lucis longus lie laterally.
ANTERIOR OR EXTENSOR COMPARTMENT
Vascular supply The main body of tibialis anterior is supplied by a
The anterior compartment contains muscles that dorsiflex the ankle series of medial and anterior branches of the anterior tibial artery; the
when acting from above (see Fig. 83.2A, B; Fig. 83.6). When acting from branches may occur in two columns. There is a proximal accessory
below, they pull the body forwards on the fixed foot during walking. supply from the anterior tibial recurrent artery. The tendon is supplied
Two of the muscles, extensor digitorum longus and extensor hallucis by the anterior medial malleolar artery and network, dorsalis pedis
longus, also extend the toes, and two muscles, tibialis anterior and artery, medial tarsal arteries, and by the medial malleolar and calcaneal
fibularis tertius, have the additional actions of inversion and eversion, branches of the posterior tibial artery.
respectively.
Innervation Tibialis anterior is innervated by the deep fibular nerve,
Tibialis anterior
L4 and L5.
Attachments Tibialis anterior is a superficial muscle and is therefore
readily palpable lateral to the tibia. It arises from the lateral condyle Actions Tibialis anterior dorsiflexes and inverts the foot. It is most
and proximal onehalf to twothirds of the lateral surface of the tibial active when both movements are combined, as in walking. Its tendon
shaft; the adjoining anterior surface of the interosseous membrane; the can be seen through the skin lateral to the anterior border of the tibia
deep surface of the deep fascia; and the intermuscular septum between and can be traced downwards and medially across the front of the ankle
itself and extensor digitorum longus. The muscle descends vertically to the medial side of the foot. Tibialis anterior elevates the first meta
and ends in a tendon on its anterior surface in the lower third of the tarsal base and medial cuneiform, and rotates their dorsal aspects
leg. The tendon passes through the medial compartments of the supe laterally.
rior and inferior retinacula, inclines medially, and is inserted on to the The muscle is usually quiescent while standing, since the weight of


medial and inferior surfaces of the medial cuneiform and the adjoining the body acts through vertical lines that pass anterior to the ankle joints.
part of the base of the first metatarsal. Acting from below, it helps to counteract any tendency to overbalance


Muscles
1407
38
RETPAHC
backwards by flexing the leg forwards at the ankle. It has a role in sup
porting the medial part of the longitudinal arch of the foot; although
electromyographically detectable activity is minimal during standing, it
is manifest during any movement that increases the arch, such as toeoff Superior medial
in walking and running. genicular artery Superior lateral
genicular artery
Testing Tibialis anterior can be seen to act when the foot is dorsiflexed
against resistance. Dorsiflexion is best tested by asking the subject to
walk on their heels.
Extensor hallucis longus
Attachments Extensor hallucis longus lies between, and is partly
overlapped by, tibialis anterior and extensor digitorum longus (see Figs
Tibialis
83.6A, B). It arises from the middle half of the medial surface of the
anterior (cut)
fibula, medial to extensor digitorum longus, and from the adjacent Anterior tibial
recurrent artery
anterior surface of the interosseous membrane. Its fibres run distally
and end in a tendon that forms on the anterior border of the muscle.
The tendon passes deep to the superior extensor retinaculum and
through the inferior extensor retinaculum, crosses anterior to the ante
rior tibial vessels to lie on their medial side near the ankle, and is
inserted on to the dorsal aspect of the base of the distal phalanx of the
hallux. At the metatarsophalangeal joint, a thin prolongation from each
side of the tendon covers the dorsal surface of the joint. An expansion
from the medial side of the tendon to the base of the proximal phalanx
Anterior tibial artery
is usually present.
Extensor hallucis longus is sometimes united with extensor digit
orum longus and may send a slip to the second toe.
Relations The anterior tibial vessels and deep fibular nerve lie between
extensor hallucis longus and tibialis anterior. Extensor hallucis longus
lies lateral to the artery proximally, crosses it in the lower third of the
leg, and is medial to it on the foot.
Vascular supply Extensor hallucis longus is supplied by the anterior


tibial artery via obliquely running branches, with a variable contribu Extensor digitorum longus
tion from the perforating branch of the fibular artery (Fig. 83.7). More
distally, the tendon is supplied via the anterior medial malleolar artery
Tibialis
and network, the dorsalis pedis artery, and the plantar metatarsal artery
of the first digit via perforating branches. anterior (cut) Extensor hallucis longus
Innervation Extensor hallucis longus is innervated by the deep fibular
nerve, L5.
Anterior lateral malleolar artery
Actions Extensor hallucis longus extends the hallux and dorsiflexes Perforating branch
the foot. When the hallux is actively extended, relatively little external of fibular artery
force is required to overcome the extension of the distal phalanx, Anterior medial
malleolar artery
whereas considerable force is needed to overcome the extension of the
proximal phalanx.
Lateral tarsal artery
Testing When the hallux is extended against resistance, the tendon of
extensor hallucis longus can be seen and felt on the lateral side of the Dorsalis pedis artery
tendon of tibialis anterior.
Extensor hallucis brevis
Extensor digitorum longus
Attachments Extensor digitorum longus arises from the inferior Arcuate artery
surface of the lateral condyle of the tibia, the proximal threequarters
First dorsal
of the medial surface of the fibula, the adjacent anterior surface of the
metatarsal artery
interosseous membrane, the deep surface of the deep fascia, the anterior
intermuscular septum and the fascial septum between itself and tibialis
anterior. These origins form the walls of an osseoaponeurotic tunnel.
Extensor digitorum longus becomes tendinous at about the same level
as tibialis anterior, and the tendon passes deep to the superior extensor
retinaculum and within a loop of the inferior extensor retinaculum with
fibularis tertius (see Figs 83.6, 84.1). It divides into four slips, which Fig. 83.7 The left anterior tibial and dorsalis pedis arteries. To expose the


run forwards on the dorsum of the foot and are attached in the same anterior tibial artery, a large part of tibialis anterior has been excised.
way as the tendons of extensor digitorum in the hand. At the metatarso
phalangeal joints, the tendons to the second, third and fourth toes are
each joined on the lateral side by a tendon of extensor digitorum brevis. Tibialis anterior and extensor hallucis longus lie medially in the leg,
The socalled dorsal digital expansions thus formed on the dorsal and the fibular muscles lie laterally. In the upper part of the leg, the
aspects of the proximal phalanges, as in the fingers, receive contribu anterior tibial vessels and deep fibular nerve lie between extensor digi
tions from the appropriate lumbrical and interosseous muscles. The torum longus and tibialis anterior; the nerve runs obliquely and medi
expansion narrows as it approaches a proximal interphalangeal joint, ally beneath its upper part.
and divides into three slips. These are a central (axial) slip, attached to
the base of the middle phalanx, and two collateral (coaxial) slips, which Vascular supply The main blood supply to extensor digitorum
reunite on the dorsum of the middle phalanx and are attached to the longus is derived from anteriorly and laterally placed branches of the
base of the distal phalanx. anterior tibial artery, supplemented distally from the perforating branch
The tendons to the second and fifth toes are sometimes duplicated, of the fibular artery. Proximally, there may also be a supply from the
and accessory slips may be attached to metatarsals or to the hallux. inferior lateral genicular, popliteal or anterior tibial recurrent arteries.
At the ankle and in the foot, the tendons are supplied by the anterior
Relations Extensor digitorum longus lies on the lateral tibial condyle, lateral malleolar artery and malleolar network, and by lateral tarsal,
fibula, lower end of the tibia, ankle joint and extensor digitorum brevis. metatarsal, plantar and digital arteries.


LEg
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NOITCES
Innervation Extensor digitorum longus is innervated by the deep and on the cuboid bone. At both sites it is thickened, and at the second
fibular nerve, L5, S1. site a sesamoid fibrocartilage (sometimes a bone, the os peroneum) is
usually present. A second synovial sheath invests the tendon as it crosses
Actions Extensor digitorum longus extends the lateral four toes. the sole of the foot.
Acting synergistically with tibialis anterior, extensor hallucis longus and
fibularis tertius, it is a dorsiflexor of the ankle. Acting with extensor Relations Proximally, fibularis longus lies posterior to extensor digi
hallucis longus, it helps tighten the plantar aponeurosis. torum longus and anterior to soleus and flexor hallucis longus. Distally,
in the leg, it lies posterior to fibularis brevis. Between its attachments
Testing The tendons of extensor digitorum longus can be seen when to the head and shaft of the fibula there is a gap through which the
the toes are extended against resistance. common fibular nerve passes.
Fibularis tertius Vascular supply of lateral compartment Usually, the predomi
Attachments Fibularis tertius (peroneus tertius) often appears to be nant supply of the lateral compartment muscles is derived from
part of extensor digitorum longus and might be described as its ‘fifth branches of the anterior tibial artery; the superior is commonly the
tendon’. The muscle fibres of fibularis tertius arise from the distal third larger. There is also a lesser, variable, contribution from the fibular
or more of the medial surface of the fibula, the adjoining anterior artery in the distal part of the leg. A fibular branch may replace the
surface of the interosseous membrane, and the anterior intermuscular inferior branch of the anterior tibial artery; less commonly, the fibular
septum. The tendon passes deep to the superior extensor retinaculum artery provides the main supply to the whole compartment. The upper
and within the loop of the inferior extensor retinaculum alongside the part of fibularis longus is also supplied by the circumflex fibular branch


extensor digitorum longus (see Figs 83.6B, 84.2A). It is inserted on to of the posterior tibial artery, which is usually a branch of the anterior
the medial part of the dorsal surface of the base of the fifth metatarsal; tibial artery. The companion artery to the common fibular nerve, a
a thin expansion usually extends forwards along the medial border of branch of the popliteal artery, provides a minor contribution proxi
the shaft of the bone. mally. Distally, the tendons are supplied by the fibular perforating,
anterior lateral malleolar, lateral calcaneal, lateral tarsal, arcuate, lateral
Relations Fibularis tertius lies lateral to extensor digitorum longus. and medial plantar arteries (see Fig. 84.9).
Vascular supply Fibularis tertius is supplied by the same vessels as Innervation Fibularis longus is innervated by the superficial fibular
extensor digitorum longus. In the foot it receives an additional supply nerve, L5, S1.
from the termination of the arcuate artery and the fourth dorsal meta
tarsal artery. Actions There is little doubt that fibularis longus can evert the foot
and plantar flex the ankle, and possibly act on the leg from its distal
Innervation Fibularis tertius is innervated by the deep fibular nerve, attachments. The oblique direction of its tendon across the sole also
L5, S1. enables it to support the longitudinal and transverse arches of the foot.
With the foot off the ground, eversion is visually and palpably associ
Actions Electromyographic studies show that during the swing phase ated with increased prominence of both tendon and muscle. It is not
of gait (see Fig. 84.27), fibularis tertius acts with extensor digitorum clear to what extent this helps to maintain plantigrade contact of the
longus and tibialis anterior to produce dorsiflexion of the foot, and with foot in normal standing, but electromyographic recordings show little
fibularis longus and fibularis brevis to effect eversion of the foot (Jungers or no fibular activity under these conditions. Fibularis longus and brevis


