The Anatomy of the Achilles Tendon

https://doi.org/10.1016/j.fcl.2005.01.011Get rights and content

Section snippets

Gastrocnemius

The gastrocnemius is the most superficial muscle. A fusiform muscle, it forms the lower boundary of the popliteal fossa and accounts for the bulge of the calf (Fig. 1) [2], [20]. The medial head of the gastrocnemius arises from the popliteal surface of the femur behind the medial supracondylar line and the adductor tubercle, above the medial femoral condyle. It is larger and longer, and extends more distally in the calf than the lateral head [2].

The lateral head is shorter and arises from the

Soleus

The soleus muscle is a broad, flat pennate muscle. It is wider than the gastrocnemius, and its muscle fibers extend more distally than those of the gastrocnemius. It originates from the posterior surface of the head and upper fourth of the posterior surface of the fibula, from a fibrous arch between fibula and tibia, and from the oblique line and the middle third of the medial border of the tibia. The popliteal vessels and the tibial nerve pass under the fibrous arch.

The soleus consists of two

Plantaris

The plantaris muscle has a variable size, and is absent in 6% to 8% of individuals. It has a short, fleshy origin from the popliteal surface of the femur above the lateral femoral condyle. The muscle belly is usually 5 cm to 10 cm in length, with a long tendon that extends distally between the gastrocnemius and the soleus. The tendon inserts into the medial border of the Achilles tendon, anterior to the Achilles tendon. In 6% to 8% of subjects, it inserts into the flexor retinaculum [21]. This

Achilles tendon

The Achilles tendon is approximately 15 cm long, and starts at the musculotendinous junction of the gastrocnemius and soleus in the middle of the calf. The tendon is flattened at its junction with the gastrocnemius to become rounded until approximately 4 cm from its insertion. At this level, it flattens, then expands and becomes cartilaginous, to insert into a rough area on the middle of the lower part of the posterior surface of the calcaneus. On its anterior surface, it receives the muscular

Structure of the Achilles tendon

Tendons appear white because they are mostly avascular. A tendon is a roughly uniaxial composite that is composed of mainly type I collagen in an extracellular matrix that is composed of mucopolysaccharide and a proteoglycan gel [35]. They consist of 30% collagen and 2% elastin embedded in an extracellular matrix that contains 68% water and tenocytes [36], [37]. Elastin contributes to the flexibility of the tendon. The collagen protein, tropocollagen, forms 65% to 80% of the mass of dry weight

Blood supply

The blood supply of tendons is variable, and usually is divided into three regions: the musculo-tendinous junction, the length of the tendon, and the tendon–bone junction. Blood vessels originate from vessels in the perimysium, periosteum, and by way of the paratenon and mesotenon. The Achilles tendon is supplied at its musculotendinous junction, along the length of the tendon, and at its junction with bone. The blood supply consists mainly of longitudinal arteries that course the length of the

Nerve supply

Tendons are supplied by sensory nerves from the overlying superficial nerves or from nearby deep nerves, the tibial nerve, and its branches [23]. The nerve supply is largely, if not exclusively, afferent [48], The afferent receptors are found near the musculo-tendinous junction [23], either on the surface or in the tendon. The nerves tend to form a longitudinal plexus and enter by way of the septa of the endotenon or the mesotenon if there is a synovial sheath. Branches also pass from the

First page preview

First page preview
Click to open first page preview

References (50)

  • D.B. Clement et al.

    A survey of overuse running injuries

    Physician Sportsmed

    (1981)
  • G.W. Smart et al.

    Achilles tendon disorders in runners: a review

    Med Sci Sports Exerc

    (1980)
  • C. Johansson

    Injuries in elite orienteers

    Am J Sports Med

    (1986)
  • D.C. Jones

    Retrocalcaneal bursitis and insertional tendonitis

    Sports Med Arthroscopy Rev

    (1994)
  • P.V. Komi

    Relevance of in vivo force measurements to human biomechanics

    J Biomech

    (1990)
  • A.A. Schepsis

    Achilles tendon disorders in athletes

    Am J Sports Med

    (2002)
  • N. Maffulli et al.

    Ultrasound diagnosis of Achilles tendon pathology in runners

    Br J Sports Med

    (1987)
  • N. Maffulli et al.

    Achilles tendon rupture and sciatica: a possible correlation

    Br J Sports Med

    (1998)
  • N. Maffuli

    Rupture of the Achilles tendon

    J Bone Joint Surg

    (1999)
  • G. Jozsa et al.

    Human tendons Anatomy and Physiology

    Human Kinetics

    (1997)
  • D. Kader et al.

    Achilles tendinopathy: some aspects of basic science and clinical management

    Br J Sports Med

    (2002)
  • M. Kvist

    Achilles tendon overuse injuries [doctoral dissertation]

    (1991)
  • M. Kvist

    Achilles tendon injuries in athletes

    Sports Med

    (1994)
  • N.P. Plastanga et al.

    Anatomy and human movement structure and function

    (1994)
  • R.J. Last

    Anatomy, regional and applied

    (1984)
  • Cited by (139)

    • Current concept review of Achilles tendinopathy

      2024, Journal of Clinical Orthopaedics and Trauma
    • Current Concepts in Achilles Tendon Ruptures

      2024, Clinics in Podiatric Medicine and Surgery
    • Regional Anesthesia for Orthobiologic Procedures

      2023, Physical Medicine and Rehabilitation Clinics of North America
    View all citing articles on Scopus
    View full text