ANATOMY AND BIOMECHANICS
OF FOOT
Presenter : Dr. SYED IMRAN
Chair person : Dr. RUPAKUMAR C.S.
Dr. SRINIVAS DEEP URS
INTRODUCTION
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The human foot is a complex structure adapted
to allow orthograde foot stance and
locomotion.
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It is the only part which is in regular contact
with the ground.
ANATOMY :
1)
2)
3)
4)
5)
Bones
Joints
Ligaments
Arches
Muscles
TARSUS
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Seven tarsal bones
Larger to support and distribute weight
Tarsus and metatarsus arranged to form
intersecting longitudinal and transverse arches.
TALUS
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Link between foot and leg through ankle joint.
Head :
Directed distally and inferomedially
Long axis is inclined inferomedially to articulate
with proximal navicular surface
Plantar surface has 3 articular areas
TALUS
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The most posterior is largest,slightly convex
and rests on a shelf like medial projection,the
sustentaculum tali.
Neck :
Constricted part
Long axis is directed downwards, forwards,
medially.
Neck-body angle is 150
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Body
Cuboidal and has five surfaces
Superior surface : Articulates with tibia
Wider anteriorly than posteriorly
Inferior surface : Articulates with calcaneum
Medial surface : Articulates with M.malleoli
Lateral surface : Articulates with L.malleoli
Posterior surface : Small
VASCULAR SUPPLY :
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Tenous due to lack of muscle attachments
Extra-osseus supply from posterior
tibial,doraslis pedis, peroneal Arteries.
A of tarsal canal anastomose with A of tarsal
sinus to form a vascular sling under talar neck.
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a- Laterally A of tarsal sinus
b- A of tarsal canal
c- Deltoid branches
ATTACHMENTS ON TALUS
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Neck : Capsular ligament of ankle joint, dorsal
talonavicular ligament.
Lower non-articular part gives attachment to
deep fibers of deltoid ligament.
CALCANEUM
Largest tarsal bone
 Projects posterior to tibia and
fibula to act as a short lever
for calf muscles.
 Six surfaces
 Vascular Supply : Medial and
lateral calcaneal Arteries
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ATTACHMENTS ON CALCANEUM :
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Middle rough area on posterior surface
receives insertion of tendocalcaneus and
plantaris
Lower area is covered with dense fibrofatty
tissue and supports body weight.
Lateral part : Origin on extensor digitorum
brevis, attachment of inf extensor retinaculum,
stem of bifurcate ligament.
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Plantar Surface : Origin of abductor hallucis,
flexor digitorum brevies. Attachment of Plantar
aponeurosis.
Origin of abductor digiti minimi
Medial margin of sustentaculum tali and gives
attachment to Spring ligament ant , tibialis
posteriorly in middle , deltoid ligament ,
talocalcaneal ligament posteriorly.
NAVICULAR :
Boat shaped
 Medial side between talus
and cuneiforms
 Distal surface 3 facets
 Proximal surface articulates with talar head
 Dorsal surface rough for attachment of
ligaments
 Plantar surface is non-articular.
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ATTACHMENTS ON NAVICULAR
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Tuberosity receives insertion of tibialis posterior
Plantar surface provides attachment to spring
ligament
Calcaneonavicular part of bifurcate ligament is
attached to lateral surface.
CUBOID
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Lateral bone of distal row
Between calcaneus proximally and fourth and
fifth metatarsals distally
Dorsal surface is rough for attachment of
ligaments
Medial surface is articular for Lat. Cuneiform
and non-articular.
ATTACHMENTS OF CUBOID
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Lateral surface occupies tendon of peroneus
longus
Poseromedial part of plantar surface provides
insertion to a slip of tibialis posterior and origin
of flexor hallucis brevies.
Non-articular part of medial surface provides
attachment to lateral limb of bifurcate
ligament.
CUNEIFORMS
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Wedge like articulate with navicular proximally
and bases of first to third metatarsals distally
Medial largest , intermediate smallest
Dorsal surface of lat and intermediate
cuneiforms form base of wedge, wedge is
reversed in med cuneiform,which is prime
factor in shaping transverse arch.
MEDIAL CUNEIFORM
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Proximal surface has a piriform facet for
navicular
Distal surface has a large kidney shaped facet
for base of first metatarsal
Medial surface is rough and subcutaneous
ATTACHMENTS
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Tibialis anterior on anteroinf surface of
M.Cuneiform
Part of peroneus longus inserted on lat surface
Intermediate cuneiform attachment to part of
tibialis posterior
Plantar surface of lat cuneiform receives a slip
of tibialis posterior and part of flexor hallucis
brevies.
