L4.1 POS ab wall

Question 1

Border of the POS ab wall

Answer 1

• POS iliac crest → 12th rib

Question 2

Psoas Maj

Answer 2

• Overlying lumbar TP on either side
• Straight but oblique LAT border
• Lower border of T12 → Upper border of L5
• Passes beneath IL → inset to Lesser trochanter
• Has own fascia: Fascia psoas (v. strong)

Question 3

Psoas Min

Answer 3

• T12-L1
• Tendon blends with fascia of overlying psoas major

Question 4

Quadratus lumborum

Answer 4

• POS 1/2 of iliac crest & tips of TP & 12th ribs
• Stabilises 12th rib
• Behind lumbar-vert body (positioned on the floor of paraverterbral gutter)
• Enclosed in thoraco-lumbar fascia

Question 5

Thoraco lumbar fascia

Answer 5

• POS: tip of SP
• MID: Tip of TP
• ANT: Front of TP
• Attaches to muscles of ANT wall (however E.O doesn’t anchor due to lats)

Question 6

What does the thoraco lumbar fascia enclose?

Answer 6

• Erector spinae enclosed in MID+POS thoraco-lumbar fascia
• Q.L enclosed in ANT+MID thoraco-lumbar fascia

Question 7

Iliacus

Answer 7

• Iliac fossa → insert via conjoint tendon with P.maj → Lesser trochanter
• Own fascia: Fascia iliacus

Question 8

How does the lumbar plexus go into the ANT wall

Answer 8

• Leaves LAT → through Q.L → into neurovascular plane → ANT wall

Question 9

Retroperitoneal organs

Answer 9

• Kidney shaped ab cavity due to vert column punching in from behind
• Back directly faces fascia, covered only on the ANT surface by parietal peritoneum
  
  • Movements restricted

Question 10

What is a mesentery

Answer 10

• double layer of reflected peritoneum

Question 11

Positional characteristics of the kidney

Answer 11

• 10cm by 5cm by 2.5cm
• At the plane of paravertebral gutter
• T12-L3 (R. kidney is lower, pushed down by liver)
• Closely related to diaphragm → ∴moves with respiration
• R. Apex directly associated with supradrenal gland
• L. border/hilum associated with supradrenal gland

Question 12

Features of the kidney

Answer 12

• Has a fibrous capsule
• Perinephric fat surrounds the kidney
• Has a renal fascia
• Arranged into:
  
  • Outer pale cortex
  • Surrounding an inner medulla (discontinuous darker renal pyramid)

Question 13

Hilum of the kidney

Answer 13

• Faces A-M
• Transmit renal V/A/ureter
  
  • Hilar structures embedded in renal sinus

Question 14

Renal A

Answer 14

• Single large horizontal A
• Branches from abdominal aorta
• R.renal A passes behind IVC

Question 15

IVC

Answer 15

• Positionally R. of aorta
• L aorta passes in front of renal A

Question 16

Renal Veins

Answer 16

• Segmental V joining to make renal V → drains into IVC
• L renal vein passes in front of ab aorta
  
  • L. spermatic V into L renal V
  • R. spermatic V directly into IVC

Question 17

SUP mesenteric A

Answer 17

• Falls in front of the traversing renal V (from IVC) in front of aorta

Question 18

How is each renal segment drained?

Answer 18

• Each renal segment is drained by a renal V

Question 19

Development of kidneys

Answer 19

• Develop low → work up to final position on POS wall
• Accessory renal A → early developmental vessel supplying kidney

Question 20

Ureter

Answer 20

• Muscular tube: 25cm
• In renal sinus
• Each medullary cortex collects into a minor calyx
• 2/3 min calyces → major calyx
• 3 maj calyces → ureter

Question 21

Descent of ureter

Answer 21

• On POS ab wall (Corresponds to tip of TP)
  
  • Initially on psoas maj → over pelvic brim

Question 22

BS of the ureter

Answer 22

• Received throughout cord (multiple BS)

Question 23

Sites of narrowing of the ureter

Answer 23

1. At the top (when it becomes the ureter)
2. Dip over pelvic brim
3. Through urinary bladder