Abdominal Wall Flashcards
Superior bounds of anterolateral abdominal wall
- Xiphoid process
- Cartilage of ribs 7-10
Inferior bounds of anterolateral abdominal wall
- Inguinal ligament
- Superior pelvic girdle
Superficial fatty layer of fascia inferior to umbilicus
Camper’s fascia
Deep membranous layer (superficial) fascia
Scarpa’s fascia
Colle’s Fascia
Perineal continuation of Scarpa’s fascia
Incisional layers of abdominal wall inferior to umbilicus
- Skin
- Camper’s fascia
- Scarpa’s fascia
- Muscles (dependent on incision)
- Transversalis fascia
- Extraperitoneal fat
- Peritoneum
Limit of ectopic testes descent
Point of Colle’s fascia inserting into deep fascia of thigh 2.5cm below inguinal ligament
Site of urine tracking in bulbous urethral rupture
Scrotum, perineum, penis, abdominal wall deep to Scarpa’s fascia
External Oblique (OIIA)
O - External surface of ribs 5-12
I - Linea alba, pubic tubercle, anterior half of iliac crest
I - Thoracoabdominal nerves
A - Compresses and supports abdominal viscera, flexes/rotates trunk
Anterolateral abdominal wall neurovascular plane
Between internal oblique and transversus abdominis
Internal Oblique (OIIA)
O - Thoracolumbar fascia, anterior 2/3rd of iliac crest, connective tissue deep to lateral 1/3rd of inguinal ligament
I - Inferior borders of ribs 10-12, linea alba, pectin pubis
I - Thoracoabdominal nerves
A - compresses and supports abdominal viscera, flexes and rotates trunk
Transversus Abdominis (OIIA)
O - Internal surfaces of 7th-12th costal cartilages, thoracolumbar fascia, iliac crest, connective tissue deep to lateral 1/3rd inguinal ligament
I - linea alba with aponeurosis of internal oblique, pubic crest, pectin pubis
I - Thoracoabdominal nerves
O - compresses and supports abdominal viscera
Rectus Abdominis (OIIA)
O - pubic symphysis and pubic crest
I - xiphoid process and 5-7th costal cartilage
I - Thoracoabdominal nerves
O - flexes trunk, compresses viscera, stabilises pelvis
Components of anterior rectus sheath
- External oblique aponeurosis
2. Part of internal oblique aponeurosis
Components of posterior rectus sheath
- Part of internal oblique aponeurosis
2. Transversus abdominis aponeurosis
Rectus abdominis blood supply
Superior and inferior epigastric artery
Outline structure of rectus sheath
- Above costal margin anterior rectus is external oblique aponeurosis only (no posterior sheath)
- From costal margin to just below umbilicus there is anterior and posterior rectus sheath
- Below arcuate line - posterior recuts passes anterior to rectus abdominis (rectus abdominis lies directly on transversals fascia)
Contents of rectus sheath
- Rectus abdominis
- Pyramidalis
- Segmental nerves
- Segmental vessels from T7-12
- Superior and inferior epigastric vessels
Course of iliohypogastric nerve (L1)
- Originates from lumbar plexus (L1)
- Pierces transversus abdominis muscle to course between IO and TA, branches pierce external oblique aponeurosis of most inferior abdominal wall
Course of ilioinguinal nerve (L1)
Passes between IO and TA; then traverses inguinal canal
Distribution of ilioinguinal nerve (L1)
Skin of lower inguinal region, mons pubis, anterior scrotum or labium majus, adjacent medial thigh, inferior most IO and TA
Outline lymphatic drainage of the anterolateral abdominal wall
- Above umbilicus = drains to axillary lymph nodes with a few to the parasternal lymph nodes
- Inferior umbilicus = drains to superficial inguinal lymph nodes
Course and distribution of superior epigastric artery
- Originates from internal thoracic artery
- Descends in rectus sheath deep to rectus abdominis
- Supplies rectus abdominis, superficial and deep wall of epigastrium and upper abdomen
Course and distribution of inferior epigastric artery
- Originates from external iliac artery
- Runs superiorly to enter rectus sheath; runs deep to rectus abdominis
- Supplies rectus abdominis, deep abdominal wall of pubic and inferior umbilical regions
Describe the internal surface of anterolateral abdominal wall
Covered with transversals fascia, a variable amount of extraperitoneal fat, and parietal peritoneum
Describe the median umbilical fold
- Infraumbilical
- Extends from apex of bladder. to the umbilicus
- Covers the median umbilical ligament (obliterated urachus)
Describe the medial umbilical folds
- Infraumbilical
- Bilateral
