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Inguinal ligament

The inguinal ligament is a strong, fibrous band forming the lower border of the aponeurosis of the external oblique muscle. It extends obliquely across the groin, acting as an important anatomical landmark and boundary between the abdomen and thigh. The ligament is clinically significant because of its relationship to the inguinal canal, femoral canal, and structures passing from the pelvis to the lower limb. It is also a key reference point in hernia surgery and groin anatomy.

Synonyms

  • Poupart’s ligament

  • Fallopian ligament (historical)

  • Inguinal arch (sometimes loosely applied)

Origin, Course, and Insertion

  • Origin:

    • Arises from the anterior superior iliac spine (ASIS)

  • Course:

    • Runs medially and inferiorly in a convex arc across the groin

    • Lies between the abdominal wall and the thigh, forming the base of the inguinal canal

    • Curves inward at its medial end, contributing fibers to the lacunar ligament

  • Insertion:

    • Attaches to the pubic tubercle on the superior pubic ramus

Relations

  • Superiorly: Lower fibers of the external oblique and the inguinal canal (with spermatic cord/round ligament)

  • Inferiorly: Femoral nerve, femoral artery, femoral vein, femoral canal, and iliopsoas muscle (passing into thigh)

  • Medially: Lacunar ligament and pubic tubercle

  • Laterally: Anterior superior iliac spine (ASIS)

Nerve Supply

  • The ligament itself has no direct motor innervation but receives sensory innervation from branches of the iliohypogastric, ilioinguinal, and femoral nerves in its region

Arterial Supply

  • Supplied by small branches from the superficial circumflex iliac artery

  • Additional contributions from the superior epigastric and superficial external pudendal arteries

Venous Drainage

  • Venous return via superficial veins of the groin into the great saphenous vein and femoral vein

Function

  • Forms the floor of the inguinal canal

  • Provides a strong fibrous boundary between abdomen and thigh

  • Serves as an anatomical landmark in identifying hernias and femoral structures

  • Reinforces the lower abdominal wall and transmits tension from abdominal muscles

Clinical Significance

  • Landmark for differentiating inguinal vs femoral hernias

  • Involved in sports hernias and groin strain injuries

  • Reference in surgical procedures such as hernia repair and vascular access

  • Can be a site of calcification or enthesopathy visible on imaging

MRI Appearance

T1-weighted images:

  • Ligament appears as a thin, low-signal band spanning from ASIS to pubic tubercle

  • Adjacent fat provides bright contrast

T2-weighted images:

  • Ligament shows persistent low signal intensity

  • Injuries or enthesopathy may appear with focal bright signal intensity

STIR (Short Tau Inversion Recovery):

  • Normal ligament remains dark

  • Strains, partial tears, or inflammation demonstrate bright hyperintensity

Proton Density Fat-Sat (PD FS):

  • Normal ligament remains low signal

  • Pathologic changes (strain, tear, inflammation) show focal or diffuse bright signal

T1 Fat-Sat Post-Contrast:

  • Mild or no enhancement in normal ligament

  • Pathology may enhance focally (inflammation) or at its attachments (enthesitis)

CT Appearance

Non-Contrast CT:

  • Ligament appears as a soft tissue density band extending from ASIS to pubic tubercle

  • Calcification may be seen at its attachment sites in chronic enthesopathy

Post-Contrast CT:

  • Ligament itself does not enhance significantly

  • Enhancement may be seen in surrounding tissues in cases of inflammation, infection, or neoplastic infiltration

MRI image

Inguinal ligament MRI coronal anatomy image-img-00000-00000

MRI image

Inguinal ligament MRI AXIAL anatomy image-img-00000-00000

CT image

Inguinal ligament CT coronal anatomy image-img-00000-00000

CT image

Inguinal ligament CT AXIAL