L) Important Anatomical Compartments

Inguinal Canal


The inguinal canal is a 4 cm long passage through the anterior abdominal wall, and runs above the inguinal ligament in a inferior and medial direction. Its deep opening is superior to the middle of the inguinal ligament, whereas is superficial opening is just superior and lateral to the pubic tubercule and is formed by a opening between fibres of the external oblique aponeurosis. The aponeurosis on each side of the ring forms a crus; the medial crus is attached to the pubic tubercule and the lateral crus to the pubic crest.
The canal has four boundaries:

  • The roof is formed by an the transveraslis fascia at the deep opening, the inferior borders of inferior oblique and tranversalis within the canal, and the medial crus above the superficial opening.
  • The floor is formed by the inguinal ligament itself
  • The anterior wall is formed by the aponeurosis of the external oblique, which curves posteriorly to form the inguinal ligament and the floor of the canal
  • The posterior wall is formed by the transversalis fascia laterally, and the conjoint tendon (inferior oblique/transversalis) medially.


In men, the inguinal canal contains the spermatic cord (ductus deferens, testicular artery, cremasteric artery, the artery to ductus deferens, pampiniform venous plexus, the genital branch of the genitofemoral nerve, sympathetic nerves and lymphatics). In women the round ligament of the uterus (with associated vessels) passes through the canal and attaches into the labia majora.
The canal in both sexes contains the ilioinguinal nerve, vessels and lymphatics separate from the other structures.

Femoral Triangle


The femoral triangle is an anatomical region bounded by the inferior border of the inguinal ligament above, the medial border of sartorius laterally, and the lateral border of adductor longus medially. The floor is formed by various muscles of the thigh and pelvis: from medial to lateral they are:

  • Adductor longus
  • Pectineus
  • Iliopsoas

The roof is formed by the fascia lata.


The femoral triangle is continuous with the abdomen superiorly via the retroinguinal space. This space is divided into muscular and vascular compartments by a thickening of the iliopsoas fasica (the iliopectineal arch which runs from the inguinal ligament to the ileopectinal eminence of the ilium). The femoral artery, femoral vein and deep inguinal lymph nodes pass through the vascular compartment. The iliopsoas and femoral nerve pass through the muscular compartment.
Within the triangle, the femoral nerve lies most lateral, with the artery and then the vein medially. Lymph nodes and vessels are the most medial.

  • The femoral nerve immediately divides into anterior and posterior divisions:
    • The anterior division gives of the medial and intermediate cutaeneous nerves of the thigh, as well as the nerve to sartorious
    • The posterior division supplies the anterior compartment of the thigh (except sartorious), and then continues as the saphenous nerve. This accompanies the femoral artery and vein through the apex of the triangle, but lies just lateral to the femoral (sartorial) canal.
  • The femoral artery passes to the apex of the triangle and enters the popliteal fossa via the adductor foramen, becoming the popliteal artery. It gives off the profunda femoris (deep artery of the thigh) which passes between pectineus and adductor longus towards the femur. It supplies the majority of the anterior and adductor compartments of the thigh. Smaller branches include:
  • The external pudendal artery which provides some supply to the external genital organs
  • The circumflex femoral arteries (medial and lateral) which form anastamoses around the proximal femur
  • The superficial epigastric artery turns 180o and passes superior to the inguinal ligament to supply the soft tissues and skin of the lower anterior abdominal wall.

The femoral vein receives the long saphenous vein after it breaches the fascia lata to enter the triangle.
The superficial inguinal lymph nodes are located within the triangle, separated into three groups. The medial proximal group lie lateral to the vessels, inferior to the inguinal ligament. The lateral proximal group lie lateral to the vessels and nerves. The distal group cluster around the long saphenous vein. Deep inguinal lymph nodes, of which there are usually three, lie on the medial side of the femoral artery, typically just beneath the junction with the saphenous vein, just above it, and beneath the inguinal ligament itself.