- Cover medial umbilical ligaments (obliterated umbilical artery)
Describe the lateral umbilical folds
Cover the inferior epigastric vessels (bleed if cut - from the inferior epigastric artery)
Describe the deep inguinal ring
- Defect in transversals fascia
- 1cm above midpoint of inguinal ligament
- Immediately lateral to inferior epigastric vessels
Describe the superficial inguinal ring
- V-Shaped defect in inguinal ligament
- Lies above and medial to pubic tubercle
Composition of inguinal ligament
External oblique aponeurosis running from ASIS to pubic tubercle
Lacunar ligament
Deep fibres of the inguinal ligament attach to the superior pubic ramus
Pectineal ligament
- Lateral fibres of inguinal ligament attach to pectineal line (pectin pubis)
- Forms posterior border of femoral canal
Define the iliopubic tract
Thickened inferior margin of transversalis fascia that reinforces posterior floor of inguinal canal
Anterior relations of inguinal canal
- Skin
- Camper’s and Scarpa’s
- External oblique aponeurosis
- Internal oblique in lateral 1/3rd of canal
Posterior relations of inguinal canal
- Medial = conjoint tendon
- Lateral = transversalis fascia
Roof of inguinal canal
- Internal oblique
- Transversus abdominis
Floor of inguinal canal
Inguinal ligament (external oblique aponeurosis)
Contents of inguinal canal (men vs women)
- Men = spermatic cord and ilioinguinal nerve
- Women = round ligament and ilioinguinal nerve
Gallbladder surface marker
Tip of 9th costal cartilage where linea semilunaris intersects the costal margin (lateral edge of rectus)
Spleen surface marker
Under ribs 9-11 on the left (long axis lies under rib 10)
Pancreas surface marker
Lies along the transpyloric plane (L1)
Kidney surface marker
From T12-L3. Hilum lies at the level of the transpyloric plane (L1)
Appendix surface marker
McBurney’s point - 1/3rd distance between ASIS and umbilicus
Aortic bifurcation surface marker
Level of L4 to the LEFT of the midline
External iliac artery surface marker
Palpable between midinguinal point halfway between ASIS and symphysis pubis
Mid-point of inguinal ligament
Half way between pubic tubercle and ASIS
Mid-inguinal point
Half way between ASIS and pubic symphysis
Define a hernia
Protrusion of all or part of a viscus through the wall of the cavity in which it is usually contained
Most common side of groin hernias
RIGHT sided (due to later descent of testes or appendicectomy)
Define indirect inguinal hernia
Indirect hernia sac (remains of processes vaginalis) extends through the deep ring, inguinal canal, and superficial ring into the scrotum
Embryological cause of indirect inguinal hernia
Failure of processus vaginalis to close
Outline risk factors for indirect inguinal hernias
- Male - bigger processus vaginalis
- Prematurity - processus vaginalis not closed
- Africans - low pelvic arch
- Right sided - slower testicular descent
- Testicular feminisation syndrome
- Increased intraperitoneal fluid
Define direct inguinal hernia
Acquired weakness in the abdominal wall causing hernia sac to pass directly forwards through defect in transversalis fascia (posterior wall of inguinal canal)
Site of inguinal hernia
Above and medial to pubic tubercle
Describe the femoral sheath
- Downward protrusion into the thigh of the fascial envelope lining the abdominal wall (transversalis fascia and psoas fascia)
- Surrounds the femoral vessels until 2.5cm below the inguinal ligament
Outline the compartments of the femoral sheath
- Medial = femoral canal
- Intermediate = contains femoral vein
- Lateral = contains femoral artery
Function of femoral sheath
Provides freedom of vessel movement during hip motion
Describe the femoral canal
1.3cm long medial compartment of the femoral sheath containing lymphatics with an UPPER opening called the femoral ring
Contents of the femoral canal
- Connective tissue
- Efferent lymph vessels from deep inguinal nodes
- Deep inguinal node of Cloquet (drain penis/clitoris)
Outline the boundaries of the femoral ring
- Anterior = inguinal ligament
- Posterior = superior ramus of pubis and pectineal ligament
- Medial = lacunar ligament or iliopubic tract
- Lateral = femoral vein
Describe femoral hernia
- Enter femoral canal via femoral ring
- Hernia arrives in thigh next to saphenous opening
- Hernia enlarges upwards and medially
