pubofemoral ligament is triangular in shape (Fig. 5-5).
The base is attached above to the superior ramus of the pu- bis, and the apex is a ttached be low to the lower en d o f the
intertrochanteric line. This ligament limits abduction and
lateral rotation of the h ip joint.
Ischiofemoral Ligament
The ischiofemoral ligame nt is spiral in shape and is attached
to the body of the ischium and laterally to the greater
trochanter of the femur (Fig. 5-5). This ligament limits me-
dial rotation of the h ip joint.
Ligament of the Head of the Femur
The ligament of the head of the femur is flat and triangular
in shape (Fig. 5-4). It is attache d by its apex to the fovea c ap i-tis of the femu r and by its base to the transverse ac etabu lar
ligament and to the margins of the acetabular notch. This
ligament lies within the joint and is ensheathed b y synovial
membrane . It has a slight limiting action on add uction of the
hip joint.
SYNOVIAL MEMBRANE
The synovial membrane lines the capsule (Fig. 5-4) an d cov-
ers the portion of the femoral neck that lies within the joint
capsule. It enshea thes the ligame nt of the head of the femur
and covers the floor of the acetabular fossa. It frequently
communicates with the psoas bursa.
NERVE SUPPLY
The femoral, the obturator, and the sciatic nerves and the
nerve to the quadratus femoris supp ly the joint.
MOVEMENTS AND THE MUSCLES THAT PRODUCE
MOVEMENT
The h ip joint has a wide ran ge of movement.
• Flexion: Iliopsoas, rectus femoris, sartorius, and add uctor
muscles.
• Extension (posterior movement of the flexed thigh):
Gluteus maximus an d hamstring muscles.• Abduction: Gluteus medius and minimus, sartorius, ten-
sor fasciae latae, an d piriformis muscles.
• Adduction: Adductor longus and brevis, adductor fibers
of adduc tor magnus, pectineus, and gracilis muscles.
• Lateral rotation: Piriformis, obturator internus and exter-
nus, superior an d inferior gemelli, qua dratus femoris, and
gluteus ma ximus muscles.
• Medial rotation: Anterior fibers of the gluteus medius
and minimus and the tensor fasciae latae muscles.
• Circumduction: A combination of all the previously
described movements.
IMPORTANT RELATIONS
• Anteriorly: Femoral vessels and nerve.
• Posteriorly: Sciatic nerve.
164 CHAPTER5 Lower Limb
HIP JOINT STABILITY AND
TRENDELENBURG’S SIGN
The stability of the hip joint when a person stands on
one leg with the foot of the op posite leg raised above
the ground de pends o n three factors:
• The gluteus medius and m inimus must be function-
ing normally.
• The hea d of the femur must be located normally
within the acetabulum.
• The nec k of the femur must be intact and must have
a normal an gle with the shaft of the femur.
If one of these factors is defective, then the pelvis
will sink downward on the o pposite, unsupported
side. The patient is then said to exhibit a positive
Trendelenburg’s sign.
CLINICAL NOTES
Knee Joint
ARTICULATION
Above are the co ndyles of the femur; below are the c ond yles
of the tibia and their menisci (Fig. 5-6). In front is the articu-
lation between the lower end of the femur and the patella.
TYPE
Between the femur and the tibia is a synovial joint of the
hinge variety. Between the patella and the femur is a
synovial gliding joint.
CAPSULE
The capsule encloses the knee joint, except anteriorly,
where the capsule is deficient. Here, the synovial mem-
brane pouches upwa rd benea th the quadriceps ten do n an d
forms the sup rapatellar bursa.
LIGAMENTS
Extracapsular
Ligamentum Patellae
The ligamentum patellae is a continuation of the tendon of the
quadriceps femoris muscle. It is attached above to the lower
border of the patella and b elow to the tubercle of the tibia.
Lateral Collateral Ligament
The lateral collateral ligament is cordlike; it is attached
above to the lateral condyle of the femur and below to the
head o f the fibula (Fig. 5-6). It is separated from the lateral
meniscus by the tendon of the popliteus muscle.
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Medial Collateral Ligament
The medial co llateral ligamen t is a flat band that is attach ed
above to the medial condyle of the femur and below to
the med ial surface of the shaft of the tibia (Fig. 5-6). It is
strongly attached to the med ial meniscus.
Oblique Popliteal Ligament
The oblique po pliteal ligame nt is a tend inous expan sion of
the semimembranosus muscle. It strengthens the back
of the capsule.
Intracapsular
Cruciate Ligaments
The cruciate ligaments are two very strong ligaments that
cross each other within the knee joint (Fig. 5-6). They are
termed anterior and posterior, according to their tibial at-
tachments.
The anterior cruciate ligament is attached below to
the a nterior intercondylar area of the tibia ( Fig. 5-7), and it
passes upwa rd, backwa rd, and latera llyto b e atta ched to thelateral femoral cond yle.
The posterior cruciate ligament is attached below to
the posterior intercondylar area of the tibia (Fig. 5-7), and it
passes upwa rd, forward, and medially to b e attached to the
medial femoral condyle.
MENISCI
The menisci are C-shaped shee ts of fibrocartilage (Fig. 5-7).
The peripheral convex border of each meniscus is thick
and a ttached to the capsule, and the inner conc ave border
is thin and forms a free edge. The upper surfaces are in
CHAPTER5 Lower Limb 165
suprapatellar bursa
lateral femoral condyle
infrapatellar fold of
synovial membrane
lateral meniscus
capsule (cut open)
shaft of fibula
shaft of femur
medial femoral condyle
posterior cruciate ligament
anterior cruciate ligament
medial meniscus
patellar
shaft of tibia
medial femoral condyle
medial collateral ligament
medial meniscus
medial tibial condyle
shaft of tibia
femur
anterior cruciate ligament
lateral femoral condyle
lateral meniscuslateral collateral ligament
lateral tibial condyle
shaft of fibula
A
B
Figure 5-6 A. Anterior view of the internal asp ect of the right knee joint. Note that the capsu le has been cu t a nd th e pa te lla tu rn ed downward . B. Posterior view of the internal aspe ct of the right
knee joint. Note that the capsule and the synovial mem brane ha ve been removed.
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contact with the femoral condyles and the lower surfaces
with the tibial condyles. Each meniscus is attached to the
upper surface of the tibia by the anterior and the posterior
horns. Because the medial meniscus is also attached to
the medial collateral ligame nt, it is relatively immo bile and
is very susceptible to injury. The function of these menisci
is to deepen the articular surfaces of the tibial condyles to
receive the convex femoral condyles.
BURSAE RELATED TO THE KNEE JOINT
Suprapatellar Bursa
The suprapatellar bursa lies beneath the quadriceps muscle.
It is the largest bursa , and it always communicates with the
knee joint.
Prepatellar Bursa
The p repatellar bursa lies between the pa tella and the skin.
Infrapatellar Bursae
The superficial infrapatellar bursa lies be tween the liga-
mentum patellae and the skin. The deep infrapatellar
bursa lies between the ligamentum patellae and the tibia.
Popliteal Bursa
The p opliteal bursa surrounds the tendo n of the popliteus. It
always communicates with the joint cavity.
Semimembranosus Bursa
The semime mbran osus bursa lies between the ten don o f the
semimembranosus muscle and the medial condyle of the
tibia. It may communicate with the joint cavity.
NERVE SUPPLY
Femoral, obturator, common peroneal, and tibial nerves
supply the joint.
MOVEMENTS AND THE MUSCLES THAT PRODUCE
MOVEMENT
• Flexion: Biceps femoris, semitendinosus, and semi-
memb ranosus muscles.
166 CHAPTER5 Lower Limb
anterior cruciate ligament
medial meniscus
medial collateral ligament
semimembranosus
medial head of gastrocnemius
prepatellar bursa
ligamentum patellae
capsule
lateral meniscus
lateral collateral ligament
tendon of popliteus
deep fascia
popliteal artery
posterior cruciate ligament
Figure 5-7 Cross-section of the right knee joint as se en from a bove. Note the po sitions o f the ligam ents a nd the me nisci.
