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Sartorius Tendon (Proximal)

The sartorius tendon is the proximal tendinous portion of the sartorius muscle, the longest muscle in the human body. The sartorius originates from the anterior superior iliac spine (ASIS) via this tendon, then descends obliquely across the thigh. The proximal tendon is relatively short but strong, serving as the anchor for the muscle onto the pelvis. It plays a critical role in hip flexion, abduction, and external rotation, as well as knee flexion when the muscle acts as a whole.

Synonyms

  • Proximal sartorius tendon

  • Tendon of sartorius at ASIS

  • Hip origin tendon of sartorius

Origin and Insertion

  • Origin:

    • The tendon arises from the anterior superior iliac spine (ASIS) and adjacent notch

  • Course:

    • Short tendon quickly transitions into the muscular belly of sartorius

    • Runs obliquely across the anterior thigh from lateral to medial

  • Insertion (muscle as a whole):

    • The tendon transitions to muscle belly; distal insertion is at the pes anserinus (anteromedial proximal tibia), together with tendons of gracilis and semitendinosus

Nerve Supply

  • Femoral nerve (L2–L4) supplies the sartorius muscle, including its tendon origin

Arterial Supply

  • Femoral artery (muscular branches)

  • Lateral circumflex femoral artery branches

Venous Drainage

  • Femoral vein and its tributaries

Function

  • Proximal tendon provides firm attachment to the ASIS

  • Sartorius muscle actions include:

    • Flexion, abduction, and external rotation of the hip

    • Flexion of the knee

    • Helps assume the “cross-legged” sitting posture

  • Stabilizes the pelvis during hip and knee movement

Clinical Significance

  • Can be involved in apophyseal avulsion injuries at the ASIS, especially in adolescents and athletes

  • May be affected in sports-related groin injuries or tendinopathy

  • Palpable landmark at the ASIS in surface anatomy

  • Important in surgical approaches to the hip and pelvis

MRI Appearance

T1-weighted images:

  • Tendon appears as a low-signal (dark) structure at its origin on ASIS

  • Surrounded by bright fat, allowing clear visualization

T2-weighted images:

  • Normal tendon remains dark (low signal)

  • Tendinopathy or partial tear shows focal bright areas within or around tendon

STIR (Short Tau Inversion Recovery):

  • Normal tendon remains dark

  • Pathology (strain, tear, inflammation) shows bright hyperintensity

Proton Density Fat-Saturated (PD FS):

  • Normal tendon is dark

  • Pathological changes (tendinopathy, tear, peritendinous edema) appear bright

T1 Fat-Sat Post-Contrast:

  • Normal tendon shows little or no enhancement

  • Pathologic tendon may show enhancement at enthesis or surrounding soft tissues in cases of inflammation, avulsion, or bursitis

CT Appearance

Non-Contrast CT:

  • Tendon is not separately visualized; appears as a soft-tissue band at ASIS

  • Calcification or ossification may be seen in chronic enthesopathy or avulsion injury

  • Surrounding fat planes enhance visibility

Post-Contrast CT:

  • Normal tendon does not enhance

  • Enhancement may be seen in surrounding soft tissues with inflammation, infection, or trauma

  • Bony avulsion at ASIS is well seen with cortical irregularity or fracture fragment

MRI image

Sartorius Tendon (Proximal) MRI axial anatomy image-img-00000-00000

MRI image

Sartorius Tendon (Proximal) MRI axial anatomy image-img-00000-00000_00001

CT image

Sartorius Tendon (Proximal) CT axial anatomy