Inguinal Canal And Hernias

Question 1

What is the definition of a hernia?

Answer 1

Protrusion of tissue/organ through a retaining tissue

Question 2

What are the best regional landmarks to position the inguinal canal/inguinal hernias?

Answer 2

Hard tissues e.g. bone = most reliable
Inguinal ligament spans the ASIS and pubic tubercle bone running along the free lower border of the external oblique muscle

Question 3

What does the space behind the inguinal canals surface contain?

Answer 3

• Muscles e.g. psoas major that come through and go to femur
• Blood vessels e.g. external iliac artery/vein going down to form the femoral artery/vein (when they pass below the level of this ligament)

Question 4

What are the regional landmarks for the midpoint of the inguinal ligament?

Answer 4

Halfway between the ASIS and pubic tubercle

Question 5

What are the regional landmarks for the midinguinal point?

Answer 5

Halfway between ASIS and pubic symphysis (pubic bone in midline)

Question 6

What is an important surface marker that is found at the midinguinal point that you will be able to feel?

Answer 6

The pulsating femoral artery (+/- 1 cm) because it serves as a approximate marker of the deep inguinal ring i.e. the deeper entrance into the inguinal canal

Question 7

Who is most likely to get umbilical hernias?

Answer 7

• Newborn/young
• Woman after pregnancy (rectus abdominis moves to the side lower down stretching the anterior abdominal wall tissue making it weaker)

Question 8

Where do inguinal hernias occur and who is most likely to get one?

Answer 8

Origin of swelling is above/above + medial to the public tubercle - can test this by asking patient to push it in and their hand will trace to above pubic tubercle (if cannot push it in - risk of strangulation)
More common in males vs. females (testicles descend through inguinal canal into scrotum, so apertures are larger forming a weak spot)

Question 9

What can auscultation of a hernial sac often reveal?

Answer 9

If bowel sounds are present, the hernia will contain a loop of intestine passing through the inguinal canal

Question 10

Where do femoral hernias occur and who is most likely to get one?

Answer 10

Origin of swelling is below + lateral to the public tubercle (not through inguinal canal but through femoral triangle in groin region)
More common in females vs. males (female pelvises wider due to childbirth so space for hernia to come through is larger)

Question 11

Where are the 2 typical weak spots on the posterior abdominal wall where hernias can occur? Who is most likely to get them?

Answer 11

1. Inferior lumbar (Peptit’s) triangle: bordered by iliac crest, latissimus dorsi + external oblique - occurs commonly in males 50-70 yrs
2. Superior lumbar (Grynfeltt/Lesshaft) triangle: bordered by 12th rib, quadratus lumborum + internal oblique

Question 12

What is the main reason there are 2 weak spots in the posterior abdominal wall?

Answer 12

They are small regions where there is no muscle supporting/covering them

Question 13

List a few reasons why hernias can occur in the inguinal region.

Answer 13

Anatomical deficits in muscle supporting region
Previous surgery damaging nerve supply to region making abdominal wall muscles weaker/less supportive
Men due to testicles descending through it creating a weak spot

Question 14

What is the inguinal canal?

Answer 14

Passageway through anterior abdominal wall extending between the 2 inguinal rings (deep + superficial)

Question 15

Where is the deep + superficial inguinal rings located?

Answer 15

Deep: inner surface of abdominal wall in invagination of transversalis fascia - located between midpoint of inguinal ligament + midlinguinal point (1cm above inguinal ligament)
Superficial: in external oblique aponeurosis supero-lateral to public tubercle - point of emergence of spermatic cord (male) or round ligament + coverings (females)

Question 16

What is in the inguinal canal in a female and male?

Answer 16

Female: Round ligament of uterus + lymphatics from uterus
Male: Spermatic cord + contents
Both: ilioinguinal nerve + genital branch of genitofemoral nerve

Question 17

What is the process that testicles go through in development?

