Myotendinous Junction

Original Editor - Lucinda hampton

Top Contributors - Lucinda hampton  

Introduction[edit | edit source]

MTJ structure

Myotendinous junction (MTJ) is a part of the myotendinous unit. The myotendinous unit consists usually of bone, enthesis, tendon, myotendinous junction and muscle, and is responsible for producing skeletal movement[1].

The MTJ has a distinctive form with the muscle membrane having many infolds which the collagen fibrils from the tendon join with (see image 1) . This unique structure creates an increased area for force transmission between muscle and tendon resulting in better force dispersal and less focal stress[2][3].

The MTJ transmits large forces from muscle to tendon in strenuous exercise, and hence is a common location for muscle strains. Most of these can be prevented by heavy eccentric exercise[3].

Physiotherapy Implications[edit | edit source]

Dissection of the gastrocnemius–soleus MTJ

The myotendinous unit weakest region is the MTJ, and as such it is its most commonly injured part.

  • Large pennate muscle that are multi arthrodial and produce large tensile stresses are the most likely to suffer from MTJ injuries e.g. biceps femoris, quadratus femoris, biceps brachii[2].
  • The interdigitations of the MTJ become shorter with aging, lessening the contact area for force transmission, and increase risk of injury.[4]

US and MRI[edit | edit source]

For correct diagnosis a grading system of MTJ injuries exists based on MRI or US scan results.

  1. Mild strain: feathery interstitial edema and fluid/hemorrhage around the MTJ
  2. Moderate strain: intramuscular hematoma and perifascial fluid/hemorrhage
  3. Severe strain: MTJ tear with laxity/discontinuity of the tendon and muscle ends, sometimes with retraction

Scar tissue, old blood products and atrophy/fatty degeneration of the muscle are indicative of an old strain[2].

Myotendinous unit

References[edit | edit source]

  1. Radiopedia Myotendinous unit Available: 12.6.2022)
  2. 2.0 2.1 2.2 Radiopedia Myotendinous junction Available: (accessed 12.6.2022)
  3. 3.0 3.1 Jakobsen JR, Krogsgaard MR. The Myotendinous Junction—A Vulnerable Companion in Sports. A Narrative Review. Frontiers in physiology. 2021;12. Available; (accessed 12.6.2022)
  4. Wikimsk MTJ Available: (accessed 12.6.2022)