et al 1993). This levels the foot and helps the toes to clear the ground, come strongly into action to maintain the concavity of the foot during
an action that improves the efficiency and enhances the economy of toeoff and tiptoeing. If the subject deliberately sways to one side,
bipedal locomotion. Fibularis tertius is not active during the stance fibularis longus and brevis contract on that side, but their involvement
phase, a finding that is at variance with the suggestion that the muscle in influencing postural interactions between the foot and leg remains
acts primarily to support the lateral longitudinal arch and to transfer uncertain.
the centre of pressure of the foot medially.
Testing Fibularis longus and brevis are tested together by eversion of
Testing Fibularis tertius cannot be tested in isolation, but its tendon the foot against resistance; the tendons can be identified laterally at the
can sometimes be seen and felt when the foot is dorsiflexed against ankle and in the foot.
resistance.
Fibularis brevis
Attachments Fibularis brevis arises from the distal twothirds of the
LATERAL (FIBULAR OR PERONEAL) COMPARTMENT lateral surface of the fibula, anterior to fibularis longus, and from the
anterior and posterior crural intermuscular septa. It passes vertically
The lateral compartment contains fibularis (peroneus) longus and fibu downwards and ends in a tendon that passes behind the lateral malleo
laris (peroneus) brevis (see Figs 83.2A, B, 83.6A, B). Both muscles evert lus together with, and anterior to, that of fibularis longus. The two
the foot and are plantar flexors of the ankle, and both probably play a tendons run deep to the superior fibular retinaculum in a common
part in balancing the leg on the foot in standing and walking. synovial sheath. The tendon of fibularis brevis then runs forwards on
the lateral side of the calcaneus above the fibular trochlea and the
Fibularis longus tendon of fibularis longus, and is inserted into a tuberosity on the
Attachments Fibularis longus is the more superficial of the two lateral side of the base of the fifth metatarsal.


muscles of the lateral compartment. It arises from the head and proxi
mal twothirds of the lateral surface of the fibula, the deep surface of Relations Anteriorly lie extensor digitorum longus and fibularis ter
the deep fascia, the anterior and posterior intermuscular septa, and tius. Fibularis longus and flexor hallucis longus are posterior. On the
occasionally by a few fibres from the lateral condyle of the tibia. The lateral surface of the calcaneus, the tendons of fibularis longus and fibu
muscle belly ends in a long tendon that runs distally behind the lateral laris brevis occupy separate osteofascial canals formed by the calcaneus
malleolus in a groove it shares with the tendon of fibularis brevis. The and the inferior fibular retinaculum; each tendon is enveloped in a sepa
groove is converted into a canal by the superior fibular retinaculum, so rate distal prolongation of the common synovial sheath (see Fig. 84.2A).
that the tendon of fibularis longus and that of fibularis brevis, which
lies in front of the longus tendon, are contained in a common synovial Vascular supply See ‘Fibularis longus’.
sheath. If the fibular retinaculum is ruptured by injury and fails to heal,
the tendons can dislocate from the groove. The fibularis longus tendon Innervation Fibularis brevis is innervated by the superficial fibular
runs obliquely forwards on the lateral side of the calcaneus, below the nerve, L5, S1.
fibular trochlea and the tendon of fibularis brevis, and deep to the
inferior fibular retinaculum. It crosses the lateral side of the cuboid and Actions Fibularis brevis may limit inversion of the foot and so relieve
then runs under the cuboid in a groove that is converted into a canal strain on the ligaments that are tightened by this movement (the lateral
by the long plantar ligament (see Fig. 84.20). It crosses the sole of the part of interosseous talocalcaneal, lateral talocalcaneal and calcaneo


foot obliquely and is attached by two slips, one to the lateral side of fibular ligaments). It participates in eversion of the foot and may help
the base of the first metatarsal and one to the lateral aspect of the medial to steady the leg on the foot. See also ‘Fibularis longus’.
cuneiform; occasionally, a third slip is attached to the base of the second
metatarsal. The tendon changes direction below the lateral malleolus Testing See ‘Fibularis longus’.


Muscles
1409
38
RETPAHC
Variants of fibular muscles
Tendinous slips from fibularis longus may extend to the base of the
Biceps femoris Gastrocnemius, medial head
third, fourth or fifth metatarsals, or to adductor hallucis. Fusion of
fibularis longus and brevis has been reported but is rare. Fibularis tertius Semimembranosus
is highly variable in its form and bulk but is seldom completely absent; Gastrocnemius,
its distal attachment may be to the fourth metatarsal rather than the lateral head
Medial subtendinous
fifth. Two other variant fibular muscles, arising from the fibula between bursa of gastrocnemius
fibularis longus and fibularis brevis, have been described. These are Semimembranosus bursa
fibularis accessorius, whose tendon joins that of fibularis longus in the
sole, and fibularis quartus, which arises posteriorly and inserts on to Popliteal artery Oblique popliteal ligament
and vein; tendinous
the calcaneus or on to the cuboid.
arch of soleus
POSTERIOR (FLEXOR) COMPARTMENT Plantaris
The muscles in the posterior compartment of the lower leg form super
ficial and deep groups, separated by the transverse intermuscular septum.
Superficial flexor group
Soleus
The superficial muscles – gastrocnemius, plantaris and soleus (Fig.
83.8; see Figs 83.2A, 82.3) – form the bulk of the calf. Gastrocnemius
and soleus, collectively known as the triceps surae, constitute a powerful
muscular mass whose main function is plantar flexion of the foot,
although soleus in particular has an important postural role (see Tendon of plantaris
below). Their large size is a defining human characteristic, and is related
to the upright stance and bipedal locomotion of the human. Gastroc Gastrocnemius
nemius and plantaris act on both the knee and the ankle joints, soleus
on the latter alone.
Gastrocnemius
Attachments Gastrocnemius is the most superficial muscle of the Fibularis longus


group and forms the ‘belly’ of the calf (see Fig. 82.3). It arises by two
heads, connected to the condyles of the femur by strong, flat tendons.
The medial, larger head is attached to a depression at the upper and
posterior part of the medial condyle behind the adductor tubercle, and
to a slightly raised area on the popliteal surface of the femur just above
the medial condyle. The lateral head is attached to a recognizable area
Flexor hallucis longus
on the lateral surface of the lateral condyle and to the lower part of the
corresponding supracondylar line. Both heads also arise from subjacent
areas of the capsule of the knee joint. The tendinous attachments
Flexor digitorum longus
expand to cover the posterior surface of each head with an aponeurosis,
from the anterior surface of which the muscle fibres arise. The fleshy
part of the muscle extends to about midcalf. The muscle fibres of the
Tibialis posterior
larger medial head extend lower than those of the lateral head. As the
muscle descends, the muscle fibres begin to insert into a broad aponeu
rosis that develops on its anterior surface; up to this point, the muscular Medial malleolus
masses of the two heads remain separate. The aponeurosis gradually Superior fibular
retinaculum
narrows and receives the tendon of soleus on its deep surface to form Calcaneal tendon
the calcaneal tendon (for a detailed description of the calcaneal tendon,
see page 1440). Flexor retinaculum
On occasion, the lateral head, or the whole muscle, is absent. A third
head arising from the popliteal surface of the femur is sometimes
present.
Relations Proximally, the two heads of gastrocnemius form the lower
boundaries of the popliteal fossa. The lateral head is partially overlaid
by the tendon of biceps femoris, the medial head by semimembrano
sus. Over the rest of its length, the muscle is superficial and the two Fig. 83.8 Muscles of the left leg, posterior aspect. Gastrocnemius has
heads can easily be seen in the living subject. The superficial surface of been partially removed. (With permission from Waschke J, Paulsen F


(eds), Sobotta Atlas of Human Anatomy, 15th ed, Elsevier, Urban &
the muscle is separated by the deep fascia from the short saphenous
Fischer. Copyright 2013.)
vein and the fibular communicating and sural nerves. The common
fibular nerve crosses behind the lateral head of the muscle, partly under
cover of biceps femoris. The deep surface lies posterior to the oblique muscle head with its nerve of supply, the pedicle entering the muscle
popliteal ligament, popliteus, soleus, plantaris, popliteal vessels and the near its axial border at the level of the middle of the popliteal fossa.
tibial nerve. A bursa, which communicates with the knee joint, is Medial or lateral gastrocnemius musculocutaneous flaps may be raised,
located anterior to the tendon of the medial head; if the bursa expands each based on its neurovascular pedicle. Minor accessory sural arteries
into the popliteal fossa, it does so in the plane between the medial head arise from the popliteal or from the superior genicular arteries.
of gastrocnemius and semimembranosus. The tendon of the lateral The blood supply to the calcaneal tendon is described on page 1440.
head frequently contains a sesamoid bone, the fabella, where it moves
over the lateral femoral condyle. A sesamoid bone may occasionally Innervation Gastrocnemius is innervated by the tibial nerve, S1
occur in the tendon of the medial head. and S2.
Vascular supply Each head of gastrocnemius is supplied by its own Actions The action of gastrocnemius is considered with soleus.
sural artery. These arteries are branches of the popliteal artery and arise
at variable levels, usually at the level of the tibiofemoral joint line. The Testing Gastrocnemius is tested by plantar flexion of the foot against
medial sural artery almost always arises more proximally than the resistance, in the supine position and with the knee extended. Plantar
lateral; the medial may arise proximal to the joint line, the lateral flexion (gastrocnemius and soleus) is best tested by asking the subject
sometimes distal to the line. Each sural artery enters the corresponding to perform repetitive unilateral toe rises.