INJURIES TO THE LIGAMENTS AND MENISCI
The ligaments and menisci are commonly injured in
active sports. The medial men iscus is damaged m uch
more frequen tly than the lateral, probab ly bec ause of
its strong attachment to the medial collateral liga-
ment, which restricts its mobility.
CLINICAL NOTES
SYNOVIAL MEMBRANE
The synovial membrane lines the capsule. Anteriorly, itforms a pouch that extends up beneath the quadriceps
femoris muscle to form the suprapatellar bursa. Posteri-
orly, it is prolonged downward on the tendo n of the popliteus
muscle to form the popliteal bursa. The synovial mem-
bra ne is also re flected forward and around the front of the
cruciate ligaments; as a result, the c ruciate ligaments lie be-
hind the synovial cavity.
In the anterior part of the lower region of the joint, the
synovial membrane is reflected backward from the liga-
mentum patellae to form the infrapatellar fold. The ed ges
of this fold are called the alar folds.
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• Extension: Quadriceps femo ris muscle.
• Medial rotation: Sartorius, gracilis, and semitendinosus
muscles.
• Lateral rotation: Biceps femoris mu scle.
The knee joint is most stable when in full extension. As
the knee joint assumes this position, med ial rotation of thefemur results in a twisting and tightening of all the major lig-
aments of the joint. During flexion, the ligaments are un-
twisted by contraction of the popliteus muscle, which
laterally rotates the femur on the tibia.
The inferior transverse tibiofibular ligament deepens
the socket into which the b ody of the talus fits snugly.
TYPE
The ankle is a synovial hinge joint.
CAPSULE
The c apsule en closes the joint.
LIGAMENTS
Medial (Deltoid) Ligament
The medial ligament is very strong and is attached by its
apex to the tip of the medial malleolus ( Fig. 5-8). Below, the
dee p fibers are attache d to the me dial surface of the body of
the talus. The superficial fibers are attached to the medial
side of the talus, the sustentaculum tali, the plantar calca-
neonavicular ligament, and the tuberosity of the navicular
bo ne .
Late ral Ligament
The lateral ligament is weaker than the medial ligament
(Fig. 5-8) an d has three b and s.
Anterior Talofibular Ligament
The anterior talofibular ligame nt runs from the lateral malle-
olus to the lateral surface of the talus.
CHAPTER5 Lower Limb 167
fibula
lateral malleolus
posterior talofibular ligament
calcaneofibular ligament
tibia
talus
anterior talofibular ligament
bifurcated ligament
tibia
navicular
medial malleolus
medial (deltoid) ligament
calcaneum
sustentaculum tali
A
B
Figure 5-8 Right ankle joint. A. Late ral view. B. Med ial view.
STRENGTH OF THE K NEE JOINT
The strength of the kne e joint depen ds on the strength
of the ligaments that bind the femur to the tibia and o n
the tone of the muscles acting on the joint. The most
important muscle group is the quadriceps femoris;
provided tha t this is we ll d eveloped , it is capable of
stabilizing the knee in the p resence of torn ligaments.
CLINICAL NOTES
Ankle Joint
ARTICULATION
The articulation is between the lower end of the tibia, the
malleoli above, and the body of the talus below (Fig. 5-8).
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168 CHAPTER5 Lower Limb
Calcaneofibular Ligament
The calcaneofibular ligament runs from the lateral malleo-
lus to the lateral surface of the calcane um.
Posterior Talofibular Ligament
The posterior talofibular ligament runs from the lateral
malleolus to the p osterior tubercle of the talus.
SYNOVIAL MEMBRANE
The synovial membrane lines the capsule.
NERVE SUPPLY
Deep peron eal and tibial nerves supp ly the joint.
MOVEMENTS AND THE MUSCLES THAT PRODUCE
MOVEMENT
• Dorsiflexion (toes pointing upward): Tibialis anterior, ex-tensor ha llucis longus, extensor digitorum longus, and p er-
one us tertius muscles.
• Plantar flexion (toes pointing downward): Gastrocne-
mius, soleus, plantaris, peroneu s longus, peroneu s brevis,
tibialis posterior, flexor digitorum longus, and flexor hal-
lucis longus muscles.
IMPORTANT RELATIONS
• Anteriorly: Anterior tibial vessels and the dee p pe ronea l
nerve (Fig. 5-9).
• Posteriorly: Tendo calcaneus (Fig. 5-10).
• Behind the lateral malleolus: Tendons of peroneus
longus a nd brevis (Fig. 5-10).• Behind the medial malleolus:Posterior tibial vessels, tib-
ial nerve, and the long flexor ten dons of the foot (Fig. 5-10).
Intertarsal Joints
SUBTALAR JOINT
Articulation
The articulation is between the concave inferior surface of
the bod y of the talus and the convex face t on the uppe r sur-
face of the c alcaneum.
Type
The subta lar joint is a synovial gliding joint.
TALOCALCANEONAVICULAR J OINT
Articulation
Articulation is between the rounde d head o f the talus, upper
surface o f the sustentaculum tali of the calcaneum, and pos-
terior concave surface of the navicular bone.
Type
The talocalcaneonavicular joint is a synovial joint.
Ligaments
Plantar Calcaneonavicular (Spring) Ligament
The p lantar calcan eonavicular ligame nt runs from the ante-
rior border o f the sustentaculum tali to the inferior surface
and the tuberosity of the navicular bone. It supports the
head of the talus.
CALCANEOCUBOID JOINT
Articulation
Articulation is between the anterior end of the calcaneum
and posterior surface of the cu boid.
Type
The calcan eocubo id joint is a synovial gliding joint.
Ligaments
Long Plantar Ligament
The long plantar ligame nt is strong and connec ts the under-
surface of the c alcaneum to the cub oid and the bases of the
third, the fourth, and the fifth me tatarsal bones.
Short Plantar Ligament
The short plantar ligament is wide and strong and conne cts
the undersurface of the calcaneum to the adjoining part
of the cuboid.
MOVEMENTS AND THE MUSCLES THAT PRODUCE
MOVEMENT
The movements of the subtalar, the talocalcaneonavicular,
and the calcaneocuboid joints are inversion and eversion.Inversion is more extensive than eversion.
• Inversion (movement of the foot so that the sole faces
medially): Tibialis anterior, extensor hallucis longus, me-
dial tendo ns of extensor digitorum longus, and tibialis pos-
terior muscles.
• Eversion (op posite movement of the foot so that the sole
faces laterally): Peroneus longus, peroneus brevis, per-
oneus tertius, and lateral tendons of extensor digitorum
longus muscles.
CUNEONAVICULAR J OINT
ArticulationArticulation is between the three cuneiform bones and the
navicular bo ne.
Type
This is a synovial gliding joint.
CUBOIDEONAVICULAR JOINT
The cub oideon avicular joint is a fibrous joint. The bon es are
connected by dorsal, plantar, and interosseous ligaments,
and a small amoun t of moveme nt is possible.
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CHAPTER5 Lower Limb 169
Figure 5-9 Structures of the anterior and lateral right leg and o f the do rsum of the foot.
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170 CHAPTER5 Lower Limb
flexor hallucis longus
peroneal artery
tendocalcaneus
abductor digiti minimi
inferior peroneal retinaculum
fifth metarsal bone
inferior extensor retinaculum
synovial sheath
superior peroneal retinaculum
lateral malleolus
peroneus longus
peroneus brevis
tibia
tibialis posterior
flexor digitorum longus
posterior tibial artery
tibial nerveflexor hallucis longus
medial malleolus
tibialis anterior
flexor hallucis longus
medial plantar nerve
medial plantar artery
lateral plantar artery
lateral plantar nerve
abductor hallucisflexor digitorum brevis
medial calcanealnerve and artery
tendo calcaneus
flexor retinaculum
A
B
Figure 5-10 Structures pa ssing be hind the lateral ma lleolus (A) and the m edial malleolus (B). Notethe p osition o f the retinacula.
