attached to the dorsolateral aspect of the navicular. plane joint.
Long plantar ligament The long plantar ligament is the longest liga Articulating surfaces The navicular articulates distally with the
ment associated with the tarsus (see Figs 84.13C, 84.17; Fig. 84.18). It cuneiform bones where the distal navicular surface is transversely
extends from the plantar surface of the calcaneus (anterior to the pro convex and divided into three facets by low ridges that are adapted to
cesses of its tuberosity) and from its anterior tubercle, to the ridge and the proximal, slightly curved surfaces of the cuneiforms.
tuberosity on the plantar surface of the cuboid. Deep fibres are attached
to the cuboid and more superficial fibres continue to the bases of the Fibrous capsule The fibrous capsule is continuous with those of the
second to fourth, and sometimes fifth, metatarsals. This ligament,
intercuneiform and cuneocuboid joints, and it is also connected to the
together with the groove on the plantar surface of the cuboid, makes a
second and third cuneometatarsal joints and intermetatarsal joints
tunnel for the tendon of fibularis longus. It is a most powerful factor
between the second to fourth metatarsals.
limiting depression of the lateral longitudinal arch.
Ligaments The ligaments of the naviculocuneiform joint are the
Plantar calcaneocuboid ligament This short ligament (see Fig. 84.17)
dorsal and plantar ligaments.
is deeper than the long plantar ligament, from which it is separated by
areolar tissue. It is a short, wide and strong band stretching from the
anterior calcaneal tubercle and the depression anterior to it, to the Dorsal and plantar ligaments The dorsal and plantar ligaments
adjoining part of the plantar surface of the cuboid; it also supports connect the navicular to each cuneiform; of the three dorsal ligaments,
the lateral longitudinal arch. one is attached to each cuneiform. The fasciculus from the navicular to
the medial cuneiform is continued as the capsule of the joint around


Synovial membrane A synovial membrane lines the calcaneocuboid its medial aspect, and then blends medially with the plantar ligament.
joint. Plantar ligaments have similar attachments and receive slips from the
tendon of tibialis posterior.
Innervation The calcaneocuboid joint is innervated on its plantar
aspect by the lateral plantar nerve, and dorsally by the sural and deep Synovial membrane The synovial membrane lines the fibrous
fibular nerves. capsule in the manner outlined above.
Tibia
Flexor hallucis longus
Extensor hallucis longus
Ankle joint Calcaneal tendon
Subtalar joint (talocalcaneal joint)
Talotarsal joint
Talocalcaneonavicular joint
Navicular Talus
Intermediate cuneiform
Tarsometatarsal joint
Tendon of fibularis longus Talocalcaneal interosseous ligament
Second metatarsal
First dorsal interosseous
Calcaneus
Calcaneal tuberosity
Proximal phalanx, base Calcaneal fat pad
Metatarsophalangeal joint
(second toe) Adductor hallucis, oblique head Long plantar ligament Plantar aponeurosis
Flexor accessorius Flexor digitorum brevis
Fig. 84.18 A sagittal section of the foot showing ankle and tarsal joints. (With permission from Waschke J, Paulsen F (eds), Sobotta Atlas of Human
Anatomy, 15th ed, Elsevier, Urban & Fischer. Copyright 2013.)


Joints
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Innervation The naviculocuneiform joint is innervated dorsally by the tubercle of the fifth metatarsal to the tarsometatarsal joint of the
branches from the deep fibular nerve. The medial plantar nerve inner great toe, except for that between the second metatarsal and intermedi
vates the medial and intermediate naviculocuneiform joints, and the ate cuneiform, which is 2–3 mm proximal to this line (see Figs 84.5A,
lateral plantar nerve innervates the lateral naviculocuneiform joint. 84.11). Ryan et al (2012) reported that the average joint depths for the
first, second and third metatarsal–cuneiform joints were 32.3, 26.9, and
Relations The tendon of tibialis posterior sends fibres to the medial 23.6 mm, respectively.
cuneiform and crosses the joint on its medial side; it is vulnerable to
injury when a medial surgical approach is used, as are the dorsal venous Fibrous capsule The tarsometatarsal joint of the great toe has its
arch and the saphenous nerve. The tendon of tibialis anterior passes own capsule. The articular capsules and cavities of the second and third
over the dorsomedial aspect of the joint and the tendon of extensor toes are continuous with those of the intercuneiform and naviculo
hallucis longus is lateral. Running over the intermediate cuneiform, cuneiform joints, but are separated from the fourth and fifth joints by
from medial to lateral, are the deep fibular nerve, the dorsalis pedis an interosseous ligament between the lateral cuneiform and fourth
artery and extensor hallucis brevis, all of which are vulnerable during metatarsal base.
dorsal exposure of the joint. On the lateral aspect of the joint, the
superficial structures at risk are the superficial fibular nerve and the Ligaments The bones are connected by dorsal and plantar tarsometa
dorsal venous arch of the foot. tarsal and cuneometatarsal interosseous ligaments.
Muscles producing movement Movements at the naviculocunei Dorsal ligaments The dorsal ligaments are strong and flat. The first


form, cuboideonavicular, intercuneiform and cuneocuboid joints are metatarsal is joined to the medial cuneiform by an articular capsule,
slight and subtle gliding and rotational movements that occur during and the other tarsometatarsal capsules blend with the dorsal and
pronation or supination of the foot; when alterations occur in a loaded plantar ligaments. The second metatarsal receives a band from each
foot in contact with the ground, they increase suppleness when the cuneiform, the third from the lateral cuneiform, the fourth from the
forefoot is stressed, e.g. in the initial thrust of running and jumping. lateral cuneiform and the cuboid, and the fifth from the cuboid alone.
The muscles responsible for these slight movements are tibialis anterior,
tibialis posterior, fibularis longus and brevis, and the long flexors and Plantar ligaments The plantar ligaments are longitudinal and oblique
extensors of the toes. bands, and are less regular than the dorsal ligaments. Those for the first
and second metatarsals are strongest. The second and third metatarsals
Cuboideonavicular joint are joined by oblique bands to the medial cuneiform, and the fourth
and fifth metatarsals by a few fibres to the cuboid.
The cuboideonavicular joint is usually a fibrous joint, the bones being
connected by dorsal, plantar and interosseous ligaments. This syn Cuneometatarsal interosseous ligaments There are three cuneometa
desmosis is often a synovial joint that is almost plane; its articular tarsal interosseous ligaments. One (the strongest) passes from the
capsule and synovial lining are continuous with that of the naviculo lateral surface of the medial cuneiform to the adjacent angle of the
cuneiform joint. The dorsal ligament extends distolaterally, and the second metatarsal (see Fig. 84.17). Known as Lisfranc’s ligament, it is
plantar nearly transversely from the cuboid to the navicular. The inter crucial to the stability of the tarsometatarsal joint complex. Disruption
osseous ligament is made of strong transverse fibres and connects non of this ligament can lead to instability and deformity, and subsequent


articular parts of adjacent surfaces to the two bones. degenerative changes. A second ligament connects the lateral cuneiform
to the adjacent angle of the second metatarsal; it does not divide the
Intercuneiform and cuneocuboid joints joint between the second metatarsal and lateral cuneiform, and is
inconstant. A third ligament connects the lateral angle of the lateral
cuneiform to the adjacent fourth metatarsal base.
The intercuneiform and cuneocuboid joints are all synovial and approx
imately plane or slightly curved. Their articular capsules and synovial
Synovial membrane The first tarsometatarsal joint has its own
linings are continuous with those of the naviculocuneiform joints. The
capsule, with a synovial lining. The other joints are similarly arranged,
bones are connected by dorsal, plantar and interosseous ligaments (see
but there is a communication between the second and third and
Figs 84.13B,C, 84.15A).
between the fourth and fifth tarsometatarsal joints.
Ligaments The ligaments of the intercuneiform and cuneocuboid
Innervation The interosseous cuneometatarsal ligaments are inner
joints are the dorsal, plantar and interosseous ligaments.
vated dorsally via the deep fibular nerve. The plantar aspects of the
medial two joints are innervated from the medial plantar nerve, and
Dorsal and plantar ligaments The dorsal and plantar ligaments each
the plantar aspects of the lateral joints are innervated by the lateral
have three transverse bands that pass between the medial and inter
plantar nerve.
mediate cuneiforms, the intermediate and lateral cuneiforms, and the
lateral cuneiform and cuboid. The plantar ligaments receive slips from
Relations From medial to lateral, the following structures cross the
the tendon of tibialis posterior.
dorsal aspect of the tarsometatarsal joints: the saphenous nerve, the
dorsal venous arch, the tendon of extensor hallucis longus, the dorsalis
Interosseous ligaments The interosseous ligaments connect non
pedis artery, the deep fibular nerve, extensor hallucis brevis, the tendons
articular areas of adjacent surfaces and are strong agents in maintaining


of extensor digitorum longus, extensor digitorum brevis, fibularis tertius
the transverse arch.
and fibularis brevis. Branches of the superficial fibular nerve are variable
Innervation The intercuneiform and cuneocuboid joints are inner in location on the dorsum. The sural nerve lies just inferior to the
vated dorsally via the deep fibular nerve. The plantar aspect of the tendon of fibularis brevis in the subcutaneous tissues. Surgery involving
medial two joints is innervated from the medial plantar nerve, and the the tarsometatarsal joints is performed through a dorsal approach, and
plantar aspect of the lateral joints is innervated from the lateral plantar therefore all of these structures are potentially at risk of injury.
nerve.
Factors maintaining stability The major stabilizers of the tarso
Muscles producing movement The muscles producing move metatarsal joints are the associated ligaments. However, despite the
ment are as described above for the naviculocuneiform joint. strength of the ligaments, this joint complex is vulnerable to injury
because of the lack of ligamentous connection between the first and
second metatarsal bases. The medial interosseous ligament or Lisfranc’s
TARSOMETATARSAL JOINTS ligament is responsible for the telltale avulsion fracture of the second
metatarsal base, which may be the only radiographic indication of
Tarsometatarsal articulations are approximately plane synovial joints. abnormality after injury to this part of the foot. It is a highly significant
injury that is often missed; failure to recognize and treat this injury by
Articulating surfaces The first metatarsal articulates with the surgical reduction and fixation can lead to longterm disability.
medial cuneiform; the second is recessed between the medial and
lateral cuneiforms and articulates with the intermediate cuneiform; the Muscles producing movement Movements between the tarsals
third articulates with the lateral cuneiform; the fourth articulates with and metatarsals are limited to flexion and extension, except in the first
the lateral cuneiform and the cuboid; and the fifth articulates with the tarsometatarsal joint, where some abduction and rotation occur. The


cuboid. The joints are approximately on an imaginary line traced from muscles that produce this motion are tibialis anterior and fibularis