LEg
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9
NOITCES
Plantaris proportion of this type of fibre in soleus approaches 100%. However,
Attachments Plantaris arises from the lower part of the lateral supra such a rigid separation of functional roles seems unlikely in humans;
soleus probably participates in locomotion, and gastrocnemius in
condylar line and the oblique popliteal ligament (see Fig. 83.8). Its
posture. Nevertheless, the ankle joint is loosepacked in the erect
small fusiform belly is 7–10 cm long and ends in a long slender tendon,
posture, and since the weight of the body acts through a vertical line
which crosses obliquely, in an inferomedial direction, between gastroc
that passes anterior to the joint, a strong brace is required behind the
nemius and soleus, then runs distally along the medial border of the
joint to maintain stability. Electromyography shows that these forces
calcaneal tendon and inserts on to the calcaneus just medial to the cal
are supplied mainly by soleus; during symmetrical standing, soleus is
caneal tendon. Occasionally, it ends by fusing with the calcaneal tendon.
continuously active, whereas gastrocnemius is recruited only intermit
The muscle is sometimes double, and occasionally absent. Occasion
tently. The relative contributions of soleus and gastrocnemius to phasic
ally, its tendon merges with the flexor retinaculum or with the fascia of
activity of the triceps surae in walking have yet to be satisfactorily
the leg.
analysed.
Vascular supply Plantaris is supplied superficially by the lateral sural
Deep flexor group
and popliteal arteries, and deeply by the superior lateral genicular
artery. The distal tendon shares a blood supply with the calcaneal
tendon. The deep flexor group (see Fig. 83.2A, B; Figs 83.9–83.10) lies beneath
(anterior to) the transverse intermuscular septum and consists of pop
Innervation Plantaris is innervated by the tibial nerve, often from the liteus, which acts on the knee joint, and flexor digitorum longus, flexor


ramus that supplies the lateral head of gastrocnemius, S1 and S2. hallucis longus and tibialis posterior, which all produce plantar flexion
at the ankle in addition to their specific actions on joints of the foot
Actions In many mammals, plantaris is well developed and inserts and digits.
directly or indirectly into the plantar aponeurosis. In humans, the
Popliteus
muscle is almost vestigial and is normally inserted well short of the
plantar aponeurosis, usually into the calcaneus. It is therefore presumed Popliteus is described on page 1397.
to act with gastrocnemius.
Flexor digitorum longus
Soleus Attachments Flexor digitorum longus is thin and tapered proximally,
Attachments Soleus is a broad, flat muscle situated immediately but widens gradually as it descends (see Figs 83.9A, B). It arises from
deep (anterior) to gastrocnemius (see Fig. 83.8). It arises from the the posterior surface of the tibia medial to tibialis posterior from just
posterior surface of the head and proximal quarter of the shaft of the below the soleal line to within 7 or 8 cm of the distal end of the bone;
fibula; the soleal line and the middle third of the medial border of the it also arises from the fascia covering tibialis posterior. The muscle ends
tibia; and from a fibrous band between the tibia and fibula (tendinous in a tendon that extends along almost the whole of its posterior surface.
arch of the soleus) that arches over the popliteal vessels and tibial nerve. The tendon gradually crosses tibialis posterior on its superficial aspect
This origin is aponeurotic; most of the muscular fibres arise from its and passes behind the medial malleolus where it shares a groove with
posterior surface and pass obliquely to the tendon of insertion on the tibialis posterior, from which it is separated by a fibrous septum, i.e.
posterior surface of the muscle. Other muscle fibres arise from the each tendon occupies its own compartment lined by a synovial sheath
anterior surface of the aponeurosis. They are short, oblique and bipen (see Fig. 84.2B). The tendon of flexor digitorum longus then curves


nate in arrangement, and converge on a narrow, central intramuscular obliquely forwards and laterally, in contact with the medial side of the
tendon that merges distally with the principal tendon. The latter gradu sustentaculum tali, passes deep to the flexor retinaculum, and enters
ally becomes thicker and narrower, and joins the tendon of gastrocne the sole of the foot on the medial side of the tendon of flexor hallucis
mius to form the calcaneal tendon. The muscle is covered proximally longus. It crosses superficial to that tendon and receives a strong slip
by gastrocnemius, but below midcalf it is broader than the tendon of from it (and may also send a slip to it). The tendon of flexor digitorum
gastrocnemius and is readily accessible on either side of the tendon. longus then passes forwards as four separate tendons, one each for the
An accessory part of the muscle is sometimes present distally and second to fifth toes, deep to the tendons of flexor digitorum brevis. After
medially. It may be inserted into the calcaneal tendon, the calcaneus or giving rise to the lumbricals, it passes through the fibrous sheaths of
the flexor retinaculum. the lateral four toes. The tendons of flexor accessorius insert into the
long flexor tendons of the second, third and fourth digits; flexor hallucis
Relations The superficial surface of soleus is in contact with gastroc longus makes a variable contribution through the connecting slip men
nemius and plantaris. Its deep surface is related to flexor digitorum tioned above. The long flexor tendons of the lateral four digits are
longus, flexor hallucis longus, tibialis posterior and the posterior tibial attached to the plantar surfaces of the bases of their distal phalanges;
vessels and tibial nerve, from all of which it is separated by the trans each passes between the slips of the corresponding tendon of flexor
verse intermuscular septum of the leg. digitorum brevis at the base of the proximal phalanx.
A supplementary head of the muscle, flexor accessorius longus, with


Vascular supply Soleus is supplied by two main arteries: the supe its own tendon, may arise from the fibula, tibia or deep fascia and insert
rior arises from the popliteal artery at about the level of the soleal arch, into the main tendon or into flexor accessorius in the foot. It may send
and the inferior from the proximal part of the fibular artery or some communicating slips to tibialis anterior or to flexor hallucis longus.
times from the posterior tibial artery. A secondary supply is derived
from the lateral sural, fibular or posterior tibial vessels. Relations Flexor digitorum longus lies medial to flexor hallucis
There is a venous plexus within the muscle belly that is important longus. In the leg, its superficial surface is in contact with the transverse
physiologically as part of the muscle pump complex (see below). Patho intermuscular septum, which separates it from soleus, and distally from
logically, it is a common site of deep vein thrombosis. the posterior tibial vessels and tibial nerve. Its deep surface is related to
the tibia and to tibialis posterior. In the foot, it is covered by abductor
Innervation Soleus is innervated by two branches from the tibial hallucis and flexor digitorum brevis, and it crosses superficial to flexor
nerve, S1 and S2. hallucis longus.
Actions See ‘Triceps surae’. Vascular supply A series of transversely running branches of the
posterior tibial artery enters the lateral border of flexor digitorum
Testing Soleus is tested by plantar flexion of the foot against resistance longus. There may be a secondary supply from fibular branches to flexor
in the supine position, with hip and knee flexed; the muscle belly can hallucis longus. The tendons are supplied by the vessels of the ankle
be palpated separately from those of gastrocnemius. and sole of the foot.
Actions of triceps surae Innervation Flexor digitorum longus is innervated by branches of the
Gastrocnemius and soleus are the chief plantar flexors of the foot; gas tibial nerve, L5, S1 and S2.
trocnemius is also a flexor of the knee. The muscles are usually large


and correspondingly powerful. Gastrocnemius provides force for pro Actions See ‘Flexor hallucis longus’.
pulsion in walking, running and leaping. Soleus, acting from below, is
said to be more concerned with steadying the leg on the foot in stand Testing Flexor digitorum longus is tested by flexing the toes against
ing. This postural role is also suggested by its high content of slow, resistance. Aberrant function of flexor digitorum longus is implicated
fatigueresistant (type 1) muscle fibres. In many adult mammals, the in toe deformities such as hammer toe, claw toe and mallet toe. Its


Muscles
1411
38
RETPAHC
A B
Femur, popliteal surface
Gastrocnemius,
Biceps femoris medial head
Medial subtendinous
Gastrocnemius, bursa of gastrocnemius
lateral head
Bursa of semimembranosus Plantaris
Plantaris
Tendon of semimembranosus
Popliteus
Oblique popliteal ligament
Tendon of
Popliteus biceps femoris
Subpopliteal
recess
Tibialis posterior
Soleus
Fibula, Tibia
interosseous
border
Tibialis posterior
Flexor digitorum longus
Flexor digitorum longus (cut)
Fibularis longus
Flexor hallucis longus
Flexor hallucis
longus
Flexor digitorum longus
Flexor hallucis longus
Tibia Flexor digitorum longus (cut)
Fibularis brevis
Tibialis posterior
Flexor retinaculum
Superior fibular
retinaculum
Calcaneal tendon
Fig. 83.9 Muscles of the left leg, posterior aspect. A, The superficial muscles have been extensively removed. B, The superficial muscles have been
extensively removed, popliteus has been sectioned and the tendon of flexor digitorum longus removed as it crosses the tendon of tibialis posterior. (With
permission from Waschke J, Paulsen F (eds), Sobotta Atlas of Human Anatomy, 15th ed, Elsevier, Urban & Fischer. Copyright 2013.)
tendon may be used in transfer procedures for the surgical treatment of the calcaneus (see Fig. 84.2B). Fibrous bands convert the grooves on
tibialis posterior tendon dysfunction. the talus and calcaneus into a canal lined by a synovial sheath. In
dancers, overuse causes thickening of the tendon in this region, and
Flexor hallucis longus
pain and even ‘triggering’ can occur (hallux saltans). In the sole of the
Attachments Flexor hallucis longus arises from the distal twothirds foot, the tendon of flexor hallucis longus passes forwards in the second


of the posterior surface of the fibula (except for the lowest 2.5 cm of layer like a bowstring. It crosses the tendon of flexor digitorum longus
this surface); the adjacent interosseous membrane and the posterior from lateral to medial, curving obliquely superior to it. At the crossing
crural intermuscular septum; and from the fascia covering tibialis pos point (knot of Henry), it gives off two strong slips to the medial two
terior, which it overlaps to a considerable extent (see Fig. 83.9). Its fibres divisions of the tendons of flexor digitorum longus and then crosses
pass obliquely down to a tendon that occupies nearly the whole length the lateral part of flexor hallucis brevis to reach the interval between
of the posterior aspect of the muscle. This tendon grooves the posterior the sesamoid bones under the head of the first metatarsal. It continues
surface of the lower end of the tibia, then, successively, the posterior on the plantar aspect of the hallux, and runs in an osseoaponeurotic
surface of the talus and the inferior surface of the sustentaculum tali of tunnel to be attached to the plantar aspect of the base of the distal


LEg
1412
9
NOITCES
Anterior tibial artery hallucis longus and flexor digitorum longus, and is overlapped by both,
but especially by the former. Its proximal attachment consists of two
Extensor digitorum
Deep fibular nerve longus tapered processes, separated by an angular interval that is traversed by
the anterior tibial vessels. The medial process arises from the posterior
Extensor hallucis surface of the interosseous membrane, except at its most distal part, and
Tibialis anterior longus
from a lateral area on the posterior surface of the tibia between the
Superficial fibular soleal line above and the junction of the middle and lower thirds of
Tibia nerve the shaft below. The lateral part arises from a medial strip of the pos
terior fibular surface in its upper twothirds. The muscle also arises from
Saphenous nerve Fibularis tertius
the transverse intermuscular septum, and from the intermuscular septa
Long saphenous
Fibula that separate it from adjacent muscles. In the distal quarter of the leg,
vein
its tendon passes deep to that of flexor digitorum longus, with which
Perforating branch it shares a groove behind the medial malleolus, each enclosed in a
of fibular artery
separate synovial sheath (see Fig. 84.2B). It then passes deep to the
Tibialis posterior flexor retinaculum and superficial to the deltoid ligament to enter the
foot. In the foot, it is at first inferior to the plantar calcaneonavicular
Fibular artery
Flexor digitorum ligament, where it contains a sesamoid fibrocartilage. The tendon then
longus Fibularis longus divides into two. The more superficial and larger division, which is a
direct continuation of the tendon, is attached to the tuberosity of the
Fibularis brevis
Posterior tibial navicular, from which fibres continue to the inferior surface of the
artery Flexor hallucis medial cuneiform. A tendinous band also passes laterally and a little
longus
proximally to the tip and distal margin of the sustentaculum tali. The
Tibial nerve Sural nerve deeper lateral division gives rise to the tendon of origin of the medial


