Inguinal canal and hernia Flashcards
What is the inguinal canal?
An oblique intermuscular passage in the lower anterior abdominal wall.
Where is the inguinal canal located?
Just above the medial half of the inguinal ligament.
What is the length of the inguinal canal?
About 4 cm (1.5 inches).
In what direction does the inguinal canal run?
Downwards, forwards, and medially.
What are the two openings of the inguinal canal?
Deep inguinal ring and superficial inguinal ring.
What is the deep inguinal ring?
An oval opening in the fascia transversalis.
Where is the deep inguinal ring located?
1.2 cm above the midinguinal point, lateral to the inferior epigastric artery.
What is the superficial inguinal ring?
A triangular gap in the external oblique aponeurosis.
What forms the base of the superficial inguinal ring?
The pubic crest.
What forms the margins of the superficial inguinal ring?
Lateral and medial crura.
What unites the crura of the superficial inguinal ring?
Intercrural fibers.
What structures form the anterior wall of the inguinal canal?
Skin, superficial fascia, and external oblique aponeurosis.
What additionally strengthens the lateral one-third of the anterior wall?
Fleshy fibers of the internal oblique muscle.
What structures form the posterior wall of the inguinal canal?
Fascia transversalis, extraperitoneal tissue, and parietal peritoneum.
What reinforces the medial two-thirds of the posterior wall?
Conjoint tendon and reflected part of the inguinal ligament.
What forms the roof of the inguinal canal?
Arched fibers of the internal oblique and transversus abdominis muscles.
What forms the floor of the inguinal canal?
Inguinal ligament and lacunar ligament at the medial end.
Which sex has a larger inguinal canal?
Males.
What structure passes through the inguinal canal in males?
Spermatic cord.
What structure passes through the inguinal canal in females?
Round ligament of the uterus.
How does the ilioinguinal nerve enter the inguinal canal?
Through the interval between the external and internal oblique muscles.
What are the components of the spermatic cord?
Ductus deferens, testicular and cremasteric arteries, pampiniform plexus, lymph vessels, nerves, and remains of processus vaginalis.
What are the coverings of the spermatic cord?
Internal spermatic fascia, cremasteric fascia, and external spermatic fascia.
What is the internal spermatic fascia derived from?
Fascia transversalis.
What is the cremasteric fascia derived from?
Internal oblique and transversus abdominis muscles.
What is the external spermatic fascia derived from?
External oblique aponeurosis.
Why is the inguinal canal a site of weakness?
Due to its anatomical position and presence of openings.
What prevents herniation through the inguinal canal?
Various protective mechanisms such as the flap valve and shutter mechanisms.
What is the flap valve mechanism?
Approximation of the anterior and posterior walls of the canal when intra-abdominal pressure rises.
How is the superficial inguinal ring reinforced?
By the conjoint tendon and reflected part of the inguinal ligament.
What protects the deep inguinal ring?
Fleshy fibers of the internal oblique muscle.
What is the shutter mechanism of the internal oblique?
The internal oblique muscle contracts and approximates the roof to the floor.
What is the ball valve mechanism?
Contraction of the cremaster muscle plugging the superficial inguinal ring.
What is the slit valve mechanism?
Contraction of the external oblique approximating the crura of the superficial inguinal ring.
How does intra-abdominal pressure affect the inguinal canal?
It activates the protective mechanisms to prevent herniation.
What is the role of hormones in the inguinal canal?
They may maintain the tone of the inguinal musculature.
What does the inguinal canal develop from?
The passage of the gubernaculum through the abdominal wall.
Where does the gubernaculum extend from and to?
From the caudal end of the developing gonad to the labioscrotal swelling.
Why is man predisposed to inguinal hernia?
Evolutionary changes due to upright posture.
How has the iliac crest changed in humans?
It has grown forwards into the external oblique muscle, limiting its role in reinforcing the inguinal canal.
How has the internal oblique and transversus abdominis changed?
Their origin shifted, reducing their role as a sphincter.
Why is the crural passage wider in humans?
Due to hip bone and pelvic growth, predisposing to femoral hernia.
What is a hernia?
Protrusion of abdominal contents through its walls.
What is an external hernia?
Hernia that protrudes through the abdominal wall.
What is an internal hernia?
Herniation within the peritoneal cavity.
What are the components of a hernia?
Sac, contents, and coverings.
What is the sac of a hernia?
Protrusion of peritoneum containing herniated contents.
What are the contents of a hernia?
Coils of intestine, omentum, or other viscera.
What is irreducible hernia?
When the herniated loop does not return to the abdomen.
What is obstructed hernia?
When the intestinal contents cannot move forward due to narrowing.
What is strangulated hernia?
When arterial supply is cut off, leading to necrosis.
What are the types of abdominal hernia?
Internal and external hernias.
Where do internal hernias commonly occur?
Epiploic foramen, lesser sac, paraduodenal recesses.
What are the types of external hernias?
Umbilical, paraumbilical, femoral, inguinal, epigastric, incisional, lumbar.
What is congenital umbilical hernia?
Due to non-return of midgut loop to the abdominal cavity.
What is acquired infantile umbilical hernia?
Due to weakness of the umbilical scar.
What is paraumbilical hernia?
Herniation through the linea alba near the umbilicus.
Which type of hernia is more common in females?
Femoral hernia.
Where is the neck of a femoral hernia located?
Below and lateral to the pubic tubercle.
What is inguinal hernia?
Protrusion of intestine through the inguinal wall or canal.
What is indirect inguinal hernia?
Hernia passing through deep ring, inguinal canal, and superficial ring into the scrotum.
Who is more prone to indirect inguinal hernia?
Male infants and children.
What is direct inguinal hernia?
Hernia passing through the posterior wall of the inguinal canal.
Where does direct inguinal hernia occur?
Hesselbach�s triangle or posterior wall of inguinal hernia.
What is epigastric hernia?
Hernia through the linea alba above the umbilicus.
What is incisional hernia?
Hernia through a previous surgical incision.
What is lumbar hernia?
Hernia through the lumbar triangle in the posterior abdominal wall.
