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Adductor longus muscle

The adductor longus is a long, flat muscle of the medial thigh, forming part of the adductor group. It is more superficial than the adductor brevis and magnus, and contributes to the muscular mass at the inner thigh. It is clinically important because of its frequent involvement in sports-related strains (“groin pulls”) and its role in stabilizing gait.

Synonyms

  • Long adductor of the thigh

  • Medial thigh adductor (longus)

  • Adductor longus of the medial compartment

Origin, Course, and Insertion

  • Origin:

    • The adductor longus originates from the body of the pubis, specifically from the pubic crest and pubic symphysis region, just below the pubic tubercle.

  • Course:

    • The muscle passes inferiorly and laterally from its pubic origin, lying superficially in the medial thigh.

    • It runs anterior to the adductor brevis and adductor magnus, and medial to the pectineus muscle.

    • Its belly forms the medial border of the femoral triangle, a key surface landmark.

  • Insertion:

    • It inserts into the middle third of the linea aspera of the femur on the medial lip, between the insertions of the adductor magnus and vastus medialis.

Nerve Supply

  • Obturator nerve (anterior division, roots L2–L4)

Arterial Supply

  • Obturator artery (primary supply)

  • Contributions from the deep femoral (profunda femoris) artery and medial circumflex femoral artery

Venous Drainage

  • Venous blood drains into the obturator vein and the deep femoral vein, eventually reaching the femoral vein

Function

  • Adduction of the thigh at the hip joint

  • Assists in flexion of the thigh

  • Stabilizes the pelvis during standing, walking, and running

  • Provides medial thigh contour and surface landmark (femoral triangle border)

MRI Appearance

T1-weighted images:

  • Normal adductor longus appears as  intermediate signal  

  • Fatty septa or chronic fatty infiltration may appear T1 hyperintense

  • Hemorrhage may be iso- to hyperintense depending on stage

T2-weighted images:

  • Normal muscle is low-to-intermediate signal (darker than fat, brighter than cortical bone)

  • Muscle strain, edema, or acute injury: hyperintense signal, especially at the myotendinous junction

STIR (Short Tau Inversion Recovery):

  • Fat suppressed; normal muscle remains low-to-intermediate

  • Edema, inflammation, or acute strain: bright hyperintensity

Proton Density Fat-Sat (PD FS):

  • Normal muscle: low-to-intermediate signal

  • Muscle strain or tear: bright hyperintense foci or streaks

T1 Fat-Sat Post-Contrast:

  • Normal muscle: mild, homogeneous enhancement

  • Myositis, neoplasm, or abscess: heterogeneous or focal enhancement

  • Complete tear or abscess: rim enhancement with non-enhancing center

CT Appearance

Non-Contrast CT:

  • Muscle appears isodense with other skeletal muscles (~40–50 HU)

  • Fat planes distinguish it from adductor brevis, magnus, and pectineus

  • Hematoma: hyperdense acutely

Post-Contrast CT:

  • Normal muscle: mild homogeneous enhancement

  • Pathology: greater, heterogeneous enhancement (inflammatory, neoplastic, or traumatic changes)

  • Abscess or necrotic tumor: rim enhancement with central low density

MRI image

Adductor longus muscle MRI axial anatomy image-img-00000-00000

CT image

Adductor longus muscle CT axial anatomy image-img-00000-00000

CT image

Adductor longus muscle ct coronal

MRI image

Adductor longus muscle MRI coronal anatomy image-img-00000-00000