The Achilles tendon ( lat. Tendo calcaneus , tendo musculi tricipitis surae or tendo Achillis ) is the common tendon of the three members of the calf muscle ( musculus triceps surae ), consisting of the two-headed calf ( Musculus gastrocnemius ) and the soleus ( soleus muscle ), to the heel .
Achilles tendon in humans
The Achilles tendon is the thickest and strongest tendon in humans. It is underlaid on the heel bone by the bursa tendinis calcanei and starts at the very back at the top of the calcaneal tuberosity ( tuber calcanei ) over the entire width of this bone protrusion. Then, thinning a little, it runs straight up, has its narrowest point about 4 cm above the origin, and from there it becomes continuously wider again. The average length is 20-25 cm, with muscle fibers inserting on the front almost to the base . The mean cross-section is 80 mm².
The Achilles tendon transmits the force of the triceps surae muscle , which comes from the gastrocnemius muscle (two heads, originating on both sides of the thighbone in the hollow of the knee) and the soleus muscle (one head, originating on the back of the tibia and on the back of the neck and head of the fibula ) ; the tendon of the musculus plantaris (origin directly above the outer head of the musculus gastrocnemius) radiates at the medial edge . In this way, the Achilles tendon enables powerful plantar flexion (bending of the foot in the direction of the sole of the foot), but also inversion ( supination , outward bending ) of the foot.
The Achilles tendon reflex (plantar flexion of the foot after striking the slightly forward tendon) is the characteristic reflex for segment S1 (-S2) .
Change in the Achilles tendon after exercise
The Achilles tendon consists of a tissue that reacts quickly to mechanical stress on the molecular and cellular level. Anabolic and / or catabolic proteins can change significantly within hours during / after exercise and return to baseline within 72 hours. The effects of stress on the Achilles tendon can be determined with high-resolution three-dimensional ultrasound images. As a result of a competitive load in Australian football, it was found that in the Achilles tendon, similar to the muscle (sore muscles), significant negative changes are to be found on the 2nd day after the exercise, which normalize again by the 4th day. In contrast, a Finnish study showed no significant changes in the mechanical properties after a marathon or half-marathon.
Overloading or incorrect loading of the Achilles tendon can lead to a pain syndrome in the area of the Achilles tendon ( Achillodynia ) or at its attachment to the heel bone ( Achilles tendon inflammation ). Also one can Haglund's deformity occur.
Achilles tendon tear
- → Main article Achilles tendon rupture
The Achilles tendon has grown with loads of 60–100 N / mm², which corresponds to a load capacity of up to 800 kg for an area of 80 mm². A rupture of the Achilles tendon when the triceps surae muscle is suddenly tensed therefore usually only occurs in the event of previous damage due to excessive or incorrect loading. The tendon repeatedly experiences minor injuries that disrupt the blood supply to the tissue and thus degenerate its strength. These changes are most pronounced in an area 2–6 cm above the insertion (so-called "Achilles tendon waist"), where the tendon is poorly supplied and where the tear usually also occurs. The tendon suddenly breaks with a loud, whip-crack-like sound. The plantar flexion is then only a very limited extent.
In principle, a conservative or surgical approach can be used in the event of a crack. In young, sporty people, surgical treatment is usually sought, because on the one hand a safe approach of the two tendon stumps is ensured and on the other hand a very high primary stability is achieved, which in turn is of great advantage in further treatment. For older people or skin problems ( varicose veins , "cortisone skin "), a conservative approach can definitely be chosen. If possible, ultrasound should be used to check whether the two torn ends of the tendon are approaching each other during plantar flexion in the ankle.
Achilles tendon in animals
In quadruped mammals, other muscles ( semitendinosus muscle , biceps femoris muscle , flexor digitorum pedis superficialis muscle ) radiate into the Achilles tendon, so that the tendon cord of the animal's heel cannot be equated with the human Achilles tendon. It is therefore called the common heel tendon cord ( Tendo calcaneus communis ). Under his approach is a bursa ( Bursa subtendinea calcanea ) whose swelling as eggs bile is referred to. There is also a bursa ( bursa subcutanea calcanea ) between the skin and the heel tendon , the swelling of which is known as a pie-ax .
Historical origin of the name
The naming of the Achilles tendon is based on the legend of Achilles , a hero of Greek mythology . Achilles (Eng. Achilles or Achilles, ancient Greek Ἀχιλλεύς ) is the son of Peleus and the sea nymph Thetis in Greek mythology . As the son of a human father and a divine mother, he was mortal. Thetis tried to at least make him invulnerable and dipped him into the Styx , the river that separates the underworld from the upper world. The place on the heel where Achilles held her hand, however, remained unwetted by the water of the river, and thus became the only vulnerable place (→ Achilles heel ).
- ^ Arnd Krüger : Achilles tendon. In: competitive sport. Vol. 44, 3, 2014, pp. 30-31.
- ↑ SD Rosengarten, JL Cook, AL Bryant and others. a .: Australian football players' Achilles tendons respond to game loads within 2 days: an ultrasound tissue characterization (UTC) study. In: British Journal Sports Med. 2015, pp. 183-187. doi: 10.1136 / bjsports-2013-092713 .
- ↑ Tendon with perseverance. Scienceticker.info, September 27, 2012.
- Franz-Viktor Salomon: muscle tissue . In: Franz-Viktor Salomon, Hans Geyer and Uwe Gille (eds.): Anatomy for veterinary medicine . 3. Edition. Enke, Stuttgart 2015, ISBN 978-3-8304-1288-5 , pp. 244-245 .