Transcript foot anatomy

FOOT
TARSALS, METATARSALS &
PHALANGES
The human foot is a complex structure containing 26
bones, 33 joints and more than 100 tendons, muscles,
and ligaments.
Tarsus = ankle
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Proximal region of the foot
7 tarsal bones
Talus: ankle bone
Calcaneus: heel bone
Navicular: ‘like a little boat’
3 Cuniform bones: wedge shaped lateral, intermediate, medial
• Cuboid: cube shaped
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Ankle
• Talus is the only bone that articulates with
the fibula and tibia to form the ankle joint
[talocrural joint]
• tibia medial malleolus
• Fibula lateral malleolus
• During walking the talus distributes about
half the weight to the calcaneus the rest to
the other tarsal bones
Metatarsus
• 5 metatarsal bones: numbered I – V [ 1 –
5] medial to lateral
• Each has a proximal base, an intermediate
shaft and a distal head
• articulate proximally with the first second
and third cuneiform bones and the cuboid
to form the tarsometatarsal joints
• Articulate distally with the phalanges to
form the metatarsophalangeal joint
Phalanges [digits]
• Numbered I – V medial to lateral
• Each phalanx : proximal base,
intermediate shaft and distal head.
• Hallux: has two phalanges [proximal &
distal]
• Other toes have three phalanges:
proximal, middle and distal
• Interphalangeal joints [between
phalanges]
Sesamoid bones are always present at the
metatarsophalangeal joint of the great toe.
Function: protect the tendon that flexes the
toe, [flexor hallicus longus/brevis] by
protecting it from the body's weight.
At the upper and forepart of the medial surface of the
calcaneusis a horizontal eminence, the sustentaculum
tali, which gives attachment to a slip of the tendon of
the Tibialis posterior.
Arches of Foot
• Two arches held by tendons & ligaments
• Allow foot to support weight of the body: ball of
foot – 40% weight. Heel – 60% weight
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Leverage for walking
Fully developed by age 13
Longitudinal arch: medial and lateral parts
Transverse arch
The longitudinal arch of the foot is higher on the
medial side, where it forms the instep as can be
seen on a foot-print. It is made up of the 1st
three digits and their metatarsals, the
cuneiforms, the navicular bone and the talus.
The lateral longitudinal arch is made up of digits
4 and 5 and their metatarsals, the cuboid and
the calcaneum. It is much shallower than the
medial arch.
The transverse arch of the foot is primarily
formed by the 5 metatarsal bones.
Every ligament that connects the bones of the foot plays a part in the maintenance
of the arches, but some which pass across two or more joints are especially
important. Among these are the long plantar ligament, the plantar calcaneocuboid
ligament and the plantar calcaneonavicular ligament, on which the head of the talus
rests.
While the normal tone of the small intrinsic muscles of the foot also plays an
essential part in keeping the arches intact, the long muscles which are inserted by
tendons into the bones of the foot have an even more important role. These are the
tendon of the tibialis anterior muscle, the tendon of the tibialis posterior muscle, the
tendon of the peroneus longus and the tendons of the flexor hallucis longus and
flexor digitorum longus muscles.
Finally, more superficially, the plantar aponeurosis also plays an important part in
maintaining the medial longitudinal arch.
Once the skin of the sole of the foot
has been removed, there is a very
dense organized layer of deep
fascia that runs down the middle of
the sole; this is the plantar
aponeurosis. There is also deep
fascia covering the medial and
lateral muscle groups but it has
been removed in this image.
The plantar aponeurosis is thought
to help maintain the medial
longitudinal arch of the foot.
Plantar Fasciitis:"heel spurs“: an overuse injury
affecting the sole or flexor surface (plantar) of the foot.
A diagnosis of plantar fasciitis means you have
inflamed the tough, fibrous band of tissue (fascia)
connecting your heel bone to the base of your toes.
Higher risk: female, overweight, a job that requires a lot
of walking or standing on hard surfaces; walk or run for
exercise, especially if you have tight calf muscles that
limit how far you can flex your ankles. People with very
flat feet or very high arches are also more prone to
plantar fasciitis.
•starts gradually with mild pain at the heel bone often
referred to as a stone bruise.
•more likely to feel it after (not during) exercise.
•The pain classically occurs again after arising from a
midday lunch break.
If you don't treat plantar fasciitis, it may become a
chronic condition. You may not be able to keep up your
level of activity and you may also develop symptoms of
foot, knee, hip and back problems because of the way
plantar fasciitis changes the way you walk.
• In order for these flexor and extensor
tendons to perform their duty properly,
they must be kept close to the bones of
the ankle. The structures that keep them
close are the retinaculae:
• superior extensor retinaculum
• flexor retinaculum
• inferior extensor retinaculum
the superior and inferior peroneal
retinaculaem keep the tendons of
the peroneus longus and brevis
close to the lateral malleolus.
After the plantar aponeurosis has been
removed you can see the muscles
that make up the first layer of the
sole of the foot and the arteries and
nerves entering the foot.
The muscles of the first layer are:
abductor hallucis
flexor digitorum brevis
abductor digiti minimi
When the flexor digitorum brevis is
removed, the muscles of the
second layer can be seen:
accessory flexor (quadratus plantae)
lumbricals
tendons of the flexor digitorum longus
from which the lumbricals arise
The muscles of the
third layer
include the:
flexor hallucis brevis
adductor hallucis
oblique head
transverse head
flexor digiti minimi
brevis
The fourth layer of muscles are the:
dorsal interossei (dab) meaning
dorsal abduct
plantar interossei (pad) meaning
plantar adduct
At this level, you can also see the
tendon of the peroneus longus
crossing the sole of the foot.