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longus. Flexion and extension are brought about by the long and short ments of adjoining metatarsophalangeal joints. The interossei are
flexors and extensors of the toes. Movement between the medial cunei dorsal to, and the lumbricals, digital vessels and nerves are plantar to,
form and first metatarsal, and between the fourth and fifth metatarsal these ligaments. They resemble the deep transverse metacarpal liga
bases and the cuboid, is moderate and allows the foot to adapt to ments except that, in the foot, there is a deep transverse metatarsal liga
uneven surfaces, whereas movement between the second and third ment between the plantar ligament of the second metatarsophalangeal
metatarsal bases and their corresponding cuneiforms is very limited. joint and that of the first metatarsophalangeal joint (see Fig. 84.17).
Collateral ligaments The collateral ligaments are strong cords flanking
INTERMETATARSAL JOINTS each joint. They are attached to the dorsal tubercles on the metatarsal
heads and the corresponding side of the phalangeal bases, and they
The intermetatarsal ligaments are very strong and are present between slope inferodistally. The first metatarsophalangeal joint also contains
all the lateral four metatarsals; they are absent between the first and metatarsosesamoid ligaments. On either side, the ligaments arise from
second metatarsals. The base of the second metatarsal is joined to the metatarsal head with a narrow origin and then fan out to insert on
the first tarsometatarsal joint by the cuneometatarsal interosseous the border of the proximal phalanx and the plantar plate. Each collat
ligament. eral ligament consists of the phalangeal collateral ligament, which
inserts into the base of the proximal phalanx, and the accessory col
Ligaments The ligaments of the intermetatarsal joints include the lateral ligament, which inserts into the plantar plate.
dorsal and plantar intermetatarsal ligaments.
Synovial membrane Each metatarsophalangeal joint is a separate


Dorsal and plantar intermetatarsal ligaments As with their dorsal synovial joint.
counterparts, the plantar intermetatarsal ligaments are longitudinal,
oblique or transverse and they vary considerably in both number and Innervation The main nerve supply of the metatarsophalangeal joints
organization. The plantar ligaments are significantly stronger than the is from the plantar digital nerves, which supply the first, second, third
corresponding dorsal ligaments. The strongest is the second oblique and medial half of the fourth metatarsophalangeal joint on their plantar
plantar ligament, which connects the medial cuneiform to the bases of aspects. Digital branches of the lateral plantar nerve supply the lateral
the second and third metatarsals. half of the fourth joint, and both medial and lateral aspects of the fifth
joint, on their plantar sides. The medial dorsal cutaneous branch of the
Other ligaments All the metatarsal heads are connected indirectly by superficial fibular nerve supplies the dorsomedial side of the hallucal
deep transverse metatarsal ligaments. Dorsal and plantar ligaments pass metatarsophalangeal joint. The deep fibular nerve supplies the dorso
transversely between adjacent bases; interosseous ligaments are strong lateral side of the hallucal metatarsophalangeal joint and the medial
transverse bands that connect nonarticular parts of the adjacent sur side of the metatarsophalangeal joint of the second toe.
faces (see Fig. 84.17).
Relations Dorsally, the tendon of extensor hallucis longus lies medial
to the tendon of extensor hallucis brevis. The same arrangement occurs
METATARSOPHALANGEAL JOINTS in the lateral four toes with the tendons of extensor digitorum longus
and brevis. The interossei are plantarmedial and plantarlateral, dorsal
Metatarsophalangeal articulations are ovoid or ellipsoid joints between to the transverse intermetatarsal ligament, whereas the lumbrical ten
the rounded metatarsal heads and shallow cavities on the proximal dons and the digital artery and nerve are plantar to the transverse
phalangeal bases. They are usually 2.5 cm proximal to the web spaces intermetatarsal ligament. The extrinsic and intrinsic flexors lie on the


of the toes. plantar aspect of the joint in the midline. If approaching the metatar
sophalangeal joint surgically from the plantar surface, it is important
Articulating surfaces Articular surfaces cover the distal and plantar, not to stray from the midline.
but not the dorsal, aspects of the metatarsal heads. The plantar aspect
of the first metatarsal head has two longitudinal grooves separated by Factors maintaining stability The first metatarsophalangeal joint
a ridge (the crista). Each articulates with a sesamoid bone embedded owes its stability to its capsuloligamentous structures, and to flexor and
in the capsule of the joint, formed here by the two tendons of flexor extensor hallucis brevis, with a small contribution from flexor and
hallucis brevis. The sesamoid bones are connected to each other by the extensor hallucis longus or the bony contours. The collateral ligaments
intersesamoid ligament, which forms the floor of the tendinous canal and plantar plates stabilize the metatarsophalangeal joints of the lateral
for the tendon of flexor hallucis longus. The medial sesamoid bone four toes. Rupture of the plantar plate can lead to dislocation of the
receives an attachment from abductor hallucis and the lateral sesamoid metatarsophalangeal joint and, possibly, hammer toe deformity.
bone receives an attachment from adductor hallucis, forming the con
joint tendon. Muscles producing movement The types of movements that
Articular areas on the proximal phalangeal bases are concave. occur at these joints are like those that occur at the corresponding joints
The ligaments are capsular, plantar, deep transverse metatarsal and in the hand, but the range of movement is quite different. In contrast
collateral. to the metacarpophalangeal joints, the range of active extension that
can occur at the metatarsophalangeal joints (50–60°) is greater than
Fibrous capsules Fibrous capsules are attached to their articular that of flexion (30–40°); this is an adaptation to the needs of walking,
margins. They are thin dorsally, and may be separated from the extrinsic and is most marked in the joint of the great toe, where flexion is a few


extensor tendons by small bursae, or they may be replaced by the degrees while extension may reach 90°. When the foot is on the ground,
tendons, but they are inseparable from the plantar and collateral liga metatarsophalangeal joints are already extended to at least 25° because
ments. The plantar aponeurosis blends with the plantar capsule to form the metatarsals incline proximally in the longitudinal arches of the foot
the socalled ‘plantar plate’, which inserts distally into the base of the (see Fig. 84.8A). The range of passive movements in these joints is 90°
proximal phalanx via medial and lateral bundles. Proximally, the plate (extension) and 45° (flexion), according to Kapandji (2011). The fol
is attached to the metatarsal head via a thin synovial fold. It also receives lowing muscles produce movements at the metatarsophalangeal joints:
an attachment from the accessory collateral ligament.
Flexion Flexor digitorum brevis, lumbricals and interossei, assisted by
Ligaments The ligaments of the metatarsophalangeal joints are the flexor digitorum longus and flexor accessorius. In the fifth toe, flexor
plantar, deep transverse metatarsal and collateral ligaments. digiti minimi brevis assists. For the great toe, flexors hallucis longus and
brevis and the oblique head of the adductor hallucis are the only flexors.
Plantar ligaments The plantar ligaments are thick and dense. They lie
between and blend with the collateral ligaments, being loosely attached Extension Extensors digitorum longus and extensor digitorum brevis,
to the metatarsals and firmly attached to the phalangeal bases. Their extensor hallucis longus.
margins blend with the deep transverse metatarsal ligaments. Their
plantar surfaces are grooved for the flexor tendons, the fibrous sheaths Adduction Adductor hallucis; in the third to fifth toes, the first, second
of which connect with the edges of the grooves, and their deep surfaces and third plantar interossei, respectively.
extend the articular areas for metatarsal heads.
Abduction Abductor hallucis; in the second toe, the first and second


Deep transverse metatarsal ligaments The deep transverse metatarsal dorsal interossei; in the third and fourth toes, the corresponding dorsal
ligaments are four short, wide, flat bands that unite the plantar liga interossei; in the fifth toe, abductor digiti minimi.


Arches of the foot
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RETPAHC
Note that the line of reference for adduction and abduction is along (Hicks 1954). Dorsiflexion, especially of the great toe, draws the two
the second digit, which has the least mobile metatarsal. The second toe pillars together, thus heightening the arch: the socalled ‘windlass’
may therefore be ‘abducted’ medially and laterally by the first and mechanism. Next in importance is the spring ligament, which supports
second dorsal interossei, respectively. the head of the talus. If this ligament fails, the navicular and calcaneus
separate, allowing the talar head, which is the highest point of the arch,
Hallux valgus Hallux valgus is a common condition, occurring to descend, leading to a flatfoot deformity. The talocalcaneal ligaments
mainly in individuals who have a genetic predisposition. Footwear is and the anterior fibres of the deltoid ligament, from the tibia to the
implicated in the condition, which presumably accounts for the greater navicular, also contribute to the stability of the arch.
incidence in females. Metatarsus primus varus, an adduction deformity Muscles play a role in the maintenance of the medial longitudinal
of the first metatarsal, is commonly associated with hallux valgus. arch. Flexor hallucis longus acts as a bowstring. Flexor digitorum longus,
The more spheroidal the shape of the first metatarsal head, the more abductor hallucis and the medial half of flexor digitorum brevis also
likely it is to be unstable. Conversely, a flat metatarsal head is less likely contribute but to a lesser extent. Tibialis posterior and anterior invert
to be associated with hallux valgus. No muscle inserts into the first and adduct the foot, and so help to raise its medial border. The impor
metatarsal head, and therefore its position is determined by the posi tance of tibialis posterior is manifest by the collapse of the medial
tion of the proximal phalanx. As the proximal phalanx moves laterally longitudinal arch that accompanies failure of its tendon (see below).
on the metatarsal head, it pushes the head medially. This leads to


attenuation of the medial soft tissue structures and contracture of the Lateral longitudinal arch
lateral ones. The sesamoid sling (i.e. plantar plate and flexor hallucis
brevis), which is anchored laterally by adductor hallucis, remains in
The lateral longitudinal arch is a much less pronounced arch than the
place as the head moves medially, displacing the sesamoid bones from
medial one. The bones making up the lateral longitudinal arch are the
beneath the metatarsal head. As this happens, the weakest point of the
calcaneus, the cuboid and the fourth and fifth metatarsals; they con
medial capsule fails, so that abductor hallucis slips under the metatarsal
tribute little to the arch in terms of stability (see Fig. 84.8A). The pillars
head. This leads to failure of the intrinsic muscles to stabilize the joint,
are the calcaneus posteriorly and the lateral two metatarsal heads ant
and the pull of abductor hallucis leads to spinning of the proximal
eriorly. Ligaments play a more important role in stabilizing the arch,
phalanx, which results in a varus deformity. Failure to intervene surgi
especially the lateral part of the plantar aponeurosis and the long and
cally inevitably results in a progressive deformity.
short plantar ligaments. However, the tendon of fibularis longus makes
the most important contribution to the maintenance of the lateral arch.
INTERPHALANGEAL JOINTS The lateral two tendons of flexor digitorum longus (and flexor acces
sorius), the muscles of the first layer (lateral half of flexor digitorum
brevis and abductor digiti minimi), and fibularis brevis and tertius also
Interphalangeal articulations are almost pure hinge joints, in which the
contribute to the maintenance of the lateral longitudinal arch.
trochlear surfaces on the phalangeal heads articulate with reciprocally
curved surfaces on adjacent phalangeal bases. Each has an articular
Transverse arch
capsule and two collateral ligaments, as occurs in the metatarsophalan
geal joints. The plantar surface of the capsule is a thickened fibrous