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CHAPTER5 Lower Limb 171
INTERCUNEIFORM AND CUNEOCUBOID JOINTS
Intercuneiform and cuneocubo id joints are synovial gliding
join ts. The bon es are con nec ted by dorsal, plan tar, an d
interosseous ligaments.
TARSOMETATARSAL AND INTERMETATARSAL JOINTS
Tarsometatarsal and intermetatarsal joints are synovial glid-
ing joints. The b ones are connec ted by dorsal, plantar, and
interosseous ligaments.
METATARSOPHALANGEAL AND INTERPHALANGEAL
JOINTS
Metatarsopha langeal and interphalangeal joints are similar
to those of the hand ( see p. 123 and 124). Abduction an d ad-
duction of the toes, which are performed by the interossei
muscles, are small in amount and occur from the midline
of the second digit (and no t the third digit, as in the hand) .
MUSCLES OF THE LOWER LIMB
Gluteal Region
The gluteal region is bounded superiorly by the iliac crest
and inferiorly by the fold of the buttock (Fig. 5-11). This re-
gion consists largely of the gluteal muscles and a thick layer
of superficial fascia.
The m uscles of the gluteal region are described in Table
5-1.
Sacrotuberous Ligament
The sacrotuberous ligamen t conn ects the p osteroinferior il-
iac spine, the lateral part of the sacrum, and the coccyx to
the ischial tuberosity (Fig. 5-11).
Sacrospinous Ligament
The sacrospinous ligament connects the lateral part of the
sacrum and the coccyx to the spine of the ischium (Fig. 5-
11).
IMPORTANT FORAMINA
Greater Scia tic Foramen
The greater sciatic foramen is formed by the c onversion of
the greater sciatic notch of the hip bone into a foramen
by the presence of the sac rotube rous an d th e sacrospinous
ligaments.
The following structures pass through the foramen:
• Piriformis muscle.• Sciatic nerve.
• Posterior cutaneou s nerve o f the thigh.
• Superior and inferior gluteal nerves.
• Nerves to obturator internus and q uadratus femoris
muscles.
• Pudendal nerve.
• Superior and inferior gluteal arteries and veins.
• Internal puden dal artery and vein.
Lesser Sciatic Foramen
The lesser sciatic foramen is formed by the conversion of
the lesser sciatic notch of the hip bo ne into a foramen by
the presence of the sacrotuberous and the sacrospinousligaments.
The following structures pass through the foramen:
• Tendo n of the ob turator internus muscle.
• Nerve to the o bturator internus muscle.
• Pudendal nerve.
• Internal puden dal artery and vein.
Thigh
The muscles of the anterior fascial compartment (Fig. 5-12)
are d escribed in Table 5-2. The muscles of the med ial fascial
compartmen t are described in Table 5-3, and the muscles of
the p osterior fascial compa rtment ( Fig. 5-13) are d escribedin Tab le 5-4.
DEEP FASCIA OF THE THIGH (FASCIA LATA)
The deep fascia encloses the thigh as a trouser leg would.
The upper end is attached to the pelvis and its associated
ligaments.
ILIOTIBIAL TRACT
The iliotibial tract is a thickening of the fascia lata on its lat-
eral side. It is attached ab ove to the iliac tubercle and b elow
GLUTEUS MAXIMUS ANDINTRAMUSCULAR INJECTIONS
The great thickness of the gluteus maximus muscle
makes it ideal for intramuscular injections. To avoid
injury to the underlying sciatic nerve, the injection
should be given well forward on the upper outer
quadrant of the b uttock.
CLINICAL NOTES
FASCIA
Superficial Fascia
The superficial fascia is thick (especially in women) and isimpregnated with large q uan tities of fat.
Deep Fascia
The d eep fascia is continuous below with the fascia lata of the
thigh, and it splits to enclose the gluteus ma ximus muscle.
IMPORTANT LIGAMENTS
The sac rotuberou s and the sacrospinous ligaments stabilize
the sacrum and prevent its rotation by the weight of the
vertebral column.
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172 CHAPTER5 Lower Limb
posterior superior iliac spine
sacrotuberous ligament
superior gluteal artery
inferior gluteal arteryand nerve
spine of ischium
nerve toobturator internus
pudendal nervesacrospinous ligamentinternal pudendal artery
coccyx
ischiorectal fossa
anus
fat
semimembranosus
gracilis
nerve to hamstrings
adductor magnus
semitendinosus biceps femoris
gluteus maximus
sciatic nerve
iliotibial tract
adductor magnus
quadratus femoris
posterior cutaneous nerve
of thigh
greater trochanter
gemellus superior
piriformis
superior gluteal nerve
tensor fasciae latae
gluteus minimus
superior gluteal artery
gluteus medius
iliac crest
gemellus inferior
oburator internus
Figure 5-11 Structures of the right gluteal region. Note that the g reater pa rt of the gluteus m ax-imus and part of the gluteus med ius m uscles have be en remo ved.
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CHAPTER5 Lower Limb 173
Table 5-1 Muscles of the Gluteal Region of the Lower Limb
Muscle Origin Insertion Nerve Supply Action
Gluteus maximus Outer surface of the Iliotibial tract and Inferior gluteal nerve Extends and laterally
ilium, sacrum, gluteal tuberosity of rotates the thigh at the
coccyx, and the femur hip joint; it extends knee
sacrotuberous joint through the iliotibialligament tract
Gluteus medius Outer surface of the Greater trochanter of Superior gluteal Abducts the thigh at the hip
ilium the femur nerve joint; tilts the pelvis when
walking
Gluteus minimus Outer surface of the Greater trochanter of Superior gluteal Abducts the thigh at the hip
ilium the femur nerve joint; tilts the pelvis when
walking; anterior fibers
med ially rotate the thigh
Tensor fasciae latae Iliac crest Iliotibial tract Superior gluteal Assists the gluteus maximus
nerve in extending
the knee joint
Piriformis Anterior surface of the Greater trochanter of First and second Laterally rotates the thigh at
sacrum the femur sacral nerves the hip joint
Ob tu ra tor in te rn us Inn er su rfa ce o f th e Gre ate r tro ch ante r of Sa cra l p le xus La te ra lly rota te s the th igh a t
obturator membrane the femur the hip jointGemellus superior Spine of the ischium Greater trochanter of Sacral plexus Laterally rotates the thigh at
the femur the hip joint
Gemellus inferior Ischial tuberosity Greater trochanter of Sacral plexus Laterally rotates the thigh at
the femur the hip joint
Quadratus femoris Ischial tuberosity Quadrate tubercle on the Sacral plexus Laterally rotates the thigh at
upper end of the femur the hip joint
to the lateral condyle of the tibia. It rece ives the insertion of
the greater part of the gluteus maximus and the tensor
fasciae latae m uscles.
SAPHENOUS OPENING
The saphenous opening is a gap in the deep fascia in the
front of the thigh and just below the inguinal ligament. It al-
lows passage of the great saphenous vein, some small
branche s of the femoral ar tery, and lymp h vessels. The
opening is filled with loose connective tissue called the
cribriform fascia.
FASCIAL COMPARTMENTS OF THE THIGH
Three fascial septa pass from the inner aspect of the deep
fascial sheath of the thigh to the linea aspera of the femur.
By this means, the thigh is divided into three co mpa rtments,
with each having muscles, nerves, and arteries. The com-
pa rtme nts are as follows:
• Anterior with the femoral nerve.
• Medial (adduc tor) with the obturator nerve.
• Posterior with the sciatic nerve.
FEMORAL TRIANGLE
The femoral triangle is situated in the u pper part of the front
of the thigh. Its boundaries are as follows:
• Superiorly: The inguinal ligament.
• Laterally: The sartorius muscle.
• Medially: The adductor longus muscle.
The femoral triangle contains the terminal part of the
femoral nerve and its branches, the femoral sheath, the
femoral artery and its branches, the femoral vein and its
tributaries, and the inguinal lymph no des.