METATARSALS
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Lie distal in foot and connect tarsus and
phalanges
Have shaft, proximal base and distal head
Convex dorsally and concave on plantar
aspects
FIRST METATARSAL
Shortest and thickest
 Gives attachment to
tibialis anterior tendon
medially and peroneus
longus tendon on
plantar aspect
 Origin to first dorsal interosseus muscle
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SECOND METATARSAL
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Longest
Base has four articular facets
Because of its length and steep inclination and
position of base, it is at risk of stress overload
and avasular phenomena.
Third MTP is relatively stiff and predisposes to
stress fracture
PHALANGES
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14 phalanges
Two in hallux, three in other toes
Much shorter than hand
Compressed from side to side
ANKLE JOINT
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Complex, three-bone joint
It consists of the tibial plafond (including the
posterior malleolus articulating with the body of
the talus), the medial malleolus, and the lateral
malleolus.
The dome itself is wider anteriorly than
posteriorly, and as the ankle dorsiflexes, the fibula
rotates externally through the tibiofibular
syndesmosis, to accommodate this widened
anterior surface of the talar dome.
STABILITY OF ANKLE
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Passive : Medial and lateral ligaments, bony
contours and capsular attachments
Dynamic stability by gravity , muscle action and
ground reaction forces.
Stability requires continuous action of soleus
and gastronemius.
TALOCALCANEAL JOINT
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Ant and post articulations between talus and
calcaneum “ Subtalar joint ”
Post articulation is talocalcaneal joint
Ant articulation is talocalcaneonavicular joint
Inversion by Tibialis ant
and posterior
 Eversion by Peroneus
longus,brevies and tertius
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LIGAMENTS
Ankle stability is conferred by bony architecture
and ligaments supporting ankle joint
1.Syndesmotic ligaments
2.Medial collateral ligaments
3.Lateral collateral ligaments
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SYNDESMOTIC LIGAMENTS
LATERAL COLLATERAL LIGAMENTS
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Ant talo-fibular ligament
Calcaneo fibular ligament : Resists inversion
Post talofibular ligament : Strongest and
prevents posterior and
rotatory subluxation of
talus
MEDIAL COLLATERAL LIGAMENTS
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Deltoid ligament : Superficial and deep part
Superficial fibers arise from medial malleolus
and they attach into navicular, the neck of the
talus, the medial border of the sustentaculum
tali, and the posteromedial talar tubercle. The
tibiocalcaneal ligament is the strongest
component of the superficial layer of the
deltoid ligament, and it is responsible for
resisting eversion of the calcaneus.
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Deep layer of the deltoid ligament is the primary
medial stabilizer of the ankle joint. It is a short,
thick ligament
The strongest fibers insert on the medial surface
of the talus.
This ligament is virtually inaccessible from outside
the joint, and it cannot be repaired unless the
talus is displaced laterally or if the medial
malleolus is inverted distally through fracture or
osteotomy.
ARCHES OF FOOT
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Medial longitudinal arch :
Ligaments resposible for stability
Most imp is Plantar aponeurosis, Spring
ligament
Flexor hallucis longus, flexor digitorum
longus,abductor hallucis.
Tibialis ant and post : Inverting and adducting
MEDIAL LONGITUDINAL ARCH
Medial Longitudinal Arch
continued
Muscular Support
Intrinsic
Abductor Hallucis
Flexor Digitorum Brevis
Extrinsic
Tibialis Posterior
Flexor Hallucis Longus
Flexor Digitorum Longus
Tibialis Anterior
Flexor Digitorm Longus
LATERAL LONGITUDINAL ARCH
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Lateral part of plantar aponeurosis , long and
short plantar ligaments
Peroneus longus tendon
Lateral Longitudinal Arch
continued
Muscle Support
Intrinsic
Abductor Digiti Minimi
Flexor Digitorum Brevis
Extrinisic
Peroneus Longus, Brevis &
Tertius
TRANSVERSE ARCH
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Bases of 5 metatarsals , cuboid and
cuneiforms
Stability by ligaments bind cuneiform and
metatarsal bases and peroneus longus tendon.
Ligament Support
Intermetatarsal Ligaments
Plantar Fascia
Muscle Support
All intrinsic muscles
Extrinisic
Tibialis Posterior
Tibialis Anterior
Peroneus Longus
PLANTAR FASCIA
The plantar fascia is
a strong fibrous aponeurosis
that runs from the calcaneus
to the base of the phalanges.