plate, like the plantar metatarsophalangeal ligaments, and is often The bones involved in the transverse arch are the bases of the five meta
termed the plantar ligament. tarsals, the cuboid and the cuneiforms (see Fig. 84.8A). The intermedi
ate and lateral cuneiforms are wedgeshaped and thus adapted to
Innervation The interphalangeal articulations are innervated by maintenance of the transverse arch. The ligaments, which bind the
branches from the plantar digital nerves. The medial dorsal cutaneous cuneiforms and the metatarsal bases, mainly provide the stability of the
branch of the superficial fibular nerve also supplies the interphalangeal arch, as does the tendon of fibularis longus, which tends to approximate
joint of the great toe. Branches of the deep fibular, intermediate dorsal the medial and lateral borders of the foot. A shallow arch is maintained
cutaneous and sural nerves sometimes supply the joints of the lateral at the metatarsal heads by the deep transverse ligaments, transverse
four toes. fibres that tie together the digital slips of the plantar aponeurosis, and,
to a lesser extent, by the transverse head of adductor hallucis.
Muscles producing movement Movements are flexion and exten
sion, which are greater in amplitude between the proximal and middle Pes planus and pes cavus
phalanges than between the middle and distal. Flexion is marked, but
extension is limited by tension of the flexor muscles and plantar liga The term pes planus denotes an excessively flat foot. There is no precise
ments. Abduction, adduction and rotation occur to a minor extent. The degree of flatness that defines pes planus but it may be either physiologi
following muscles produce movements at the interphalangeal joints: cal or pathological. In physiological pes planus, the feet are flexible and
rarely problematic. There is a high prevalence in children of preschool
Flexion Flexor digitorum longus, flexor digitorum brevis, and flexor age. In the age group 2–6 years, normal arch volumes in the sitting and
hallucis longus. Flexor accessorius assists flexor digitorum longus to standing positions correlate with the height of the navicular (lowest


maintain an extended toe and neutralize the medial pull of flexor digi palpable medial projection of the navicular to the floor (Chang et al
torum longus. 2012)). In marked contrast, pathological pes planus is often associated
with stiffness and pain. The windlass (or ‘Jack’s great toe’) test involves
Extension Extensor digitorum longus, extensor digitorum brevis, exten passively dorsiflexing the great toe at the metatarsophalangeal joint.
sor hallucis longus and extensor hallucis brevis. This tightens the plantar aponeurosis and, in flexible pes planus, results
in accentuation of the medial longitudinal arch. In pathological pes
ARCHES OF THE FOOT planus, no accentuation of the arch is seen. This test can also be carried
out by asking the individual to stand with both feet plantar flexed while
viewing the hindfoot from behind. In flexible flat feet, the calcaneus
Three main arches are recognized in the foot. They are the medial lon swings into a varus position; in pathological pes planus it does not.
gitudinal, the lateral longitudinal and the transverse arches. The roles Causes of pathological pes planus include tarsal coalition, disruption
of the arches of the foot in standing, walking and running are discussed of the tendon of tibialis posterior, rupture of the spring ligament, tar
later in this chapter. sometatarsal arthritis (and subsequent collapse), and hindfoot (talocal
caneal or subtalar joint) degenerative or inflammatory arthritis.
Medial longitudinal arch
Pes cavus denotes an excessively higharched foot. The majority of
cases arise as a result of a neurological disorder (e.g. Charcot–Marie–
The medial margin of the foot arches up between the heel proximally Tooth disease, tethered spinal cord, poliomyelitis). According to the
and the medial three metatarsophalangeal joints to form a visible arch anatomical location of the deformity, pes cavus may be classified into
(see Fig. 84.8A). It is made up of the calcaneus, talar head, navicular, hindfoot, midfoot or forefoot cavus. When pes cavus involves all three


the three cuneiforms and the medial three metatarsals. The posterior parts of the foot, it is called ‘global’ cavus.
and anterior pillars are the posterior part of the inferior calcaneal surface In Charcot–Marie–Tooth disease, an overactive fibularis longus leads
and the three metatarsal heads, respectively. The bones themselves con to plantar hyperflexion of the first metatarsal. To keep the forefoot in
tribute little to the stability of the arch, whereas the ligaments contribute contact with the ground, the patient develops a progressive compens
significantly. The most important ligamentous structure is the plantar atory hindfoot varus. If ignored, the hindfoot varus, which is initially
aponeurosis, which acts as a tie beam between the supporting pillars flexible, becomes fixed.


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section (Ahmed et al 1998, Zantop et al 2003, Chen et al 2009). The
MUSCLES
posterior tibial artery primarily supplies the proximal and distal sec
tions, and the midsection receives a relatively poor blood supply from
The muscles acting on the foot may be divided into extrinsic and intrin the fibular artery (Chen et al 2009). These findings support previous
sic groups. work showing that the hypovascular midsection of the calcaneal
tendon is the area most prone to rupture and also underscore the
importance of avoiding disruption of the vascular supply to the tendon
EXTRINSIC MUSCLES
during percutaneous surgery. The vascularity of the skin overlying the
calcaneal tendon varies according to location: the skin on the medial
The extrinsic muscles are described in Chapter 83. Their tendons cross side of the tendon is supplied by the posterior tibial artery and on the
the ankle, and move and stabilize this joint. Distally, the tendons also lateral side by the fibular artery (Yepes et al 2010). The skin covering
act on the joints of the foot and help to stabilize them. The muscles the posterior aspect of the tendon is the most poorly vascularized;
can be grouped according to their arrangement in the leg. The extensors medial or lateral incisions of the skin surrounding the tendon should
arise in the anterior compartment of the leg and their tendons pass reduce postsurgical healing complications relative to a direct posterior
anterior to the ankle, where they are bound down by the extensor reti approach.
nacula. The lateral group arises in the relatively narrow lateral compart The calcaneal tendon is not the only plantar flexor of the ankle,
ment of the leg and their tendons pass posterior to the lateral malleolus, which is one of the reasons that ruptures of the calcaneal tendon may
bound down by the fibular retinacula. The flexors arise in the posterior not always be clinically apparent. However, it is a frequent site of
compartment of the leg and their tendons pass posterior to the ankle, pathology because of its susceptibility to rupture, degenerative change


where the tendons of the superficial group of flexors are inserted into (tendinosis) and inflammation (paratendinitis); the area of relative
the calcaneus (see below), and the tendons of the deep group of flexors avascularity in the midsubstance of the tendon is where the majority
are bound down by the flexor retinaculum. of problems occur.
Anterior group Relations The calcaneal tendon is subcutaneous. The sural nerve
crosses its lateral border about 10 cm above its insertion; the nerve is
Tibialis anterior, extensor hallucis longus, extensor digitorum longus especially vulnerable here to iatrogenic injury during surgery. Distally,
and fibularis tertius are described on pages 1406–1408. there are bursae superficial and deep to the tendon. The muscle belly
of flexor hallucis longus lies deep to the deep fascia on the anterior
Lateral group surface of the tendon.
Actions The calcaneal tendon produces plantar flexion of the ankle
Fibularis longus and fibularis brevis are described on page 1408.
joint. The tendon fibres spiral laterally through 90° as they descend, so
that the fibres associated with gastrocnemius come to insert on the bone
Posterior group
more laterally, and those associated with soleus more medially.
Superficial group Heel bursae There are three locations about the heel where bursae
Gastrocnemius, soleus and plantaris are described on pages 1409–1410; occur. The most common is the retrocalcaneal bursa, which lies between
the calcaneal tendon is described below. the calcaneal tendon and the posterior surface of the calcaneus. An
almost constant finding, it has an anterior bursal wall composed of
Calcaneal (Achilles) tendon fibrocartilage and a thin posterior wall, which blends with the thin
The calcaneal tendon is the common tendon of gastrocnemius and epitenon (epitendineum) of the calcaneal tendon. Dorsiflexion of the
soleus. It is the thickest and strongest tendon in the human body (see ankle results in compression of the bursa. Less common are an adventi


Fig. 82.3). Approximately 15 cm long, it begins near the middle of the tious bursa superficial to the calcaneal tendon, and a subcalcaneal bursa
calf; its anterior surface receives muscle fibres from soleus almost to its between the inferior surface of the calcaneus and the origin of the
inferior end. It gradually becomes more rounded until approximately plantar aponeurosis. A prominent superolateral calcaneal tuberosity
4 cm above the calcaneus; below this level, it expands and becomes may impinge on the deep aspect of the calcaneal tendon where it inserts
attached to the midpoint of the posterior surface of the calcaneus. Age on to the calcaneus (Haglund’s disease). It is often associated with a
dependent variability in the terminal insertion site of the calcaneal retrocalcaneal bursa, and symptoms are exacerbated by dorsiflexion of
tendon (Snow et al 1995, Kim et al 2010, Kim et al 2011) may explain the ankle because this movement increases the pressure within the
why calcaneal tendinopathy is infrequently found in children and adol bursa and causes impingement of calcaneus against the tendon
escents. It also has implications for the appropriate siting of surgical insertion.
entry portals about the calcaneal tendon insertion in order to reduce
the risk of iatrogenic injury to the tendon (Lohrer et al 2008). The fibres Plantaris
of the calcaneal tendon are not aligned strictly vertically and they Plantaris is described on page 1410.
display a variable degree of spiralization (Cummins and Anson 1946).
Deep group
The tendon fibres spiral laterally through 90° as they descend, so
that the fibres associated with gastrocnemius come to insert on the The deep muscles of the calf include popliteus, which acts on the knee
calcaneus more laterally, and those associated with soleus more medi joint, and flexor hallucis longus, flexor digitorum longus and tibialis
ally. The fibres in the tendon of plantaris (described in Ch. 83) exhibit posterior, which all act on the ankle joint and joints of the foot.
varying degrees of blending with the fibres of the calcaneal tendon,


sometimes blending entirely at its insertion or inserting into the plantar flexor hallucis longus
aponeurosis. Flexor hallucis longus is described on page 1411. The tendon of flexor
hallucis longus is described below.
Tensile properties The estimated tensile breaking load of a fetal
calcaneal tendon increases from 2 kg at 6 months post fertilization to flexor digitorum longus
18 kg at full term (Yamada 1970). In adults, the average estimated Flexor digitorum longus is described on page 1410.
tensile breaking load of the calcaneal tendon is 192 kg, decreasing to
160 kg in the eighth decade (Takigawa 1953), which may explain why Tibialis posterior
calcaneal tendon ruptures are infrequently encountered in youth Tibialis posterior is described on page 1412.
(Yamada 1970).
Vascular supply The blood supply to the calcaneal tendon is poor; INTRINSIC MUSCLES
the predominant artery is a recurrent branch of the posterior tibial
artery, which mainly supplies peritendinous tissues (Salmon et al The intrinsic muscles, i.e. those contained entirely within the foot,
1994). There is an additional supply from the paratenon (Carr and follow the primitive limb pattern of plantar flexors and dorsal
Norris 1989, Chen et al 2009), as well as a supply proximally from extensors.
intramuscular arterial branches and distally from the calcaneus. Micro The plantar muscles may be divided into medial, lateral and inter
dissection and angiographic studies have identified three main vascular mediate groups. The medial and lateral groups consist of the intrinsic
territories: a proximal section, a hypovascular midsection and a distal muscles of the great and fifth toes, respectively, and the central or