- Lies between superficial external pudendal and superficial epigastric veins
How do femoral veins compromise lower limb venous drainage
Compress saphenous vein as it emerges through saphenous opening
Why and to what extent are femoral hernias more common in women
- 2.5x
- Inguinal ligament makes a wider angle with the pubis
- Fat in femoral canal stretches the canal
- Pregnancy increases pressure
Site of femoral hernias
Below and lateral to pubic tubercle
Emergency indications for hernia repair
Painful irreducible hernias
Which hernias should be electively repaired
- Indirect
- Symptomatic direct
Which hernias should be repaired urgently
- All femoral hernias
- 50% strangulate within 1 month
Which hernias should be repaired promptly
- Irreducible inguinal hernia
- History <4 weeks (greater risk of strangulation within first 3 months of appearance)
Operation for primary unilateral inguinal hernia
Mesh repair (Lichtenstein or endoscopic)
Operation for primary bilateral inguinal hernia
Mesh repair
Operation for recurrent inguinal hernia
- If previously anterior = open preperitoneal mesh of endoscopic
- If previously posterior = Lichtenstein’s totally extraperitoneal (TEP)
Outline the principles of hernia repair
- Reduce hernia contents
- Remove hernia sac
- Repair defect
How does herniotomy in children differ from that in adults
No need to repair the posterior wall of the inguinal canal as there is no defect
Contraindications to mesh repair
Presence of pus or bowel contents in emergencies
What operation should be performed if mesh repair is contraindicated
Shouldice repair (transversalis flap is created)
Outline the closure of mesh and Shouldice repairs
- Inspect for potential femoral hernias
- Close external oblique aponeurosis with continuous absorbable suture (e.g. PDS) over the cord
- Close Scarpa’s fascia with interrupted vicryl
- Close skin with subcuticular monocryl
Intraoperative hazards of hernia repair
- Damage to ilioinguinal nerve (sensory loss in lower groin and anterior scrotum)
- Damage to cord structures
- Orchidectomy
What is the standard approach to elective femoral hernia repair
High inguinal (Lotheissen) approach (except in thin females where a low crural approach is acceptable)
Approach for complex, recurrent, or obstructed femoral hernias
High extraperitoneal approach (McEvedy’s)
Describe Spigellian hernia
Protrusion of the peritoneum through bands of the internal oblique muscle as the muscle enters the semilunar line
What is the Spigellian line
A.K.A. Linea semilunaris
Bilateral vertical curved line in the anterior abdominal wall where the layers of the rectus sheath fuse lateral to the rectus muscle and medial to the oblique muscles
Describe Richter’s Hernia
- Partial enterocele
- One anti-mesenteric margin of the gut is strangulated in the sac
- Obstruction may be incomplete
- Will be a tender, irreducible hernia
Describe Madyl’s hernia
- W-shaped loop of small gut lies in hernia sac
- Intervening loop is strangulated in the abdominal cavity
- Seen in very large hernias
Describe Sliding hernia (Hernia en glissade)
- Sac wall is composed in part by a RETROPERITONEAL viscus
- The bowel forms part of the hernia but is anatomically outside of the sac
Main risk when operating on sliding hernias
Opening the bowel due to mistaking it for the sac (bowel lies outside the sac in these hernias)
Describe Littre’s hernia
Hernia sac containing a strangulated Meckel’s diverticulum
Outline the pathophysiology of hernia strangulation
- Venous outflow obstruction
- Leads to oedema
- Arterial obstruction
- Ischaemia
- Necrosis of mucosal layer
- Luminal toxins and bacteria enter portal venous circulation causing sepsis
- Transudation of toxins and bacteria into peritoneal cavity causes peritonitis
Site of obstruction in indirect hernias
Deep or superficial inguinal rings
Site of obstruction in direct hernias
Defect in transversalis fascia
Site of obstruction in femoral hernias
Fibrosis of peritoneum of the neck
Site of obstruction in umbilical hernias
Rigid aponeurotic margins around the sac
Describe sublay method of incisional hernia repair
Mesh inserted between the abdominal muscles and the peritoneum
Describe the covering layers of an umbilical hernia
Skin, superficial fascia, rectus sheath, transversalis fascia, sac
How can the superficial inguinal ring be identified
Presence of crural fibres