FEMORAL SHEATHThe femoral sheath is a downward protrusion from the ab-
domen into the thigh of the fascia transversalis and the fas-
cia iliaca. The sheath surrounds the femoral blood vessels
and lymph vessels for approximately 1 in. (2.5 cm) below
the inguinal ligament. As the femoral artery enters the
thigh benea th the inguinal ligament, it occupies the lateral
compartment of the sheath. The femoral vein occupies
the intermediate compartment, and the lymph vessels
(and usually one lymph node) occupy the most medial
compartment.
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174 CHAPTER5 Lower Limb
anterior superior iliac spine
lateral cutaneous nerve of thigh
sartorius
femoral nerve
lateral femoralcircumflex artery
intermediate cutaneous nerveof thigh
nerve to vastus medialis
vastus intermedius
vastus lateralis
vastus medialis
shaft of femur
iliotibial tract
rectus femoris
ligamentum patellae
saphenous nerve
saphenous nerve
femoral artery
gracilis
adductor magnus
adductor longus
medial cutaneous nerve of thigh
pectineus
spermatic cord
deep external pudendal artery
pubic tubercle
inguinal ligamentfemoral canal
femoral sheath
femoral vein
psoas
iliacus
profunda femoris artery
tensor fasciae latae
medial femoralcircumflex artery
femoral artery
Figure 5-12 Femora l triang le and the a dductor (subs artorial) cana l in the right lower limb.
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CHAPTER5 Lower Limb 175
Table 5-2 Muscles of the Anterior Fasc ial Compartment of the Thigh
Muscle Origin Insertion Nerve Supply Action
Sartorius Anterior superior Upper medial surface Femoral nerve Flexes, abducts, and laterally
iliac spine of the shaft of the tibia rotates the thigh at the hip
joint; flexes a nd media lly
rotates the leg at the knee joint
Iliacus Iliac fossa of the With psoas into the lesser Femoral nerve Flexes the thigh on the trunk; if
hip bone trochanter of the femur the thigh is fixed, it flexes the
trunk on the thigh ( as in
sitting up from lying down)
Psoas Twelfth thoracic With the iliacus into the Lumbar plexus Flexes the thigh on the trunk; if
vertebral body; lesser trochanter of the the thigh is fixed, it flexes the
transverse processes, femur trunk on the thigh (as in
bo die s, and sitting up from lying down )
intervertebral discs
of the five lumb ar
vertebae
Pectineus Superior ramus of Upper end of the shaft of Femoral nerve Flexes and adducts the thigh at
the pubis the femur the hip joint
Quadratus femorisRectus femoris Straight head; anterior Quadriceps tendon Femoral nerve Extends the leg at the knee
inferior iliac spine; into the patella joint; flexes the thigh at the
reflected head: ilium hip joint
above the
acetabulum
Vastus lateralis Upper e nd and shaft Quad rice ps te ndon Femoral n erve Exte nd s the leg at the knee joint
of the femur into the patella
Vastus med ialis Upper e nd and shaft Quad rice ps te ndon Femoral n erve Exte nd s the leg at the kn ee
of the femur into the patella joint
Vastus intermedius Shaft of femur Quadriceps tendon Femoral nerve Extends the leg at the knee
into the patella joint
Table 5-3 Muscles of the Medial Fascial Compartment of the Thigh
Muscle Origin Insertion Nerve Supply Action
Gracilis Inferior ramus of the Upper part of the shaft Obturator nerve Adducts the thigh at the hip
pubis and ram us of the of the tibia joint; flexes th e leg at the
ischium knee joint
Adductor longus Body of the pubis Posterior surface of the Obturator nerve Adducts the thigh at the hip
shaft of the femur joint, assists in lateral
rotation
Adductor brevis Inferior ramus of the Posterior surface of the Obturator nerve Adducts the thigh at the hip
pubis sha ft of the fem ur joint, assists in lateral
rotationAd duc to r ma gn us In fe rio r ra mu s o f th e Po ste rio r su rfa ce o f th e Ob tu ra to r n erve Ad du cts th e thigh a t the h ip
pubis, ramus of the sha ft of the fem ur, ad du cto r pa rt; joint, assists in lateral
ischium, and ischial adductor tubercle sciatic nerve: rotation,
tuberosity of the femur hamstring part hamstring part
extend s the thigh at the
hip joint
Obturator externus Outer surface of the Greater trochanter Obturator nerve Laterally rotates the thigh at
obturator of the femur the hip joint
membrane
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176 CHAPTER5 Lower Limb
gluteus maximus
ischial spine
sacrotuberous ligament
ischial tuberosity
adductor magnus
(hamstring part)
semimembranosus
semitendinosus
gracilis
tibial nerve
semimembranosus
popliteus
oblique popliteal ligament
common peroneal nerve
biceps femoris(long head)
gluteus maximus
sciatic nerve
nerve to hamstrings
adductor magnus
qaudratus femoris
greater trochanter
gemellus inferior
obturator internus
gemellus superior
piriformis
gluteus minimus
gluteus medius
iliac crest
Figure 5-13 Structures of the p osterior aspe ct of the right thigh.
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CHAPTER5 Lower Limb 177
FEMORAL CANALThe femoral canal is the small, medial compartment of the
femoral sheath occupied by the lymphatics. It is approxi-
mately 0.5 in. (1.3 cm) in len gth. It is also a poten tially weak
area in the wall of the abdomen; a protrusion of peritoneum
could be forced down the femoral canal to form a femoral
hernia.
FEMORAL RING
The femoral ring is the up per op ening of the femoral canal.
It is filled by a plug of extra pe ritonea l fat ca lled the femoral
septum.
Important Relations
• Anteriorly: Inguinal ligament.
• Posteriorly: Superior ramus of the pubis and the
pe ctinea l ligament.
• Laterally: Femoral vein.
• Medially: Lacu nar ligame nt (an extension of the inguinal
ligament; see p age 39).
ADDUCTOR (SUBSARTORIAL) CANALThe adductor cana l is an intermuscular cleft on the medial as-
pect of the midd le third of the thigh beneath the sartorius mus-
cle. The posterior wall is formed by the adductor magnus
muscle, the lateral wall by the vastus medialis, and the an tero-
med ial wall by the sartorius muscle and fascia. The cana l con-
tains the femoral artery and vein, the deep lymph vessels, the
saphenous nerve, and the nerve to the vastus med ialis muscle.
Knee Region
POPLITEAL FOSSA
The popliteal fossa is a diamond-shaped, intermuscular
space at the back of the knee (Fig. 5-14). It contains the
po pliteal vessels, the sma ll sap he no us vein , the co mmon
peronea l and tibia l nerves, the poste rior cu taneo us ne rve of
the thigh, con nec tive tissue, and lymph nodes.
BOUNDARIES
• Laterally:The b iceps femo ris muscle above and the lateralhead of the gastrocnemius and plantaris muscles below.
• Medially: The semimembranosus and semitendinosusmuscles above and the med ial head of the gastrocnemius
muscle below.
Leg
The muscles of the anterior fascial compartment (Fig. 5-9)are described in Table 5-5. The muscles of the lateral fascial
compartment (Fig. 5-9) a re de scribed in Table 5-6, and the
muscles of the posterior fascial compartment (Fig. 5-15) are
described in Table 5-7. The m uscle on the dorsum of the foot
is described in Table 5-8.
FASCIAL COMPARTMENTS OF THE LEG
The deep fascia surrounds the leg and is continuous above
with the dee p fascia of the thigh. It is attache d to the anterior
and the medial borders of the tibia, and two intermuscular
septa pass from its deep aspect to be attached to the fibula.
Together with the interosseous membrane, the septa divide
Table 5-4 Muscles of the Posterior Fascial Compartment of the Thigh
Muscle Origin Insertion Nerve Supply Action
Biceps femoris Long head: ischial Head of the fibula Sciatic nerve (long Flexes and laterally rotates
tuberosity; short head: tibial nerve; the leg at the knee joint;
head: shaft of the short head: common the long head also
femur peroneal nerve) extends the thigh at thehip joint
Semiten dinosus Ischial tub erosity Uppe r part of the med ia l Scia tic ne rve (tibia l Flexes a nd media lly rotates
surface of the shaft of portion) the leg at the knee joint
the tibial and extends the thigh at
the hip joint
Semimemb ra nosus Ischial tub erosity Med ial c ond yle of the Scia tic ne rve (tibia l Flexes a nd media lly rotates
tibia, forms the oblique portion) the leg at the knee joint
po plitea l ligament an d exten ds the th igh at
the hip joint
Ad du ctor m agn us Isc hia l tu be ro sity Ad du ctor tu be rc le of the Sc ia tic n erve ( tib ia l Exte nd s th e thigh a t the h ip
(hamstring portion) femur portion) joint
FEMORAL HERNIA
• A protrusion o f the a bdominal parietal peritoneum
down through the femoral canal to form the hernial
sac.