Plantaris Small saphenous limb of flexor hallucis brevis, and then continues between this muscle
vein and the navicular and medial cuneiform to end on the intermediate
Calcaneal tendon Soleus
cuneiform and the bases of the second, third and fourth metatarsals;
Fig. 83.10 A transverse section through the left leg, approximately 6 cm
the slip to the fourth metatarsal is the strongest.
proximal to the medial malleolus.
The slips to the metatarsals vary in number. Slips to the cuboid and
lateral cuneiform may also occur. An additional muscle, the tibialis
phalanx. The tendon is retained in position over the lateral part of flexor secundus, has been described running from the back of the tibia to the
hallucis brevis by the diverging stems of the distal band of the medial capsule of the ankle joint.
intermuscular septum.
The distal extent of the muscle belly is a distinctive characteristic; in Relations The superficial surface of tibialis posterior is separated from
the posteromedial surgical approach to the ankle, flexor hallucis longus soleus by the transverse intermuscular septum, and is related to flexor
is readily identifiable by the fact that muscle fibres are evident almost digitorum longus, flexor hallucis longus, the posterior tibial vessels, the
to calcaneal level. In athletes, the muscle fibres may be present so far tibial nerve and the fibular vessels. The deep surface is in contact with
inferiorly into the tendon as to be susceptible to impingement when the interosseous membrane, tibia, fibula and ankle joint.
pulled into the tunnel at the talus.
The connecting slip to flexor digitorum longus varies in size; it Vascular supply Tibialis posterior is supplied by numerous branches
usually continues into the tendons for the second and third toes but is of small calibre arising from the posterior tibial and fibular arteries. The
sometimes restricted to the second toe and occasionally extends to the tendon is supplied by arteries of the medial malleolar network and by
fourth toe. the medial plantar artery.
Relations Soleus and the calcaneal tendon lie superficial (i.e. poste Innervation Tibialis posterior is innervated by the tibial nerve, L4


rior) to flexor hallucis longus, separated by the transverse intermuscular and L5.
septum. Deeply situated are the fibula, tibialis posterior, fibular vessels,
distal part of the interosseous membrane and the talocrural joint. Lat Actions Tibialis posterior is a powerful muscle that, on contraction,
erally lie fibularis longus and fibularis brevis; medially are tibialis pos has an excursion of only 1–2 cm. It is the principal invertor of the
terior, posterior tibial vessels and the tibial nerve. Flexor hallucis longus foot and also initiates elevation of the heel; it is responsible for the
is an important surgical landmark at the ankle; staying lateral to it hindfoot varus that occurs during a single heel raise. Due to its inser
prevents injury to the neurovascular bundle. tions on to the cuneiforms and the bases of the metatarsals, it has
long been thought to assist in elevating the longitudinal arch of the
Vascular supply Flexor hallucis longus is supplied by numerous
foot, although electromyography shows that it is actually quiescent in
branches of the fibular artery. The tendon is supplied by arteries of the
standing. It is phasically active in walking, during which it probably
ankle and foot.
acts with the intrinsic foot musculature and the lateral leg muscles to
control the degree of pronation of the foot and the distribution of
Innervation Flexor hallucis longus is innervated by branches of the
weight through the metatarsal heads. It is said that when the body is
tibial nerve, L5, S1 and S2 (mainly S1).
supported on one leg, the invertor action of tibialis posterior, exerted
Testing Flexor hallucis longus is tested by flexion of the hallux against from below, helps to maintain balance by resisting any tendency to
sway laterally.
resistance.
Tibialis posterior is also important in the maintenance of the medial
Actions of deep digital flexors part of the longitudinal arch of the foot. In overweight individuals with
Both flexor hallucis longus and flexor digitorum longus can act as pes planus (flat foot deformity), unaccustomed activity can result in


plantar flexors but this action is weak compared with that of gastrocne inflammation and degeneration of the terminal portion of the tendon,
mius and soleus. When the foot is off the ground, both muscles flex the which leads to elongation of the tendon, attenuation of the spring liga
phalanges, acting primarily on the distal phalanges. When the foot is ment and progressive collapse of the medial longitudinal arch. As the
on the ground and under load, they act synergistically with the small excursion is so short, the muscle cannot compensate for the lengthen
muscles of the foot and, especially in the case of flexor digitorum ing of its tendon, a failure that results in tibialis posterior tendon
longus, with the lumbricals and interossei to maintain the pads of the dysfunction.
toes in firm contact with the ground, enlarging the weightbearing area
and helping to stabilize the heads of the metatarsals, which form the Testing Tibialis posterior is tested by asking the subject to move the
fulcrum on which the body is propelled forwards. Activity in the long foot into a position of maximal plantar flexion and inversion against
digital flexors is minimal during quiet standing, so they apparently the resistance of the examiner’s hand; the tendon can be seen and felt
contribute little to the static maintenance of the longitudinal arch, but just proximal to the medial malleolus. Testing tibialis posterior function
they become very active during toeoff and tiptoe movements. is important in establishing a diagnosis of a common fibular nerve
neuropathy and differentiating it from an L5 radiculopathy, which are
Tibialis posterior
two common clinical conditions. In a common fibular nerve neur
Attachments Tibialis posterior is the most deeply placed muscle of opathy, tibialis posterior has normal function, whereas in an L5 radicul
the flexor group (see Fig. 83.9). At its origin it lies between flexor opathy, tibialis posterior is weak.


Vascular supply
1413
38
RETPAHC
ankle joint. Proximally, it lies between tibialis anterior and extensor
VASCULAR SUPPLY
digitorum longus, then between tibialis anterior and extensor hallucis
longus. At the ankle it is crossed superficially from the lateral side by
ARTERIES the tendon of extensor hallucis longus and then lies between this
tendon and the first tendon of extensor digitorum longus. Its proximal
Anterior tibial artery twothirds are covered by adjoining muscles and deep fascia, its distal
third by the skin, fasciae and extensor retinacula. It is accompanied by
The anterior tibial artery arises at the distal border of popliteus (Fig. venae comitantes. The deep fibular nerve, curling laterally round the
83.11; see Figs 78.4A, B, 83.7, 83.10, 82.1, 82.4, 84.9). At first in the fibular neck, reaches the lateral side of the artery where it enters the
flexor compartment, it passes between the heads of tibialis posterior extensor region, is then anterior to the artery in the middle third of
and through the oval aperture in the proximal part of the interosseous the leg, and becomes lateral again distally.
membrane to reach the extensor (anterior) compartment, passing
Branches
medial to the fibular neck; it is vulnerable here during tibial osteotomy.
Descending on the anterior aspect of the membrane, it approaches the The named branches of the anterior tibial artery are the posterior and
tibia and, distally, lies anterior to it. At the ankle, the anterior tibial anterior tibial recurrent, muscular, perforating, and anterior medial and
artery is located approximately midway between the malleoli, and it lateral malleolar arteries.
continues on the dorsum of the foot, lateral to extensor hallucis longus,
as the dorsalis pedis artery. Posterior tibial recurrent artery The posterior tibial recurrent
The anterior tibial artery may, on occasion, be small but it is rarely artery is an inconstant branch that arises before the anterior tibial artery
absent. Its function may be replaced by perforating branches from the reaches the extensor compartment of the leg. It ascends anterior to


posterior tibial artery or by the perforating branch of the fibular artery. popliteus, anastomosing with the inferior genicular branches of the
It occasionally deviates laterally, regaining its usual position at the popliteal artery. It supplies the superior tibiofibular joint.
ankle. It may also be larger than normal, in which case its territory of
supply in the foot may be increased to include the plantar surface. Anterior tibial recurrent artery The anterior tibial recurrent artery
arises near the posterior tibial recurrent artery. It ascends in tibialis
Relations anterior, ramifies on the front and sides of the knee joint, and joins the
In its proximal twothirds the anterior tibial artery lies on the interos patellar anastomosis, which interconnects with the genicular branches
seous membrane, and in its distal third it is anterior to the tibia and of the popliteal and circumflex fibular arteries.
Aorta Muscular branches Numerous branches supply the adjacent
muscles. Some then pierce the deep fascia to supply the skin, while
Common iliac artery others traverse the interosseous membrane to anastomose with branches
Internal iliac artery of the posterior tibial and fibular arteries.
External iliac artery Perforating branches Most of the fasciocutaneous perforators pass
along the anterior fibular fascial septum behind extensor digitorum
longus before penetrating the deep fascia to supply the skin.
Anterior medial malleolar artery The anterior medial malleolar
artery arises approximately 5 cm proximal to the ankle. It passes pos
terior to the tendons of extensor hallucis longus and tibialis anterior
medial to the joint, where it joins branches of the posterior tibial and
Profunda femoris artery
medial plantar arteries.
Anterior lateral malleolar artery The anterior lateral malleolar
artery runs posterior to the tendons of extensor digitorum longus and
fibularis tertius to the lateral side of the ankle and anastomoses with
Femoral artery the perforating branch of the fibular artery and ascending branches of
the lateral tarsal artery.
Posterior tibial artery
The posterior tibial artery begins at the distal border of popliteus,


between the tibia and fibula (see Figs 78.4B, 82.4, 83.11). It descends
medially in the flexor compartment and divides under abductor hal
lucis, midway between the medial malleolus and the calcaneal tubercle,
into the medial and lateral plantar arteries. The artery may be much
reduced in length or in calibre; the fibular artery then takes over its
Anterior tibial artery distal territory of supply and may consequently be increased in size.
Relations
Posterior tibial artery
The posterior tibial artery is successively posterior to tibialis posterior,
flexor digitorum longus, the tibia and the ankle joint. Proximally, gas
trocnemius, soleus and the transverse intermuscular septum of the leg
are superficial to the artery, and distally, it is covered only by skin and
fascia. It is parallel with and approximately 2.5 cm anterior to the
medial border of the calcaneal tendon; terminally, it is deep to the flexor
retinaculum. The artery is accompanied by two veins and the tibial
nerve. The nerve is at first medial to the artery but soon crosses behind
it and subsequently becomes largely posterolateral in position.
Branches
The named branches of the posterior tibial artery are the circumflex
fibular, nutrient, muscular, perforating, communicating, medial malle
olar, calcaneal, lateral and medial plantar, and fibular arteries.
Fig. 83.11 Three-dimensional CT imaging illustrating the arterial supply of Circumflex fibular artery The circumflex fibular artery, which
the lower limb. Note the relationships of the arteries to the surrounding sometimes arises from the anterior tibial artery, passes laterally round
bones. (Courtesy of Dr Yoginder Vaid and Mr Jon C Betts, Jr.) the neck of the fibula through the soleus to anastomose with the


