The
Achilles tendon also known as the
calcaneal tendon or the
tendo calcaneus, is a
tendonA tendon is a tough band of fibrous connective tissue that usually connects muscle to bone and is capable of withstanding tension. Tendons are similar to ligaments and fasciae as they are all made of collagen except that ligaments join one bone to another bone, and fasciae connect muscles to other...
of the posterior
legŁęg may refer to the following places in Poland:*A former name for the town of Ełk *Part of the Czyżyny district of Kraków*Łęg, Pleszew County in Greater Poland Voivodeship...
. It serves to attach the
plantarisPlantaris is a vestigial structure and one of the superficial muscles of the posterior crural compartment of the leg.It is innervated by the tibial nerve ....
,
gastrocnemiusIn humans, the gastrocnemius muscle is a very powerful superficial pennate muscle that is in the back part of the lower leg. It runs from its two heads just above the knee to the heel, and is involved in standing, walking, running and jumping. Along with the soleus muscle it forms the calf muscle...
(calf) and
soleus- References :* Gray, Henry. Pick, T. Pickering, & Howden, Robert . Gray's Anatomy . New York: Barnes & Noble Books.- External links :...
muscleMuscle is a contractile tissue of animals and is derived from the mesodermal layer of embryonic germ cells. Muscle cells contain contractile filaments that move past each other and change the size of the cell. They are classified as skeletal, cardiac, or smooth muscles. Their function is to...
s to the
calcaneus (heel) bone.
Anatomy
The Achilles is the tendonous extension of 3 muscles in the lower leg: gastrocnemius and soleus. In humans, the tendon passes posterior to the
ankleThe ankle joint is formed where the foot and the leg meet. The ankle, or talocrural joint, is a synovial hinge joint that connects the distal ends of the tibia and fibula in the lower limb with the proximal end of the talus bone in the foot...
. It is the thickest and strongest tendon in the body. It is about 15 centimetres (6 in) long, and begins near the middle of the calf, but receives fleshy fibers on its anterior surface, almost to its lower end. Gradually becoming contracted below, it is inserted into the middle part of the posterior surface of the calcaneus, a
bursaA bursa is a small fluid-filled sac lined by synovial membrane with an inner capillary layer of slimy fluid . It provides a cushion between bones and tendons and/or muscles around a joint. This helps to reduce friction between the bones and allows free movement...
being interposed between the tendon and the upper part of this surface. The tendon spreads out somewhat at its lower end, so that its narrowest part is about 4 centimetres (1.6 in) above its insertion. It is covered by the
fasciaA fascia is a layer of fibrous tissue that permeates the human body. A fascia is a connective tissue that surrounds muscles, groups of muscles, blood vessels, and nerves, binding those structures together in much the same manner as plastic wrap can be used to hold the contents of sandwiches...
and the
integumentThe integumentary system is the organ system that protects the body from damage, comprising the skin and its appendages...
, and stands out prominently behind the bone; the gap is filled up with areolar and
adipose tissueIn histology, adipose tissue or body fat or fat depot or just fat is loose connective tissue composed of adipocytes. It is technically composed of roughly only 80% fat; fat in its solitary state exists in the liver and muscles. Adipose tissue is derived from lipoblasts...
. Along its lateral side, but superficial to it, is the
small saphenous veinThe small saphenous vein , is a relatively large vein of the superficial posterior leg.-Path:Its origin is where the dorsal vein from the fifth digit merges with the dorsal venous arch of the foot, which attaches to the great saphenous vein...
. The Achilles' muscle reflex tests the integrity of the S1 spinal root. The tendon can receive a load stress 3.9 times body weight during walking and 7.7 times body weight when running.
Nomenclature
The oldest-known written record of the tendon being named for
AchillesIn Greek mythology, Achilles was a Greek hero of the Trojan War, the central character and the greatest warrior of Homer's Iliad.Plato named Achilles the handsomest of the heroes assembled against Troy....
is in 1899 by the Flemish/Dutch anatomist
Philip Verheyenthumb|420px|Philip Verheyen Dissecting His Amputated Leg. Anonymous. From the collection of Pieter Deheijde.Philip Verheyen was a Belgian surgeon.-His birth and the beginning of his education:...
