Week 3 - Abdominal Wall and Hernias Flashcards
State the proximal and distal attachments of rectus abdominis.
Proximal: Xiphisternum
Distal: Pubis
State the three main bony attachments for abdominal muscles.
From outermost to innermost:
- Ribs
- Iliac crest
- Transverse processes of vertebrae
State the direction in which fibres of the internal oblique muscle run.
Medially and superiorly
Define hernia.
Protrusion of part of the abdominal contents beyond the confines of the abdominal wall or its containing cavity
What is the usual sac for abdominal hernias?
Pouch of peritoneum
What are common abdominal contents found in a hernia sac?
- Loops of bowel
- Omentum
(Can be any structure found in the abdominal cavity)
What is the covering of a hernia sac?
Layers of abdominal wall through which the hernia has passed
State sites of potential weakness in the abdominal wall.
- Femoral canal
- Inguinal canal
- Umbilicus
- Previous incisions
What is the inguinal canal?
Oblique passage through lower part of abdominal wall
State the passage of structures in the inguinal canal for males.
Abdomen - Testis
State the passage of structures in the inguinal canal for females.
Round ligament: uterus - labium majus
What months does descent of the testis take place during?
7th - 8th months
What is the processus vaginalis?
A pouch of peritoneum
What is the gubernaculum?
Condensed band of mesenchyme that links the inferior portion of testis (gonad) to the labioscrotal swelling
When the processus vaginalis obliterates, what structure does it become?
Tunica vaginalis
What structure in the males runs from the peritoneal cavity to the scrotum (through the inguinal canal)?
Spermatic cord
What type of hernias can occur if the processus vaginalis fails to obliterate?
- Inguinal hernia
2. Scrotal hernia
State the layers of the abdominal wall (inguinal canal cross-section) from outermost to innermost.
- Skin
- Superficial fascia
- Deep fascia
- External oblique
- Internal oblique
- Transversus abdominus (conjoint tendon formed by IO and TA)
- Trasversali fascia
Which ligament is formed by the rolled free edge of external oblique?
Inguinal ligament
What forms the floor of the inguinal canal? What reinforces it medially?
Inguinal ligament, lacunar ligament
What forms the anterior boundary of the inguinal canal?
Aponeurosis of external oblique
What forms the roof of the inguinal canal?
Internal oblique and transverse abdominis
muscular arches + aponeurosis
What forms the posterior wall of the inguinal canal? What reinforces it medially?
Transversalis fascia
The conjoint tendon reinforces it medially
Where does the deep ring lie?
Trasversalis fascia
Where is the entrance to the inguinal canal present?
Transversalis fascia
Where does the superficial ring lie?
Aponeurosis of external oblique - anterior boundary of the inguinal canal
Which type of hernia constitutes the most common abdominal hernia?
Inguinal hernias: 75% of all abdominal hernias
Which type of inguinal hernia is more common - direct or indirect?
Indirect - 50% vs. direct - 25%
Mainly right sided, males > females (7:1)
State the percentage prevalences for abdominal hernias other than inguinal hernias.
Femoral hernia = 3-5%
Incisional hernia = 10%
Umbilical hernia = 10%
What important structure is present below the mid-inguinal point?
Femoral artery
Describe the relation of the mid point of the inguinal ligament to the mid-inguinal point.
Lateral (two finger breadths lateral) to the mid-inguinal point
What important structure is present at the mid-point of the inguinal ligament?
Deep inguinal ring
Which type of hernia passes through the deep inguinal ring?
Indirect inguinal hernia
Which type of hernia has the potential to become a scrotal hernia?
Indirect inguinal hernia
(If processus vaginalis does not obliterate - remember that direct inguinal hernias do not pass through the inguinal canal!)
What region in the abdominal wall is a potential area of weakness that a direct inguinal hernia can escape through?
Hesselbach’s triangle
State the relationship of direct and indirect inguinal hernias to the inferior epigastric vessels.
Direct: medial to the inferior epigastric vessels
Indirect: Lateral to the inferior epigastric vessels
Outline the main features of a congenital umbilical hernia.
- Omphalocele
- Contents herniate into umbilical cord
- Has peritoneal covering
What is an infantile umbilical hernia?
-Contents herniate through weakness in scar of umbilicus
What is an adult umbilical hernia?
Contents herniate through linea alba in region of umbilicus
Which gender is an umbilical hernia more common in?
Females
Outline the features of epigastric hernias.
- Occurs through line alba
- Between xiphoid process and umbilicus
- Usually starts: small hernia - extraperitoneal fat poking out through linea alba
- Chronic straining forces more fat out which can eventually pull the peritoneum through
State some possible symptoms of hernias.
- Pain
- Vomiting
- Sepsis
- Abdominal distension
- Peritonitis
Differentiate between the terms “incarcerated” and “strangulated”.
Incarcerated: stuck/irreducible
Strangulated: blood supply is disrupted - can lead to tissue necrosis
Why is the arcuate line clinically significant?
- Below this line, the rectus abdominus is surrrounded by sheath only anteriorly, and this does not come posteriorly
- At this point, an incision can be made because there is no rectal sheath to go through
- Useful landmark for Pfannenstiel incisions
State the exact anatomical position of the Douglas (arcuate) line.
Umbilicus - 1/3rd - pubic symphysis
What is referred pain?
Pain perceived at a site distant from the site causing the pain
What is somatic referred pain?
Pain caused by a noxious stimulus to the proximal part of a somatic nerve that is perceived in the distal dermatome of the nerve
State three differentials for right iliac fossa pain.
- Shingles
- Appendicitis
- Right lower lobe pneumonia
What is visceral referred pain?
- In the thorax and abdomen, visceral afferent pain fibres follow sympathetic fibres back to the same spinal cord segments that gave rise to the pre-ganglionic sympathetic fibres
- The CNS perceives visceral pain as coming from the somatic portion of the body supplied by the relevant spinal cord segments
What causes visceral pain?
- Ischaemia
- Abnormally strong muscle contractions
- Inflammation
- Stretch
Which retroperitoneal structures can cause central back pain?
Pancreas and aorta
What levels is pain from acute/chronic pancreatitis referred to?
L2-L3
State three causes of referred diaphragmatic irritation.
- Ruptured spleen
- Ectopic pregnancy
- Perforated ulcer
What is Hesselbach’s triangle normally reinforced by?
Can be reinforced by the fused fibres of the internal oblique and transversus abdominus muscle (conjoint tendon)
State the lateral border of the femoral ring.
Femoral vein
Anterior border of the femoral ring?
Inguinal ligament
Posterior border of the femoral ring?
Pectineal ligament
Medial border of the femoral ring?
Lacunar ligament
What is the initial defect a femoral hernia passes through?
Femoral ring
What anatomical structure lies below the mid point of the inguinal ligament?
Deep inguinal ring
State the relationship of the deep inguinal ring to the femoral artery.
The DIR lies lateral to the femoral artery
What anatomical structure lies below the mid-inguinal point?
Femoral artery