48
RETPAHC
Ankle and foot
1 17
14
2 16
1
3 15
4 13
5 12 2
11
6
14
3
A
4
13
7 8 9 10 5
12
6
1 11
16
15 7
10
2
14
9
13
8
12 B
3
11
10
4
9
5
8
C
6 7
Fig. 84.19 Turbo spin-echo, T1-weighted magnetic resonance (MR) images of the left ankle of a woman aged 26. A, A coronal turbo spin-echo,
T1-weighted MR image of the forefoot through a metatarsal. Key: 1, extensor hallucis longus tendon; 2, first metatarsal; 3, adductor hallucis, oblique
head; 4, flexor hallucis (medial head); 5, flexor hallucis (lateral head); 6, flexor hallucis longus tendon; 7, flexor digitorum longus tendons; 8, third
metatarsal; 9, fourth metatarsal; 10, flexor digiti minimi brevis; 11, abductor digiti minimi; 12, fifth metatarsal; 13, dorsal interossei; 14, second metatarsal.
B, An axial turbo spin-echo, T1-weighted MR image of the ankle. Key: 1, deep fibular nerve; 2, tibia; 3, tendon of tibialis posterior; 4, tendon of flexor
digitorum longus; 5, posterior tibial artery; 6, tibial nerve (early medial and lateral plantar branching); 7, tendon of flexor hallucis longus; 8, calcaneal
tendon; 9, soleus; 10, sural nerve; 11, flexor hallucis longus; 12, fibularis brevis; 13, tendon of fibularis longus; 14, fibula; 15, extensor digitorum longus;


16, extensor hallucis longus; 17, tendon of anterior tibialis. C, A sagittal turbo spin-echo, T1-weighted MR image of the ankle and hindfoot. Key: 1, flexor
digitorum longus; 2, soleus; 3, talocalcaneal (subtalar) joint; 4, calcaneal tendon; 5, calcaneus; 6, flexor digitorum brevis; 7, flexor accessorius; 8, cuboid;
9, lateral cuneiform; 10, intermediate cuneiform; 11, navicular; 12, talocalcaneal interosseous ligament; 13, talus; 14, talocrural joint; 15, tibia; 16, tibialis
anterior. (Courtesy of Robert J. Ward, MD, Tufts University School of Medicine, Boston, MA.)
1440.e1


Muscles
1441
48
RETPAHC
A B
Tendon of flexor
hallucis longus
Tendinous Cruciform Tendinous sheath of
sheath of part toes
Anular
great toe
part
Tendinous
sheath of toes
Tendon of flexor Tendons of flexor
hallucis longus digitorum longus
Tendons of
First to fourth
Flexor hallucis Adductor hallucis, flexor digitorum
lumbricals
brevis transverse head brevis
Adductor hallucis,
transverse head
First to fourth
Flexor hallucis brevis
lumbricals
Third plantar
Flexor digiti
interosseus Tendon of
minimi brevis
flexor digitorum longus
Abductor digiti
Abductor digiti minimi
minimi
Plantar tendinous sheath of
Abductor hallucis
Flexor digiti minimi brevis fibularis longus
Fourth dorsal interosseus
Tendon of
Flexor digitorum brevis flexor hallucis longus
Tendon of
fibularis longus
Plantar aponeurosis Abductor hallucis
Flexor accessorius
Abductor digiti minimi
Flexor digitorum brevis
Calcaneal tuberosity
Calcaneal tuberosity
Fig. 84.20 Muscles of the sole of the foot. A, First layer. B, Second layer. (With permission from Waschke J, Paulsen F (eds), Sobotta Atlas of Human
Anatomy, 15th ed, Elsevier, Urban & Fischer. Copyright 2013.)
intermediate group includes the lumbricals, interossei and intrinsic Clinical anatomy Abductor hallucis fascia is strong and can be used
digital flexors. It is customary to group the muscles in four layers in soft tissue augmentation following correction of hallux valgus
because this is the order in which they are encountered during dissec deformity. Rarely, persistent, exaggerated tonus in the muscle may be a
tion. In clinical practice and in terms of function, however, the former cause of varus deformity of the foot, necessitating surgical intervention.
grouping is often more useful. The vascular supply and innervation of An abductor hallucis flap is sometimes used for provision of soft tissue


the intrinsic muscles of the foot are given at the end of this section. coverage.
Plantar muscles of the foot: first layer Flexor digitorum brevis
Attachments Flexor digitorum brevis arises by a narrow tendon from
This superficial layer includes abductor hallucis, abductor digiti minimi the medial process of the calcaneal tuberosity, from the central part of
and flexor digitorum brevis (Fig. 84.20). All three extend from the the plantar aponeurosis, and from the intermuscular septa between it
calcaneal tuberosity to the toes, and all assist in maintaining the concav and adjacent muscles (see Fig. 84.20A). It divides into four tendons,
ity of the foot. which pass to the lateral four toes; the tendons enter digital tendinous
sheaths accompanied by the tendons of flexor digitorum longus, which
Abductor hallucis
lie deep to them. At the bases of the proximal phalanges, each tendon
Attachments Abductor hallucis arises principally from the flexor divides around the corresponding tendon of flexor digitorum longus;
retinaculum, but also from the medial process of the calcaneal tuberos the two slips then reunite and partially decussate, forming a tunnel
ity, the plantar aponeurosis, and the intermuscular septum between this through which the tendon of flexor digitorum longus passes to the
muscle and flexor digitorum brevis. The muscle fibres end in a tendon distal phalanx. The tendon of flexor digitorum brevis divides again and
that is attached, together with the medial tendon of flexor hallucis attaches to both sides of the shaft of the middle phalanx. The way in
brevis, to the medial side of the base of the proximal phalanx of the which the tendon of flexor digitorum brevis divides and attaches to the
great toe. Frequently, some fibres are attached more proximally to the phalanges is identical to that of the tendons of flexor digitorum super
medial sesamoid bone of this toe. The muscle may also send some ficialis in the hand. The slip to a given toe may be absent, or it may be


fibres to the dermis along the medial border of the foot. replaced by a small muscular slip from the extrinsic flexor tendons or
from flexor accessorius. Conversely, the slip may be joined by a second,
Relations Abductor hallucis lies along the medial border of the foot supernumerary slip.
and covers the origins of the plantar vessels and nerves (Fig. 84.21).
The space created for the plantar nerves and vessels by abductor hallucis Relations Flexor digitorum brevis lies immediately deep to the central
and its relationship to the calcaneus is called the porta pedis. part of the plantar aponeurosis (see Fig. 84.20A). Its deep surface is
separated from the lateral plantar vessels and nerves by a thin layer of
Actions Abductor hallucis produces abduction of the great toe relative fascia.
to the longitudinal axis of the foot at the shaft of the second metatarsal.
Actions Flexor digitorum brevis flexes the lateral four toes at the
Testing Abductor hallucis is tested clinically by instructing the subject proximal interphalangeal joint, with equal effect in any position of the
to resist a forcibly applied lateral deviation of the proximal phalanx. ankle joint.


AnklE And fooT
1442
9
noITCES
Flexor tendinous sheaths
The terminations of the tendons of the extrinsic and intrinsic flexor
muscles are contained in osseoaponeurotic canals similar to those that
occur in the fingers. These canals are bounded above by the phalanges
Tendons of and below by fibrous bands, the digital fibrous sheaths, which arch
Proper plantar digital flexor digitorum brevis across the tendons and attach on either side to the margins of the
arteries phalanges (see Fig. 84.20A). Along the proximal and middle phalanges,
the fibrous bands are strong and the fibres are transverse (anular part);
Common plantar
digital arteries opposite the joints they are much thinner and the fibres decussate
Tendon of flexor (cruciform part). Each osseoaponeurotic canal has a synovial lining,
hallucis longus which is reflected around its tendon; within this sheath, vincula tendi
Flexor hallucis Common plantar num are arranged as they are in the fingers.
brevis digital nerves
Flexor accessorius (quadratus plantae)
Tendons of flexor Attachments Flexor accessorius (quadratus plantae) arises by two
digitorum longus heads, with the long plantar ligament situated deeply in the interval
between the two heads (see Figs 84.20B, 84.19C). The medial head is
Superficial
Lateral larger and is attached to the medial concave surface of the calcaneus,
branch
plantar
below the groove for the tendon of flexor hallucis longus. The lateral
nerve
Deep branch head is flat and tendinous, and is attached to the calcaneus distal to the
Abductor hallucis
lateral process of the tuberosity, and to the long plantar ligament. The
muscle belly inserts into the tendon of flexor digitorum longus at the
Flexor accessorius point where it is bound by a fibrous slip to the tendon of flexor hallucis
longus and where it divides into its four tendons.
Cutaneous branch
Lateral plantar artery The muscle is sometimes absent altogether. Its distal attachment to
the tendons of flexor digitorum longus may vary, which means that the
Medial plantar nerve


Abductor digiti minimi fourth and fifth long flexor tendons may, at times, fail to receive slips
Flexor retinaculum from the flexor accessorius.
Plantar aponeurosis
Muscular branch
Flexor digitorum brevis Relations The medial plantar nerve passes medial to and the lateral
Posterior tibial artery plantar nerve passes superficial to flexor accessorius.
Lateral plantar nerve Actions By pulling on the tendons of flexor digitorum longus, flexor
accessorius provides a means of flexing the lateral four toes in any posi
tion of the ankle joint.
Abductor hallucis Calcaneal anastomosis
Lumbrical muscles
Attachments The lumbrical muscles are four small muscles (num
Fig. 84.21 Plantar nerves and vessels in relation to muscle layers. (With bered from the medial side of the foot) that are accessory to the tendons
permission from Waschke J, Paulsen F (eds), Sobotta Atlas of Human of flexor digitorum longus (see Fig. 84.20). They arise from these
Anatomy, 15th ed, Elsevier, Urban & Fischer. Copyright 2013.) tendons as far back as their angles of separation, each springing from
the sides of two adjacent tendons, except for the first lumbrical, which
arises only from the medial border of the first tendon. The muscles end
in tendons that pass distally on the medial sides of the four lateral toes
Testing To test the action of flexor digitorum brevis, the examiner
and are attached to the dorsal digital expansions on their proximal
passively extends the distal interphalangeal joint and asks the subject
phalanges.
to flex the toes at the proximal interphalangeal joint. Contracture of the
tendons of flexor digitorum brevis can lead to toe deformities, and
Relations The lumbricals are intimately related to the tendons of
release or lengthening procedures may be required. The muscle belly is
flexor digitorum longus before the latter enter their corresponding
sometimes excised as a flap to cover a soft tissue defect.
fibrous flexor sheaths. The lumbricals remain outside the fibrous flexor
Abductor digiti minimi sheaths and cross the plantar aspects of the deep transverse metatarsal