. In his widely used text
Corporis Humani Anatomia, Chapter XV, page 328, he described the tendon's location and said that it was commonly called "the cord of Achilles" ("quae vulgo dicitur
chorda Achillis")
The name
Achilles' heelAn Achilles’ heel is a deadly weakness in spite of overall strength, that can actually or potentially lead to downfall. While the mythological origin refers to a physical vulnerability, metaphorical references to other attributes or qualities that can lead to downfall are common.- Origin :In Greek...
comes from Greek mythology. Achilles' mother, the goddess
ThetisSilver-footed Thetis , disposer or "placer" , is encountered in Greek mythology mostly as a sea nymph or known as the goddess of water, one of the fifty Nereids, daughters of the ancient one of the seas with shape-shifting abilities who survives in the historical vestiges of most later Greek myths...
, received a prophecy of her son's death. Hearing this, she dipped him into the
River StyxIn Greek mythology the Styx is the river that forms the boundary between the underworld and the world of the living, as well as a goddess and a nymph that represents the river.Styx may also refer to:-Popular culture:...
to protect his body from harm. However, she kept hold of his heel, meaning that the water did not touch this part of his body and it was therefore vulnerable. During the
Trojan WarIn Greek mythology, the Trojan War was waged against the city of Troy by the Achaeans after Paris of Troy took Helen from her husband Menelaus, the king of Sparta. The war is among the most important events in Greek mythology and was narrated in many works of Greek literature, including the Iliad...
, Achilles was struck on his unprotected heel by a poisoned arrow shot by Paris, which killed him. In the same war, Achilles is also said to have cut behind Hector's Achilles tendons, having killed him, and threaded leather thongs through the incisions in order to drag him behind a chariot.
The Achilles tendon is also known as the calcaneal tendon. Because eponyms, names relating to people, have no relationship to the subject matter, most anatomical eponyms also have scientifically descriptive terms. The term calcaneal comes from the Latin calcaneum, meaning heel.
Role in disease
The most common Achilles tendon injuries are Achilles tendinosis and Achilles tendon rupture. Achilles tendinosis is the soreness or stiffness of the tendon, generally due to overuse. Achilles tendinitis (inflammation of the tendon) was thought to be the cause of most tendon pain, until the late 90s when scientists discovered no evidence of inflammation. Partial and full Achilles tendon ruptures are most likely to occur in sports requiring sudden eccentric stretching, such as sprinting. Maffulli et al. suggested that the clinical label of
tendinopathyTendinopathy refers to a disease of a tendon. More specifically, it can refer to:* Tendinitis* TendinosisTendon injury arise from a combination of intrinsic and extrinsic factors; acute tendon injuries may be predominantly caused by extrinsic factors, whereas in overuse syndromes as in the case of...
should be given to the combination of tendon pain, swelling and impaired performance.
Achilles tendon ruptureThe Achilles tendon is the most commonly injured tendon. Rupture can occur while performing actions requiring explosive acceleration, such as pushing off or jumping...
is a partial or complete break in the tendon; it requires immobilization or surgery.
XanthomaA xanthoma , from Greek xanthos, ξανθος, "yellow", is a deposition of yellowish cholesterol-rich material in tendons or other body parts in various disease states...
can develop in the Achilles tendon in patients with
familial hypercholesterolemiaFamilial hypercholesterolemia is a genetic disorder characterized by high cholesterol levels, specifically very high levels of low-density lipoprotein , in the blood and early cardiovascular disease...
.
Treatment of damage
Initial treatment of damage to the tendon is generally nonoperative.
OrthoticsOrthotics is a specialty within the medical field concerned with the design, manufacture and application of orthoses. An orthosis is an orthopedic device that supports or corrects the function of a limb or the torso...
can produce early relief to the tendon by the correction of malalignments,
non-steroidal anti-inflammatory drugNonsteroidal anti-inflammatory drugs, usually abbreviated to NSAIDs or NAIDs, but also referred to as nonsteroidal anti-inflammatory agents/analgesics or nonsteroidal Anti-inflammatory medicines , are drugs with analgesic and antipyretic effects and which have, in higher doses, anti-inflammatory...
s (NSAIDs) are generally to be avoided as they make the more-common tendinopathy (degenerative) injuries worse; though they may very occasionally be indicated for the rarer tendinitis (inflammatory) injuries. Physiotherapy by eccentric calf stretching under resistance is commonly recommended, usually in conjunction with podiatric insoles or heel cushioning. According to reports by Hakan Alfredson, M.D., and associates of clinical trials in Sweden, the pain in Achilles tendinopathy arises from the nerves associated with neovascularization and can be effectively treated with 1–4 small injections of a sclerosant. In a cross-over trial, 19 of 20 of his patients were successfully treated with this
sclerotherapySclerotherapy is a procedure used to treat blood vessels or blood vessel malformations and also those of the lymphatic system. A medicine is injected into the vessels, which makes them shrink. It is used for children and young adults with vascular or lymphatic malformations...