• More common in women than in men.
• The n eck of the hernial sac lies below and lateral to
the pubic tube rcle.
• The ne ck of the hernial sac lies at the femoral ring
and is related anteriorly to the inguinal ligament,
posteriorly to the pectinea l ligament, latera lly to the
femoral vein, and med ially to the sha rp, free ed ge of
the lacunar ligament.
CLINICAL NOTES
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178 CHAPTER5 Lower Limb
Figure 5-14 Boundaries an d conten ts of the right pop liteal fossa .
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CHAPTER5 Lower Limb 179
Table 5-5 Muscles of the Anterior Fascial Compartment of the Leg
Muscle Origin Insertion Nerve Supply Actiona
Tib ia lis a nte rior Sh aft of the tib ia a nd the Me dia l c un eifo rm a nd De ep p eron ea l n erve Exte nd s th e fo ot a t th e
interosseous base of the first ankle joint, inverts the
membrane metatarsal bone foot at the subtalar and
the transverse tarsal joints, and ho lds up the
med ial longitudinal
arch o f the foot
Exte nso r d igito ru m Sh aft of the fib ula an d Exte nso r e xpa nsio n of De ep p ero ne al ne rve Exte nd s th e to es a nd
longus the interosseous the lateral four toes dorsiflexes the foot at
membrane the ankle joint
Peroneus tertius Shaft of the fibula and Base of the fifth Deep peroneal nerve Dorsiflexes the foot at the
the interosseous metatarsal bone ankle joint and everts
membrane foot at the subtalar and
the transverse tarsal
joints
Exte nso r h alluc is lo ngus Sh aft of the fib ula an d Ba se of th e d ista l De ep pe ro ne al ne rve Exte nd s th e b ig to e,
the interosseous phalanx of the dorsiflexes the foot at
membrane great toe the ankle joint, and
inverts the foot at thesubtalar and the
transverse tarsal joints
aExtens ion (or dors iflexion) of the ankle is the move ment o f the foot away from the grou nd.
Table 5-6 Muscles of the Lateral Fascial Compartment of the Leg
Muscle Origin Insertion Nerve Supply Action
Pe ro ne us lo ngu s Sh aft of fib ula Ba se of first me ta ta rsa l Su pe rfic ia l p ero ne al Pla nta r fle xe s th e fo ot a t th e a nkle
bo ne an d th e med ial ne rve joint, everts the foot a t the
cuneiform subtalar and the transversetarsal joints, holds up the lateral
longitudina l arch o f the foot,
and supports the transverse arch
Pe roneus b re vis Shaft of the fib ula Base of the fifth Superfic ial perone al Plantar flexe s the foot a t the ankle
metatarsal bone nerve joint, everts the foot at the
subtalar and the transverse
tarsal joints, and ho lds up the
lateral longitudinal arch o f the
foot
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180 CHAPTER5 Lower Limb
Figure 5-15 Structures of the p osterior aspe ct of the right leg. A. The gastrocnemius muscle issho wn in full. B. Part of the gas trocnem ius m uscle has b een rem oved.
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CHAPTER5 Lower Limb 181
Table 5-7 Muscles of the Posterior Fasc ial Compartment of the Leg
Muscle Origin Insertion Nerve Supply Action
Superficial Grou p
Gastrocnemius Medial and lateral Via tendo calcaneus Tibial nerve Plantar flexes the foot at the
condyles of the femur (Achilles tendon) ankle joint, flexes the knee
into the calcaneum jointPlantaris Lateral supracondylar Calcaneum Tibial nerve Plantar flexes the foot at the
ridge of the femur ankle joint, flexes the knee
joint
Soleus Shafts of the tibia Via tendo calcaneus Tibial nerve Together with the
and the fibula (Achilles tendon) gastrocnemius and
into the calcaneum the plantaris, it is a powerful
flexor of the ankle joint;
pro vides the ma in
pro pu lsive force in walking
and running
Deep Grou p
Popliteus Lateral condyle of Shaft of the tibia Tibial nerve Flexes the leg at the knee joint;
the femur unlocks the knee joint by
laterally rotating the femur
on the tibia, thus slackeningthe ligaments of the joint
Flexor digitorum Shaft of the tibia Bases of the distal Tibial nerve Flexes the distal phalanges
longus phalanges of of the lateral four toes,
the lateral four toes plantar flexes the foot, and
supports the medial and the
lateral longitudinal arche s
of the foot
Flexor hallucis Shaft of the fibula Base of the distal Tibial nerve Flexes the distal phalanx of the
longus phalanx of the big toe big toe, plantar flexes the
foot at the ankle joint, and
supports the medial
longitudina l arch o f the foot
Tibialis posterior Shafts of the tibia Tuberosity of the Tibial nerve Plantar flexes the foot at the
and the fibula and navicular and other ankle joint, inverts the foot
the interosseous neighboring bones at the subtalar and themembrane transverse tarsal joints, and
supports the medial
longitudinal a rch o f the foot
Table 5-8 Muscle on the Dorsum of the Foot
Muscle Origin Insertion Nerve Supply Action
Exte nso r d igito ru m Ca lc an eu m By fo ur te nd on s in to th e p roxima l De ep pe ro ne al n erve Exte nd s th e first, se co nd ,
bre vis phalanx o f the b ig toe (sometimes third , an d fou rth toescalled the extensor ha llucis brevis)
and long extensor tendons to the
second, third, and fourth toes
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182 CHAPTER5 Lower Limb
the leg into three compartments, with each having its own
muscles, blood supply, and nerve supply. The compart-
ments are as follows:
• Anterior with the deep peroneal nerve.
• Lateral (peroneal) with the superficial peroneal nerve.
• Posterior with the tibial nerve.
INTEROSSEOUS MEMBRANE
The interosseous membrane binds the tibia and the fibula
together and p rovides attachmen t for the muscles.
Ankle
RETINACULA
The retinacula are thickenings of the deep fascia that keep
the long tendons around the ankle joint in position and act
as pulleys (Fig. 5-10).
Superior Extensor Retinaculum
The superior extensor retinaculum is attached to the distal
end s of the a nterior borders of the fibula and the tibia (Fig.
5-9).
Inferior Extensor Retinaculum
The inferior extensor retinaculum is a Y-shaped band
located in front of the ankle joint (Fig. 5-9).
Flexor Retinaculum
The flexor retinaculum extends from the medial malleolus
to the med ial surface of the ca lcaneum (Fig. 5-10). It binds
the deep muscles of the back of the leg to the back of themed ial malleolus as they pass forward to en ter the sole.
Superior Peroneal Retinaculum
The superior peroneal retinaculum connects the lateral
malleolus to the lateral surface of the calcane um (Fig. 5-10).
It binds the tendo ns of the peroneus longus and brevis mus-
cles to the ba ck of the lateral malleolus.
Inferior Peroneal Retinaculum
The inferior peroneal retinaculum binds the ten don s of the
pe roneus longus and b revis musc les to the latera l side o f the
calcaneum (Fig. 5-10).
Sole of Foot
The muscles of the sole (Figs. 5-16 and 5-17) are usua lly de -
scribed in four layers (from inferior to superior). These
muscles are listed in Table 5-9.
DEEP FASCIA
Plantar Aponeurosis
The plantar aponeurosis is a triangular thickening of the
deep fascia that protects the underlying nerves, blood ves-
sels, and muscles. Its apex is attached to the me dial and the
lateral tubercles of the calcaneum. The base of the aponeu-
rosis divides into five slips that pass into the toes.
