7 Abdominal wall, neuromuscular hernias 2 and incisions Flashcards
Name the 3 muscles of the posterior abdominal wall
- Quadratus lumborum
- Psoas major, possibly with poses minor overlying it
- Iliacus
(Diaphragm contributes to the upper, posterior abdominal wall)
Function of the posterior abdominal wall muscles
- Quadratus lumborum stabilises the 12th rib for diaphragmatic movement in respiration
- Psoas major and iliac pass to the lesser trochanter together and are powerful hip flexors
Diaphragm: Loop? Made up of? Function? Nerve supply?
- Loop forming a sling around the oesophagus - functional sphincter preventing reflux of stomach contents into the oesophagus during inspiration
- Sheet of muscle & tendon (i.e. central tendon)
- Functions
• Separates the thoracic &
abdominal cavities
• Responsible for inspiration at rest - Nerve supply:
• C3, C4 and C5 (phrenic nerve)
What is the position of the iliolumbar ligament?
From transverse process of L5 –> posterior superior iliac spine and adjacent iliac crest
Quadratus lumborum:
Attachments?
Nerve supply?
1. Attachments: • Iliac crest • Iliolumbar ligament • 12th rib (inf. border) • L1-4 transverse processes
- Nerve supply:
• T12 and L1 -4
Psoas major:
Attachment?
Nerve supply?
- Attachments:
• Transverse processes of L1 to L5, bodies & intervertebral discs from T12 to L5
• To lesser trochanter of femur (with Iliacus) - Nerve supply:
• L1 to 3
Psoas minor:
Attachments?
Nerve supply?
- Attachments:
• T12 & L1 bodies
• To pectineal line & iliopectineal eminence on pelvic bone - Nerve supply:
• L1
(Absent in 50%)
Iliacus:
Attachments?
Nerve supply?
- Attachments:
• Iliac fossa
• To lesser trochanter of femur (with psoas) - Nerve supply:
• Femoral nerve L2, 3, 4
What are the contents of the femoral sheath?
- Femoral artery
- Femoral vein
- Femoral canal (lymphatics e.g. Cloquet’s lymph node that receives directly from the glans of penis or clitoris)
Where is the site of a femoral hernia?
- Femoral sheath, below and lateral to the pubic tubercle
* This is an extension of the abdominal transversals fascia
What are the boundaries of the femoral canal?
Medial, lateral, posterior, anterior
- Medial: Lacunar ligament
- Lateral: Femoral vein
- Posterior: Pectineus or pectineal ligament for ring
- Anterior: Inguinal ligament
Where do spinal nerves arise from? Emerge as? Combine as? Pass through? Divide into?
- Arise from segments of the spinal cord
- Emerge as dorsal (posterior) sensory roots & ventral (anterior) motor roots
- They combine to form a mixed spinal nerve that passes through an intervertebral foramen & divides into a dorsal & a ventral ramus
What is a dermatome?
Region or strip of skin supplied by a specific spinal nerve
How is each spinal nerve named?
In relation to the intervertebral foramen from which it emerges
What is a myotome?
Muscle or group of muscles supplied by a specific spinal nerve
Which nerves supply the skin and muscle of the abdominal wall?
Supplied in segments by ventral rami of the spinal nerves T7-12 and L1 (iliohypogastric and ilio-inguinal nerves)
What is the subcostal nerve?
T12
What is the epigastric dermatome? Where does the referred pain go to?
- Epigastric: T7
* Referred pain: Stomach and oesophagus
Where is the umbilical dermatome? Where is it’s referred pain?
- Umbilical: T10
* Referred pain: Appendix, gonad, small intestine
What is the suprapubic dermatome? Where is it’s referred pain?
- Suprapubic: T12 (L1 laterally, superior to inguinal ligament)
- Referred pain: Lower colon, bladder, uterus
Where does shingles (herpes zoster) occur?
Painful skin rash in T10
In the abdominal wall muscle, nerves pass between which 2 muscle?
- Internal oblique and transverses abdominis
* Pass forwards and medially
What must be done when splitting rectus abdominis surgically to avoid denervation?
The fibres must be pushed laterally towards the nerves
What muscles do the nerves which pierce the posterior wall of the rectus sheath supply?
- Rectus abdominis muscle (T7 - T12)
* Pyramidalis (T12 only)
How do the nerves terminate in the abdominal wall muscle and what do they supply?
- Terminate by piercing the anterior wall of the sheath
* Supplying the overlying skin (anterior cutaneous branches)
Where does the iliohypogastric nerve (L1) pierce the external oblique aponeurosis?
Above superficial inguinal ring
What nerve emerges through the superficial ring?
Ilioinguinal nerve (L1)
What 2 nerves supply the skin just above the inguinal ligament? And the fibres of internal oblique and transverse abdominis?
- Iliohypogastric (L1)
2. Ilioinguinal (L1)
What are the consequences of nerve injury to iliophypogastric and ilioinguinal nerves (L1)?
- Weaken internal oblique and transverse abdominis muscles and hence conjoint tendon (iliohypogastric nerve)
- Predispose to inguinal hernias
What are the branches of the lumbar plexus and which nerve fibres do they carry?
- Iliohypogastric (L1)
- Ilioinguinal (L1)
- Genitofemoral (L1,2)
- Lateral femoral cutaneous (L2,3) - (Lateral cutaneous nerve of thigh)
- Obturator (L2,3,4)
- Femoral (L2,3,4)
- Muscular branches
Which muscle is the lumbosacral plexus formed in?
Psoas major
Which vessels provide the arterial supply to the abdominal wall?
