Generality
The Achilles tendon is the large band of fibrous connective tissue in the leg, which connects the calf muscles to the back bone of the foot known as the calcaneus.
Starting about halfway up the calf, the Achilles tendon is a very strong and resistant structure, measuring 5-6 millimeters thick and approximately 15 centimeters long.
The Achilles tendon has a fundamental role as regards the mechanics of locomotion of the human being; in fact, by connecting gastrocnemius and soleus to the heel, it allows these muscles to perform plantarflexion movements of the leg flexion towards the thigh.
The Achilles tendon is at the center of various pathological conditions, including: tendinitis (inflammation of the Achilles tendon), ruptures (lacerations of the Achilles tendon) and tendon xanthomas (accumulations of cholesterol and macrophages on the surface of the tendon of Achilles).
Short review of what a tendon is
A tendon is a band of fibrous connective tissue, with a certain flexibility and a high content of collagen, which unites a skeletal muscle to a bone.
What is Achilles Tendon?
The Achilles tendon, or calcaneal tendon, is the large tendon of the human body, which takes place in the back of the leg and has the task of joining the two main calf muscles, gastrocnemius and soleus, to the heel (or calcaneal bone ) .
Did you know that ...
The Achilles tendon is the largest tendon in the human body ; this characteristic gives it considerable resistance to stress.
Anatomy
The Achilles tendon is a thick band of fibrous connective tissue, extremely flexible and elastic, which brings together the terminal portions of the gastrocnemius and soleus calf muscles, and extends to a bony prominence of the calcaneus, known as calcaneal tuberosity, where it establishes a robust interaction.
Equal element of the human body (therefore present in each leg), the Achilles tendon is covered, in order, by the so - called crural fascia and, of course, by the skin .
The crural fascia is a deep connective structure, with a laminar appearance, which has the task of separating the layers of the skin of the leg from the muscles present in the same anatomical tract, in order to protect and provide stability to these muscles.
The crural band is in continuity with the fascia lata, which resides in the thigh.
The Achilles tendon is visible to the naked eye, for a short distance (a few centimeters), just before its insertion on the heel (the tract in question is at the same height as the two ankle bones).
Origin and Course of the Achilles Tendon
The Achilles tendon originates approximately in the middle of the posterior part of the leg ( mid-calf ) and from there, moving downwards, it reaches the posterior surface of the calcaneus, the site in which it meets the calcaneal tuberosity.
Length, Width and Thickness of the Achilles Tendon
- In a human of average height, the Achilles tendon has a length of about 15 centimeters .
- The Achilles tendon has a thickness of about 5-6 millimeters .
- In completing its course downwards, the Achilles tendon varies its width, tightening and then widening again, when a few centimeters are missing from its insertion on the heel bone.
Generally, the Achilles tendon reaches the minimum of its width at 4 centimeters from the calcaneal tuberosity.
Achilles tendon and Calcaneare bag
Shortly before the Achilles tendon enters the heel, a synovial bursa is placed, called the heel bag .
Like all synovial bags, the heel bag is also a sack filled with serous fluid and has the task of limiting the rubbing - which could then cause irritation - of the anatomical structures between which it stands.
Achilles, Gastrocnemius and Soleus tendon: some details
The gastrocnemius is a large muscle, resulting from the union of two muscular heads (the so-called medial twin and the so-called lateral twin); the soleus, on the other hand, is a smaller muscle, consisting of a single muscular head .
Within this framework, the Achilles tendon is placed as the anatomical element that brings together the terminal parts of the two ends of the gastrocnemius and the sole head of the soleus, in order to connect them to the heel bone of the foot.
Did you know that ...
Together, gastrocnemius and soleus form the so-called sip triceps .
The use of the term "triceps" (which means "three heads") wants to emphasize that, although the muscles involved are two, the muscular heads are altogether 3 (the two of the gastrocnemius, plus that of the soleus).
Achilles and Calcaneus tendon: some details
The calcaneus is one of the 7 bones of the so-called tarsus of the foot as well as the element of the human skeleton that gives shape to the anatomically called vulgar heel region .
On the calcaneus, 6 distinct surfaces are recognizable, each of which stands out for certain characteristics and functions, and whose specific names are: anterior surface, plantar surface, back surface, upper surface, lateral surface and medial surface.
When the topic of discussion is the Achilles tendon, the surface of the calcaneus of interest is the posterior one; on the posterior surface of the calcaneus, in fact, a bone growth takes shape in the median area, corresponding to the aforementioned calcaneal tuberosity and to the area in which it finds the important tendon treated in this article.
Did you know that ...
The calcaneal tuberosity is the site of insertion for the tendon of another calf muscle : the plantar muscle .
Less voluminous and deeper than the gastrocnemius and soleus muscles, the plantar muscle is known above all the aforementioned tendon is the longest in the human body.
Reports of the Achilles Tendon with neighboring structures
Among the anatomical elements bordering on the Achilles tendon, the sural nerve, the small saphenous vein and the plantar muscle tendon stand out (see the previous box):
- The sural nerve passes on the external edge of the Achilles tendon, approximately 10 centimeters higher than where the latter finds insertion on the heel;
- The small saphenous vein follows a path that leads it to pass, with respect to the Achilles tendon, first on the external side and then above it;
- The tendon of the plantar muscle approaches the Achilles tendon on the medial front, just before both are inserted on the medial tuberosity.
Did you know that ...
The small saphenous vein is a tributary vein of the saphenous vein, that is, the large subcutaneous venous vessel that covers the entire lower limb.