LEg
1414
9
NOITCES
inferior medial and lateral genicular and anterior tibial recurrent arter Figs 78.4B, 82.4, 83.2, 83.10). Reaching the inferior tibiofibular syn
ies. It supplies bone and related articular structures. desmosis, it divides into calcaneal branches that ramify on the lateral
and posterior surfaces of the calcaneus. Proximally, it is covered by
Nutrient artery of the tibia The nutrient artery of the tibia arises soleus and the transverse intermuscular septum between soleus and the
from the posterior tibia near its origin. After giving off a few muscular deep muscles of the leg, and distally it is overlapped by flexor hallucis
branches, it descends into the bone immediately distal to the soleal longus.
line. It is one of the largest of the nutrient arteries. The fibular artery may branch high from the posterior tibial artery
or may even branch from the popliteal artery separately, resulting in a
Muscular branches Muscular branches are distributed to the soleus true ‘trifurcation’. It may also branch more distally from the posterior
and deep flexors of the leg. tibial artery, sometimes 7 or 8 cm distal to popliteus. Its size tends to
be inversely related to the size of the other arteries of the leg. It may be
Perforating branches Approximately five fasciocutaneous perfor reduced in size but is more often enlarged, when it may join, reinforce
ators emerge between flexor digitorum longus and soleus, and pass or even replace the posterior tibial artery in the distal leg and foot.
through the deep fascia, often accompanying the perforating veins that
connect the deep and superficial venous systems. The arterial perfor Branches
ators then divide into anterior and posterior branches to supply the The fibular artery has muscular, nutrient, perforating, communicating
regional periosteum and skin. These vessels are utilized in raising and calcaneal branches.
medial fasciocutaneous perforator flaps in the leg.
Muscular branches Multiple short branches supply soleus, tibialis
Communicating branch The communicating branch runs posteri posterior, flexor hallucis longus and the fibular muscles.
orly across the tibia approximately 5 cm above its distal end, deep to


flexor hallucis longus, to join a communicating branch of the fibular Nutrient artery The nutrient artery branches from the main trunk
artery. approximately 7 cm from its origin and enters the fibula 14–19 cm
from the apex of the head of the fibula.
Medial malleolar branches The medial malleolar branches pass
round the medial malleolus to the medial malleolar network, which Perforating branches The main perforating branch traverses the
supplies the skin. interosseous membrane approximately 5 cm proximal to the lateral
malleolus to enter the extensor compartment, where it anastomoses
Calcaneal branches Calcaneal branches arise just proximal to the with the anterior lateral malleolar artery. Descending anterior to the
terminal division of the posterior tibial artery. They pierce the flexor inferior tibiofibular syndesmosis, it supplies the tarsus and anastomoses
retinaculum to supply fat and skin behind the calcaneal tendon and in with the lateral tarsal artery. This branch is sometimes enlarged and may
the heel, and muscles on the tibial side of the sole; the branches anas replace the dorsalis pedis artery.
tomose with medial malleolar arteries and calcaneal branches of the Fasciocutaneous perforators from the lateral muscular branches pass
fibular artery. along the posterior fibular fascial septum to penetrate the deep fascia
and reach the skin. These vessels are utilized in raising fasciocutaneous
Medial plantar artery posterolateral leg flaps (see below).
Communicating branch The communicating branch connects to
The medial plantar artery is the smaller terminal branch of the posterior
a communicating branch of the posterior tibial artery approximately
tibial artery and passes distally along the medial side of the foot, medial
5 cm proximal to the ankle.
to the medial plantar nerve (see Figs 78.4B, 84.25). At first deep to
abductor hallucis, it runs distally between this muscle and flexor digi
Calcaneal branches Calcaneal (terminal) branches anastomose
torum brevis, and supplies both. Near the first metatarsal base, its size,
with the anterior lateral malleolar and calcaneal branches of the pos
already diminished by muscular branches, is further reduced to a super
terior tibial artery.


ficial stem that divides to form three superficial digital branches. These
accompany the digital branches of the medial plantar nerve and join
Perforator flaps in the knee and leg
the first to third plantar metatarsal arteries. The main trunk of the
The perforators, which arise from the rich vascular anastomosis around
medial plantar artery then runs on to reach the medial border of the
the patella, generally traverse the tendon of quadriceps femoris to
hallux, where it anastomoses with a branch of the first plantar metatar
supply the skin over the patella and the peripatellar region (see Fig.
sal artery.
78.7). The skin flaps based on these perforators may be used as distally
based or proximally based flaps to cover defects over the knee and
Lateral plantar artery
popliteal region. The direct cutaneous branch of the popliteal artery and
a superficial sural artery, which accompanies the sural nerve, provide
The lateral plantar artery is the larger terminal branch of the posterior additional perforators to the skin over the back of the knee. The poste
tibial artery (see Figs 78.4B, 84.25). It passes distally and laterally to rior tibial artery gives off an average of ten perforators to the skin cover
the fifth metatarsal base, lateral to the lateral plantar nerve. (The medial ing the anteromedial and posterior parts of the leg. In the upper third
and lateral plantar nerves lie between the corresponding plantar arter of the leg, the perforating vessels are predominantly muscular and
ies.) Turning medially with the deep branch of the lateral plantar nerve, periosteocutaneous, while in the lower third, the perforating vessels are
it reaches the interval between the first and second metatarsal bases, mainly direct subcutaneous types. They anastomose with the perforat
and unites with the deep plantar artery to complete the plantar arch. ing branches of the anterior tibial artery anteriorly and fibular artery
As it passes laterally, it is first between the calcaneus and abductor hal posteriorly. Inferiorly, the posterior tibial artery forms a rich anasto
lucis, then between flexor digitorum brevis and flexor accessorius. motic ring around the ankle joint with the fibular and anterior tibial


Running distally to the fifth metatarsal base, it passes between flexor arteries. Perforators from these vessels supply the calcaneal tendon and
digitorum brevis and abductor digiti minimi, and is covered by the the overlying skin. The posterior tibial artery gives off three direct cuta
plantar apo neurosis, superficial fascia and skin. neous perforators in the lower part of the leg; a distally based skin or
adipofascial flap based on one of these perforators may be used to
Branches
reconstruct a defect over the anterior or the posterior aspect of the lower
Muscular branches supply the adjoining muscles. Superficial branches
leg. The anterior tibial artery gives off an average of six perforators,
supply the skin and subcutaneous tissue along the lateral sole. Anasto
which supply the anterolateral part of the leg. They emerge in two
motic branches run to the lateral border of the foot, joining branches
longitudinal rows; one perforator is fairly large and accompanies the
of the lateral tarsal and arcuate arteries. A calcaneal branch sometimes
superficial fibular nerve. A small skin flap based on any one of these
pierces abductor hallucis to supply the skin of the heel.
perforators may be used to cover small defects over the tibia, and a
neurocutaneous flap that includes the superficial fibular nerve may
Fibular artery
be used.
The fibular artery has an average of five perforators. A constant
The fibular artery arises from the posterior tibial artery approximately perforator pierces the deep fascia approximately 5 cm above the
2.5 cm distal to popliteus and passes obliquely to the fibula, descend lateral malleolus and divides into an ascending and a descending
ing along its medial crest either in a fibrous canal between tibialis branch. A vascularized fibula graft based on the fibular artery is now
posterior and flexor hallucis longus or within flexor hallucis longus (see the standard graft used in reconstruction of the mandible, while small


Innervation
1415
38
RETPAHC
fasciocutaneous and adipofascial flaps based on the perforators of the tibialis posterior for most of its course except distally, where it adjoins
fibular artery are useful in covering soft tissue defects over the heel and the posterior surface of the tibia. The tibial nerve ends under the flexor
proximal part of the foot. retinaculum by dividing into the medial and lateral plantar nerves.
Branches
DEEP AND SUPERFICIAL VENOUS SYSTEM
The branches of the tibial nerve are articular, muscular, sural, medial
calcaneal and medial and lateral plantar nerves. The medial and lateral
Posterior tibial veins plantar nerves and the medial calcaneal nerve are described on page
1447.
The posterior tibial veins accompany the posterior tibial artery (see Fig.
78.8). They receive tributaries from the calf muscles (especially from Articular branches Articular branches to the knee joint accompany
the venous plexus in the soleus) and connections from superficial veins the superior and inferior medial genicular arteries and the middle
and the fibular veins. genicular artery; they form a plexus with a branch from the obturator
nerve and also supply the oblique popliteal ligament. The branches
Fibular veins accompanying the superior and inferior medial genicular arteries supply
the medial part of the capsule. A branch of the nerve to popliteus (tibial
nerve) supplies the posterior portion of the superior tibiofibular joint.
The fibular veins, running with their artery, receive tributaries from
Just before the tibial nerve bifurcates, it gives off branches that supply
soleus and from superficial veins.
the ankle joint.
Anterior tibial veins
Muscular branches Proximal muscular branches arise between the
heads of gastrocnemius and supply gastrocnemius, plantaris, soleus and
The anterior tibial veins, continuations of the venae comitantes of the
popliteus. The nerve to soleus enters its superficial aspect. The branch
dorsalis pedis artery, leave the anterior compartment between the tibia
to popliteus descends obliquely across the popliteal vessels, curling
and fibula, and pass through the proximal end of the interosseous
round the distal border of the muscle to its anterior surface. It also


membrane. They unite with the posterior tibial veins to form the pop
supplies tibialis posterior, the superior tibiofibular joint and the tibia,
liteal vein at the distal border of popliteus.
and gives off an interosseous branch that descends near the fibula to
reach the distal tibiofibular joint.
Long and short saphenous veins
Muscular branches in the leg, either independently or by a common
trunk, supply soleus (on its deep surface), tibialis posterior, flexor digi
The long and short saphenous veins are described on pages 1370–1371 torum longus and flexor hallucis longus. The branch to flexor hallucis
and 1399, respectively. longus accompanies the fibular vessels.
Venous disease Sural nerve The sural nerve descends between the heads of gastroc
nemius, pierces the deep fascia proximally in the leg, and is joined at
Chronic venous disease is common. Sustained overdistension of the a variable level by the sural communicating branch of the common
superficial veins of the lower limb may result in the development of fibular nerve. Some authors term this branch the lateral sural cutaneous
short, dilated venous segments or varicosities. Varicose veins can occur nerve, and call the main trunk (from the tibial nerve) the medial sural
as a consequence of venous valve failure at the proximal end of the long cutaneous nerve. The sural nerve descends lateral to the calcaneal
saphenous vein at the saphenofemoral junction, or in the perforating tendon, near the short saphenous vein, to the region between the lateral
veins that pass from the superficial system to the highpressure deep malleolus and the calcaneus, and supplies the posterior and lateral skin
veins. Varicose veins have thin walls and ‘leak’ red blood cells into of the distal third of the leg. It then passes distal to the lateral malleolus
adjacent soft tissues. As these cells are broken down, haemosiderin is along the lateral side of the foot and fifth toe, supplying the overlying
deposited in the soft tissues, resulting in a brown pigmentation. This skin. It connects with the posterior femoral cutaneous nerve in the leg