ARCHES OF THE FOOT
There a re three bon y arches in the sole.
Medial Longitudinal Arch
The medial longitudinal arch is formed by the calcaneum,
the talus, the navicular bone, three cuneiform bones,
and the first (medial) three metatarsal bones.
• Muscular support: Medial part of the flexor digitorum
bre vis, a bd uc tor ha llucis, flexor ha llucis longus, me dia l
pa rt of the flexor digitoru m longus, flexor hallucis b revis,
tibialis anterior, and ten dinous e xtensions of the insertion
of the tibialis posterior.
• Ligamentous support: Plantar and dorsal ligaments, in-
cluding the important calcaneonavicular (spring) liga-
men t, the medial ligament of the ankle joint, and the p lan-
tar aponeurosis.
Lateral Longitudina l Arch
The lateral longitudinal arch is formed by the calcaneum,
the cub oid, and the fourth and the fifth metatarsal bones.
• Muscular support: Abductor digiti minimi, lateral part of
the flexor digitorum longus and brevis, and peroneus
longus and brevis.
• Ligamentous support: Long and short plantar ligame nts
and plantar aponeurosis.
Transverse ArchThe transverse arch is formed by the b ases of the me tatarsal
bon es, the cu boid , an d the three cun eifo rm bon es. The
wedge shape of the cuneiform bones and the bases of
the metatarsal bone s play a large role in the support of the
transverse arch .
• Muscular support: Dorsal interossei, transverse he ad of
the adductor hallucis, and peroneus longus and brevis.
• Ligamen tous support: Deep transverse ligaments and
very strong plantar ligaments.
ARTERIES OF THE LOWER LIMB
Femoral Artery
The femo ral artery is a con tinuation o f the external iliac a rtery
(Fig. 5-18). It begins behind the inguinal ligament, where it
lies midway between the an terior superior iliac spine an d the
symphysis pubis (the site for taking a femoral pulse). The
artery descends through the femoral triangle (Fig. 5-12) and
the adduc tor canal, and it leaves the front of the thigh by pass-
ing through the opening in the add uctor magnus and then e n-
tering the popliteal space as the po pliteal artery (Fig. 5-14).
In the femora l triangle, the artery is related latera lly to the
femo ral nerve and med ially, in the upper part of its course,
to the femo ral vein and the femoral cana l.
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CHAPTER5 Lower Limb 183
third lumbrical
fourth lumbrical
digital nerve
plantar arch
deep branch of lateral plantar nerve
lateral plantar nerve
lateral plantar artery
flexor digitorum
accessorius
(quadratus plantae)
medial plantar artery
flexor digitorum longus
medial plantar nerve
flexor hallucis longus
digital nerves
second lumbrical
first lumbrical
Figure 5-16 Secon d layer of the plantar m uscles of the right foot. Note the m edial and the lateral
p lanta r a rt erie s and ne rves .
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184 CHAPTER5 Lower Limb
184
fibrous flexor sheath of second toe
digital synovial sheaths
flexor digitorum longus
synovial sheathof peroneus brevis
synovial sheathof peroneus longus
synovial sheathof flexor hallucis longus
tibialis posterior
synovial sheathof flexor digitorum
longus
flexor hallucislongus
Figure 5-17 Synovial she aths of tendo ns on the so le of the right foot.
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Table 5-9 Muscles of the Sole
Muscle Origin Insertion Nerve Supply Action
First Laye r
Ab ductor Medial tub erc le of the Me dia l side of the ba se Media l plantar nerve Fle xes and abd uc ts the big toe ,
hallucis calcaneum, flexor of the proximal phalanx supports the medial longitudinal
retinaculum of the big toe arch
Flexor d igito rum Medial tuberc le of the Media l phalanx of the Media l p lan tar nerve Flexes the la tera l four toes,
bre vis ca lcane um four la tera l toes sup ports the media l and th e
lateral longitudinal arche sAb du cto r d igiti Me dia l a nd la te ra l La te ra l sid e o f th e b ase La te ra l p la nta r n erve Fle xe s a nd ab duc ts the fifth to e,
minimi tubercles of the of the proximal phalanx supports the lateral longitudinal
calcaneum of the fifth toe arch
Second Layer
Fle xor d igitoru m Me dia l a nd la te ra l Te nd on of th e fle xo r La te ra l p la nta r n erve Assists th e lon g fle xo r te nd on s
accessorius sides of the digitorum longus to flex the lateral four toes
calcaneum
Flexor digitorum Shaft of the tibia Base of the distal phalanx Tibial nerve Flexes the distal phalanges of
longus of the lateral four toes the lateral four toes, plantar
flexes the foot, and supp orts
the longitudinal arches
Lumbricals (4) Tendons of the flexor Dorsal extensor expansion First lumbrical: medial Extends the toes at the
digitorum longus of the lateral four toes plantar nerve; interphalangeal joints
remainder: deep
bra nch of the la tera l planta r ne rve
Flexor hallucis Shaft of the fibula Base of the distal phalanx Tibial nerve Flexes the distal phalanx of the big
longus of the big toe toe, plantar flexes the foot, and
supports the med ial longitudinal
arch
Third Layer
Fle xor ha llu cis Cub oid a nd la te ra l Me dia l a nd la te ra l sid es Me dia l p la nta r n erve Fle xe s th e me ta ta rso ph ala nge al
bre vis cu ne iform b on es; of the ba se o f the joint o f the b ig toe, supports
tibialis posterior proximal phalanx of the medial longitudinal arch
insertion the big toe
Addu ctor hallucis
Ob liq ue he ad Ba se s of th e se co nd , La te ra l sid e o f th e b ase De ep bra nc h o f th e Fle xe s th e b ig toe , sup po rts the
third, and fourth of the proximal pha la nx la te ra l plantar nerve transverse arc h
metatarsal bones of the big toe
Transverse Plantar ligaments Lateral side of the base Deep branch of the Flexes the big toe, supports the
head of the proximal phalanx lateral plantar nerve transverse arch
of the big toe
Flexor digiti Base of the fifth Lateral side of the base Lateral plantar nerve Flexes the little toe
minimi brevis metatarsal bone of the proximal phalanx
of the little toe
Fourth Layer
Interossei
Dorsa l ( 4) Ad ja ce nt sid es o f th e Ba se s o f th e p ha la nge s La te ra l p la nta r n erve Ab du ct th e to es from th e se co nd
metatarsal bones and the dorsal expansion toe, flex the metatarsophalangeal
of the corresponding toes joints, and extend the
interphalangea l joints
Planta r (3) In fe rio r su rfaces o f th e Bases o f th e p ha langes La te ra l p lanta r n erve Ad du ct th e to es to th e seco nd to e,
third, fourth, and and the dorsal expansion flex the metatarsophalangeal
fifth metatarsal of the corresponding toes joints, and extend the
bo nes interph alangeal joints
Peroneus longus Shaft o f the fibula Base of the first meta tarsa l Superfic ia l peroneal Plantar flexes the foot a t the ankle
bo ne an d th e med ial ne rve joint, everts the foot a t the
cuneiform subtalar and the transverse tarsal
joints, and ho lds up the la tera l
longitudinal and the transverse
arche s of the foot
Tib ia lis p oste rio r Sh afts o f th e tib ia an d Tu be ro sity o f th e n avicula r Tib ia l n erve Planta r flexes th e fo ot a t th e ankle
the fibula and the and other neighboring joint, inverts the foot at the
interosseous bones subtalar and the transverse tarsal
membrane joints, and supports the medial
longitudinal a rch o f the foot
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186 CHAPTER5 Lower Limb
inguinal ligament
profunda artery
lateral femoralcircumflex
artery
anterior tibial
artery
dorsalis pedis artery
arcuate artery
peroneal artery
posterior tibial artery
popliteal artery
perforating branchesof profunda femoris
artery
femoral artery
medial femoralcircumflex artery
femoral artery
external iliac artery
Figure 5-18Major arteries of the lower limb .
