Topics

Topic

design image
Medial gastrocnemius tendon

The medial gastrocnemius tendon is the strong fibrous structure formed by the convergence of fibers from the medial head of the gastrocnemius muscle. It plays a crucial role in transmitting muscular force from the calf to the Achilles tendon and contributes to knee flexion and plantar flexion of the foot. It is clinically significant as a common site of strain, partial tears, and involvement in injuries such as “tennis leg.”

Synonyms

  • Tendon of medial head of gastrocnemius

  • Medial gastrocnemius aponeurosis

  • Inner calf tendon

Origin and Insertion

  • Origin (muscle attachment):

    • The medial head of gastrocnemius originates from the posterior aspect of the medial femoral condyle and adjacent popliteal surface of femur, just superior to the medial condyle

  • Course (tendon):

    • Fibers converge into a strong tendon that joins with the lateral gastrocnemius tendon and soleus tendon

    • Forms part of the Achilles tendon in the distal calf

  • Insertion (common tendon):

    • Ultimately inserts into the posterior surface of the calcaneus via the Achilles tendon

Relations

  • Anteriorly: Posterior capsule of the knee joint, semimembranosus tendon, and medial meniscus

  • Posteriorly: Subcutaneous tissue and skin of the calf

  • Medially: Semitendinosus and gracilis tendons

  • Laterally: Lateral head of gastrocnemius tendon and plantaris tendon

  • Inferiorly: Soleus muscle fibers merging with Achilles tendon

Nerve Supply

  • Supplied by the tibial nerve (S1–S2), which innervates the gastrocnemius muscle

Arterial Supply

  • Sural branches of the popliteal artery

  • Additional contributions from posterior tibial artery and peroneal artery branches

Venous Drainage

  • Venous return via sural veins → popliteal vein

Function

  • Enables plantar flexion of the foot at the ankle joint

  • Contributes to flexion of the knee joint

  • Provides propulsive force in gait, running, and jumping

  • Assists in stabilizing the knee joint during weight-bearing

Clinical Significance

  • Common site of injury in tennis leg (strain of medial gastrocnemius)

  • Can be affected by myotendinous junction tears, tendinopathy, or intramuscular hematomas

  • May be involved in posterior knee pain syndromes

  • Important in Achilles tendon pathology, since it forms part of the tendon complex

MRI Appearance

T1-weighted images:

  • Tendon appears as a low-signal linear structure

  • Surrounded by bright fat, improving visualization

  • Chronic degeneration may show focal thickening with slightly higher signal

T2-weighted images:

  • Normal tendon shows low signal

  • Partial tears or degeneration show focal bright signal intensity within tendon fibers

  • Acute strain at myotendinous junction appears bright

STIR (Short Tau Inversion Recovery):

  • Normal tendon: dark, low signal

  • Pathology (strain, tear, inflammation): bright hyperintense signal at myotendinous junction or within tendon

Proton Density Fat-Saturated (PD FS):

  • Normal tendon: low signal

  • Injuries, tendinopathy, or partial tears: bright hyperintense areas clearly highlighted after fat suppression

T1 Fat-Sat Post-Contrast:

  • Normal tendon: minimal to no enhancement

  • Pathological tendon: enhancement at sites of inflammation, partial tears, or neoplastic infiltration

CT Appearance

Non-Contrast CT:

  • Tendon appears as a dense soft tissue structure blending into Achilles tendon

  • Calcifications or ossification may be seen in chronic tendinopathy

  • Hematoma in surrounding tissues may appear as hyperdense collections

Post-Contrast CT:

  • Normal tendon shows no significant enhancement

  • Enhancement may occur in surrounding soft tissues in cases of tendinitis, tear, or infection

  • Contrast highlights associated fluid collections or hematomas

MRI images

Medial gastrocnemius tendon axial cross sectional anatomy 3T MRI radiology anatomy image-img-00000-00000

MRI images

Medial gastrocnemius tendon sag cross sectional anatomy 3T MRI radiology anatomy image-img-00000-00000

CT image

Medial gastrocnemius tendon ct axial image

CT image

Medial gastrocnemius tendon sag image