Attachments Abductor digiti minimi arises from both processes of ligaments before reaching the dorsal digital expansions.
the calcaneal tuberosity, from the plantar surface of the bone between
them, from the plantar aponeurosis and from the intermuscular septum Actions The lumbricals help to maintain extension of the interphalan
between the muscle and flexor digitorum brevis. Its tendon glides in a geal joints of the toes. In injuries of the tibial nerve, and in conditions
smooth groove on the plantar surface of the base of the fifth metatarsal such as the hereditary motor–sensory neuropathies (e.g. Charcot–
and is attached, with flexor digiti minimi brevis, to the lateral side of Marie–Tooth disease), lumbrical dysfunction contributes to clawing of
the base of the proximal phalanx of the fifth toe; hence it is more a the toes.
flexor than an abductor. Some of the fibres arising from the lateral
calcaneal process usually reach the tip of the tuberosity of the fifth Plantar muscles of the foot: third layer
metatarsal (see Fig. 84.5B) and may form a separate muscle: abductor
ossis metatarsi digiti quinti. An accessory slip from the base of the fifth The third layer of the foot contains the shorter intrinsic muscles of the
metatarsal is not infrequent. toes, i.e. flexor hallucis brevis, adductor hallucis and flexor digiti minimi
brevis (Fig. 84.22).
Relations Abductor digiti minimi lies along the lateral border of the
foot, and its medial margin is related to the lateral plantar vessels and Flexor hallucis brevis
nerve (see Fig. 84.21). Attachments Flexor hallucis brevis has a bifurcate tendon of origin
(see Figs 84.20, 84.22). The lateral limb arises from the medial part of
Actions Despite its name, abductor digiti minimi is more a flexor than
the plantar surface of the cuboid, posterior to the groove for the tendon
an abductor of the metatarsophalangeal joint of the fifth toe.
of fibularis longus, and from the adjacent part of the lateral cuneiform.
The medial limb has a deep attachment directly continuous with the


Plantar muscles of the foot: second layer
lateral division of the tendon of tibialis posterior, and a more superficial
attachment to the middle band of the medial intermuscular septum.
The second layer consists of flexor accessorius and the four lumbrical The belly of the muscle divides into medial and lateral parts, the twin
muscles. The tendons of flexor hallucis longus and flexor digitorum tendons of which are attached to the sides of the base of the proximal
longus run in the same plane as the muscles of the second layer (see phalanx of the great toe. The medial part blends with the tendon of
Fig. 84.20B); flexor hallucis longus and flexor digitorum longus are abductor hallucis, and the lateral with that of adductor hallucis, as they
described on pages 1410–1412. reach their terminations.


Muscles
1443
48
RETPAHC
is no phalangeal attachment for the transverse part of the muscle; fibres
that fail to reach the lateral sesamoid bone are attached with the oblique
Tendons of part.
flexor digitorum longus The transverse part of adductor hallucis is sometimes absent; part of
the muscle may be attached to the first metatarsal, constituting an
Tendon of opponens hallucis; a slip may also extend to the proximal phalanx of
flexor hallucis longus the second toe.
Tendons of Relations Adductor hallucis lies plantar to the metatarsal shafts and
flexor digitorum brevis interossei and the long and short toe flexors. The medial and lateral
plantar arteries and nerves are superficial, and flexor hallucis brevis is
proximal and medial.
Lumbricals Actions Adductor hallucis partly flexes the proximal phalanx of the
great toe, but also stabilizes the metatarsal heads.
Transverse
Adductor head Third dorsal
hallucis Oblique head interosseus Clinical anatomy Adductor hallucis is one of the deforming forces
Second and third in hallux valgus and needs to be released during a distal soft tissue
plantar interossei release when there is a fixed deformity.
Flexor hallucis brevis Fourth dorsal interosseus
Opponens digiti Flexor digiti minimi brevis
minimi Attachments Flexor digiti minimi brevis arises from the medial part
Abductor hallucis Flexor digiti
minimi brevis of the plantar surface of the base of the fifth metatarsal, and from the
Tendon of sheath of fibularis longus (see Figs 84.20B, 84.22 and 84.19A). It has
Abductor digiti minimi
flexor hallucis longus a distal tendon that inserts into the lateral side of the base of the proxi
Tendon of fibularis longus
Tendon of mal phalanx of the fifth toe; this tendon usually blends laterally with
flexor digitorum that of abductor digiti minimi. Occasionally, some of its deeper fibres
longus Flexor accessorius extend to the lateral part of the distal half of the fifth metatarsal, con


Tendon of tibialis posterior stituting what may be described as a distinct muscle: opponens digiti
Flexor retinaculum Long plantar ligament minimi.
Tendon of
flexor hallucis longus Abductor digiti minimi Relations The fifth metatarsal shaft lies on the deep surface of flexor
Plantar aponeurosis digiti minimi brevis, the interossei lie medially and abductor digiti
Abductor hallucis
minimi is lateral. The most lateral branch of the lateral plantar nerve
Flexor digitorum brevis lies superficially and just medial to flexor digiti minimi brevis.
Actions Flexor digiti minimi brevis flexes the metatarsophalangeal
joint of the fifth toe.
Fig. 84.22 Muscles of the sole of the foot, third layer. (With permission
from Waschke J, Paulsen F (eds), Sobotta Atlas of Human Anatomy, 15th Plantar muscles of the foot: fourth layer
ed, Elsevier, Urban & Fischer. Copyright 2013.)
The fourth layer of muscles of the foot consists of the plantar and dorsal
interossei and the tendons of tibialis posterior and fibularis longus
A sesamoid bone usually occurs in each tendon near its attachment. (tibialis posterior and fibularis longus are described in Ch. 83). The
Clinical problems with flexor hallucis brevis are usually related to the interossei resemble their counterparts in the hand except that, when
associated sesamoid bones. However, excision of both sesamoid bones describing adduction and abduction of the toes, the axis of reference is
leads to disruption of both tendons and a subsequent extension deform a longitudinal axis corresponding to the shaft of the second metatarsal
ity at the first metatarsophalangeal joint; such surgery is, therefore, not (unlike in the hand, where reference is made to the long axis of the
recommended. third metacarpal).
Accessory slips may arise proximally from the calcaneus or long
Dorsal interossei
plantar ligament. A tendinous slip may extend to the proximal phalanx
of the second toe. Attachments The dorsal interossei (Fig. 84.23A; see Fig. 84.19A) are


situated between the metatarsals. They consist of four bipennate
Relations Flexor hallucis brevis lies on the underside of the first muscles, each arising by two heads from the sides of the adjacent meta
metatarsal shaft; abductor hallucis lies medially. The medial digital tarsals. Their tendons are attached to the bases of the proximal phalanges
nerve to the great toe and the tendon of flexor hallucis longus pass to and to the dorsal digital expansions. The first inserts into the medial
the great toe on its plantar surface. The medial plantar nerve lies more side of the second toe; the other three pass to the lateral sides of the
superficially on its lateral side. second, third and fourth toes.
Actions Flexor hallucis brevis flexes the proximal phalanx of the great Relations Between the heads of each of the three lateral muscles, there
toe. is an angular space through which a perforating artery passes to the
dorsum of the foot. Between the heads of the first muscle, the corres
Testing The individual is asked to flex the first metatarsophalangeal ponding space transmits the terminal part of the dorsalis pedis artery
joint with the interphalangeal joint extended, thereby eliminating the to the sole (see Fig. 84.1).
action of flexor hallucis longus.
Actions Dorsal interossei abduct the toes relative to the longitudinal
Adductor hallucis
axis of the second metatarsal. They also flex the metatarsophalangeal
Attachments Adductor hallucis arises by oblique and transverse joints and extend the interphalangeal joints of the lateral four toes. The
heads (see Figs 84.20B, 84.22 and 84.19A). The oblique head arises great and fifth toes have their own abductors.
from the bases of the second, third and fourth metatarsals, and from
the fibrous sheath of the tendon of fibularis longus. The transverse head Clinical anatomy Denervation of the interossei leads to clawtoe
– a narrow, flat fasciculus – arises from the plantar metatarsophalangeal deformities. Development of clawed toes should alert the clinician to


ligaments of the third, fourth and fifth toes (sometimes only from the the possibility of a neuropathic process (e.g. Charcot–Marie–Tooth
third and fourth), and from the deep transverse metatarsal ligaments disease, tethered spinal cord).
between them. The oblique head has medial and lateral parts. The
medial part blends with the lateral part of flexor hallucis brevis and is Plantar interossei
attached to the lateral sesamoid bone of the great toe. The lateral part There are three plantar interossei (see Fig. 84.23B). They lie below,
joins the transverse head and is also attached to the lateral sesamoid rather than between, the metatarsals, and each is connected to only one
bone and directly to the base of the first phalanx of the great toe. There metatarsal. They are unipennate, unlike the dorsal interossei; they arise


AnklE And fooT
1444
9
noITCES
The muscle belly and tendon of extensor hallucis brevis serve as guides
A B to the location of the dorsalis pedis artery and deep fibular nerve. The
tendon of extensor hallucis brevis can be used as a local graft.
Vascular supply to the intrinsic muscles of the foot
Abductor hallucis is supplied by the medial malleolar network, medial
calcaneal branches of the lateral plantar artery (see Fig. 84.9), the
medial plantar artery (directly and via superficial and deep branches),
the first plantar metatarsal artery and perforators from the plantar art
erial arch. Flexor digitorum brevis is supplied by the lateral and medial
plantar arteries, the plantar metatarsal arteries and the plantar digital
arteries to the lateral four toes. Abductor digiti minimi is supplied by
the medial and lateral plantar arteries (see Figs 84.21, 84.25A), the
plantar digital artery to the lateral side of this muscle, branches from
1st the deep plantar arch, the fourth plantar metatarsal artery, and end
twigs from the arcuate and lateral tarsal arteries (see Fig. 84.9). Flexor
2nd 1st
2nd accessorius is supplied by the stem of the medial plantar artery (to the
3rd
3rd medial head), the lateral plantar artery and the deep plantar arch. The
4th lumbricals are supplied by the lateral plantar artery and deep plantar
arch and by four plantar metatarsal arteries (four distal perforating
arteries joined by three proximal perforating arteries). Their tendons are
supplied by twigs from the dorsal digital arteries (and their parent
dorsal metatarsal arteries) to the lateral four toes. Flexor hallucis brevis
is supplied by branches of the medial plantar artery, the first plantar
metatarsal artery, the lateral plantar artery and the deep plantar arch.
Fig. 84.23 The interossei of the left foot. A, The dorsal interossei viewed
Adductor hallucis is supplied by branches of the medial and lateral
from the dorsal aspect. B, The plantar interossei viewed from the plantar
plantar arteries, the deep plantar arch and the first to fourth plantar


aspect. The axis to which the movements of abduction and adduction are
metatarsal arteries. Flexor digiti minimi brevis is supplied by end twigs
referred is indicated.
of the arcuate and lateral tarsal arteries, and the lateral plantar artery
and its digital (plantar) branch to the lateral side of the fifth toe. Dorsal
interossei are supplied by the arcuate artery, lateral and medial tarsal
from the bases and medial sides of the third, fourth and fifth metatar
arteries, the first to fourth plantar arteries and the first to fourth dorsal
sals, and insert into the medial sides of the bases of the proximal
metatarsal arteries (receiving proximal and distal perforating arteries),
phalanges of the numerically corresponding toes, and into their dorsal
and by the dorsal digital arteries of the lateral four toes. Plantar inter
digital expansions.
ossei are supplied by the lateral plantar artery, the deep plantar arch,
Relations The plantar interossei lie plantar to the dorsal interossei the second to fourth plantar metatarsal arteries and the dorsal digital
and deep to the muscles of the third layer. arteries of the lateral three toes. Extensor digitorum brevis is supplied
by the anterior perforating branch of the fibular artery, the anterior
Actions Plantar interossei adduct the third, fourth and fifth toes, flex lateral malleolar artery, lateral tarsal arteries, dorsalis pedis artery,
the metatarsophalangeal joints and extend the interphalangeal joints. arcuate artery, the first, second and third dorsal metatarsal arteries,
proximal and distal perforating arteries, and the dorsal digital arteries
Clinical anatomy The clinical anatomy of the plantar interossei is to the medial four toes (including the great toe).
similar to that of the dorsal interossei.
Innervation of the intrinsic muscles of the foot Abductor
Extensor muscles of the foot hallucis is innervated by the medial plantar nerve, S1 and S2. Contrac
tion of the muscle confirms an intact medial plantar nerve when the
Extensor digitorum brevis and extensor integrity of this nerve is in question.
Flexor digitorum brevis is innervated by the medial plantar nerve,
hallucis brevis
S1 and S2. Abductor digiti minimi and flexor accessorius are innervated