phenomenon, together with the fact that venous stasis produces and with the superficial fibular nerve on the dorsum of the foot.
oedema, renders the soft tissues of the leg unhealthy and prone to The sural nerve is often used as an autologous peripheral nerve graft
ulceration, particularly after minor trauma. on the grounds that it is easily harvested, readily identified and exclu
Acute venous disease occurs most commonly in the posterior com sively cutaneous.
partment of the leg. This is attributed to the sluggish blood flow that
Lesions of the tibial nerve
occurs, at times, in the deep veins of the calf. This relative stasis predis
poses to the formation of venous thrombi. Fragments of these thrombi The tibial nerve is vulnerable to direct injury in the popliteal fossa,
may become dislodged and carried in the venous return to the heart to where it lies superficial to the popliteal vessels at the level of the knee,
cause a lifethreatening pulmonary embolism. Blockage of the normal or to compression at the tendinous arch of the soleus. It may be
venous system may contribute to increased local venous pressure and damaged in compartment syndrome that affects the deep flexor com
oedema. partment of the calf. The tibial nerve or the medial and lateral plantar
nerves may become entrapped beneath the flexor retinaculum or the
socalled plantar tunnels (beneath the fascia of the abductor hallucis)
INNERVATION at the ankle, resulting in tarsal tunnel syndrome.
Tibial nerve Common fibular nerve
The tibial nerve, the larger component of the sciatic nerve, is derived The common fibular nerve (common peroneal nerve) is approximately
from the ventral branches (anterior divisions) of the fourth and fifth half the size of the tibial nerve and is derived from the dorsal branches
lumbar and first to third sacral ventral rami. It descends along the back of the fourth and fifth lumbar and first and second sacral ventral rami.
of the thigh and popliteal fossa to the distal border of popliteus. It It descends obliquely along the lateral side of the popliteal fossa to the


then passes anterior to the arch of soleus with the popliteal artery and fibular head, medial to biceps femoris. It lies between the tendon of
continues into the leg. In the thigh, it is overlapped proximally by the biceps femoris, to which it is bound by fascia, and the lateral head of
hamstring muscles but it becomes more superficial in the popliteal gastrocnemius (Fig. 83.12). The nerve then passes into the anterolateral
fossa, where it is lateral to the popliteal vessels. At the level of the knee, compartment of the leg through a tight opening in the thick fascia
the tibial nerve becomes superficial to the popliteal vessels and crosses overlying tibialis anterior. It curves lateral to the fibular neck, deep to
to the medial side of the artery. In the distal popliteal fossa, it is over fibularis longus, and divides into superficial and deep fibular nerves; an
lapped by the junction of the two heads of gastrocnemius. articular trunk, derived from the deep fibular nerve, provides an articu
In the leg, the tibial nerve descends with the posterior tibial vessels lar branch that travels with the anterior tibial recurrent artery and a
to lie between the heel and the medial malleolus (see Fig. 82.4). Proxi proximal branch to tibialis anterior.
mally, it is deep to soleus and gastrocnemius, but in its distal third is
covered only by skin and fasciae, and overlapped sometimes by flexor Branches
hallucis longus. At first medial to the posterior tibial vessels, it crosses The common fibular nerve has articular and cutaneous branches, and
behind them and descends lateral to them until it bifurcates. It lies on terminates as the superficial and deep fibular nerves.


38
RETPAHC
Leg
Common fibular nerve
Lateral sural cutaneous nerve
Deep fibular nerve
Superficial fibular nerve
Sural nerve
Superficial fibular nerve
Deep fibular nerve
Fascia of the leg
Deep fibular nerve,
cutaneous branch
Dorsal branch of plantar
Lateral calcaneal branches digital nerve of great toe
Fig. 83.12 The course, relations and branches of the right common fibular
nerve. (Courtesy of Rolfe Birch, all rights reserved, published in Birch R,
Surgical Disorders of the Peripheral Nerve. 2nd edition, 2011. Springer-
Verlag, London.)
1415.e1


LEg
1416
9
NOITCES
Articular branches There are three articular branches. Two accom to the lateral malleolus. Branches of the superficial fibular nerve supply
pany the superior and inferior lateral genicular arteries; they may arise the skin of the dorsum of all the toes except that of the lateral side of
in common. The third, the recurrent articular branch, arises near the the fifth toe (supplied by the sural nerve) and the adjoining sides of the
termination of the common fibular nerve. It ascends with the anterior great and second toes (supplied by the medial terminal branch of the
recurrent tibial artery through tibialis anterior and supplies the antero deep fibular nerve). Some of the lateral branches of the superficial
lateral part of the knee joint capsule and the proximal tibiofibular fibular nerve are frequently absent and are replaced by sural nerve
joint. branches.
Cutaneous branches The two cutaneous branches, often from a Accessory fibular nerves An accessory superficial fibular nerve
common trunk, are the lateral sural and sural communicating nerves. and an accessory deep fibular nerve have been described as variant
The lateral sural cutaneous nerve (lateral cutaneous nerve of the calf) branches of the superficial fibular nerve; both are probably the product
supplies the skin on the anterior, posterior and lateral surfaces of the of atypical branching of the parent nerve deep to the deep fascia (see
proximal leg. The sural communicating nerve arises near the head of above).
the fibula and crosses the lateral head of gastrocnemius to join the sural
Lesions of the superficial fibular nerve
nerve. It may descend separately as far as the heel.
A lesion of the superficial fibular nerve causes weakness of foot eversion
Lesions of the common fibular nerve and sensory loss on the lateral aspect of the leg that extends on to the
The common fibular nerve is relatively unprotected as it traverses the dorsum of the foot. The nerve can be subject to entrapment as it pen
lateral aspect of the neck of the fibula and is easily compressed at this etrates the deep fascia of the leg and it may also be involved in compart
site, e.g. by plaster casts or ganglia. The nerve may also become entrapped ment syndrome that affects the lateral compartment of the leg.


by a fascial band beneath fibularis longus within the socalled fibular
Deep fibular nerve
tunnel, between the attachments of fibularis longus to the head and
The deep fibular nerve (deep peroneal nerve) begins at the bifurcation
shaft of the fibula. Traction lesions can accompany dislocations of the
of the common fibular nerve, between the fibula and the proximal part
lateral compartment of the knee, and are most likely to occur if the
of fibularis longus. It passes obliquely forwards deep to extensor digi
distal attachments of biceps femoris and the ligaments that insert on
torum longus to the front of the interosseous membrane and reaches
to the fibular head are avulsed, possibly with a small part of the fibular
the anterior tibial artery in the proximal third of the leg. It descends
head; the nerve is tethered to the tendon of biceps femoris by dense
with the artery to the ankle, where it divides into lateral and medial
fascia and so is pulled proximally. Severe traction lesions may produce
terminal branches. As it descends, the nerve is first lateral to the artery,
longitudinal injuries affecting a long segment of the common fibular
then anterior, and finally lateral again at the ankle.
nerve. Torsional injury following ankle injury (sprain or fracture) may
result in common fibular neuropathy; the injury is transmitted from
Branches
the ankle along the interosseous membrane to the proximal leg (Lal
The deep fibular nerve supplies muscular branches to tibialis anterior,
ezari et al 2012). Patients with such injury present with a foot drop.
extensor hallucis longus, extensor digitorum longus and fibularis
Physical examination reveals weakness or paralysis of ankle dorsiflex
tertius, and an articular branch to the ankle joint.
ion, toe extension and eversion of the foot, but inversion and plantar
The lateral terminal branch crosses the ankle deep to extensor digi
flexion are normal. Sensation on the dorsum of the foot, including the
torum brevis, enlarges as a pseudoganglion and supplies extensor digi
first dorsal web space, is diminished. The ankle reflex is preserved. Since
torum brevis. From the enlargement, three minute interosseous


the common fibular nerve divides at the fibular neck into the superficial
branches supply the tarsal and metatarsophalangeal joints of the middle
and deep fibular nerves, injuries to the nerve at this level may damage
three toes.
either the main trunk or its branches. Electrodiagnostic studies can help
The medial terminal branch runs distally on the dorsum of the foot
localize a common fibular nerve injury to the fibular neck region. At
lateral to the dorsalis pedis artery, and connects with the medial branch
this level, nerve conduction studies may show slowed velocities and
of the superficial fibular nerve in the first interosseous space. It divides
electromyography would demonstrate denervation in the muscles
into two dorsal digital nerves, which supply adjacent sides of the great
innervated by the common fibular nerve (such as tibialis anterior or
and second toes. Before dividing, it gives off an interosseous branch,
fibularis longus), whereas more proximally innervated muscles (par
which supplies the first metatarsophalangeal joint. The deep fibular
ticularly the short head of biceps femoris) would be normal.
nerve may end as three terminal branches.
Superficial fibular nerve
Lesions of the deep fibular nerve
The superficial fibular nerve (superficial peroneal nerve) begins at the
Isolated injury to the deep fibular nerve may result from compartment
bifurcation of the common fibular nerve. It lies deep to fibularis longus
syndrome that affects the anterior compartment of the leg or from an
at first, then passes anteroinferiorly between fibularis longus and brevis
intraneural ganglion cyst (mucinous cyst within the nerve derived from
and extensor digitorum longus, and pierces the deep fascia in the distal
the superior tibiofibular joint via the articular branch that travels with
third of the leg (see Fig. 83.12). It divides into a large medial dorsal
the anterior tibial recurrent artery (Spinner et al 2003)). Individuals
cutaneous nerve and a smaller, more laterally placed, intermediate
with lesions of the deep fibular nerve have weakness of ankle dorsiflex
dorsal cutaneous nerve, usually after piercing the deep fascia, but some


ion and extension of all toes but normal foot eversion. Sensory impair
times while it is still deep to the fascia. As the nerve lies between the
ment is confined to the first interdigital web space.
muscles it supplies fibularis longus, fibularis brevis and the skin of the
lower leg. The deep course, i.e. the compartmental localization, and the
Saphenous nerve
peripheral digital distribution of the superficial fibular nerve are subject
to considerable variation (see Kosinksi’s classification; Kosinski 1926,
Solomon et al 2001). The saphenous nerve is described on page 1399.
Branches
The medial dorsal cutaneous nerve passes in front of the ankle joint
and divides into two dorsal digital branches; one of these supplies the Bonus e-book images
medial side of the hallux and the other supplies the adjacent side of
the second and third toes. It communicates with the saphenous and
deep fibular nerves. The smaller intermediate branch crosses the dorsum Fig. 83.2 C, An axial T2-weighted MRI of the leg in a patient with
of the foot laterally. It divides into dorsal digital branches that supply anterior compartment denervation.
the contiguous sides of the third to fifth toes and the skin of the lateral
aspect of the ankle, where it connects with the sural nerve. Both Fig. 83.12 The course, relations and branches of the right common
branches, especially the intermediate, are at risk during the placement fibular nerve.
of portal skin incisions for arthroscopy and during surgical approaches


