Inguinal canal and inguinal hernias

Question 1

Inguinal canal

Answer 1

• Oblique tunnel-like fissure in anterior abdominal wall
• Over the central part of the inguinal ligament
• 4cm in length
• Runs mediocaudally and ventrally (parallel to Inguinal lig.)
• Opens medially under abdominal skin as the superficial inguinal ring (SIR) - in aponeurosis of EOAM
• Laterally and more profoundly (as well as more cranially) opens into the peritoneal cavity as the deep inguinal ring (DIR) - in aponeurosis of IOAM and TAM

Question 2

Contents of inguinal canal

Answer 2

• Genital branch of the genitofemoral nerve
• Spermatic cord - in men
• Round ligament of the uterus - in women
• Ilio-inguinal nerve passes through part of the canal, exiting through the superficial inguinal ring with the other contents

Question 3

Deep inguinal ring (DIR)

Answer 3

• Point midway between ASIS and the pudic symphysis
• Above inguinal ligament and lateral to inferior epigastric vessels It is the beginning of the tubular evagination of transversalis fascia that forms the internal spermatic fascia

Question 4

Superficial inguinal ring (SIR)

Answer 4

• At the end of the inguinal canal and is superior to the pubic tubercle
• It is a triangular opening in the aponeurosis of the external oblique abdominal muscle
• Apex points siperolaterally
• Base formed by pubic crest
• Medial crus - attached to the pubic symphysis
• Lateral crus - attached to the pubic tubercle
• At the apex the two crura are held together by crossing (intercrural) fibres - prevent widening of the SIR
• Beginning of tbular evagination of the aponeurosis of the EOAM onto structures traversing the inguinal canal and emerging from the SIR - the continuation over the spermatic cord is the external spermatic fascia

Question 5

Anterior wall of the inguinal canal

Answer 5

• Formed along its entire length by the aponeurosis of the EOAM
• Reinforced laterally by lower fibres of the IOAM that originate from the lateral 2/3s of the inguinal lig. - additional covering of the DIR which is a potential point f weakness in the anterior abdominal wall
• IOAM covers the DIR and also contributes a layer (the cremasteric fascia containing the cremasteric muscle) to the coverings of the structures traversing the inguinal canal

Question 6

Posterior wall of the inguinal canal

Answer 6

• Formed by the transversalis fascia
• Reinforced along medial 1/3 by the conjoint tendon (inguinal falx) - the combined insertion of the TAM and IOAM into the pubic crest and pectineal line

Question 7

Roof of the inguinal canal

Answer 7

• Formed by arching fibres of the TAM and IOAM
• They pass from their lateral points of origin fron the inguinal lig. to their common medial attachment as the conjoint tendon

Question 8

Floor of the inguinal canal

Answer 8

• Formed by medial 1/2 of the inguinal ligament
• Rolled-under, free margin of the lowest part of the aponeurosis of the EOAM forms a gutter or trough on which the contents of the inguinal canal are positioned
• The lacunar ligament reinforces the medial part of this gutter

Question 9

Inguinal hernias

Answer 9

• Is a protrusion or passage of a peritoneal sac, with or without abdominal contents, throguh a weakened part of the abdominal wall in the groin
• Can be:

1. Direct: passes through the deep inguinal ring
2. Indirect: passes through the posterior wall of the inguinal canal

Question 10

Indirect inguinal hernia

Answer 10

• More common than direct
• More common in men (older)
• Occurs because some part or all of the embryonic processus vaginalis remains open or patent
• It is congenital
• Protruding peritoneal sac passes through the DIR
• Lateral to inferior epigastric vessels
• Extend of excursion depends on the amount of processus vaginalis that remained patent
• If it is completely patent, then it my traverse the entire canal and exit through the SIR and continue into the scrotum/labia majus
• In this case it will acquire the same coverings as the spermatic cord/round ligament of the uterus

Question 11

Direct inguinal hernia

Answer 11

• When the peritoneal sac enters the medial end of the inguinal canal directly throug a weakend posterior wall
• Usually acquired
• Develops when abdominal musculature has been weakened
• More commonly seen in men
• Bulging occurs medial to inferior epigastric vessels in the inguinal triangle (Hasselbach’s triangle)
• Iliopubic tract (a thickening of the transversalis fascia) follows the course of the inguinal ligament
• Does not traverse entire length of canal, but may exit through superficial inguinal ring, when this occurs the peritoneal sac acquires a layer of the external spermatic fascia and can extend into the scrotum

Question 12

Hasselbach’s triangle boundaries

Answer 12

• Laterally by the inferior epigastric artery
• Medially by the rectus abdominis muscle
• Inferiorlly by the inguinal ligament