Function

The inguinal canal is an area of potential weakness of the abdominal wall. Herniation of abdominal contents through the canal is minimised by:

• the eccentricity of the superficial and deep rings:
  • due to the obliquity of the canal, the two rings do not coincide in position
  • any increase in intra-abdominal pressure forces the posterior wall against the anterior wall, so compressing the contents of the canal in the manner of a flap valve; this would not be possible if the rings were in alignment
• contraction of the muscles within the canal:
  • approximates the anterior and posterior walls of the canal
  • lowers the roof of the canal: the specific action of transversus abdominis and internal oblique inserting into the conjoint tendon
  • tonic contraction on standing
  • increased reflex contraction on coughing or straining