 It supports the arches and
protects structures in the foot.
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MUSCLES
Superficial Layer
Abductor Hallucis
Abductor Digiti Minimi
Flexor Digitorum Brevis
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Middle Layer
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Quadratus Plantae
Lumbricals
Deep Layer
Flexor Hallucis Brevis
Adductor Hallucis
Transverse and Oblique
Heads
Flexor Digiti Minimi
Interosseus Layer
Plantar Interossei
Dorsal Interossei
BIOMECHANICS
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1.
2.
3.
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Most of motion of foot occurs at three synovial
joints
Talocrural joint
Subtalar joint
Mid-tarsal joint
Most of motion occuring in hind foot
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Normal motion of the ankle joint is predominantly
in the sagittal plane
Axis of the ankle joint as passing approximately 5
mm distal to the tip of the medial malleolus and 3
mm distal and 8 mm anterior to the lateral
malleolus . a continuously changing axis of
rotation. In dorsiflexion, the axis is inclined
downward and laterally, whereas in plantar flexion,
the axis is inclined downward and medially.
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Plantarflexion (PF) and dorsiflexion (DF) occur
about a mediolateral axis running through the
ankle joint. The range of motion for
plantarflexion and dorsiflexion is approximately
50° and 20°, respectively.
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During dorsiflexion of the ankle, the
intermalleolar distance increases
approximately 1.5 mm as the fibula rotates
externally and displaces laterally.
With the deltoid ligament, it contributes to the
rotational stability of the talus Stability of the
ankle joint in stance appears to be conferred
mostly by articular congruity
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The axis of rotation for the subtalar joint runs
obliquely from the posterior lateral plantar
surface to the anterior dorsal medial surface of
the talus
Obliquity of axis
Pronation
1. Eversion in frontal plane
2. Abduction in Transverse plane
3. Dorsiflexion in Sagittal plane
 Supination is opposite
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Prime function of the subtalar joint is to
absorb the rotation of the lower extremity
during the support phase of gait. With the foot
fixed on the surface and the femur and tibia
rotating internally at the beginning of stance
and externally at the end of stance, the
subtalar joint absorbs the rotation through the
opposite actions of pronation and supination
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Midtarsal joints consist of calcaneocuboid joint
and talonavicular joint.
Each joint has an axis of rotation that runs
obliquely across the joint. When the two axes
are parallel to each other, the foot is flexible
and can freely move. If the axes do not run
parallel to each other, the foot is locked in a
rigid position.
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Movement at the midtarsal joint depends on
the subtalar joint position. When the subtalar
joint is in pronation, the two axes of the
midtarsal joint are parallel, which unlocks the
joint, creating hypermobility in the foot.
This allows the foot to be very mobile in
absorbing the shock of contact with the ground
and also in adapting to uneven surfaces
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During supination of the subtalar joint, the two
axes run through the midtarsal joint converge. This
locks in the joint, creating rigidity in the foot
necessary for efficient force application during the
later stages of stance.
The motion at the midtarsal joint is unrestricted
from heel strike to foot flat
The midtarsal joint becomes rigid and more stable
from foot flat to toe-off in gait as the foot supinates
BIOMECHANICS WHILE STANDING
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In standing, half of the weight is borne by the
heel and half by the metatarsals. One third of
the weight borne by the metatarsals is on the
first metatarsal, and the remaining load is on
the other metatarsal heads
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Lateral longitudinal arch relatively flat and
limited in mobility it is lower than the medial
arch, it may make contact with the ground and
bear some of the weight in locomotion, thus
playing a support role in the foot.
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Dynamic medial longitudinal arch. It is much
more flexible and mobile than the lateral arch
and plays a significant role in shock absorption
upon contact with the ground.
BIOMECHANICS WHILE WALKING
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At heel strike, part of the initial force is
attenuated by compression of a fat pad
positioned on the inferior surface of the
calcaneus. This is followed by a rapid
elongation of the medial arch that continues to
maximum elongation at toe contact with the
ground
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The medial arch shortens at midsupport and
then slightly elongates and again rapidly
shortens at toe-off . Flexion at the transverse
tarsal and tarsometatarsal joints increases the
height of the longitudinal arch as the
metatarsophalangeal joints extend at pushoff .
The movement of the medial arch is important
because it dampens impact by transmitting the
vertical load through deflection of the arch
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