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Sartorius tendon (Distal)

The distal sartorius tendon is the terminal portion of the sartorius muscle, the longest muscle in the body. After descending obliquely across the thigh, the sartorius narrows into a tendon that inserts on the medial side of the knee. It is part of the pes anserinus, along with the tendons of gracilis and semitendinosus. This tendinous insertion stabilizes the medial knee, assists in knee flexion, and provides dynamic support to the joint. It is clinically important in pes anserinus bursitis, medial knee injuries, and reconstructive procedures.

Synonyms

  • Pes anserinus tendon (sartorius component)

  • Medial sartorius insertion

  • Distal sartorius aponeurosis

Origin and Insertion

  • Origin: From the sartorius muscle belly coursing down the anterior thigh

  • Course: Becomes tendinous in the distal third of the thigh, continuing obliquely toward the medial knee

  • Insertion: Medial surface of the proximal tibia, anterior to gracilis and semitendinosus insertions, forming the pes anserinus

Relations

  • Anteriorly: Subcutaneous tissue of medial knee

  • Posteriorly: Medial collateral ligament (MCL) and tibial surface

  • Superiorly: Tendons of gracilis and semitendinosus (pes anserinus group)

  • Inferiorly: Pes anserinus bursa separating tendons from tibia

Nerve Supply

  • Supplied by the femoral nerve (L2–L4) via the sartorius muscle belly

Arterial Supply

  • Muscular branches of the femoral artery

  • Descending genicular artery

  • Medial inferior genicular artery

Venous Drainage

  • Femoral vein and its genicular tributaries

Function

  • Contributes to flexion of the knee

  • Assists in medial rotation of tibia on femur when knee is flexed

  • Provides medial stabilization to knee joint via pes anserinus group

  • Protects medial collateral ligament during dynamic activity

Clinical Significance

  • Pes anserinus bursitis: Inflammation beneath the tendon insertion causes medial knee pain

  • Medial knee injuries: Distal sartorius may be strained or inflamed with overuse

  • Surgical relevance: Pes anserinus tendons may be harvested for ACL reconstruction grafts

  • Imaging importance: MRI helps differentiate tendon injury from bursitis or meniscal pathology

MRI Appearance

T1-weighted images:

  • Tendon appears as a low-signal linear structure inserting onto medial tibia

  • Surrounded by bright subcutaneous and intermuscular fat

T2-weighted images:

  • Tendon remains low signal

  • Pathology (strain, partial tear, bursitis) appears as bright fluid or edema adjacent to tendon

STIR (Short Tau Inversion Recovery):

  • Normal tendon is dark (low signal)

  • Edema or bursitis shows bright hyperintensity in surrounding tissue or bursa

Proton Density Fat-Sat (PD FS):

  • Tendon is dark (low signal)

  • Injury or inflammation shows bright hyperintense regions near insertion

T1 Fat-Sat Post-Contrast:

  • Normal tendon enhances minimally

  • Bursitis shows rim enhancement of inflamed bursal lining

  • Tendinopathy or inflammation may show focal or linear enhancement

CT Appearance

Non-Contrast CT:

  • Tendon not well visualized; seen as a thin soft tissue band inserting at medial tibia

  • Pes anserinus bursa may appear as subtle hypodense region if distended

Post-Contrast CT:

  • Tendon itself does not enhance significantly

  • Bursitis shows mild rim enhancement

  • Adjacent inflammatory or infectious processes may show heterogeneous enhancement

MRI images

Sartorius tendon (Distal) axial cross sectional anatomy 3T MRI AI enhanced radiology anatomy image-img-00000-00000

MRI images

Sartorius tendon (Distal) sagittal cross sectional anatomy 3T MRI AI enhanced radiology anatomy image-img-00000-00000

MRI images

sartorius tendon anatomy image 3t mri

MRI images

sartorius tendon anatomy image

CT image

Sartorius tendon (Distal) ct axial image

CT image

Sartorius tendon (Distal)