Blood Spread of the Achilles Tendon
The supply of oxygenated blood to the Achilles tendon is poor .
To provide this contribution are, in particular, a recurrent branch of the posterior tibial artery and some branches of the arterial vessels that supply the muscles of the leg.
Function
The Achilles tendon plays a pivotal role in locomotion; in fact, by connecting gastrocnemius and soleus to the heel, it allows:
- The plantarflexion of the foot . Plantarflexion is the heel lifting and forefoot lowering, in fact the ability that allows the human being to walk on the toes.
- Flexion of the leg on the thigh . Flexion of the leg on the thigh is the movement that brings the leg closer to the back of the thigh. It is important to point out that this ability depends exclusively on the gastrocnemius muscle (the soleus does not participate).
The Achilles tendon is also responsible for supporting and absorbing the forces of tension and the powerful stresses created by the movement of the lower limb during a walk, a run or a jump; all this reduces the shocks to the foot deriving from the motor activities just mentioned.
Curiosity: the strength of the Achilles tendon in numbers
According to biomechanical studies, the Achilles tendon receives and supports a load stress equal to 3.9 times the weight of the body, during a normal walk, and a load stress equal to a good 7.7 times the weight of the body, during a race.
diseases
The Achilles tendon may be at the center of various pathological conditions, including: inflammation, ruptures and tendon xanthomas.
Inflammation of the Achilles tendon
An example of tendonitis, the inflammation of the Achilles tendon (or yarrow tendinitis ) is usually a suffering from overload or traumatic origin, which recognizes in circumstances such as excessive and incorrect sports practice, a sedentary lifestyle, the use of shoes incorrect, rheumatoid arthritis and improper intake of corticosteroids are its main risk factors.
Regardless of its nature, inflammation of the Achilles tendon is associated with some typical symptoms, which are:
- Pain in the leg, which worsens during any physical exercise involving the lower limbs;
- Swelling in the anatomical area where the Achilles tendon resides;
- Sense of stiffness at the ankle level.
To reach the diagnosis of a condition such as inflammation of the Achilles tendon, they are generally sufficient: the patient's account of the symptoms, the physical examination and the anamnesis; only in rare cases, radiological examinations are also required.
The first-line treatment of yarrow tendonitis is conservative and is based on:
- The rest of the lower limb in pain, until the complete disappearance of the pain and the other symptoms (in this case, rest is meant not to practice any physical activity that requires some effort to the Achilles tendon);
- The application of ice on the painful area from 3 to 5 times a day and for a duration of 15-20 minutes at a time;
- The intake of Non-Steroidal Anti-Inflammatory Drugs ( NSAIDs ), in order to promote the disappearance of pain;
- Physiotherapy sessions aimed at improving the elasticity of the inflamed tendon and related muscles.
If the conservative management of inflammation of the Achilles tendon should fail and the symptoms associated with the condition remain unabated for more than 6 months, the patient can do nothing but undergo a decisive surgical operation, with all that follows (period of convalescence, physiotherapy and gradual recovery of physical activity, even the lightest).
Did you know that ...
Especially for those who practice sports, carefully treating the stretching of the calf muscles is an excellent strategy, to prevent the inflammation due to overload of the Achilles tendon.
Rupture of the Achilles tendon
The rupture of the Achilles tendon is a serious injury, which occurs when the tendon in question is torn and drastically limits the motor skills of a person.
The rupture of the Achilles tendon usually has a traumatic origin; however, it can also derive from a poorly cured or neglected Achilles tendinitis.
Injury that affects 1 people every 10, 000 per year, the rupture of the Achilles tendon is associated with an unequivocal symptomatology, which includes:
- Sharp and sudden pain in the posterior department of the leg, which appears immediately after the tendon is torn;
- Snap to the occurrence of the laceration event;
- Lameness and inability to move the foot of the lower limb involved in the injury correctly;
- Severe swelling in the anatomical area where the Achilles tendon resides;
- Sense of ankle stiffness.
In general, the diagnosis of a ruptured Achilles tendon is based on: symptom reporting, physical examination, medical history and an imaging test such as, for example, nuclear magnetic resonance.
The therapeutic management of achilles tendon rupture always requires the use of surgery, since, given the scarce blood supply of the tendon in question, there is no possibility of a spontaneous healing of the laceration.
Surgical treatment of episodes of rupture of the Achilles tendon consists of an operation aimed at restoring the physiological continuity of the injured tendon structure.
After surgery, the perfect recovery from a ruptured Achilles tendon requires the patient several months of physiotherapy and a gradual approach to any physical activity .
Did you know that ...
For a good level sportsman who has suffered the rupture of the Achilles tendon, the return to sports as before injury occurs after 7-8 months.
Xanthoma with Achilles tendon
A xanthoma is a plaque or a yellowish nodule, generally subcutaneous, which originates from the unusual accumulation of lipids and macrophages .
As a rule, the formation of xanthomas is associated with conditions such as: hypercholesterolemia or familial hypertriglyceridemia, biliary cirrhosis, pancreatitis, diabetes, some forms of cancer, heart failure and some chronic inflammatory diseases.
An xanthoma in the Achilles tendon is an example of tendon xanthoma, which is a xanthoma that attacks the tendons of the human body.
In the xanthoma at the Achilles tendon, the latter develops a nodule rich in cholesterol and macrophages on its surface.
Did you know that ...
Xanthomas in the Achilles tendon represent a highly specific sign of familial hypercholesterolemia .
