consists of the following bones:
? Tarsals
? Metatarsals
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? Phalanges? TARSAL BONES
? These are short bones & arranged in three rows:
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(a)Proximal row Talus and calcaneus.(b) Middle row Navicular.
(c) Distal row Three cuneiforms (medial,
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intermediate, and lateral) and cuboid.? METATARSAL BONES
? These are five miniature long bones.
? The five metatarsal bones together constitute the
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metatarsus.
? They are numbered from medial to lateral sides as
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first, second, third, fourth, and fifth.? PHALANGEAL BONES
? The phalangeal bones are miniature long bones.
? They are 14 in number in each foot--two for the
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great toe and three for each of the other four toes.
? The foot performs two major functions
1. It acts as a pliable platform to support the body
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weight during standing position.? For this function foot is designed in the form of
elastic arches.
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? These arches are segmented so that they can
sustain the stress of weight and thrusts at the
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optimum level.2. It acts as a lever to propel the body forward during
walking, running, and jumping.
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? For this function, the foot is so constructed that it istransformable in a lever.
? The segmented arched lever converts the foot into
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a spring, which is ideally suited for its functions.
? The foot and its bones are
divided into three
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anatomical and functional
segments:
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1.Hindfoot consists of talusand calcaneus.
2.Midfoot consists of
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navicular, cuboid,&
cuneiforms.
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3.Forefoot consists ofmetatarsals and
phalanges.
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? The skeleton of the foot is arched bothlongitudinally and transversely, with the concavity
directed towards the plantar surface.
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? The presence of arches makes the sole concave
both anteroposteriorly and transversely
? During the standing position, the weight of the
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body is distributed among three points:
(a) Posteroinferior tuberosity of the calcaneum (heel)
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(b) Head of first metatarsal, and
(c) Head of fifth metatarsal
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Factors Maintaining the Arches of theFoot
? The devices used
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to support a stone
bridge are:
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1. Shape of stones.2. Intersegmental
ties (staples).
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3. Slings.4. Tie beams
TYPES OF ARCHES
LONGITUDINAL ARCHES
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? Each longitudinal arch has: (a) two pillars, (b) asummit, and (c) joints.
? MEDIAL LONGITUDINAL ARCH
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? Formed by the calcaneum, talus, navicular, threecuneiforms, and medial three metatarsals
? Pillars
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1. Posterior pillar medial half of calcaneum.2. Anterior pillar heads of the medial three
metatarsals.
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? Summit
? The talus lies at the summit of this arch. Therefore,
the talus is the keystone of this arch.
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? Joints
? The main joints of the medial longitudinal arch are
talocalcaneonavicular and subtalar joints.
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? LATERAL LONGITUDINAL ARCH? Formed by the calcaneum cuboid and lateral two
metatarsals.
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? It is characteristically low and almost touches the
ground.
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? It is involved in receiving and supporting the bodyweight during walking and running.
? Pillars
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? Posterior pillarlateral tubercle of the calcaneum? Anterior pillarheads of the lateral 2 metatarsals.
? Summit
? Lies at the level of articular facets on the superior
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surface of the calcaneum.
? Joints
? The main joint of the arch is calcaneocuboid joint.
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FACTORS MAINTAINING THE LONGITUDINAL ARCHES? Factors Maintaining the Medial Longitudinal Arch
? Bones
? The sustentaculum tali partly support the head of talus.
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? Ligaments(a) Plantar calcaneonavicular ligament (spring ligament)
which provides dynamic support to the head of talus
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(b) Interosseous ligaments connecting the adjacent bones(c) Interosseous talocalcanean ligament, connecting these
bones.
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? These ligaments act as intersegmental ties.? Muscles, tendons, and aponeurosis
1. Acting as slings (suspending arch from above):
? The tendon of tibialis posterior lying below the
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spring ligament provides supports to the head of
talus and suspends the arch from above.
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? The flexor hallucis longus muscle, has threefunctions to support the medial longitudinal arch.
(a) It stretches the arch like the string of a bow.
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(b) It supports the calcaneus by passing underneaththe sustentaculum tali.
(c) It supports the talus by passing along its posterior
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groove
? The tendon of tibialis anterior also exerts a sling
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action.? 2. Acting as tie beams (structures which prevent
separation of the pillars):
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? The medial part of the plantar aponeurosis and
abductor hallucis assisted by the flexor hallucis
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brevis act as tie beam to maintain the height ofthe medial longitudinal arch.