1417
38
RETPAHC
References
REFERENCES
Bayram H, Herdem M, Temoçin AK 1996 Fibular dimelia and mirror foot A paper that provides magnetic resonance imaging evidence to support
without associated anomalies. Clin Genet 49:311–3. the notion that coexisting ankle and common fibular nerve injuries occur
Cormack GC, Lamberty BGH 1994 The Arterial Anatomy of Skin Flaps. by translational forces distributed along the interosseous membrane of
Edinburgh: Elsevier, Churchill Livingstone. the leg.
A definitive anatomical reference on blood supply to the skin, which focuses
Oeffinger D, Conaway M, Stevenson R et al 2010 Tibial length growth curves
on using skin flaps in plastic and reconstructive surgical procedures.
for ambulatory children and adolescents with cerebral palsy. Dev Med
Eckhoff DG, Kramer RC, Watkins JJ et al 1994 Variation in tibial torsion. Child Neurol 52:e195–201.
Clin Anat 7:76–9. A study that investigates growth of the tibia in children with and without
A paper that discusses the wide variability of tibial torsion in individuals cerebral palsy.
and populations.
Pritchett JW, Bortel DT 1997 Single bone straight line graphs for the lower
Ganey TM, Carey TP, O’Neal ML, Ogden JA 2000 Morphologic and radio extremity. Clin Orthop Relat Res 342:132–40.
graphic characterization of fibular dimelia. J Pediatr Orthop B 9: Presents a method for the accurate prediction of growth for the femur and
293–305. tibia.
Jungers WL, Meldrum DJ, Stern JT Jr 1993 The functional and evolutionary Solomon LB, Ferris L, Tedman R et al 2001 Surgical anatomy of the sural
significance of the human peroneus tertius muscle. J Hum Evol 25: and superficial fibular nerves with an emphasis on the approach to the
377–86. lateral malleolus. J Anat 199:717–23.
A paper that discusses the functional role of peroneus tertius in human gait, A study that calls attention to the vulnerability of the sural and superficial


compared to non-human primates in whom this muscle is lacking. fibular nerves during approaches to the lateral malleolus.
Kärrholm J, Hansson LI, Selvik G 1984 Longitudinal growth rate of the distal
Spinner RJ, Atkinson JL, Tiel RL 2003 Peroneal intraneural ganglia: the
tibia and fibula in children. Clin Orthop Relat Res 191:121–8.
importance of the articular branch. A unifying theory. J Neurosurg 99:
A radiological study of the growth rates of the distal tibia and fibula in
330–43.
children.
A paper that provides layers of anatomical and pathological evidence to
Kosinski C 1926 The course, mutual relations and distribution of the cutan substantiate a unifying articular theory explaining all cases of intraneural
eous nerves of the metazonal regions of the leg and foot. J Anat Physiol ganglion cysts.
60:274–97.
Taylor GI, Razaboni RM (eds) 1994 Michael Salmon: Anatomic Studies.
A paper that describes the relations, distributions and variations of the
Book 1, Arteries of the Muscles of the Extremities and the Trunk.
cutaneous nerves of the leg and foot.
St Louis: Quality Medical Publishing.
Kristiansen LP, Gunderson RB, Steen H et al 2001 The normal development A translated, edited version of a classic French text, first published in 1933.
of tibial torsion. Skeletal Radiol 30:519–22. Now a major source book in plastic surgery.
A study that uses computed tomography to elucidate the normal
Tubbs RS, Apaydin N, Uz A et al 2009 The clinical anatomy of the ligament
development of tibial torsion in adults and children. The authors conclude
of Barkow at the proximal tibiofibular joint. Surg Radiol Anat 31:
that tibial torsion in children mainly develops during the first four years of life.
161–3.
Lalezari S, Amrami KK, Tubbs RS et al 2012 Interosseous membrane: the A first-of-its-kind study aimed at examining the anatomy of the so-called
anatomic basis for combined ankle and common fibular (peroneal) ligament of Barkow at the proximal tibiofibular joint. The ligament was


nerve injuries. Clin Anat 25:401–6. observed in the majority of specimens and was ossified in one.


CHAPTER
84
Ankle and foot
The ankle joint (talocrural joint) is a diarthrodial articulation involving 78.14). Innervation of the dorsum of the foot is provided medially by
the distal tibia and fibula and the body of the talus; it is the only the saphenous nerve, centrally by the superficial fibular nerve, and lat
example in the human body of a true mortise joint. The human foot is erally by the sural nerve; the deep fibular nerve supplies the dorsum of
a complex structure adapted to allow orthograde bipedal stance and the first web space. Dorsal branches of the medial and lateral plantar
locomotion and is the only part of the body that is in regular contact nerves supply the nail beds. The plantar aspect of the foot is supplied
with the ground (Jones 1949). There are 28 separate bones in the by the medial and lateral plantar nerves, which arise as terminal
human foot, including the sesamoid bones of the first metatarsophalan branches of the tibial nerve. The medial plantar nerve supplies sens
geal joint, and 31 joints, including the ankle joint. The hindfoot com ation to the plantar aspect of the great toe and the second, the third
prises the calcaneus and talus; the midfoot comprises the navicular, and the medial half of the fourth toes. The lateral plantar nerve supplies
cuboid and three cuneiforms; the forefoot comprises five metatarsals, the remaining lateral aspect of the fourth and the entire fifth toe. The
fourteen phalanges and two sesamoid bones. With regard to the nomen heel is innervated by calcaneal branches of the tibial and sural nerves.
clature of the surfaces of the foot, the terms ‘plantar’ and ‘dorsal’ are Injury to any of these nerves can lead to painful neuromas and loss of
used to denote inferior and superior surfaces, respectively. protective sensation. The sural nerve and its branches are especially
prone to neuroma formation.
SKIN AND SOFT TISSUES
SOFT TISSUES
SKIN
Retinacula at the ankle
Vascular supply and lymphatic drainage
In the vicinity of the ankle joint, the tendons of the muscles of the leg


The skin around the ankle is supplied by anterior lateral and anterior are bound down by localized, bandshaped thickenings of the deep
medial malleolar arteries from the anterior tibial artery, posterior fascia termed retinacula, which collectively serve to prevent bowstring
medial malleolar branches from the posterior tibial artery, posterior ing of the underlying tendons during muscle contraction. There are
lateral malleolar branches from the fibular artery, and fasciocutaneous superior and inferior extensor retinacula, superior and inferior fibular
perforators from the anterior and posterior tibial and fibular arteries. retinacula, and a flexor retinaculum.
The main blood supply to the medial side of the heel is from the medial
Extensor retinacula
calcaneal branches of the posterior tibial artery or, sometimes, the
lateral plantar artery passing through the flexor retinaculum. The skin Superior extensor retinaculum
of the lateral side of the heel is supplied by lateral calcaneal branches The superior extensor retinaculum binds down the tendons of tibialis
of the fibular artery and the lateral tarsal artery. The arterial supply to anterior, extensor hallucis longus, extensor digitorum longus and fibu
the skin of the foot is rich and is derived from branches of the dorsalis laris tertius immediately proximal to the anterior aspect of the ankle
pedis (the direct continuation of the anterior tibial artery), posterior joint (see Fig. 83.6; Fig. 84.1). The anterior tibial vessels and deep
tibial and fibular arteries. The skin covering the dorsum of the foot is fibular nerve pass deep to the retinaculum, and the superficial fibular
supplied by the dorsalis pedis artery and by its continuation, the first nerve passes superficially. The retinaculum is attached laterally to the
dorsal metatarsal artery, with smaller contributions from the anterior distal end of the anterior border of the fibula and medially to the ant
perforating branch of the fibular artery and the marginal anastomotic erior border of the tibia. Its proximal border is continuous with the
arteries on the medial and lateral borders of the foot. The skin covering deep fascia of the leg, and dense connective tissue connects its distal


the plantar surface of the foot is supplied by perforating branches of border to the inferior extensor retinaculum. Laterally, it blends with the
the medial and lateral plantar arteries (the terminal branches of the superior fibular retinaculum and medially with the upper border of the
posterior tibial artery). The skin of the forefoot is supplied by cutaneous extensor retinaculum. The tendon of tibialis anterior is the only exten
branches of the common digital arteries. sor tendon that possesses a synovial sheath at the level of the superior
Cutaneous venous drainage is via dorsal and plantar venous arches, extensor retinaculum.
which drain into medial and lateral marginal veins. The medial and
lateral marginal veins form the long and small saphenous veins, respec Inferior extensor retinaculum
tively. On the plantar aspect of the foot, a superficial venous network
The inferior extensor retinaculum is a Yshaped band lying anterior to
forms an intradermal and subdermal mesh that drains to the medial
the ankle joint (see Fig. 83.6; Fig. 84.2). The stem of the Y is at the
and lateral marginal veins. Branches that accompany the medial and
lateral end, where it is attached to the upper surface of the calcaneus,
lateral plantar arteries arise from a deep venous network. Uniquely
anterior to the calcaneal sulcus. The band passes medially, forming a
within the lower limb, venous flow in the foot is bidirectional. However,
strong loop around the tendons of fibularis tertius and extensor digit
when valves are present, flow is from the plantar to the superficial dorsal
orum longus (see Fig. 84.2A). From the deep surface of the loop, a band
system. From here, blood leaves the foot in the superficial and deep
passes laterally behind the interosseous talocalcaneal ligament and the
veins of the lower limb.
cervical ligament, and is attached to the calcaneal sulcus. At the medial
Superficial lymphatic drainage of all areas of the leg and foot
end of the loop, two diverging limbs extend medially to complete the
(except the superficial posterolateral area) is via lymphatic vessels that


‘Y’ shape of the retinaculum. The proximal limb consists of two layers.
accompany the long saphenous vein and its tributaries. The superficial
The deep layer passes deep to the tendons of extensor hallucis longus
posterolateral foot and leg drain into the popliteal lymph nodes via
and tibialis anterior, but superficial to the anterior tibial vessels and
lymphatic vessels that accompany the small saphenous vein. Deep
deep fibular nerve, to reach the medial malleolus. The superficial layer
lymphatic vessels that accompany the dorsalis pedis, posterior tibial
crosses superficial to the tendon of extensor hallucis longus and then
and fibular arteries drain into the popliteal lymph nodes.
adheres firmly to the deep one; in some cases, it continues superficial
to the tendon of tibialis anterior, before blending with the deep layer.
Innervation
The distal limb extends downwards and medially, and blends with the
plantar aponeurosis. It is superficial to the tendons of extensor hallucis
The skin covering the ankle and foot is supplied by nerves derived from longus and tibialis anterior, the dorsalis pedis artery and the terminal
1418 the fourth and fifth lumbar and first sacral spinal nerves (see Figs 78.12, branches of the deep fibular nerve.


