posterior abdominal wall and retroperitoneal organs Flashcards
What is the primary function of the kidneys?
The kidneys produce urine, which is conveyed by the ureters to the urinary bladder.
What is the role of the suprarenal (adrenal) glands?
They function as part of the endocrine system, having distinct functions from the kidneys.
Are the kidneys and suprarenal glands intraperitoneal or retroperitoneal?
They are primary retroperitoneal structures.
At which vertebral levels are the kidneys positioned?
T12-L3, overlapping the 11th and 12th ribs.
Which kidney is lower, and why?
The right kidney is lower than the left because of the space occupied by the liver.
Which structures are anterior to the right kidney?
The liver, duodenum, and possibly the ascending colon.
Which structures are anterior to the left kidney?
The stomach, spleen, pancreas, and descending colon.
Where are the suprarenal (adrenal) glands located in relation to the kidneys?
They are positioned superomedially to the kidneys.
What type of structure are the kidneys classified as?
Retroperitoneal structures, meaning they are located behind the peritoneum.
What surrounds the kidneys for protection?
A large amount of perinephric fat.
What is the thin layer covering the kidney’s surface?
The renal fibrous capsule.
What is the renal hilum?
The entrance and exit point for structures that serve the kidney (e.g., renal artery, renal vein, ureter).
Where is the hilum of the left kidney located?
Near the transpyloric plane.
How are the renal artery and vein positioned at the hilum?
The renal vein is anterior to the renal artery.
What is the renal pelvis?
The superior expansion of the ureter that collects urine from the kidney.
How does urine pass through the renal pelvis?
The renal pelvis receives 2-3 major calyces, and each major calyx receives 2-3 minor calyces.
What is the function of the renal papilla?
It is the apex of the renal pyramid, where urine is excreted into the minor calyces.
What is the renal pyramid and where is it found?
The renal pyramid is part of the inner medulla, containing urine-collecting tubules.
What are the renal cortex and renal columns?
The outer cortex surrounds the medulla, and the renal columns extend between the pyramids.
What are the two main parts of the suprarenal (adrenal) glands?
The cortex and medulla.
What does the adrenal cortex secrete?
Corticosteroids and androgens.
How do corticosteroids affect the body?
They help the kidneys retain salts and water, increasing blood volume and blood pressure.
What 2 things does the adrenal medulla secrete?
Adrenaline and noradrenaline.
What is the role of chromaffin cells in the adrenal medulla?
They secrete adrenaline and noradrenaline, triggering the fight or flight response.
What arteries and veins supply the kidneys and suprarenal glands?
Renal arteries (L1/2 level) and renal veins.
How do renal arteries divide near the hilum?
They divide into five segmental arteries.
What are the three sources of arterial supply to the suprarenal glands?
Superior – from inferior phrenic arteries
Middle – from the abdominal aorta
Inferior – from renal arteries
Where do the right and left suprarenal veins drain?
Right suprarenal vein → drains into IVC
Left suprarenal vein → drains into the left renal vein then into the IVC
How does the left renal vein compare to the right renal vein?
The left renal vein is longer than the right renal vein.
how many branches supply the suprarenal glands
50-60 branches
What is the main nerve supply to the suprarenal glands?
The suprarenal plexus supplies the suprarenal glands.
Where does the suprarenal plexus receive fibers from?
The coeliac ganglion and aorticorenal ganglion.
How is the suprarenal medulla different from other organs?
It functions like a sympathetic ganglion and receives preganglionic sympathetic fibers directly.
What do chromaffin cells in the medulla secrete?
Adrenaline and noradrenaline (fight-or-flight hormones).
What activates the suprarenal cortex?
ACTH (adrenocorticotropic hormone) from the anterior pituitary gland.
What type of nerve fibers supply the abdominal viscera?
Autonomic nerve fibers (both sympathetic and parasympathetic).
which nerves provide sympathetic innervation to the abdominal viscera?
Splanchnic nerves from different spinal levels:
T5-9 → Greater splanchnic nerve
T10-11 → Lesser splanchnic nerve
T12 → Least splanchnic nerve
L1-2/3 → Lumbar splanchnic nerves
Which 2 nerves provide parasympathetic innervation to the abdominal viscera?