? Factors Maintaining the Lateral Longitudinal Arch
? Bones
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? The proper shaping of the distal end of calcaneus andproximal end of cuboid. The cuboid is the keystone of
longitudinal arch.
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? Ligaments
1. Short plantar ligament: broad and thick.
It lies deep to the long plantar ligament and supports
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the calcaneocuboid joint from below.2. Long plantar ligament: long and supports the joints
between the calcaneum, cuboid, and relate metatarsals
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? These ligaments act as intersegmental ties.
? Muscles, tendons, and aponeurosis
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1. Acting as tie beams:? The lateral part of the plantar aponeurosis and the
intrinsic muscles of the little toe (lateral part of the
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flexor digitorum brevis, abductor digiti minimibrevis, and flexor digiti minimi brevis) function as
tie beams of this arch.
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2. Acting as slings: The tendons of peroneus brevis
and peroneus tertius, which are inserted on the
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base of the fifth metatarsal, act as weak slingsfrom above.
? The tendon of peroneus longus supports the
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cuboid bone from above through its pulley-like
action
Differ. between the medial and lateral longitudinal arches
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Medial longitudinal arch
Lateral longitudinal arch
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Formed by more bones and more joints Formed by less bones and less jointsCharacteristic feature is resiliency
Characteristic feature is rigidity
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Higher and more mobile
Lower and less mobile
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Involved in propulsion duringInvolved in receiving and supporting the
locomotion
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body weight
(initiating the next step during walking)
Summit is formed by the talus
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Summit is formed by the calcaneum
Main joint is talocalcaneonavicular joint Main joint is calcaneocuboid
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(the most vulnerable part of the arch)(the most vulnerable part of the arch)
TRANSVERSE ARCHES
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? Anterior Transverse Arch? Formed by the heads of the metatarsals.
? It is a complete arch because during standing
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position the heads of first and fifth metatarsals
come into contact to the ground and form the
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two ends of the arch.? Posterior Transverse Arch
? Formed by greater parts of
the tarsus and metatarsus.
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? It is an incomplete arch
because only its lateral end
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comes into contact withthe ground during standing
position.
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? The complete dome is
formed when the two feet
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are brought togetherFactors Maintaining the Transverse Arches
? Bones
? Tarsal and metatarsal bones maintain the concavity
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on the plantar aspect of the foot skeleton.
? Ligaments
? Superficial and deep transverse metatarsal
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ligaments at the heads of metatarsals function as
intersegmental ties to maintain the shallow arch at
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the heads of metatarsals.? Muscles and tendons
1. Acting as tie beams:
The tendons of peroneus longus and tibialis
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posterior support the transverse arch as tie beam.2. Acting as slings:
The peroneus tertius and peroneus brevis on the
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lateral side and tibialis anterior on the medial sidesupport the transverse arch as slings.
3. Acting as intersegmental ties:
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The dorsal interossei act as intersegmental ties.FUNCTIONS OF THE ARCHES
1. Distribute the body weight to the weight-bearing
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points of the sole2. Act as shock absorber during jumping by their
spring like action
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3. The medial longitudinal arch provides a
propulsive force during locomotion.
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4. The lateral longitudinal arch functions as a staticorgan of support and weight transmission.
5. The concavity of the arches protects the nerves
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and vessels of the sole.
CLINICAL CORRELATION
? Flat foot (pes planus):
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? Commonest problem of foot.
? It occurs due to collapse of medial longitudinal arch.
? During long periods of standing the plantar aponeurosis
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and spring ligament are overstretched.? As a result, the support of the head of talus is lost and
is pushed downward between the calcaneus and the
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navicular bones. This leads to flattening of the medial
longitudinal arch with lateral deviation of the foot.
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? The effects of the flat foot are:(a) The person usually has clumsy shuffling gait due
to the loss of spring in the foot.
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(b) Liable to trauma due to loss of the shock
absorbing function.
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(c) The compression of the nerves and vessels of thesole is due to the loss of concavity of the sole.
? The compression of the communication between
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the medial and lateral plantar nerves leads to
neuralgic pain in the forefoot (metatarsalgia).
? High arched foot (pes cavus)
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? The exaggeration of the longitudinal arch of the
foot causes pes cavus.
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? This usually occurs because of a contracture(plantar flexion) at the transverse tarsal joint.
When the patient walks with a high arched foot
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there is dorsiflexion of the metatarsophalangeal
joints and the plantar flexion of th interphalangeal
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joints of the toes.