Answer 17

1. Develop retroperitoneally behind peritoneum on posterior abdominal wall 2. Descend down a fibrous cord called the gubernaculum (ovaries go through first 2 steps as well)
2. Continues to descend through anterior abdominal wall dragging down a loop of parietal peritoneum (processus vaginalis) with it which will come to sit next to testicles
3. Becomes surrounded by extensions of 3 layers of the abdominal wall
4. Processes vaginalis should degenerate

Question 18

What are the 2 aspects of the parietal peritoneum pulled down with the testicles when they descend? What are there key characteristics?

Answer 18

1. Tunica vaginalis: loop of parietal peritoneum pulled down alongside testicle - contains lots of fluid allowing testicle to move around freely
2. Processus vaginalis: area inside the tunica vaginalis that is a potential route for indirect inguinal hernias toward the scrotum if the connecting stalk does not close

Question 19

What route does the spermatic cord take?

Answer 19

Goes through the deep inguinal ring through the inguinal canal and emerges at the superficial inguinal ring into the scrotum

Question 20

Where are the ilioinguinal + iliohypogastric sensory nerves and what do they do?

Answer 20

Ilioinguinal: passes into inguinal canal from lateral direction (not through deep ring)
Iliohypogastric: runs parallel just above it
-> supply muscles of abdominal wall + overlying skin would be a dermatome

Question 21

Where is the inferior epigastric artery and why is it surgically a useful landmark for figuring out the type of hernia a patient has?

Answer 21

On inner surface of abdominal wall

Because some hernias will have their origin lateral OR medial to it

Question 22

What are the layer that make up the inguinal canal?

Answer 22

• Internal oblique + transversus abdominis forms roof arching over most of canal
• Transversalis fascia forms posterior wall
• Conjoint tendon is behind superficial ring
• Aponeurosos + muscle fibres come off of it

Question 23

What could happen if a patient has a weakness in their internal oblique muscle/loss of nerve supply to it? Why?

Answer 23

The internal oblique aponeuroses travel down to attach to the pubic tubercle. These fibres support the superficial ring as they sit behind it stopping the GI tract herniating through the superficial ring. If a patient has weakness/loss of nerve supply, fibres will get sloppy so loops of intestine + abdominal wall can come through the superficial ring.

Question 24

What is a direct hernia? What route does it take?

Answer 24

Peritoneal sac presses directly onto Hesselbach’s triangle (may or may not go through superficial ring)
Sits medial to inferior epigastric artery
Caused by weakness of conjoint tendon/abdominal musculature

Question 25

What is an indirect inguinal hernia? What route does it take?

Answer 25

Peritoneal sac passes through the deep inguinal ring, inguinal canal + superficial inguinal ring into the scrotum taking an INDIRECT route to the superficial ring
Sit lateral to inferior epigastric artery
More common in males (failure of processus vaginalis to regress)

Question 26

What is Hesselbach’s (inguinal) triangle?

Answer 26

A triangle that can only be seen on the inside of the abdominal wall that delineates the region of bulging with a direct inguinal hernia - the borders of the triangle include the rectus abdominis, inferior epigastric artery + inguinal ligament (indirect hernia will form lateral to this)

Question 27

If the ilioinguinal + iliohypogastric nerves were damaged in inguinal canal surgery what would the effects be? What surgery could cause this?

Answer 27

Iliohypogastric: make muscles paralysed causing predisposition to hernial sac in superficial ring as conjoint tendon has become weak
Ilioinguinal: sensory loss/changes, parethesia or and pain in the anterior scrotum, labia majora (females), proximal penis + groin (not well tolerated by patients)
E.g. in vasectomy

Question 28

Where can the ilioinguinal nerve be seen during surgery?

Answer 28

If external oblique is peeled back, it can be seen as a thick white band just below the internal oblique aponeuroses

Question 29

What makes up Hesselbach’s triangle?

Answer 29

On anterior abdominal wall bordered by:
Medial: lateral border of the rectus abdominis muscle.
Lateral: inferior epigastric vessels.
Inferior: inguinal ligament.