What is The superior inguinal ring is opening due to defect in the aponeurosis of which of the following muscles? and explain in detail?
Ans. a (External oblique) (Ref. Bailey and Love 24th ed., 1274)INGUINAL CANAL# In adults the inguinal canal, which is 3.75 cm long, is directed downwards and medially from the deep to the superficial inguinal ring.# Superficial Inguinal Ring- The superficial inguinal ring is a triangular aperture in the aponeurosis of the external oblique and lies 1.25 cm above the pubic tubercle.- The ring is bounded by a superomedial and inferolateral crus joined by crisscross intercrural fibres.# Deep Inguinal Ring- The deep inguinal ring is a U-shaped condensation of the transversalis fascia and it lies 1.25 cm above the inguinal (Poupart's) ligament, midway between the symphysis pubis and the ASIS.- The transversalis fascia is the fascial envelope of the abdomen and the competency of the deep inguinal ring depends on the integrity of this fascia.- The inferior epigastric vessels lie posteriorly and medially to the deep inguinal ring.# BOUNDARIES OF THE CANALAnteriorPosteriorExternal oblique aponeurosis with the conjoined muscle laterally.Fascia transversalis and the conjoined tendon (internal oblique and transversus abdominus medially).SuperiorInferiorConjoined muscles (internal oblique and transversus).Inguinal ligamentA helpful mnemonic to remember inguinal canal walls include :MALT (2M, 2A, 2L, 2T) - Mnemonic=Starting from superior, moving around in order to posterior:# Superior wall (roof): 2 Muscles: -internal oblique Muscle: -transverse abdominus Muscle# Anterior wall: 2 Aponeuroses:-Aponeurosis of external oblique: -Aponeurosis of internal oblique# Lower wall (floor): 2 Ligaments:-inguinal Ligament: -lacunar Ligament# Posterior wall: 2Ts:-Transversalis fascia: -conjoint Tendon# Contents of the canal:- In the male the inguinal canal transmits the spermatic cord, the ilio-inguinal nerve and the genital branch of the genitofemoral nerve.- In the female the round ligament replaces the spermatic cord. Indirect HerniaDirect HerniaTravels down the canal on the outer (lateral and anterior) side of the spermatic cord.Comes out directly forwards through the posterior wall of the inguinal canal.Neck of the indirect hernia is lateral to the inferior epigastric vessels.Direct hernia usually emerges medial to inferior epigastric vessels except in the saddle-bag or pantaloon type, which has both a lateral and a medial component.# An inguinal hernia can be differentiated from a femoral hernia by ascertaining the relation of the neck of the sac to the medial end of the inguinal ligament and the pubic tubercle, i.e., in the case of an inguinal hernia the neck is above and medial, while that of a femoral hernia is below and lateral.# Digital control of the internal ring may help in distinguishing between an indirect and a direct inguinal hernia.