BRANCHES
• Superficial circumflex iliac artery, which a rises just be-
low the inguinal ligame nt and runs laterally toward the an-
terior superior iliac spine.
• Superficial epigas tric artery, which a rises just below the
inguinal ligame nt and runs upward to the abd omina l wall.
• Superficial e xternal puden dal artery.
• Deep external pudendal artery and the superficial ex-
ternal pudendal artery arise just below the inguinal liga-
ment and run medially to supply the skin of the scrotum
(or labium majus).
• Profunda femoris artery, which is a large branch that
arises from the femo ral artery approximately 1.5 in. (4 c m)
be low the inguin al ligament ( Fig. 5-12). It sup plies struc-
tures in the anterior, medial, and posterior fascial com-
pa rtme nts of the thigh via the following branche s: medial
and lateral femoral circumflex arteries and four per-
forating arteries.
• Descend ing genicular artery.
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TROCHANTERIC ANASTOMOSIS
The trocha nteric anastomo sis provides the ma in blood sup-
ply to the head of the femur (in ad ults) via the following
arteries:
• Supe rior gluteal artery.
• Inferior gluteal artery.• Medial femoral circumflex artery.
• Lateral femoral circumflex artery.
CRUCIATE ANASTOMOSIS
Together with the trochanteric anastomosis, the cruciate
anastomosis provides the important connection between
the internal iliac and the femoral arteries. The following
arteries are involved:
• Inferior gluteal artery.
• Medial femoral circumflex artery.
• Lateral femoral circumflex artery.
• First perforating artery, which is a branch of the profundaartery.
Popliteal Artery
The popliteal artery (Fig. 5-18) is a continuation of the
femo ral artery. It extends from the op ening in the a ddu ctor
magnus to the lower border of the pop liteus muscle, where
it divides into the anterior and the posterior tibial arteries. It
is deeply placed in the popliteal fossa and lies close to the
posterior surface o f the femur and the kne e joint.
BRANCHES
• Muscular branches.
• Articular branches to the knee joint.
• Terminal branches: Anterior and posterior tibial
arteries.
ANASTOMOSIS AROUND THE KNEE JOINT
The a rteries involved in ana stomosis aroun d the knee joint
are as follows:
• The descending genicu lar artery from the femoral artery.
• The lateral femoral circumflex artery from the profunda
femoris.
• The articular branches from the pop liteal artery.
• The b ranche s from the anterior and the po sterior tibial
arteries.
Anterior Tibial Artery
The anterior tibial artery arises at the bifurcation of the
popliteal artery in the pop liteal fossa ( Fig. 5-18). It passes for-
ward between the tibia and the fibula through the upper
pa rt of the inte rosseus me mb rane an d en ters the an terior
compartment of the leg. It then d escends with the deep p er-
oneal nerve to the front of the ankle joint, where it becomes
the dorsalis pedis artery (Fig. 5-9).
At the ankle, the anterior tibial artery lies midway be-
tween the malleoli and has the tendon of the extensor hal-
lucis longus muscle on its med ial side and the tendon s of ex-
tensor digitorum longus muscle o n its lateral side (the site
for taking an anterior tibial pulse).
BRANCHES
• Muscular branches.
• Anastomotic branches, which anastomose with
branch es of other arteries aroun d the knee an d an kle
joints.
Dorsalis Pedis Artery
The dorsalis pedis artery begins in front of the ankle joint
midway between the malleoli and is a continuation of the
anterior tibial artery (Figs. 5-9 and 5-18). The dorsalis pedis
artery end s by entering the sole through the proximal part of
the space between the first and second metatarsal bones.Having passed between the two he ads o f the first dorsal in-
terosseous muscle, it joins the lateral plantar artery and
completes the plantar a rch (Fig. 5-16).
At first, the a rtery is supe rficial, having the tend ons of the
extensor digitorum longus mu scle on its lateral side an d the
tendon of the extensor hallucis longus muscle on its med ial
side (the site for taking a dorsalis pedis pulse ).
BRANCHES
• Lateral tarsal artery, which supplies the dorsum of the
foot.
• Arcuate artery, which runs laterally across the bases of
the me tatarsal bones and gives off branc hes to the toes.• First dorsal metatarsal artery, which supplies both
sides o f the big toe.
Posterior Tibial Artery
The posterior tibial artery arises at the bifurcation of the
popliteal artery in the po plitea l fossa ( Fig. 5-18). It descen ds
in the posterior compartment of the leg and is accompanied
by the tibia l nerve. The artery terminates beh ind the me dia l
malleolus by dividing into the med ial and the lateral plantar
arteries. The pulse may be felt midway between the med ial
malleolus and the hee l.
BRANCHES
• Peroneal artery, which is a large artery that arises close
to the origin of the posterior tibial artery. It descends in
close association with the flexor hallucis longus muscle
to the region o f the a nkle, and it gives off muscular
branches, a nutrient artery to the fibula, and anasto-
motic branches around the ankle joint.
• Muscular branches.
• Nutrient artery to the tibia.
• Anastomotic branche s around the ankle joint.
• Medial and lateral plantar arteries.
CHAPTER5 Lower Limb 187
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Medial Plantar Artery
The medial plantar artery is the smaller of the terminal
branches of the posterior tibial artery (Fig. 5-16). It runs forward
along the medial border of the foot with the medial plantar
nerve, and it gives off many muscular and cutaneous branches.
Lateral Plantar Artery
The lateral plantar artery is the larger of the terminal
branc hes of the posterior tibia l arte ry (Fig. 5-16). It run s for-
ward dee p to the abd uctor hallucis and the flexor digitorum
brevis musc les with th e latera l plan tar nerve, and it end s by
curving medially to form the plantar arch through anasto-
mosis with the dorsalis pedis artery. The plantar arch gives
off perforating an d metatarsal arteries; the metatarsal arter-
ies give rise to digital arteries.
VEINS OF THE LOWER LIMB
The superficial veins lie in the superficial fascia and are of
great clinical importance. The deep veins acc ompan y the
main arteries.
Superficial Veins
DORSAL VENOUS NETWORK
The dorsal venous network lies on the dorsum of the foot
(Fig. 5-19). It is drained on the medial side by the great
saphenous vein and on the lateral side by the small saphe-
nous vein.
GREAT SAPHENOUS VEIN
The great saphenous vein arises from the med ial side of the
dorsal venous network of the foot ( Fig. 5-19), and it ascend s
directly in front of the medial malleolus. Accompanied by
the sapheno us nerve, it ascends the leg in the superficial fas-
cia, passes beh ind the knee, and c urves forward around the
medial side of the thigh. It then passes through the saphe-
nous opening in the deep fascia and joins the femoral vein
approximately 1.5 in. (4 cm) b elow and lateral to the pu bic
tubercle. The great saphenous vein possess numerous
valves, and it is connected to the small saphenous vein by
bra nc hes tha t pass be hind the kne e. Several perforating
veins conne ct the great saphenous vein with the de ep veins
along the me dial side of the c alf.
The great saphenous vein receives the following small
tributaries near its termination:
• Th e superficial circumflex iliac ve in.
• The superficial epigastric ve in.
• Th e superficial external pudendal vein.
188 CHAPTER5 Lower Limb
COMPRESSION OF ARTERIES OF THE
LOWER LIMB
Medica l personal should know the precise position of
the main arteries within the lower limb.
• Femo ral artery: This enters the thigh behind the in-
guinal ligament at a point midway between the an-
terior superior iliac spine an d the symphysis pub is.
• Popliteal artery: This artery can be felt by gentle
pa lpation in the de pths of the popliteal space , pro-
vided that the deep fascia is fully relaxed by pas-
sively flexing the knee joint.
• Dorsalis pe dis artery: This artery lies between the
tendons of the extensor hallucis longus and the ex-tensor digitorum longus, midway between the me-
dial and lateral malleoli on the front of the a nkle.
• Posterior tibial artery: This artery passes behind
the medial malleolus, beneath the flexor retinacu-
lum, and lies between the tendons of flexor digito-
rum longus and the flexor hallucis longus. The
pulsation s of the a rtery ca n be felt midway between
the medial malleolus and the heel.
