Abdominal Wall 1 Flashcards
What are the 2 factors required for the development of a hernia?
1. Structural weakness (normal and abnormal): Normal: - diaphragm - umbilicus - inguinal canal - femoral canal
Abnormal:
- congenital diaphragmatic
- surgical scars
- Increased pressure (from repeated bouts of increased intra-abdominal pressure):
- chronic cough
- pregnancy
- strenuous activity
- straining during bowel movements or urination
What lines will you find on the anterolateral abdo wall?
- linea semilunaris (curved side abs)
- linea alba (line in middle)
What muscle sits anteriorly in the abdominal wall?
rectus abdominus
What are the layers of muscles in the lateral abdo wall from superficial to deep and their fibre arrangements?
- external oblique (anteroinferior fibres)
- internal oblique (anterosuperior fibres)
- transverse abdominis (horizontal fibres)
What is the role of the lateral muscles of the abdo wall?
they contract to guard the abdominal organs when injury threatens
Describe the different layers of the lateral abdominal wall
- skin
- subcutaneous tissue
- subcutaneous fatty layer (Camper’s fascia)
- deep membranous layer (Scarpa’s fascia)
- abdominal muscles with their investing fascia
- transversalis fascia
- extraperitoneal fat
- parietal peritoneum
Describe how the abdominal wall continues as the perineum wall
- Camper’s fascia is continuous with the subcutaneous tissue of the perineum (Cruveilhier’s fascia)
- Scarpa’s fascia is continuous with perineal fascia (Colle’s fascia)
Describe the functions and nerve supply of the abdominal wall muscles
Functions:
- support abdominal contents
- raise intra-abdominal pressure
- withstand pressure from descent of diaphragm
- respiration
- support vertebral column
- flex, laterally flex and rotate trunk
- supplied by thoraco-abdominal (7-11th IC nerves)
- subcostal nerve L1
Describe the Rectus Sheath above the arcuate line
Anterior Rectus Sheath:
aponeurosis of:
- external oblique muscle
- internal oblique muscle
Posterior Rectus Sheath:
aponeurosis of:
- internal oblique muscle
- transverse abdominis muscle
Describe the Rectus Sheath below the arcuate line
Anterior Rectus Sheath: apneurosis of: - external oblique muscle - internal oblique muscle - transverses abdominis
Describe the nerve supply to the anterolateral abdominal wall
Enters laterally
- 7-11th intercostal nerves (become thoraco-abdominal nerves)
- subcostal nerve (T12)
- iliohypogastric nerve (L1)
- ilioinguinal nerve (L1)
all travels in plane between internal oblique and transverse abdominis
What arteries supply the anterolateral abdominal wall and where are they located?
superior epigastric arteries (of ITA):
- emerges at superior aspect of abdo wall
- lies posterior to rectus abdominis
inferior epigastric arteries (from external iliac artery):
- emerges at inferior aspect of abdo wall
- lies posterior to rectus abdominis
intercostal and subcostal arteries (from posterior intercostal arteries):
- emerge at lateral aspect
What is the inguinal ligament?
- inferior thickening of the external oblique muscle
- marks anterior boundary between abdomen and thigh
What is the inguinal canal and its contents?
- inferomedial oblique passage between abdomen and perineum
Contents:
- spermatic cord (males)
- round ligament of uterus (females)
- blood and lymphatic vessels
- ilioinguinal nerve
What are the boundaries of the inguinal canal?
Anterior wall:
- external oblique aponeurosis (total)
- internal oblique muscle (laterally)
Posterior wall:
- transversalis fascia (laterally)
- conjoint tendon (medially)
Floor:
- medial half of external oblique aponeurosis (inguinal ligament)
Roof:
- transversalis fascia (laterally)
- arches of internal oblique and transversus abdominis aponeurosis (centrally)
- external oblique aponeurosis (medially)
What makes up Hesselbach’s triangle and what is it?
- site of direct inguinal herniation
- inferior epigastric artery (superiorly)
- inguinal ligament
- lateral border of rectus abdominis
Describe direct inguinal herniation
- directly through abdominal wall structures
- medial to inferior epigastric artery
- passes through Hesselbach’s triangle to superficial ring
- parallel to spermatic cord
Describe indirect inguinal herniation
- uses inguinal canal and deep inguinal ring
- lateral to inferior epigastric artery
- passes through superficial ring
- within spermatic cord or laters of abdo wall
Describe the surface anatomy of the deep and superficial inguinal ring
deep inguinal ring: just superior to half way point along inguinal ligament
superficial inguinal ring: just superior and lateral to pubic tubercle
Describe femoral herniation
- occuring in subinguinal space (posterior and inferior to inguinal ligament)
- hip flexors, femoral artery and vein, lymphatics and nerves
- medial to vessels in femoral canal
What is the origin, insertion and function of rectus abdominis?
- origin: pubic crest and pubic symphysis
- insertion: 5-7th CC and xiphoid process
- function: stabilises pelvis during gait
What is the origin and insertion of the external oblique muscle?
- origin: lower 8 ribs
- insertion: iliac crest, anterior superior iliac spine, linea alba, xiphoid process and pubic tubercle
What is the origin and insertion of the internal oblique muscle?
- origin: thoracolumbar fascia, anterior 2/3 iliac crest, lateral 2/3 of inguinal ligament
- insertion: inferior 3-4 ribs, linea alba, xiphoid process and pubic tubercle
What is the origin and insertion of the transversus abdominis?
- origin: thoracolumbar fascia, iliac crest, lateral 1/3 of inguinal ligament, inferior 6 ribs and CC
- insertion: linea alba (xiphoid process and pubic tubercle)
