91 - Posterior Abdominal Wall Flashcards
*Layout of posterior abdominal wall
Proportion of people who have a psoas minor
~2/3
Muscle inferolateral to psoas major
Iliacus muscle
Muscle posteromedial to psoas
Anterior abdominal muscles
Psoas major location
In paravertebral gutter
Shape of psoas lateral border
A straight, oblique line
Origin of psoas major
One continuous origin along the spine. From T12 to L5. Attaches to vertebral bodies, IV discs, medial edges of transverse processes
Psoas major function
Flexor of the vertebral column
Where is the lumbar plexus located?
Within psoas major
Where does psoas major attach to?
Lesser trochanter of femur
Location of vessels and nerves, relative to psoas major
Lumbar plexus is within psoas major. Vessels are behind. Sympathetic trunk is in front.
Psoas minor
Phylogenetically degenerating muscle. In about 2/3 of people overlies psoas major. Doesn’t enter inguinal canal.
Quadratus lumborum attachment
Attaches between T12 and Iliac crest. Attaches to the transverse processes between these.
Function of quadratus lumborum
Stabilises the 12th rib, and acts as a flexor
Iliacus muscle shape
Inverted triangle
Iliacus muscle origin
Iliac crest
Iliacus muscle attachment
Attaches to lesser trochanter of the femur
Muscles with a common insertion into the lesser trochanter
Iliacus and psoas major
Iliopsoas
Conjoined tendon of iliacus and psoas major, inserting into the lesser trochanter of the femur
Arrangement of fascia of the posterior abdominal wall
All muscles have their own fascia, except for quadratus lumoborum and erector spinae. Erector spinae and quadratus lumborum are enclosed in thoracolumbar fascia.
Thoracolumbar fascia attachments
One layer behind tips of spinous processes. Middle layer attaches to transverse processes. Most anterior layer attaches to the front of transverse processes.
Thoracolumbar fascia structure
Trilaminar
Where do all the layers of the thoracolumbar fascia fuse?
Along line of the 12th rib
Muscles enclosed by thoracolumbar fascia
Quadratus lumborum and erector spinae
How are quadratus lumborum enclosed in thoracolumbar fascia?
In anterior compartment
Where on the posterior abdominal wall do the internal obliques and transversus abdominis attach?
Lateral edge of thoracolumbar fascia.
Why don’t the external obliques attach to the thoracolumbar fascia?
Lats intervene.
How can a psoas abscess arise?
TB osteomyelitis can lead to an eruption of the psoas.
Are kidneys intra- or retro-peritoneal?
Retroperitoneal
Where in the body do the kidneys sit?
In the paravertebral gutters. Almost posterior to spine. Overlie quadratus lumborum.
Relative positions of kidneys to one another.
Right sits a bit lower than the left because of the liver superiorly.
Why do the kidneys move on inspiration?
Associated with the diaphragm
Size of kidneys
10cm long 5cm wide 2.5cm thick
Shape of adrenal glands.
Asymmetrical. Party hat shape on the right kidney. Crescent shape on the left kidney.
Broad divisions of kidneys
Outer cortex - Continuous band of pale tissue Inner medulla - Discontinuous, dark, pyramids
Broad divisions of kidneys
Outer cortex - Continuous band of pale tissue Inner medulla - Discontinuous, dark, pyramids
What surrounds the kidneys?
Fibrous capsule, fat, renal fascia
Which direction do the renal hila face?
Antero-medially
Anterior to posterior structures inserting into the kidney hila
Vein, artery, duct
Cavity within kindey
Renal sinus
What fills renal sinus
Fat
Structures embedded in fat within the renal sinus
Vein, artery, ureteric pelvis
Structure of main renal artery
One enters hilum, splits into five segmental arteries.
Effect of kidney position change during development
Loses lower blood supply, gains upper blood supply. In ~25% of people can see accessory renal artery, which has persisted.
Which vessel do the renal veins join to?
IVC
Where do the renal arteries arise from?
Abdominal aorta
Path of the right renal vein relative to aorta
Passes anterior to aorta
Structure of ureteric/renal pelvis
Two-three major calyces. Each of these collect from two or three minor calyces. Minor calyces each receive apex of renal pyramids.
Length of ureters
25-30cm
Most superior part of ureters
Ureteric pelvis
Path of ureters
Descend on anterior face of psoas major. Run along lateral wall of pelvis. Enter bladder obliquely
Ureter blood supply
Take blood supply from whatever they’re passing
Areas of narrowing of ureters where kidney stones can lodge 1 2 3
1) Ureteropelvic junction 2) Crossing of iliac artery (mid-ureter) 3) Ureto-vesicular junction (where inserts into bladder)