CLINICAL NOTES
LIGATION OF ARTERIES OF THE LOWER LIMB
Sudd en occ lusion of the femoral artery by ligature is
usually followed by gangrene. However, gradual oc-
clusion , such as occurs in atherosc lerosis, is less likely
to be followed by necrosis because the collateral
blood vessels have time to dilate fully. The co llateral
circulation for the proximal part of the femoral artery
is through the cruciate and troch anteric anastomoses;
for the femoral artery in the adductor canal, it is
through the perforating branches of the profunda
femoris artery and the articular and muscular
bra nches of the femoral and popliteal arteries.
CLINICAL NOTES
THE CLINICAL IMPORTANCE OF THE GREATSAPHENOUS VEIN
• Blood transfusions: The constant position of the
great saphenous vein in front of the medial malleo-
lus should be remembered for patients requiring
emergency blood transfusion.• Bypass operations: The insertion of a graft of a por-
tion of the great saphenous vein can be used in oc-
clusive coronary artery disease and also to bypass
obstructions of the brachial or femoral arteries.
CLINICAL NOTES
SMALL SAPHENOUS VEIN
The small saphenous vein a rises from the lateral side o f the
dorsal venous network of the foot (Fig. 5-19). It ascends
behind the lateral malleolus in company with the sural
nerve, passes up the back of the leg, and pierces the deep
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CHAPTER5 Lower Limb 189
saphenous opening
femoral vein
femoral artery
great saphenous vein
accessory vein
dorsal venous arch
medial malleolus
smallsaphenous vein
great saphenous vein
superficial external pudendal vein
pubic tubercle
superficial epigastric vein
superficial circumflex iliac vein
popliteal vein
lateralmalleolus
perforating vein
muscle
superficialfascia
skin
saphenous veindeep fascia
"Venous pump"
venae comitantes
Figure 5-19 Sup erficial veins of the right lowe r limb . Note the imp ortance of the valved p erforatingveins in the “venou s pum p.”
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fascia to e nter the p opliteal fossa. It drains into the pop liteal
vein. The small saphenous vein communicates with the
deep veins and with the great saphenous vein.
The superficial veins of the lower limbs are common sites
for varicosities.
Deep Veins
VENAE COMITANTES
The deep veins accomp any the respective arteries as vena e
comitantes. The venae comitantes of the anterior and the
posterior tibia l a rteries un ite in the popliteal fossa to form
the po pliteal vein.
POPLITEAL VEIN
The popliteal vein is formed by the union of the venae comi-
tantes of the anterior and the p osterior tibial arteries (Fig. 5-
14). It end s by passing through the open ing in the ad duc tor
magnus muscle to become the femoral vein. The poplitealvein receives numerous tributaries, including the small
saphenous vein.
FEMORAL VEIN
The femoral vein is a continuation of the popliteal vein at
the ope ning in the addu ctor magnus muscle. It ascends
through the adductor canal and the femoral triangle and is
accomp anied by the femoral artery. In the femoral sheath, it
lies on the me dial side of the femoral artery and on the lat-
eral side to the femoral canal. As it ascends behind the in-
guinal ligament, it become s continuous with the external il-
iac vein. The femoral vein receives the great saphe nous veinand the veins that correspond to branches of the femoral
artery.
LYMPHATIC DRAINAGE OF THELOWER LIMB
The superficial lymph vessels ascend the limb in the su-
pe rficia l fascia with th e superficial veins. The deep lymph
vessels lie deep to the deep fascia and follow the deep ar-
teries and veins. All the lymph vessels of the lowe r limb ulti-
mately drain into the dee p inguinal group of nodes that are
situated in the groin.
Superficial Inguinal Nodes
The superficial inguinal nodes lie in the superficial fascia
just be low the inguinal ligamen t and d rain into the de ep in-
guinal nodes. The superficial inguinal nodes may be
divided into a horizontal and a vertical group .
HORIZONTAL GROUP
The horizontal group receives lymph from the superficial
lymph vessels of the anterior abdominal wall below the
level of the umbilicus, the p erineum, the external genitalia
in both sexes (but not the testes), and the lower half of
the anal canal. It also receives lymph from the skin of the
bu ttocks.
VERTICAL GROUP
The vertical group lies alongside the terminal part of the
great saphenous vein and receives most of the superficial
lymph vessels of the lower limb (except from the bac k and
lateral side of the ca lf and the lateral side o f the foot, which
drain into the popliteal nodes).
Deep Inguinal Node s
The deep inguinal nod es are usually three in number and lie
along the me dial side of the femoral vein and in the femoral
canal. They receive all the lymph from the superficial in-
guinal nodes and the dee p structures of the lower limb . The
efferent lymph vessels pass upward through the femoral
canal into the abdominal cavity, and they drain into theexternal iliac nodes.
Popliteal Lymph Node s
Situated in the pop liteal fossa, the popliteal lymph node s re-
ceive the superficial lymph vessels that accompany the
small saphenous vein from the lateral side of the foot and
from the bac k and the lateral side of the calf. They also re-
ceive lymph from the deep structures of the leg below the
knee. The efferent vessels from the se nodes d rain upward to
the deep inguinal nodes.
NERVES OF THE LOWER LIMBFemoral Nerve
The femo ral nerve arises from the lumba r plexus (L2, 3, and
4). It enters the thigh behind the inguinal ligament, and it
lies lateral to the femoral vessels and the femoral shea th in
the femoral triangle (Fig. 5-12). It quickly terminates by di-
viding into the anterior and the posterior divisions.
BRANCHES OF THE FEMORAL NERVE IN THE THIGH
• Cutaneous branches: Medial cutaneous ne rve of the
thigh, which supplies the skin on the medial side of the
thigh. Intermediate cutaneous nerve of the thigh,
which supplies the skin on the anterior surface of thethigh. Saphenous nerve, which descends through the
femoral triangle and the adductor canal and crosses the
femoral artery. The nerve emerges on the medial side of
the knee joint between the tendo ns of the sartorius and the
gracilis muscles, and it accompanies the great saphe nous
vein down the med ial side of the leg and in front of the me-
dial malleolus. It passes along the medial border of the
foot a s far as the ball of the b ig toe.
• Muscular branches to the sartorius, the pectineus, and
the qua driceps femo ris muscles.
• Articular branches to the hip and knee joints.
190 CHAPTER5 Lower Limb
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The branches of the femoral nerve are summarized in
Figure 5-20. Dermatomal charts for the anterior and poste-
rior surfaces of the b ody are shown in Figures 2-3 and 2-4.
Obturator Nerve
The obturator nerve arises from the lumbar plexus (L2, 3,
and 4) and runs forward on the lateral wall of the pelvis to
reach the o bturator canal ( the uppe r part of the obturator foramen) . The obturator nerve divides into the an terior and
the posterior divisions.
BRANCHES OF THE OBTURATOR NERVE IN THE THIGH
The anterior division descends into the thigh anterior to
the obturator externus and the adductor brevis muscles.
• Muscular branches: Gracilis, adductor b revis, addu ctor
longus, and sometimes the pectineus muscles.
• Cutaneous branch: Skin on the med ial side of the thigh.
• Articular branch: Hip joint.
The posterior division descends through the ob turator
externus muscle and passes behind the adduc tor brevis and
in front of the ad duc tor magnus muscles.
• Muscular branches: Obturator externus, adductor mag-
nus (ad ductor part), and sometimes the add uctor brevis
muscles.
• Articular branch: Knee joint.
The branches of the obturator nerve are summarized inFigure 5-21. Dermatomal charts for the anterior and the pos-
terior surfaces o f the bo dy are shown in Figures 2-3 and 2-4.
Sciatic Nerve
The sciatic nerve arises from the sacral plexus (L4 and 5 and
S1, 2, and 3). It passes out of the pelvis and into the gluteal
region through the greater sciatic foramen (Fig. 5-11). The
nerve appears below the piriformis muscle and is covered
by the glute us ma ximus mu scle . It d esc en ds thro ugh the
gluteal region, and it enters the posterior compartment of