Anatomy and Structure
The inguinal ligament spans between the anterior superior iliac spine (spina iliaca anterior superior) and the pubic tubercle (tuberculum pubicum). Its length ranges from 12 to 16 cm.
Anatomically, it represents the thickened, folded inferior border of the broad, flat aponeurosis of the external oblique muscle (m. obliquus abdominis externus).
Medially, near the pubic tubercle, the ligament extends to form the lacunar ligament (lig. lacunare). The transversus abdominis muscle (m. transversus abdominis) originates from the lateral third of the inguinal ligament.
Role in Canal Formation
The ligament forms key boundaries for the canals of the inguinal and femoral regions:
- Inguinal canal (canalis inguinalis): The inguinal ligament forms its floor (inferior wall). The oblique slit-like canal lies 1.0–1.5 cm superior and parallel to the ligament. The superficial inguinal ring lies over the medial part of the ligament, formed by the splitting of the aponeurosis fibers into lateral (attaching to the pubic tubercle) and medial (attaching to the pubic symphysis) crura.
- Femoral canal (canalis femoralis): The ligament forms the anterior boundary of the femoral ring. The superficial layer of the fascia lata stretches between the inguinal ligament and the superior cornu of the saphenous opening, forming the anterior wall of the femoral canal.
Structures Passing Deep to the Inguinal Ligament
- External iliac artery and vein (a. et v. iliacae externae) become the femoral vessels (a. et v. femorales) after passing deep to the inguinal ligament. The femoral vein lies in the vascular compartment (lacuna) medial to the artery.
- Femoral nerve (n. femoralis) enters the thigh lateral to the vessels.
- Lymphatics: Directly inferior to the inguinal ligament, in the most medial part of the vascular compartment medial to the femoral vein, lies the largest deep inguinal lymph node—the node of Cloquet (Rosenmüller).
Additional note: Several superficial veins drain into the femoral or great saphenous vein near the inguinal ligament, including the superficial epigastric, superficial external pudendal, and superficial circumflex iliac veins.
Clinical Significance
- Hernia Surgery (Bassini repair / Cooper's ligament repair): During hernia repairs, the inguinal ligament is retracted, and deep sutures may approximate it to Cooper's (pectineal) ligament.
- Suppurative Infections: When deep abscesses track from the retroperitoneum along the iliopsoas muscle beneath the inguinal ligament, the resulting swelling may take an hourglass shape restricted by the tight inguinal ligament.
- Neurological Dermatomes: In transverse spinal cord lesions at the L1 level, the upper sensory loss boundary corresponds to the inguinal fold (ligamentum inguinale) and upper thigh.