Attachments Extensor digitorum brevis (see Fig. 84.2A) is a thin
by the lateral plantar nerve, S1, S2 and S3. The first lumbrical is supplied
muscle that arises from the distal part of the superolateral surface of
by the medial plantar nerve; the other lumbricals are supplied by the
the calcaneus in front of the shallow lateral groove for fibularis brevis,
deep branch of the lateral plantar nerve, S2 and S3. Flexor hallucis
from the interosseous talocalcaneal ligament, and from the deep surface
brevis is supplied by the medial plantar nerve, S1 and S2. Adductor
of the stem of the inferior extensor retinaculum. It slants distally and
hallucis is innervated by the deep branch of the lateral plantar nerve,
medially across the dorsum of the foot and ends in four tendons. The
S2 and S3. Flexor digiti minimi brevis is innervated by the superficial
medial part of the muscle is usually a more or less distinct slip, ending
branch of the lateral plantar nerve, S2 and S3. Dorsal interossei are
in a tendon that crosses the dorsalis pedis artery superficially to insert
supplied by the deep branch of the lateral plantar nerve (S2 and S3),
into the dorsal aspect of the base of the proximal phalanx of the great
except that of the fourth intermetatarsal space, which is supplied by the
toe; this slip is termed extensor hallucis brevis. The other three tendons
superficial branch of the lateral plantar nerve. Plantar interossei are
attach to the lateral sides of the tendons of extensor digitorum longus
supplied by the deep branch of the lateral plantar nerve (S2 and S3),
for the second, third and fourth toes.
except that of the fourth intermetatarsal space, which is supplied by the
The muscle is subject to much variation, e.g. accessory slips from the
superficial branch of the lateral plantar nerve. Extensor digitorum brevis
talus and navicular, an extra tendon to the fifth digit, or an absence of
is supplied by the lateral terminal branch of the deep fibular nerve, L5


one or more tendons. It may be connected to the adjacent dorsal
and S1.
interossei.
Relations The most medial tendon, that of extensor hallucis brevis, VASCULAR SUPPLY
courses dorsomedially and passes superficial to the dorsalis pedis artery
and the deep fibular nerve. The remaining three tendons pass obliquely ARTERIES
deep to the corresponding tendons of extensor digitorum longus.
Dorsalis pedis artery
Actions The muscle assists in extending the phalanges of the middle
three toes via the tendons of extensor digitorum longus; for the great
toe, it assists in extension of the metatarsophalangeal joint. The dorsalis pedis artery (see Fig. 84.1; Fig. 84.24) is usually the con
tinuation of the anterior tibial artery distal to the ankle. It passes to the
Clinical anatomy Laceration of extensor digitorum brevis leads to proximal end of the first intermetatarsal space, where it turns into
little in the way of functional impairment because the long extensors the sole between the heads of the first dorsal interosseous to complete
can compensate for the loss of the muscle. The proximal part of the the deep plantar arch, and provides the first plantar metatarsal artery.
muscle can be used as interposition material to prevent bone fusion The artery may be larger than normal, to compensate for a small
after resection of a calcaneonavicular bar (a common tarsal coalition). lateral plantar artery. It may be absent, in which event it is replaced by


Vascular supply
1445
48
RETPAHC
First dorsal metatarsal artery The first dorsal metatarsal artery
(see Fig. 84.24) arises just before the dorsalis pedis artery enters the
sole. It runs distally on the first dorsal interosseous and divides at the
Anterior tibial artery
cleft between the first and second toes. One branch passes under
the tendon of extensor hallucis longus and supplies the medial side of
the great toe; the other bifurcates to supply the adjoining sides of the
great and second toes.
Anterior medial Perforating branch of Cutaneous vessels from the dorsalis pedis artery The dor
malleolar artery fibular artery salis pedis artery and its first dorsal metatarsal branch give rise to small
Anterior lateral direct cutaneous branches that supply the dorsal foot skin between the
malleolar artery extensor retinaculum and the first web space. This vessel provides the
Dorsalis pedis artery Lateral basis for a fasciocutaneous flap raised from this region, and which may
tarsal artery be used to cover superficial defects elsewhere.
Deep plantar arch
Medial tarsal arteries
Arcuate artery The deep plantar arch (Fig. 84.25B) is deeply situated, extending from
the fifth metatarsal base to the proximal end of the first intermetatarsal
space. Convex distally, it is plantar to the bases of the second to fourth
metatarsals and corresponding interossei, but dorsal to the oblique part
of adductor hallucis.
Branches
Dorsal metatarsal
arteries The deep plantar arch gives rise to three perforating and four plantar
metatarsal branches, and numerous branches that supply the skin,
fasciae and muscles in the sole. Three perforating branches ascend
through the proximal ends of the second to fourth intermetatarsal
spaces, between the heads of dorsal interossei, and anastomose with the
dorsal metatarsal arteries. Four plantar metatarsal arteries extend distally
between the metatarsals in contact with the interossei (Fig. 84.25). Each
divides into two plantar digital arteries, supplying the adjacent digital
aspects. Near its division, each plantar metatarsal artery sends a distal
Dorsal digital


perforating branch dorsally to join a dorsal metatarsal artery. The first
arteries
plantar metatarsal artery springs from the junction between the lateral
plantar and dorsalis pedis arteries, and sends a digital branch to the
Fig. 84.24 The dorsal arteries of the foot. medial side of the great toe. The lateral digital branch for the fifth toe
arises directly from the lateral plantar artery near the fifth metatarsal
base. Haemorrhage from the deep plantar arch is difficult to control
because of the depth of the vessel and its important close relations.
a large perforating branch of the fibular artery. It often diverges laterally
from its usual route. Surface anatomy
The lateral plantar artery begins between the heel and medial malleolus,
Relations
and crosses obliquely to a point 2.5 cm medial to the tuberosity of the
The dorsalis pedis artery crosses, successively, the talocrural articular
fifth metatarsal. With a slight distal convexity, it reaches the proximal
capsule, talus, navicular and intermediate cuneiform and their liga
end of the first intermetatarsal space.
ments; superficial to it are the skin, fasciae, inferior extensor retinacu
lum and, near its termination, extensor hallucis brevis. Medial to it is Posterior tibial artery
the tendon of extensor hallucis longus and lateral to it are the medial
tendon of extensor digitorum longus and medial terminal branch of
Before the posterior tibial artery divides into its two main terminal
the deep fibular nerve. The tendons are useful landmarks in the plan
branches, it gives off a communicating branch that runs posteriorly
ning of safe anatomical approaches in surgery of the ankle and foot.
across the tibia approximately 5 cm above its distal end, deep to flexor
Branches hallucis longus, and joins a communicating branch of the fibular artery;
calcaneal branches, which arise just proximal to the termination of the
The dorsalis pedis artery gives rise to the tarsal, arcuate and first dorsal
posterior tibial artery, pierce the flexor retinaculum and supply the skin
metatarsal arteries (see Figs 84.1, 84.9, 84.24).


and fat behind the calcaneal tendon; and the artery of the tarsal canal.
Tarsal arteries There are two tarsal arteries, lateral and medial (see The terminal branches of the posterior tibial artery are the medial and
lateral plantar arteries.
Fig. 84.24). They arise as the dorsalis pedis artery crosses the navicular.
The lateral runs laterally under extensor digitorum brevis; it supplies Branches
this muscle and the tarsal articulations, and anastomoses with branches Medial plantar artery The medial plantar artery is the smaller ter
of the arcuate, anterior lateral malleolar and lateral plantar arteries, and
minal branch of the posterior tibial artery (see Fig. 84.25). It arises
the perforating branch of the fibular artery. Two or three medial tarsal
midway between the medial malleolus and the medial calcaneal tuber
arteries ramify on the medial border of the foot and join the medial
cle, and passes distally along the medial side of the foot, with the medial
malleolar arterial network.
plantar nerve lateral to it. At first deep to abductor hallucis, it runs dis
tally between abductor hallucis and flexor digitorum brevis, supplying
Arcuate artery The arcuate artery (see Fig. 84.24) arises near the
both. Near the first metatarsal base, when its calibre is already dimin
medial cuneiform, passes laterally over the metatarsal bases, deep to
ished as a result of supplying numerous muscular branches, it is further
the tendons of the digital extensors, and anastomoses with the lateral
diminished by a superficial stem. It passes to the medial border of the
tarsal and plantar arteries. It supplies the second to fourth dorsal meta
great toe, where it anastomoses with a branch of the first plantar meta
tarsal arteries, running distally superficial to the corresponding dorsal
tarsal artery. Its superficial stem then trifurcates and supplies three super
interossei, and divides into two dorsal digital branches for the adjoining
ficial digital branches that accompany the digital branches of the medial
toes in the interdigital clefts. Proximally, these branches receive proxi


plantar nerve and join the first to third plantar metatarsal arteries.
mal perforating branches from the deep plantar arch. Distally, they are
joined by distal perforating branches from the plantar metatarsal arter Lateral plantar artery The lateral plantar artery is the larger termi
ies. The fourth dorsal metatarsal artery sends a branch to the lateral side nal branch of the posterior tibial artery (see Fig. 84.25). It passes distally
of the fifth toe. and laterally to the fifth metatarsal base; the lateral plantar nerve is
The frequency of the arcuate artery has been reported to range from medial. The plantar nerves lie between the plantar arteries. Turning
10% to 67%, depending on the precise definition of the artery (DiLan medially, with the deep branch of the nerve, it gains the interval between
dro et al 2001). the first and second metatarsal bases, and unites with the dorsalis pedis


