MRCS Part B (OSCE) - Online Resources

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The borders of the inguinal canal are:

• Anterior :     External oblique aponeurosis; reinforced by the muscle fibres                     of internal oblique in the lateral 1/3^rd.
• Posterior :     Transversalis fascia; and conjoint tendon in the medial 1/3^rd.
• Roof :     Musculo aponeurotic arches of internal oblique and                                     transverse abdominis.
• Floor :     Inguinal ligament; lacunar ligament in the medial 1/3^rd.

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"The superficial (external) ring is a ‘V’ shaped defect in external oblique, located superolateral to the pubic tubercle. It is the ‘exit’ from the inguinal canal. "

The deep (internal) ring is a defect in the transversalis fascia and is located approximately 1.5-2 cm above the mid-point of the inguinal ligament (half way between the pubic tubercle and anterior superior iliac spine). The deep ring is the ‘entrance’ to the inguinal canal.

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The inguinal canal contains:

• Round ligament of the uterus in the female
• Spermatic cord in the male
• In both sexes - ilioinguinal nerve

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The spermatic cord contains the following structures:

• Fascial coverings: External spermatic fascia, internal spermatic fascia and cremastric fascia.
• Arteries: Testicular artery, artery to the vas deferens and cremasteric artery
• Nerves: Genital branch of the genitofemoral nerve, sympathetic nerve fibres and ilioinguinal nerve (lies outside the spermatic cord).
• Other structures: Pampiniform venous plexus, ductus deferens (vas deferens) and lymphatics.

Note: The structures of the spermatic cord can be remembered using the rule of “3’s” (3 facial coverings; 3 arteries; 3 nerves and 3 other structures).

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• Indirect inguinal hernias enter the inguinal canal through the deep inguinal ring, traverses the inguinal canal and exits the superficial ring either to lie within the inguinal region or to enter the scrotum.
• Direct inguinal hernias do not enter the inguinal canal but occur as a weakness in the tranversalis fascia and thus lies above and medial to the pubic tubercle.

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Hesselbach’s triangle is an area in the anterior abdominal wall bounded by:

Inferior       :      Inguinal ligament

Lateral        :      Inferior epigastric artery

Medial         :      Lateral border of rectus abdominis muscle

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"A direct inguinal hernia lies medial to the inferior epigastric artery, protruding into Hesselbach’s triangle. An indirect hernia commences lateral to the inferior epigastric artery. "

"Femoral hernias occur below and lateral to the pubic tubercle. "

"The femoral canal is the most medial compartment of the femoral sheath. The femoral canal extends from the femoral ring proximally to the level of the saphenous opening distally. The femoral canal allows expansion of the femoral vein when there is increased venous return from the lower limb "

The femoral canal contains connective tissue, fat and lymphatics. It can contain a deep inguinal lymph node named the ‘Cloquet’s node’.

The femoral ring is the proximal opening of the femoral canal bounded by:
 Anterior: Inguinal ligament
 Posterior: Pectineal ligament overlying the superior ramus of the pubis

 Medial: Lacunar ligament
 Lateral: Femoral vein

"Elective repair can be considered if the hernia is symptomatic. Asymptomatic patients, who are medically fit, should be offered surgical repair to prevent complications. Due to the higher risk of complications such as strangulation, there should be a lower threshold to repair femoral hernias. The indications for emergency hernia repair include obstruction, incarceration or strangulation. "