- Superior, inferior and superficial epigastrics
* Superficial and deep circumflex iliacs
Superior epigastric artery:
Pathway?
Supplies which muscles?
• Branch of the internal thoracic (mammary) artery entering the upper part of the rectus sheath between the sternal & costal origins of the diaphragm
• Descends behind the rectus abdominis
- supplying the upper central part of the anterior abdominal wall
-anastomoses with the inferior epigastric artery (may form a collateral circulation for an obstructed aorta)
What artery supplies the upper lateral abdominal wall?
Branches from the musculophrenic branch of the internal thoracic artery
What artery supplies the upper central part of anterior abdominal wall?
Superior epigastric artery
Inferior epigastric artery:
Branch of which vessel?
Pathway?
Supplies?
- Branch of the external iliac
- It runs upward & medially along the medial side of the deep inguinal ring & pierces the transversalis fascia to enter the rectus sheath anterior to the arcuate line
- It ascends behind the rectus muscle supplying the lower central part of the anterior abdominal wall & anastomoses with the superior epigastric artery
What artery supplies the lower central part of the anterior abdominal wall?
Inferior epigastric artery
Deep circumflex iliac artery:
Branch from which vessel?
Pathway?
Supplies what?
- Branch of external iliac just above the inguinal ligament
- Runs upward & laterally toward the anterior superior iliac spine & then continues along the iliac crest
- Supplies lower lateral part of the abdominal wall
What artery supplies the lower lateral part of the abdominal wall?
Deep circumflex artery
Superficial epigastric and superficial circumflex iliac arteries:
Branch of which vessel?
Supply what?
• Arise from the femoral just below the
inguinal ligament
• Supply the lower abdominal wall
Which arteries supply the lower abdominal wall?
- Superficial epigastric
* Superficial circumflex iliac
Which vessels pass forwards between the muscle layers and supply the lateral abdominal wall?
- Lower 2 posterior intercostal arteries (i.e. branches of the descending thoracic aorta)
- 4 lumbar arteries (i.e. branches of the abdominal aorta)
What is the structure of the abdominal wall venous drainage system?
- Superficial epigastric & superficial circumflex iliac veins drain into the proximal end of the great (long) saphenous vein along with the superficial & deep external pudendal veins
- These 4 veins are important in varicose vein surgery
What direction do the arteries and veins run in the abdominal wall in relation to umbilicus?
- Arteries converge towards the umbilicus
* Veins radiate out from umbilicus
Veins radiate out from the umbilicus, which eventually drain into the femoral & external iliac veins inferiorly &
the internal thoracic & axillary veins superiorly:
• What vessel forms the portosystemic venous anastomosis?
• What is the result of obstruction of this vessel?
- Para-umbilical veins connect the system through the umbilicus to the portal veins of the liver
- Obstruction of the portal vein may cause venous back pressure into the veins of the abdominal wall => Caput Medusae
What is the superficial lymphatic drainage of the abdominal wall? (anterior, posterior)
- Anterior:
• Above umbilicus to anterior axillary nodes
• Below umbilicus to superficial inguinal nodes - Posterior
• Above iliac crests to posterior axillary nodes
• Below iliac crests to superficial inguinal nodes
Where do the axillary nodes empty into?
Subclavian lymph trunk
The anterior/ pectoral group of axillary lymph nodes are the lymph drainage for which area?
Anterior superficial abdominal wall above umbilicus
The posterior/ subscapular group of axillary lymph nodes are the lymph drainage for which area?
Posterior superficial abdominal wall above iliac crests
The superficial inguinal nodes are the lymph drainage for which area? Where does it extend to?
- Below inguinal ligament
- Extending inferiorly along the great (long) saphenous vein for anterior & posterior lower superficial abdominal wall (below umbilicus & below iliac crests)
Where do the superficial inguinal nodes drain into?
Deep inguinal nodes (in the femoral canal) that drain into the external iliac & then the para-aortic nodes
What is the deep lymph drainage of the abdominal wall?
Drains in parallel to the epigastrics:
• Inferiorly to the
external iliac & then the para-aortic nodes
• Superiorly to the parasternal nodes alongside the internal thoracic artery & then mediastinal nodes
List the main surgical incisions? (6)
- Kocher’s - right subcostal
- Thoraco-abdominal
- Midline
- Muscle splitting/ Gridiron
- Pfannenstiel
- Paramedian
What is Kocher’s surgical incision used for?
- Right subcostal
* For removal of gallbladder
What is thoraco-abdominal surgical incision used for?
For accessing oesophagus
What is midline surgical incision used for?
For rapid access through the almost avascular line alba but has poor healing
What is muscle splitting/ Gridiron surgical incision used for?
For appendicectomy with muscles split in the direction of their fibres rather than incised with good strong healing
What is pfannenstiel surgical incision used for?
For gynaecological and other pelvic procedures (no posterior rectus sheath)
What is paramedical surgical incision used for?
Similar to midline, but avoiding the lines alba for better healing with the fibres of rectus abdominis split or reflected laterally towards their nerve supply
Where is McBurney’s point?
What does it overlie?
What surgical incision is made here?
- 1/3 of distance from right ASIS to umbilicus
- Typically overlies the base of vermiform appendix as this attaches to the caecum
- Appendicectomy incisions are made here
Extending the appendicectomy incision laterally may put what nerves at risk?
Iliohypogastric and ilioinguuinal nerves
- possibile consequence of weakening the muscles supplied (inguinal hernia)
How do skin flaps work?
- It is possible to remove a piece of abdominal wall skin & close the wound behind it while moving this skin flap to replace an area of lost skin
- Essential to maintain the vascular pedicle both arterial & venous
