Abdominal walls and hernias Flashcards
Define fasciae
a sheet or band of fibrous tissue such as lies deep to the skin or invests muscles and various body organs
Which structures does the abdominal wall extend between?
Anterior aspect of the ribcage and the pelvic girdle
How many muscle are there in the anterolateral abdominal wall?
5
List the 5 muscles in the anterolateral abdominal wall by category - 3 flat and 2 vertical
Flat: transversus abdominis, internal oblique and external oblique
Vertical: rectus abdominis and pyramidalis muscles
List the anterolateral abdominal wall muscles form deepest to most superficial
Transversus abdominis
Rectus abdominis
Internal oblique
External oblique
What is the linea alba composed of and where is it connected to?
A mainly connective tissue fibrous structure formed form the fusion of the aponeuroses of the abdominal muscles. It connects the xiphoid process to the pubic symphis
Which structures does the linea alba separate?
Left and right rectus abdominus muscles
In which direction does the internal oblique muscles run?
Diagonally ‘up’ from lateral to medial
In which direction does the external oblique muscle run?
Diagonally ‘down’ from lateral to medial - like someone putting their hands in their pockets!
What are aponeuroses?
Layers of flat broad tendons
What is the rectus sheath and what structures does it enclose?
It is formed from the aponeuroses of the transversus abdominis, internal and external oblique muscles.
It encloses the rectus abdominis muscles and the pyramidalis muscles
Define the 9 regions of the abdominal area
right hypochondriac region epigastric region left hypochondriac region right lumbar region umbilical region left lumbar region right iliac region hypogastric region left iliac region
What path does a direct hernia follow as it leaves the abdomen?
It passes through a weakness in the anterior abdominal wall = Hesselbach’s triangle.
Medial to the inferior epigastric vessels, above the inguinal ligament
What are the borders of Hesselbach’s triangle?
Inguinal ligament
Inferior epigastric vessels
Lateral border of rectus abdominus muscles
Where does an indirect hernia pass through?
Lateral to the inferior epigastric vessels, above the inguinal ligament and through the deep inguinal ring into the inguinal canal. If the pocessus vaginalis has failed to close the hernia can pass through the inguinal ring, out of the superficial inguinal ring and even into the scrotum
Which type of hernia can descend into the scrotum?
Indirect hernia - depending on where the processus vaginalis obliterates
Where does a femoral hernia pass?
Below the inguinal ligament
Which structure forms the floor of the inguinal canal?
Inguinal ligament
What forms the posterior wall of the inguinal canal?
Transversalis fascia
The conjoint tendon reinforces the medial aspect of the posterior wall
What forms the roof of the inguinal canal?
Arching fibres of internal oblique and the transverse abdominal muscle
What forms the anterior wall of the inguinal canal?
Aponeurosis of external oblique
What type of hernia might be precipitated by a weakened conjoint tendon?
Direct inguinal hernia
The conjoint tendon serves to reinforce the medial part of the posterior wall of the inguinal canal. It lies behind the superficial inguinal ring. This is the location a direct inguinal hernia can form, so if the conjoint tendon is weakened a direct inguinal hernia is more likely
What is an umbilical hernia?
When the umbilical ring fails to close properly after the natural herniation of the midgut into the proximal umbilicus that occurs during embryological herniation, this creates a weakness in the anterior abdominal wall through which abdominal contents can protrude
How is an umbilical hernia treated?
They are usually observed, as most spontaneously reduce within the first few years of life. They are at a lower risk of obstruction and strangulation than other types of hernia (e.g. inguinal hernias) because the defect in the abdominal wall is usually larger
Why do femoral hernias need to be treated immediately?
Because of the narrow femoral canal that they herniate through, incarceration and strangulation are not uncommon
Why do femoral hernias occur more frequently (but are still rare) in females than males?
Due to the anatomy of the female pelvis…
What is the main reason a strangulated abdominal hernia requires urgent medical attention?
Blood supply to the hernia is compromised - this needs to be treated immediately as otherwise the contents will undergo necrosis which could prove fatal to the patient
What is an incarcerated hernia?
