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by
Maria Antonietta Fusco
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It
is hardly necessary to demonstrate the importance of the foot
as the base upon which our body stands. What is necessary to
study is in more depth,is our understanding
of the foot as a postural receptor and as a venous and
lymphatic pump. The nerve endings enable the foot to act as an
informer on the posture and Lejars' venous sole has a role that is
indispensable for the venous and lymphatic system of the lower
limbs. |
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Anatomy and function of the foot
The foot is highly complex from the anatomical and functional point of
view.
There are numerous joints that place the tarsal bones in relation to
each other and to the metatarsal bones, and the whole assembly in
relation to the talotibial joint. This enables the foot to orient itself
on the various planes in order to present the right stance on the ground
at all times, to modify its shape and the curvature of its arches in order
to adapt to the different features of the terrain, and also to create a
shock-absorbing system between the supporting surface and the leg to
ensure a safe and smooth stepping action. Another extremely important
structure for the proper function of the foot is the plantar aponeurosis,
which can be divided into the dorsal fascia and the plantar fascia, the
latter being further classified as deep or superficial. The superficial
plantar fascia lies beneath the skin and is divided into three parts:
lateral, intermediate and medial. The lateral fascia extends from the
lateral process of the tuberosity of the heel to the little toe, lining
the toe muscles; the intermediate fascia is the thickest and extends
from the heel to the head of the metatarsals, covering the muscles of
the intermediate loggia; the medial fascia extends from the medial
process of the tuberosity of the heel to the base of the big toe and
lines the muscles for this toe. Two septa depart from the deep fascia of
the superficial plantar aponeurosis, dividing the region into three
muscle loggias, i.e. the medial, intermediate and lateral. The deep
plantar aponeurosis is a thin aponeurotic sheet that covers the
inter-osseous muscles and extends transversally from the inferior margin
of the first metatarsal to the inferior margin of the fifth metatarsal.
In the space coming between these two aponeuroses, in addition to the
muscles, there is some relaxed tissue rich in nerve endings and blood-
and lymph-carrying capillaries (Lejars' venous sole). It is this complex
muscular-ligamentous and articular structure that enables the
three-dimensional organization of the plantar arches to be maintained in
statics and also permits a modification of the curvature of the arches
in dynamics. |
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The foot as a postural organ
The nerve endings are stimulated when standing upright and stepping enable the
foot to act as a postural organ and a provider of information to the brain; the
sensory nerves convey to the brain all the information received from
the feet, principally on a level with the skin, the tendons and the
joints, be they tactile, vibratory, spatial and traumatic sensations.
Thanks to this information, associated with information coming from
other sources such as the eyes, labyrinth and mandible, the brain
formulates an involuntary tendinous-muscular motor response. The
pressoreceptive and proprioceptive stimulation of the sole of the foot
triggers numerous reflexes, both monosynaptic, directed towards the
intrinsic musculature of the foot, and polysynaptic, directed towards
the rest of the body. Stimulation at plantar level involves at least
four sensory mechanisms (Fig 1): |
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- Cutaneous pressoreceptors, such as the Pacini corpuscles, the
stimulation of which determines polysynaptic reflexes also of a
postural type;
- Muscular proprioceptors, such as the neuromuscular poles, the Golgi' s
organs, with monosynaptic reflexes directed towards the
muscles themselves and heterosegmental polysynaptic reflexes. These
are sensitive to tension and have an inhibitory effect. They
probably protect the muscles from excessive stress;
- Deep articular proprioceptors, the stimulation of which modifies
the articular relationships and they are sensitive to variations in
pressure during stance. They have an important role as postural
reflexes;
- Neurovegetative receptors, that follow the abundant
vascularization of the sole of the foot.
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The foot as a vascular organ
Lejars' venous sole has a role that is indispensable for the
venous and lymphatic system of the lower limbs. The blood
pumped by the heart towards the distal extremities of the
body encounters various obstacles to its return to the heart:
the distance, which cancels the initial pressure effect; and
gravity, which tends to favor stagnation in the vessels
furthest away from the heart. Venous return is strongly
facilitated by standing upright since this causes a
contraction of the muscles of the lower limbs, which has a
genuine massaging action on the veins (or pump effect). In
deambulation, there is also a mechanical compression of the
plantar veins that are emptied at every step. Throughout
this composite mechanism, the sole of the foot can be
considered as a genuine "peripheral heart",
capable of exerting a centripetal compulsive force on the
blood and lymph, the so-called vis a tergo. |
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Pic.2 |
Pic.3 |
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Alterations in stance
Starting from this physiological preamble and bearing in mind that form,
structure and function are intimately related in our body, it has been
suggested that many situations of peripheral superficial venous
circulatory deficiency and slow lymphatic circulation in the legs could
be attributable to an altered three-dimensional arrangement of the foot
and that, as a consequence, recovering the shape and structure of the
foot system would restore this to a normal function and thus induce a
regression, of the signs and symptoms of such
pathologies. We therefore studied the functional alterations of the
plantar stance in patients with superficial venous circulatory
deficiency of the lower limbs, we used proprioceptive orthotics capable of restoring a balance to the whole podalic stance for
correction and stimulation of the sole of the foot and we then verified
the results in the short, medium and long-term. The symptoms of
heaviness in the legs were reduced within a few days, to the point of
disappearing altogether within one month; but the degree of venous
ectasia also regressed with a marked improvement in the appearance of
the legs. The valid results obtained with this method and with the use
of this type of proprioceptive orthotics are maintained in the long term
and prevent any rapid worsening of the vascular problem. All this
entitles us to believe that we are on the right road and convinces us
more and more that a re-adjustment of the sole of the foot towards a
functional recovery is essential even in venous and lymphatic peripheral
vasculopathies. |
