Inguinal ligament

At a glance

English

Inguinal ligament

Latin (TA2)

Ligamentum inguinale

System

Muscle

Region

Trunk

Side

Paired, left and right

About the inguinal ligament

The inguinal ligament marks the boundary between the front of the abdomen and the thigh. It is not a separate ligament in the usual sense but the thickened, rolled lower edge of the external oblique aponeurosis. It is also known by its older name, Poupart's ligament, after the French surgeon who drew attention to it in the repair of hernias.

Laterally it is anchored on the anterior superior iliac spine; medially it ends on the pubic tubercle. Between these points it curves gently downward towards the thigh and its lower edge is turned back on itself to make a shallow gutter that forms the floor of the inguinal canal. Near the pubis some fibres sweep backward to the pectineal line as the lacunar ligament, and these continue along that line as the pectineal ligament. The deep fascia of the thigh, the fascia lata, is fixed to its lower border, which is why the ligament is pulled into a downward curve when the thigh is extended.

Several large structures pass beneath it from the abdomen into the lower limb. Laterally, under the outer part, run iliopsoas and the femoral nerve, with the lateral cutaneous nerve of the thigh close to the spine. More medially the femoral artery, femoral vein and lymph vessels pass through the femoral sheath, with the femoral canal on the inner side. The ligament also forms the upper border of the femoral triangle and the lower border of the inguinal triangle on the inner abdominal wall.

Clinically, it is a key surface landmark. The femoral pulse is felt just below the mid-inguinal point, halfway from the spine to the pubic symphysis, and the femoral nerve lies a little lateral to it. An inguinal hernia appears above and medial to the pubic tubercle, while a femoral hernia lies below and lateral to it; this relationship to the ligament helps to tell the two apart. Squeezing of the lateral cutaneous nerve as it passes under the ligament near the iliac spine causes burning numbness on the outer thigh, known as meralgia paraesthetica.

Attachments, action and supply

Origin

Anterior superior iliac spine.

Insertion

Pubic tubercle, with fibres reflected to the pectineal line as the lacunar ligament.

Action

Forms the floor of the inguinal canal and the boundary between abdomen and thigh, holding in the structures that pass beneath it into the lower limb.