Abdomen: Abdominal Wall, Hernias, Peritoneum Flashcards
Layers of the abdominal wall: anterolateral
Skin Camper's Fascia (fatty) Scarpa's Fascia (membranous) External oblique Internal oblique Transversus abdominis Transversalis fascia Extra peritoneal fascia Parietal peritoneum
Layers of the abdominal wall: posterior
Muscles of the anterior abdominal wall
Rectus abdominis Pyramidialis External oblique Internal oblique transversus abdominis
Rectus abdominis
Long paired muscle. Split in 2 by linea alba. Muscles is intersected by fibrous strips, tendinous intersections. Giving rise to ‘6-pack’ shape.
Origin: crest of pubis
Insertion: diploid process, costal cartilage ribs 5-7
Innervation: Thoracoabdominal nerves (T7-T11
Function: depresses the ribs
Internal oblique
Origin: inguinal ligament, iliac crest, lumbodorsal fascia
Insertion: ribs 10-12
Innervation: thoracoabdominal nerves (T7-T11), subcostal nerve, branches of lumbar plexus
Function: compresses abdominal cavity, ipsilateral rotation of torso
External oblique
Origin: ribs 5-12
Insertion: iliac crest, pubic tubercle
Innervation: thoracoabdominal nerves (T7-T11) and subcostal nerve (T12)
Function: contralateral rotation of torso
Transversus abdominis
Origin: inguinal ligament, costal cartilage 7-12, iliac crest, thoracolumbar fascia
Insertion: conjoint tendon, xiphoid process, linea alba, pubic crest
Innervation: thoracoabdominal nerves (T7-T11), subcostal nerve (T12), branches of lumbar plexus
Function: compression of abdominal cavity
Pyramidalis
Origin: pubic crest and pubis symphysis
Insertion: linea alba
Innervation: subcostal n. (T12)
Function: tenses linea alba
Linea alba
Midline of abdomen
Formed from the aponeuroses of external oblique, internal oblique, transverse abdominis
Rectus sheath
Formed by the aponeurosis of external oblique, internal oblique and transverses abdominis
Linea semilunaris
Formed from the lateral border of rectus abdominis
Superficial fascia of abdominal wall
Above umbilicus: single sheet
Below umbilicus: superficial: Camper’s fascia and deep: Scarpa’s fascia
Camper’s Fascia
Superficial fatty layer of fascia
Scarpa’s fascia
Deep membranous later of fascia
Incisions into the abdomen
Midline Paramedian Pararectal Gridiron Lanz Pfannenstiel Transverse Kocher, Rooftop (Chevron), Mercedes-Benz Rutherford-Morrison
Midline incision
Xiphisternum to pubis symphasis (or any length along this plane)
Layers: skin, camper’s, Scarpa’s, linea alba, transversales fascia, extra-peritoneal fascia, parietal peritoneum
Gridiron incision
Centred over McBurney’s point (2/3 distance between umbilicus & ASIS)
Layers: skin, Camper’s, Scarpa’s, external oblique, internal oblique, transversus abdominis, transversals fascia, extra-peritoneal facia, parietal peritoneum
Risk of injury to ilioinguinal and iliohypogastric nerves
Arc can be extended anteriorly and laterally to form Rutherford-Morrison (to access ascending bowel)
Lanz incision
Inferior to the Gridiron incision
High risk of severing the ilioinguinal and ilihypogastric nerves
Pfannenstiel incision
Curvilinear incision is made through skin and subcutaneous fat. Longitudinal incision is made through linea alba.
Kocher Incision
Parallel to subcostal margin on right
Used to access liver and biliary tree. Used of open cholecystectomy.
Mirrored on contralateral side to create Rooftop/Chevron incision. Extended down midline to create Mercedes Benz incision.
Risk of injuring superior epigastric vessels. Lateral extension risks damage to intercostal nerves.
Types of Hernia
Indirect inguinal Direct inguinal Femoral Umbilical Epigastric Spigelian Obturator Lumbar
Borders of the inguinal canal
Anterior wall: aponeurosis of external oblique, reinforced by internal oblique laterally
Posterior wall: transversalis fascia
Roof: transversals fascia, internal oblique, transversus abdominis
Floor: inguinal ligament, thickened medially by the lacunar ligament
Openings of the inguinal canal
Deep (internal) ring
Superficial (external) ring
Deep (internal) ring
Midpoint of inguinal ligament
Lateral to epigastric vessels
Created by transversalis fascia
Superficial (external) ring
End of the inguinal canal
Superior to pubic tubercle
Triangle shaped opening
Formed by the evagination of external oblique
Contents of the inguinal canal
Spermatic cord (males only)
Round ligament (females only)
Ilioinguinal nerve
Genital branch of genitofemoral n.
Coverings of the spermatic cord
External spermatic fascia: derived from scarpa’s fascia
Cremaster muscle and fascia: derived from internal oblique
Internal spermatic fascia: derived from transversalis fascia
Contents of the spermatic cord
Vessels: Testicular artery Cremasteric artery and vein Artery to vas deferens Pampiniform plexus of testicular veins
Nerves:
Genital branch of genitofemoral nerve
Autonomic nerve fibres
Others:
Vas deferens
Processus vaginalis
Lymph vessels (drain to para-aortic)
Inguinal ligament
Formed from external oblique aponeurosis
Runs from pubic tubercle to ASIS
indirect inguinal hernia
80%
Bowel enters inguinal canal via deep inguinal ring
Direct inguinal hernia
20%
Bowel enters inguinal canal directly through weakness in posterior wall, termed Hesselbach’s triangle
Borders of Hesselbach’s Triangle
Medial: lateral border of Rectus abdominis muscle
Lateral: inferior epigastric vessels
Inferior: inguinal ligament
Muscles of the posterior abdominal wall
Erector Spinae
Quadratus Lumborum
Psoas Major
Psoas Minor
Iliac
Fascia of the posterior abdominal wall
Psoas fascia
Thoracolumbar fascia: Posterior, middle, anterior
Psoas Major
Insertion: Vertebral bodies of T12-L4, transverse process of L1-L5
Insertion: ileopsoas tendon on lesser trochanter of hip
Action: flexion of hip, lat rotation of thigh
Innervation: anterior ramp of spinal nerves (L1-3)
Blood supply: lumbar branch of olio lumbar artery
Iliacus
Origin: iliac fossa
Insertion: lesser trochanter of femur
Action: hip flexion
Innervation: femoral nerve (L1-3)
Blood supply: iliolumbar, circumflex iliac, obturator, femoral
Erector Spinae
3 muscles: Iliocostalis, Longissimus, Spinalis (lateral to medial: I like standing)