Skin and soft tissues
1419
48
RETPAHC
Inferior fibular retinaculum
The inferior fibular retinaculum is continuous in front with the infe
Anterior tibial artery rior extensor retinaculum, and is attached posteriorly to the lateral
surface of the calcaneus. Some of its fibres are fused with the perios
teum on the fibular trochlea (peroneal trochlea or tubercle) of the
calcaneus, forming a septum between the tendons of fibularis longus
and brevis.
Superior extensor
Anterior medial retinaculum Synovial sheaths at the ankle
malleolar artery
Anterior to the ankle, the synovial sheath for tibialis anterior extends
Anterior lateral
Synovial sheath surrounding malleolar artery from the proximal margin of the superior extensor retinaculum to the
tibialis anterior
interval between the diverging limbs of the inferior retinaculum (see
Dorsalis pedis Figs 84.1–84.2B). A common sheath encloses the tendons of extensor
artery Inferior extensor digitorum longus and fibularis tertius, starting just above the level of
retinaculum the malleoli, and reaching to the level of the base of the fifth metatarsal
Common (see Figs 84.1, 84.2A). Although variable, the sheath for extensor hal
Medial and lateral
synovial sheath lucis longus begins near that for extensor digitorum longus and extends
tarsal branches
surrounding tendons as far as the base of the first metatarsal (see Figs 84.1–84.2).
of extensor digitorum Posteromedial to the ankle, the sheath for tibialis posterior starts
longus and fibularis tertius
approximately 4 cm above the medial malleolus and ends just proximal
Dorsalis pedis to the attachment of the tendon to the tuberosity of the navicular (see
artery Arcuate artery Fig. 84.2B). The sheath for flexor hallucis longus begins at the level of
the medial malleolus, and extends distally as far as the base of the first
Synovial sheath surrounding


metatarsal (see Fig. 84.2B). Occasionally, as a result of overuse, particu
tendon of extensor
larly in ballet dancers where balance on the tips of the toes en pointe
hallucis longus
involves sustained extreme plantar flexion of the ankle and great toe in
the weightbearing position, a fibrous nodule may develop in the
Tendon of tendon, just proximal to the tendon sheath. This may result in the
First dorsal metatarsal extensor digitorum thickened tendon being caught intermittently in the sheath, causing
artery
longus to second toe pain and ‘triggering’ of the great toe, a condition referred to as hallux
saltans. Surgical opening of the sheath may be required. In athletes, the
muscle belly of flexor hallucis longus may be abnormally large and
First dorsal interosseus
may extend more distally than usual; it can also catch at the opening
of the sheath. The sheath for flexor digitorum longus begins slightly
superior to the level of the medial malleolus and ends at the level of
the navicular.
Posterolateral to the ankle, the tendons of fibularis longus and brevis
are enclosed in a single sheath deep to the superior fibular retinaculum.
This sheath splits into two separate sheaths enclosing their respective
tendons deep to the inferior fibular retinaculum (see Fig. 84.2A). From
the lateral malleolus, it extends for about 4 cm both proximally and
distally.
Plantar aponeurosis
Fig. 84.1 The synovial sheaths of the tendons of the ankle, anterior
aspect. (With permission from Drake RL, Vogl AW, Mitchell A (eds), Gray’s The plantar aponeurosis is composed of densely compacted collagen
Anatomy for Students, 2nd ed, Elsevier, Churchill Livingstone. Copyright fibres orientated mainly longitudinally, but also transversely (Fig.
2010.) 84.3). Its medial and lateral borders overlie the intrinsic muscles of the
great and fifth toes, respectively, while its dense central part overlies the
extrinsic and intrinsic flexors of the digits.
The central part is the strongest and thickest. The fascia is narrow


Flexor retinaculum posteriorly, where it is attached to the medial process of the calcaneal
The flexor retinaculum is attached anteriorly to the medial malleolus, tuberosity proximal to flexor digitorum brevis, and traced distally it
distal to which it is continuous with the deep fascia on the dorsum of becomes broader and somewhat thinner. Just proximal to the level of
the foot (see Fig. 84.2B). From its malleolar attachment, it extends the metatarsal heads, it divides into five bands, one for each toe. As
posteroinferiorly to the medial process of the calcaneus and the plantar these five digital bands diverge below the metatarsal shafts, they are
aponeurosis. Proximally, there is no clear demarcation between its united by transverse fibres. Proximal, plantar and a little distal to the
border and the deep fascia of the leg, especially the deep transverse layer metatarsal heads and the metatarsophalangeal joints, the superficial
of the deep fascia. Distally, its border is continuous with the plantar stratum of each of the five bands is connected to the dermis by skin
aponeurosis, and many fibres of abductor hallucis are attached to it. ligaments (retinacula cutis). These ligaments reach the skin of the first
The flexor retinaculum converts grooves on the tibia and calcaneus into metatarsophalangeal joint proximal to, and in the floors of, the furrows
canals for the tendons, and bridges over the posterior tibial vessels and that separate the toes from the sole; Ledderhose’s disease (plantar
tibial nerve. As these structures enter the sole, they are, from medial to fibromatosis) may involve these ligaments, resulting in contractures of
lateral, the tendons of tibialis posterior and flexor digitorum longus, the affected digits. The deep stratum of each digital band of the aponeu
the posterior tibial vessels, the tibial nerve and the tendon of flexor rosis yields two septa that flank the digital flexor tendons and separate
hallucis longus (see Fig. 84.14). them from the lumbricals and the digital vessels and nerves. These septa


pass deeply to fuse with the interosseous fascia, the deep transverse
Fibular retinacula metatarsal ligaments (which run between the heads of adjacent meta
The fibular retinacula are fibrous bands that retain the tendons of fibu tarsals), the plantar ligaments of the metatarsophalangeal joints, and
laris longus and brevis in position as these tendons cross the lateral the periosteum and fibrous flexor sheaths at the base of each proximal
aspect of the ankle region (see Fig. 84.2A). phalanx. Pads of fat develop in the web spaces between the metatarsal
heads and the bases of the proximal phalanges; they cushion the digital
Superior fibular retinaculum nerves and vessels from adjoining tendinous structures and extraneous
The superior fibular retinaculum is a short band that extends from the plantar pressures. Just distal to the metatarsal heads, a plantar interdig
back of the lateral malleolus to the deep transverse fascia of the leg and ital ligament (superficial transverse metatarsal ligament) blends pro
the lateral surface of the calcaneus. Damage to the retinaculum can lead gressively with the deep aspect of the superficial stratum of the plantar
to instability of the tendons of fibularis longus and brevis. aponeurosis where it enters the toes (see Fig. 84.3). The central part of


AnklE And fooT
1420
9
noITCES
A
Tendon of extensor hallucis longus
Extensor digitorum longus
Fibularis brevis
Synovial sheath surrounding tendons of
extensor digitorum longus and fibularis tertius Fibula
Synovial sheath of extensor hallucis longus tendon
Fibularis longus
Extensor hallucis brevis Inferior extensor retinaculum
Calcaneal tendon
Tendons of extensor digitorum longus
Superior fibular retinaculum
Inferior fibular retinaculum
Extensor digitorum brevis
Tendon of fibularis tertius
Common synovial sheath for tendons
Tendon of fibularis brevis of fibularis longus and fibularis brevis
B
Synovial sheath of
tibialis posterior
tendon
Synovial sheath of flexor
digitorum longus tendon Synovial sheath of tibialis anterior tendon
Synovial sheath of
flexor hallucis longus
Inferior extensor retinaculum
tendon
Calcaneal tendon Synovial sheath of extensor hallucis longus tendon
Flexor retinaculum Synovial sheath of flexor hallucis longus tendon
Synovial sheath of
tibialis posterior
tendon
Tendon of abductor hallucis
Abductor hallucis
Synovial sheaths of
Flexor digitorum brevis tendons in toes
Synovial sheath of flexor digitorum longus tendon
Fig. 84.2 The synovial sheaths of the tendons of the ankle. A, Lateral aspect. B, Medial aspect. (With permission from Waschke J, Paulsen F (eds),
Sobotta Atlas of Human Anatomy, 15th ed, Elsevier, Urban & Fischer. Copyright 2013.)
the plantar aponeurosis thus provides an intermediary structure between an intermuscular septum, and dorsally by the first metatarsal. The
the skin and the osteoligamentous framework of the foot via numerous central compartment contains flexor digitorum brevis, the lumbricals,
cutaneous retinacula and deep septa that extend to the metatarsals and flexor accessorius (quadratus plantae), adductor hallucis, and the


phalanges. The central part is also continuous with the medial and tendons of flexor digitorum longus. The central compartment is
lateral parts; at the junctions, two intermuscular septa, medial and bounded by the plantar aponeurosis inferiorly, the osseofascial tar
lateral, extend in oblique vertical planes between the medial, intermedi sometatarsal structures dorsally and intermuscular septa medially and
ate and lateral groups of plantar muscles to reach bone. Thinner, hori laterally. The lateral compartment contains abductor digiti minimi and
zontal intermuscular septa, derived from the vertical intermuscular flexor digiti minimi brevis, and its boundaries are the fifth metatarsal
septa, pass between the muscle layers. dorsally, the plantar aponeurosis inferiorly and laterally, and an inter
The lateral part of the plantar aponeurosis, which covers abductor muscular septum medially. The interosseous compartment contains the
digiti minimi, is thin distally and thick proximally, where it forms a seven interossei and its boundaries are the interosseous fascia and the
strong band, sometimes containing muscle fibres, between the lateral metatarsals.
process of the calcaneal tuberosity and the base of the fifth metatarsal. The dorsal aspect of the foot effectively contains a single compart
It is continuous medially with the central part of the aponeurosis, and ment, which is occupied by the extrinsic extensor tendons and exten
with the fascia on the dorsum of the foot around its lateral border. The sor digitorum brevis, and is roofed by the deep dorsal fascia (see
medial part of the plantar aponeurosis, which covers abductor hallucis, below).
is thin. It is continuous proximally with the flexor retinaculum, medi
ally with the dorsal fascia of the foot, and laterally with the central part Lateral intermuscular septum
of the plantar aponeurosis. The lateral intermuscular septum is incomplete, especially at its proxi
mal end where the lateral plantar artery and nerve enter the lateral
Plantar fasciitis
compartment. Distally, its deep attachments are to the fibrous sheath


Plantar fasciitis is a common cause of plantar heel pain. of fibularis longus and to the fifth metatarsal.
Fascial compartments of the foot Medial intermuscular septum
The medial intermuscular septum is incomplete where the tendon of
There are four main compartments of the plantar aspect of the foot (Fig. flexor digitorum longus enters the central compartment and where
84.4). The medial compartment contains abductor hallucis and flexor adductor hallucis and the lateral head of flexor hallucis brevis enter the
hallucis brevis, as well as the tendon of flexor hallucis longus. The medial compartment. The septum divides into three bands – proximal,
medial compartment is bounded inferiorly and medially by the medial intermediate and distal, each of which displays lateral and medial divi
part of the plantar aponeurosis and its medial extension, laterally by sions as it approaches its deep attachments. The proximal band is


48
RETPAHC
Ankle and foot
Many contributing aetiological factors have been reported, such as
obesity, abnormal posture, advanced age, and extrinsic factors such as
poor footwear and excessive biomechanical stressors (League 2008).
These factors may lead to inflammation and degeneration of the plantar
aponeurosis. However, recent histological studies have called into ques
tion the role of inflammation in the aetiology of the disease and have
led to the recommendation that the term ‘fasciitis’ be replaced with
‘fasciosis’ (Lemont et al 2003). The stress and strain applied to the
plantar aponeurosis may lead to the formation of a bony spur at its
proximal attachment to the calcaneus. Clinically, palpation of the
plantar aponeurosis at the medial tubercle of the calcaneus may result
in localized tenderness and exacerbated heel pain in patients. Multiple
treatments, from conservative therapies to surgical interventions, have
been used to provide pain relief. Nonoperative treatments include
stretching exercises, orthoses, extracorporeal shockwave therapy, mult
iple steroid injections, padding and strapping (Landorf and Menz
2008). Recently, the use of cryosurgery has been investigated for this
condition (Cavazos et al 2009). Surgical treatments include partial or
complete release of the plantar aponeurosis with concomitant heel spur
resection and nerve decompression, when necessary (League 2008).
1420.e1