AnklE And fooT
1446
9
noITCES
A B
Plantar digital arteries
Adductor hallucis, tendon of Plantar digital arteries
oblique head
Abductor hallucis
Tendon of flexor hallucis brevis,
lateral part Adductor hallucis,
transverse head
Dorsalis pedis artery, junction
with deep plantar arch Plantar metatarsal arteries
Digital branch to fifth toe
Flexor hallucis brevis
Deep plantar arch
Superficial digital branch
Medial plantar artery
Lateral plantar artery Medial plantar artery Adductor hallucis,
oblique head
Flexor digitorum brevis
Cutaneous branch
Lateral plantar artery
Abductor digiti minimi
Flexor accessorius
Abductor hallucis
Abductor digiti minimi
Calcaneal branches
Flexor digitorum brevis
Plantar aponeurosis Abductor hallucis
Fig. 84.25 The plantar arteries of the left foot. A, Superficial dissection. B, Deep dissection.
artery to complete the deep plantar arch. As it passes laterally, it is first The principal named superficial veins are the long and short saphen
between the calcaneus and abductor hallucis, then between flexor digi ous. Their numerous tributaries are mostly (but not wholly) unnamed;
torum brevis and flexor accessorius. Running distally to the fifth meta named vessels will be noted (see Fig. 78.9). As in the upper limb, the
tarsal base, it passes between flexor digitorum brevis and abductor digiti vessels will be described centripetally from peripheral to major drainage
minimi, and is covered by the plantar aponeurosis, superficial fascia channels.
and skin. Dorsal digital veins receive rami from the plantar digital veins in the
Muscular branches supply the adjoining muscles. Superficial clefts between the toes and then join to form dorsal metatarsal veins,
branches emerge along the intermuscular septum to supply the skin which are united across the proximal parts of the metatarsals in a dorsal
and subcutaneous tissue over the lateral part of the sole. Anastomotic venous arch. Proximal to this arch, an irregular dorsal venous network


branches run to the lateral border and join branches of the lateral tarsal receives tributaries from deep veins and is continuous proximally with
and arcuate arteries. Sometimes, a calcaneal branch pierces abductor a venous network in the leg. At each side of the foot, this network con
hallucis to supply the skin of the heel. Anastomosis between the medial nects with medial and lateral marginal veins, which are both formed
and lateral plantar arteries superficial to the flexor digitorum brevis is mainly by veins from more superficial parts of the sole. In the sole,
sometimes present and is termed the superficial plantar arch. superficial veins form a plantar cutaneous arch across the roots of the
toes and also drain into the medial and lateral marginal veins. Proximal
Perforator flaps in the ankle and foot region to the deep plantar arch there is a plantar cutaneous venous plexus,
especially dense in the fat of the heel. It connects with the plantar
cutaneous venous arch and other deep veins, but drains mainly into the
The arteries around the ankle and in the foot are the medial and lateral
marginal veins. The veins of the sole are an important part of the lower
calcaneal arteries, medial and lateral plantar arteries and the dorsalis
limb ‘venous pump’ system aiding propulsion of blood up the limb
pedis artery (see Fig. 78.7). In the foot, the two plantar arteries with
(Broderick et al 2008). Intermittent foot compression devices are avail
communicating arteries from the dorsalis pedis artery give rise to mul
able to enhance this flow and so reduce the risk of deep vein thrombosis
tiple small perfor ators. In the sole of the foot, the perforators emerge
during periods of increased risk, e.g. after surgery.
on either side of the plantar aponeurosis, and also pass through it, to
supply the skin. ‘Island flaps’ from these perforators may be advanced
to reconstruct small defects in the weightbearing area. The skin of the INNERVATION
sole of the foot is highly specialized and therefore, ideally, defects in
this region should be reconstructed using local skin.
Superficial fibular nerve
DEEP AND SUPERFICIAL VENOUS SYSTEMS The superficial fibular nerve is described on page 1416.
IN THE FOOT
Deep fibular nerve


Plantar digital veins arise from plexuses in the plantar regions of the
toes. They connect with dorsal digital veins to form four plantar meta The deep fibular nerve is described on page 1416.
tarsal veins, which run proximally in the intermetatarsal spaces and
Tibial nerve
connect via perforating veins with dorsal veins, then continue to form
the deep plantar venous arch, which is situated alongside the deep
plantar arterial arch. From this venous arch, medial and lateral plantar The branches of the tibial nerve that innervate structures in the ankle
veins run near the corresponding arteries and, after communicating and foot are articular, muscular, sural, medial calcaneal and medial and
with the long and short saphenous veins, form the posterior tibial veins lateral plantar nerves. The course and distribution of the tibial nerve in
behind the medial malleolus. the calf are described on page 1415.


Biomechanics of standing, walking and running
1447
48
RETPAHC
Medial calcaneal nerve Proper plantar digital arteries
The medial calcaneal nerve arises from the tibial nerve and perforates Proper plantar digital nerves
the flexor retinaculum to supply the skin of the heel and medial side
of the sole.
Medial plantar nerve
The medial plantar nerve is the larger terminal division of the tibial
nerve, and lies lateral to the medial plantar artery. From its origin under
the flexor retinaculum, it passes deep to abductor hallucis, then appears
between it and flexor digitorum brevis, gives off a medial proper digital Common plantar
nerve to the great toe, and divides near the metatarsal bases into three digital nerves
common plantar digital nerves (Fig. 84.26; see Fig. 84.21). Plantar metatarsal
Cutaneous branches pierce the plantar aponeurosis between abduc arteries
tor hallucis and flexor digitorum brevis to supply the skin of the sole
of the foot. Muscular branches supply abductor hallucis, flexor digit
orum brevis, flexor hallucis brevis and the first lumbrical. The first two
arise near the origin of the nerve and enter the deep surfaces of the Lateral plantar nerve,
muscles. The branch to flexor hallucis brevis is from the hallucal medial Medial plantar nerve superficial branch
digital nerve, and that to the first lumbrical from the first common
plantar digital nerve. Articular branches supply the joints of the tarsus
and metatarsus.
Three common plantar digital nerves pass between the slips of the
plantar aponeurosis, each dividing into two proper digital branches.
The first supplies adjacent sides of the great and second toes; the second Plantar aponeurosis
supplies adjacent sides of the second and third toes; and the third sup
plies adjacent sides of the third and fourth toes, and also connects with
the lateral plantar nerve. The first gives a branch to the first lumbrical.
Each proper digital nerve has cutaneous and articular branches: near
the distal phalanges, a dorsal branch supplies structures around the Flexor retinaculum
nail. Abductor hallucis, flexor hallucis brevis and the first lumbrical are
Medial calcaneal branches


all supplied by the medial plantar nerve. (tibial nerve)
Medial plantar nerve
Lateral plantar nerve
Posterior tibial artery
The lateral plantar nerve supplies the skin of the fifth toe, the lateral Lateral plantar nerve
half of the fourth toe, and most of the deep muscles of the foot (see
Fig. 84.21). It is located medial to the lateral plantar artery and courses
anteriorly towards the tubercle of the fifth metatarsal. Next, it passes Fig. 84.26 The plantar digital nerves. (With permission from Waschke J,
Paulsen F (eds), Sobotta Atlas of Human Anatomy, 15th ed, Elsevier,
between flexor digitorum brevis and flexor accessorius, and ends
Urban & Fischer. Copyright 2013.)
between flexor digiti minimi brevis and abductor digiti minimi by
dividing into superficial and deep branches. Before division, it supplies
flexor accessorius and abductor digiti minimi, and gives rise to small
branches that pierce the plantar aponeurosis to supply the skin of the nerve can be damaged in severe inversion injuries of the ankle, and the
lateral part of the sole (see Fig. 84.26). The superficial branch splits into deep fibular nerve is sometimes compressed by osteophytes in the
two common plantar digital nerves: the lateral supplies the lateral side region of the second tarsometatarsal joint. Sural nerve entrapment is
of the fifth toe, flexor digiti minimi brevis and the two interossei in the usually not due to compression by fascial elements. Entrapment of the
fourth intermetatarsal space; the medial connects with the third third common digital nerve as it passes deep to the intermetatarsal liga
common plantar digital branch of the medial plantar nerve and divides ment of the third (or less commonly the second) web space can result
into two to supply the adjoining sides of the fourth and fifth toes. The in a Morton’s neuroma, which is probably the most common form of
deep branch accompanies the lateral plantar artery deep to the flexor nerve entrapment in the foot.
tendons and adductor hallucis, and supplies the second to fourth lum
bricals, adductor hallucis and all the interossei (except those of the


fourth intermetatarsal space). Branches to the second and third lumbri ANATOMY OF THE TOENAILS
cals pass distally deep to the transverse head of adductor hallucis, and
travel around its distal border to reach them. See Video 84.1. NAIL STRUCTURE
Nerve entrapment syndromes in the foot A toenail consists of a nail plate and unit (Dykyj 1989; pages 151–152).
The toenail is commonly a site of several pathologies, including ony
All nerves of the foot can be affected by entrapment, leading classically chomycosis and onychocryptosis (Jules 1989, Eekhof et al 2012).
to a burning sensation in the distribution of that nerve. Tarsal tunnel
syndrome is much less common than carpal tunnel syndrome. The BIOMECHANICS OF STANDING, WALKING
flexor retinaculum may compress the tibial nerve or either of its
AND RUNNING
branches (medial and lateral plantar nerves); entrapment at this level
is most commonly due to a spaceoccupying lesion, e.g. a ganglion, or
to compression by either a leash of vessels or the deep fascia associated PLANES OF MOTION
with abductor hallucis. Compression of the first branch of the lateral
plantar nerve (Baxter’s nerve) by the deep fascia that covers abductor Much confusion surrounds the descriptive terms for movement in the
hallucis has been implicated as a possible cause of chronic heel pain foot and ankle. Plantar flexion and dorsiflexion refer to movement in
and of plantar fasciitis. (Plantar fasciitis, often caused by repetitive high the sagittal plane and occur principally, but not exclusively, at the ankle,
impact injury to the foot, may be associated with pain, especially over metatarsophalangeal and interphalangeal joints. Inversion is tilting of
the medial calcaneal process, which may be exacerbated by passive the plantar surface of the foot towards the midline, and eversion is
ankle or great toe flexion.) The medial plantar nerve can be compressed tilting away from the midline. This is motion in the coronal plane and


at the ‘knot of Henry’, which is the point where the tendon of flexor takes place principally in the talocalcaneal and transverse tarsal joints.
hallucis longus crosses deep to the tendon of flexor digitorum longus, Adduction is movement of the foot towards the midline in the trans
to reach its medial side in the sole of the foot. The superficial fibular verse plane; abduction is movement away from the midline. This


48
RETPAHC
Ankle and foot
Patients with Morton’s neuroma usually present with a main com
plaint of metatarsalgia. While there is no pathognomonic clinical test,
diagnostic imaging coupled with clinical tests can provide convergent
validity to help with diagnosis (Owens et al 2011). Two commonly used
clinical tests are webspace tenderness and forefoot squeeze tests. The
webspace tenderness test is performed by placing the side of the thumb
into the third web space and pressing down. The forefoot squeeze test
is performed by squeezing the forefoot from side to side while concur
rently performing the webspace test.
1447.e1