When a hernia is irreducible (stuck) - this can cause obstruction but is not as urgently requiring attention as a strangulated hernia because the blood supply is still intact.
Name two potential sites of weakness in the anterior abdominal wall
Superificial inguinal ring (external)
Deep inguinal ring (internal)
What is the name of the area between the two weaknesses in the anterior abdominal wall: the superificial and deep inguinal rings?
Inguinal canal
What does the inguinal canal allow?
Structures to leave and enter the abdomino-pelvic cavity
What direction does the inguinal canal travel?
Obliquely inferior and medial
What makes up the inguinal ligament?
A roll of the inferior border of the aponeurosis of the external oblique muscle
Between which structures is the inguinal ligament attached?
Laterally - anterior superior iliac spine
Medially - pubic tubercle
What passes through the inguinal canal in men?
spermatic chord
What passes through the inguinal canal in women?
Round ligament of the uterus
What passes through part of the inguinal canal in both sexes?
the ilioinguinal nerve passes through part of the inguinal canal and exits through the superificial inguinal ring with other contents
What is a hernia?
describes the bulge or protrusion of an organ through the structure or muscle that usually contains it
What are abdominal hernia usually covered with?
skin, subcutaneous tissues and often layers of the abdominal wall through which the hernia passes
What are the three common regions of hernias in the abdomen?
- Epigastric
- Umbilical
- Inguinal
Where do diaghragmatic, hiatus and rolling hiatus hernias occur?
Within the thoraco-abdominal cavity
Which is the most common type of hernia?
indirect inguinal hernia
If an indirect inguinal hernia travels all the way through and out of the inguinal canal, where does it end up in males?
scrotum
If an indirect inguinal hernia travels all the way through and out of the inguinal canal, where does it end up in females?
labium majora (large outer folds of the vulva)
In which sex are indirect inguinal hernias more common?
males
How does a direct inguinal hernia enter the inguinal canal?
Directly through its posterior wall - as the conjoint tendon covers this point a direct inguinal hernia is usually seen only as a bulge in the inguinal region
In inguinal hernias, where does the neck of the hernia sac appear?
above the inguinal ligament
Where does the hernia sac protrude in a femoral hernia?
unto the upper thigh, MEDIAL to the femoral vein. The neck of the hernia is therefore BELOW the inguinal ligament
What are diaphragmatic hernias?
Developmental defects of the diaphragm which allow any viscus (e.g. the large intestine) to herniate into the chest
Hiatus hernias are a special type of diaphragmatic hernia. What is the difference between a sliding and rolling hernia?
Sliding hiatus hernia -gastro-oesophageal junction may slide through the diaphragm into the chest
Rolling hiatus hernia - part of the fundus may pass into the chest alongside the oesophagus
Why do umbilical hernias occur?
Sometimes occurs in children due to a weakness in the umbilical scar - area where physiological herniation of the midgut into the proximal umbilicus is healed after the midgut structures are returned into the abdominal cavity
What causes paraumbilical and epigastric hernias in adults?
Hernia of the abdominal wall which protrudes through linea alba anywhere between the xiohisternum and the umbilicus
What is an incisional hernia?
A hernia of the abdominal wall where an old surgical scar breaks down, usually because of obesity or poor abdominal musculature
Where does a direct inguinal hernia arise?
This hernia bulges outwards, medial and inferior to the inferior epigastric vessels and pushes into
the superficial inguinal ring. In reality it does not enter the scrotum.
Please note that direct inguinal
hernias can push out anywhere in Hesselbachs triangle, but the superficial inguinal ring is a further
area of weakness and so the hernia tends to be located around there
What are the boundaries of an umbilical hernia?
The boundaries of an umbilical hernia are the same as the boundaries of the umbilicus (wow, no
way!) as any hernia will simply pass through the umbilical ring. This is a gap in the Linea alba, which
is bounded on either side by the rectus abdominus muscles
What are the clinical consequences of an incarcerated hernia?
If its bowel that has become herniated, it can become obstructed. This could lead to vomiting
(especially if small bowel), massive electrolyte imbalance problems, perforation of the bowel, colicky
abdominal pain etc.