.
In a case where
Achilles tendon ruptureThe Achilles tendon is the most commonly injured tendon. Rupture can occur while performing actions requiring explosive acceleration, such as pushing off or jumping...
is concerned, there are three main types of treatment: the open and the percutaneous operative methods, and nonoperative approaches.
Depending on the severity of the injury, recovery from an Achilles injury can take up to 12–16 months.
Imaging findings
Achilles tendon degeneration (tendinosis) is typically investigated with either MRI or
ultrasoundUltrasound is cyclic sound pressure with a frequency greater than the upper limit of human hearing. Ultrasound is thus not separated from "normal" sound based on differences in physical properties, only the fact that humans cannot hear it. Although this limit varies from person to person, it is...
. In both cases, the tendon is thickened, may demonstrate surrounding inflammation by virtue of the presence of paratenonitis, retrocalcaneal or retroAchilles
bursitisBursitis is the inflammation of one or more bursae of synovial fluid in the body. The bursae rest at the points where internal functionaries, such as muscles and tendons, slide across bone. Healthy bursae create a smooth, almost frictionless functional gliding surface making normal movement painless...
. Within the tendon, increased blood flow, tendon fibril disorganisation and partial thickness tears may be identified. Achilles tendinosis frequently involves the mid portion of the tendon, however may involve the insertion where this is known as enthesopathy. Though
enthesopathyIn medicine, an enthesopathy refers to a disorder of entheses .If the condition is known to be inflammatory, it can more precisely be called a enthesitis.Enthesopathies are disorders of peripheral ligamentous or muscular attachments,...
may be seen in the context of advancing age, it is also associated with
arthritisArthritis is a form of joint disorder that involves inflammation of one or more joints....
such as
goutGout is a medical condition usually characterized by recurrent attacks of acute inflammatory arthritis—a red, tender, hot, swollen joint. The metatarsal-phalangeal joint at the base of the big toe is the most commonly affected . However, it may also present as tophi, kidney stones, or urate...
and the
seronegative spondyloarthitidesSpondyloarthropathy is any joint disease of the vertebral column. Spondyloarthropathy with inflammation is called spondylarthritis. In contrast, spondylopathy is a disease of the vertebra itself, but many conditions involve both spondylopathy and spondyloarthropathy...
. Achilles tendinosis is a known risk factor for calf muscle tears.
Evolution and function
The Achilles tendon is short or absent in
great apeThe Hominidae or include them .), as the term is used here, form a taxonomic family, including four extant genera: chimpanzees , gorillas , humans , and orangutans ....
s, but long in arboreal
gibbonGibbons are apes in the family Hylobatidae . The family is divided into four genera based on their diploid chromosome number: Hylobates , Hoolock , Nomascus , and Symphalangus . The extinct Bunopithecus sericus is a gibbon or gibbon-like ape which, until recently, was thought to be closely related...
s and humans. It provides elastic energy storage in hopping, walking, and running. Computer models suggest this energy storage Achilles tendon increases top running speed by >80% reduces running costs by more than three-quarters. It has been suggested that the "absence of a well-developed Achilles tendon in the nonhuman African apes would preclude them from effective running, both at high speeds and over extended distances."
Role in postural orientation
Bilateral Achilles tendon vibration in the absence of vision has a major impact on
posturalHuman positions refers to the different positions that the human body can take.There are several synonyms that refer to the human position, often used interchangeably, but having specific flavors....
orientation. Vibration applied to the Achilles tendon is well known to induce in freely standing subjects a backward body displacement and in restrained subjects an illusory forward body tilt. The vibrations stimulate
muscle spindleMuscle spindles are sensory receptors within the belly of a muscle, which primarily detect changes in the length of this muscle. They convey length information to the central nervous system via sensory neurons. This information can be processed by the brain to determine the position of body parts...
s in the calf muscles. The muscle spindles alert the brain that the body is moving forward, so the
central nervous systemThe central nervous system is the part of the nervous system that integrates the information that it receives from, and coordinates the activity of, all parts of the bodies of bilaterian animals—that is, all multicellular animals except sponges and radially symmetric animals such as jellyfish...
compensates by moving the body backwards.
External links