AnklE And fooT
1448
9
noITCES
movement occurs at the transverse tarsal joints and, to a limited degree, force fluctuations have to be larger at higher speeds, to give the same
the first tarsometatarsal and metatarsophalangeal joints. vertical movement in less time.
Supination describes a threedimensional movement and is a com
Development of walking
bination of adduction, inversion and plantar flexion. Pronation is the
opposite motion, i.e. a combination of abduction, eversion and dorsi The average child sits at 6 months, crawls at 9 months, walks with
flexion. Pronation and supination are usually better terms than eversion support at 12 months, and walks without support at 18 months. The
and inversion, as the latter rarely occur in isolation and the former characteristic early gait matures rapidly and is similar to that of the
describe the ‘compound’ motion that usually occurs. adult by 3 years. Some minor changes occur up to 7 years, which are
Active movements occur at the ankle, talocalcaneonavicular and sub largely a reflection of neurological development but are also related to
talar joints. Movements at the ankle joint are almost entirely restricted stature (Thomson & Volpe 2001). Early gait is jerky, unsteady and wide
to dorsiflexion and plantar flexion, but slight rotation may occur in based. Initial ground contact varies, and heel–toe, whole foot and toe–
plantar flexion. The ranges of movement at the talocalcaneonavicular heel are all possible. Generally, a plantar flexed posture is adopted,
and subtalar joints are greater; inversion and eversion mainly occur which contrasts with the adult pattern. In adults, heel strike is accom
here. panied by a straight knee, which then flexes. A child strikes the ground
with a flexed knee, which is then extended in response to weight
bearing, and a short time is spent in singleleg stance (Fig. 84.28).
STANDING Maturation is associated with diminution of base width and increase
in step length and velocity. The earliest changes are development of
heelstrike, knee flexion during stance, and reciprocal upper limb swing.
Humans are bipedal: we stand and walk with an erect trunk and knees


that are almost straight. Moreover, we are plantigrade, i.e. we set the
Running
whole length of the foot down on the ground, whereas most medium
to large mammals are digitigrade, i.e. they stand and walk on their toes,
and ungulates stand on hooves on the tips of their toes. In the sagittal Walking involves dualsupport phases, but in running each foot is on
plane, body weight acts along a line that passes a few centimetres ant the ground for 40% (jogging) to 27% (sprinting) of the stride, so there
erior to the tibiotalar joint, exerting a moment that must be balanced is an aerial phase – the ‘doublefloat’ phase – when neither foot is on
by the plantar flexor muscles. the ground. The faster the subject runs, the shorter the stance phase;
worldclass sprinters spend approximately 22% of the gait cycle in
stance. During each aerial phase, the body rises and then falls under
PROPULSION gravity, which means that its height and potential energy are maximal
in the middle of this phase and minimal at midstance, when, in
marked contrast to walking, the knee of the supporting leg bends. The
The contraction of tibialis posterior, gastrocnemius and soleus is the
changes in muscle belly lengths are relatively slight during running. The
chief factor responsible for propulsion in walking, running and
muscles are acting as tensioners of the tendons; indeed, most of the
jumping. The propulsive action of these calf muscles is enhanced by
change of length is produced by the stretch and recoil of the tendons.
arching of the foot and flexion of the toes. In walking, the weight on
It has been estimated that, of the kinetic and potential energy lost and
the foot is taken successively on the heel, lateral border and the first
regained in each stance phase, 35% is stored temporarily as elastic strain
metatarsophalangeal joint. The last part of the foot to leave the ground
energy in the calcaneal tendon, and 17% in the ligaments of the arch
is the anterior pillar of the medial longitudinal arch and the medial
of the foot. Together, these springs approximately halve the work
three toes. In the act of sprinting, the heel does not touch the ground,


required from the muscles.
but the point of takeoff is still the anterior pillar of the medial longi
The calcaneal tendon is the most important ‘spring’ in the leg. Most
tudinal arch. As the heel leaves the ground, the toes gradually extend.
runners strike the ground first with the heel, and the centre of pressure
Extension, of the great toe particularly, tightens the plantar aponeurosis
moves rapidly forwards to the distal heads of the metatarsals, where it
and thus heightens the arch. At the same time, flexor hallucis longus
remains for most of the stance phase.
and flexor digitorum longus elongate, which increases their subsequent
As in walking, the ground force acts more or less in line with the
contraction. The extrinsic and intrinsic toe flexors increase the force of
leg, so the body is decelerated and reaccelerated during each stance
takeoff by exerting force on the ground. The most important muscle
phase. The stance phase starts with deceleration and absorption of
in this respect is flexor hallucis longus, which is strongly assisted by the
energy. Power is generated after stance phase reversal as the limb pushes
intrinsic toe flexors. The lumbricals provide a balancing action to the
up with the knee extending and foot plantar flexed, and this continues
extrinsic flexors and prevent buckling of the toes during the toeoff
in the swing phase as the limb is accelerated forwards. Once the limb
phase of gait.
is ahead of the trunk, the final phase of swingphase absorption is initi
ated, during which the limb is decelerated.
Walking
The ground force acts upwards on the metatarsal heads, and the
calcaneal tendon pulls upwards on the calcaneus. The necessary balan
In walking, each foot is on the ground (stance phase) for approximately cing reaction occurs at the ankle, where the tibia presses downwards on
60% of the stride, and off the ground (swing phase) for approximately the talus. Together, these three forces flatten the longitudinal arch of
40% (Fig. 84.27). Thus, singlesupport phases (one foot on the ground) the foot, forcing the ankle 10 mm nearer to the ground than it would


alternate with doublesupport phases (two feet on the ground). The be if the foot were rigid. Mechanical tests on amputated feet have shown
knee is straight at heel strike and remains nearly straight (10–30°) for that the foot is a reasonably good spring, giving an energy return of
most of the stance phase of that leg, bending more only immediately nearly 80%. The plantar aponeurosis, long and short plantar ligaments
before toeoff. During the swing phase, the knee flexes to a maximum and the plantar calcaneonavicular ligament are all involved in the
of 60° at midswing. spring action; they are predominantly collagenous but presumably have
Stance phase starts with ‘heel strike’. With the foot still planted in elastic properties similar to those of tendon.
front of the body, ‘foot flat’ is reached, and becomes ‘midstance’ when
the body comes to be directly above the planted foot. The heel then
rises as the contralateral foot makes contact with the ground (the MOVEMENTS OF THE FOOT
‘double stance’ phase). The last event of stance is ‘toeoff’ when the
‘swing phase’ starts. Early in the stance phase, while it is ‘foot flat’ in With the foot on the ground, body weight causes some supination
front of the trunk, the foot pushes downwards and forwards on the (used here to imply uneven distribution of weight to the lateral side of
ground, decelerating the body as well as supporting it. Later, when the the foot) and flattening of the longitudinal arches; about onethird of
foot is behind the trunk, it pushes downwards and backwards, the weight borne by the forefoot is taken by the head of the first meta
reaccelerating the body (see Fig. 84.27). tarsal (McDonald and Tavener 1999). When a resting position becomes
The height of the centre of gravity, and therefore the potential energy active, as occurs on starting to walk, the foot is pronated (used here to
of the body, also fluctuates. This is inevitable if the knee is kept nearly imply uneven distribution of weight to the medial side of the foot) by
fully extended, making the hip move in a nearcircular arc about the muscular effort, and the first metatarsal is depressed (the second less


ankle of the supporting foot. The vertical component of the total force so), which accentuates the longitudinal arch to its maximum height
exerted by both feet on the ground in the doublesupport phase is (Hicks 1954). Similar changes can be imposed on a weightbearing foot
greater than body weight, giving the body an upward acceleration. The by active lateral rotation, which is transmitted through the tibia to the
vertical component of the ground force during the singlesupport phase talus and entails passive supination of the foot. Medial rotation has an
is less than body weight, giving the body a downward acceleration. The opposite effect. When the foot is grounded and immobile, muscles that


Biomechanics of standing, walking and running
1449
48
RETPAHC
Phase of gait Stance phase Swing phase
Double Double
support Single-limb support support Single-limb support
(opposite side)
Pressure Heel strike Foot flat Mid-stance Heel-off Toe-off Mid-swing Heel strike
distribution
Hip
Joint angle
(extension = 0º) 45º 40º 30º 20º 5º 0º 20º 40º 50º 45º
Flexor mm
Extensor mm
Abductor mm
Adductor mm
Knee
Joint angle
(extension = 0º) 5º 10º 15º 10º 5º 10º 65º 55º 30º 5º
Flexor mm
Extensor mm
Ankle foot
Joint angle 5º 10º 0º 5º 5º 0º 5º 0º 5º 5º
(neutral = 0º) plantar- plantar- dorsi- dorsi- plantar- plantar- plantar-
Dorsiflexor mm
Plantar flexor mm
Inverter mm
Everter mm
Intrinsic mm
Ground reaction force
% Body
weight
100
Vertical force
15 Deceleration
0
Acceleration
–15
Sagittal force
% Gait cycle 0 10 20 30 40 50 60 70 80 90 100
Fig. 84.27 The events that occur during the different phases of a normal gait cycle. Depicted are: distribution of pressure on the plantar surface of the
foot; changes in the angles of hip, knee and ankle joints, together with activity in the corresponding muscle groups; and vertical and horizontal (sagittal
plane) components of the ground reaction force during stance phase. (Chart collated from various sources by Michael Gunther, Department of Human
Anatomy and Cell Biology, University of Liverpool.)


AnklE And fooT
1450
9
noITCES
A
A
B
B
C
C
Fig. 84.29 The concept of the foot skeleton as a twisted plate that may
be untwisted (supination) or further twisted (pronation) during the
maintenance of a plantigrade stance in various positions of the foot.
A, The foot skeleton in supination, as in standing with the feet widely
separated. Note the marked medial tilting of the talus and, to a lesser
Fig. 84.28 Development of a mature gait. A, A 1-year-old. Note the flexed
degree, of the calcaneus and the depression of the medial longitudinal
elbows and lack of arm swing. The foot is plantar flexed at contact. B, A
arch. B, Relative pronation of the foot, as in standing with the feet close
3-year-old. Arm swing is now present, as is heel strike. C, A 6-year-old.
together. C, Supination of the foot when standing on an inclined surface;
There is now an adult-type gait. (With permission from Benson MKD,
if the position of the wedge had been reversed, the foot skeleton would,
Fixsen JA, MacNicol MF (eds) 2001 Development of a mature gait. In:
of course, approach maximal pronation. (Based on MacConaill MA 1945
Children’s Orthopaedics and Fractures, 2nd edn. Edinburgh: Churchill
The postural mechanism of the human foot. Proc Roy Irish Acad
Livingstone.)
50:265–278.)
move it when it is freely suspended may exert effects on the leg, e.g. the
dorsiflexors can then pull the leg forwards at the ankle joint. (though this varies with the position of the feet (Fig. 84.29), the devel
The foot has two major functions: to support the body in standing opment of associated soft tissues, and the nature of the surface). In any
and progression, and to lever it forwards and absorb shock in walking, activity, as soon as the heel rises, the toes are extended and muscular
running and jumping (Alexander 1992). To fulfil the first function, the structures (including the plantar aponeurosis) tighten up in the sole,