Vagus nerve (from brainstem)
Pelvic splanchnic nerves (from S2-4)
Where do the autonomic fibers synapse?
In the abdominal aortic plexuses and associated sympathetic ganglia.
How do autonomic fibers reach the abdominal organs?
Via peri-arterial extensions of the plexuses.
What is the role of prevertebral ganglia?
They are autonomic ganglia where preganglionic sympathetic fibers synapse before innervating abdominal organs.
Which splanchnic nerves supply sympathetic fibers to the prevertebral ganglia?
How do parasympathetic fibers reach prevertebral ganglia?
Where do the splanchnic nerve fibers synapse?
In prevertebral ganglia, before continuing to abdominal organs.
What are periarterial plexuses and their function?
Abdominal aortic plexuses and associated sympathetic ganglia
Contain both sympathetic & parasympathetic fibers
Distribute autonomic fibers along arteries to corresponding organs.
Which plexuses supply specific regions?
What kind of fibers do these plexuses carry?
Sympathetic & Parasympathetic → Coeliac, superior mesenteric, aortico-renal
Sympathetic only → Inferior mesenteric
Parasympathetic only → Inferior hypogastric
What do visceral afferent fibres do?
Carry pain sensations from organs
Travel with sympathetic efferent fibres
How do visceral afferent fibres travel?
Follow the retrograde path of motor fibres
Pass through peri-arterial plexuses, prevertebral ganglia, splanchnic nerves, and the sympathetic chain
Enter the posterior root → spinal sensory ganglia → spinal cord
which 6 places is visceral pain felt?
Liver, gallbladder, duodenum → Right shoulder (diaphragmatic irritation)
Stomach → Epigastric region
Appendix → Periumbilical region
Small intestine → Central abdomen
Sigmoid colon → Lower abdomen
Kidneys, ureters → Flank & lower back
What are the 5 major structures of the posterior abdominal wall?
- Fiver lumbar vertebrae and their intervertebral discs
- Psoas, quadratus lumborum, iliacus, posterior portions of the oblique and transversus abdominis muscles
- Diaphragm
- Lumbar plexus
- IVC and abdominal aorta
How many lumbar vertebrae are there
Five lumbar vertebrae (L1-L5)
where are the 5 lumbar vertebrae located
between the thoracic and sacral vertebrae
whats the function of the lumbar vertebrae
Weight-bearing, strong and sturdy for support
What are the 6 main structures of a lumbar vertebra?
✔️ Vertebral body – Large, for weight-bearing
✔️ Vertebral foramen – Space for spinal cord
✔️ Transverse process – Lateral projections for muscle attachment
✔️ Spinous process – Posterior projection for ligament/muscle attachment
✔️ Articular process – Forms joints with adjacent vertebrae
✔️ Lamina & Pedicle – Parts of the vertebral arch
What are the key differences between lumbar and thoracic vertebrae’s vertebral body?
Lumbar vertebral body – kidney-shaped body when viewed superiorly
Thoracic vertebral body – Heart-shaped body when viewed superiorly with costal facets
How does the vertebral foramen differ in lumbar vs. thoracic vertebrae?
Lumbar – Triangular
Thoracic – Circular
How do transverse processes differ in lumbar and thoracic vertebrae?
Lumbar – Long and slender
Thoracic – Long, strong, extends posterolaterally, articulates with ribs (T1-T10)
How are the articular processes oriented in lumbar vs. thoracic vertebrae?
Lumbar – Superior facets directed posteromedially, inferior facets directed anterolaterally
Thoracic – Facets directed posteriorly in a coronal plane
How do lumbar and thoracic spinous processes compare?
Lumbar – Short, thick, broad, projects posteriorly
Thoracic – Long, slopes posteroinferiorly
What is the action and innervation of the Quadratus Lumborum?
Action – Laterally flexes the vertebral column
Innervation – Subcostal nerve (T12)
What are the actions of the Psoas Major muscle?
Unilateral contraction – Flexes vertebral column laterally
Bilateral contraction – Raises trunk from supine position
What are the nerve supplies of Psoas Major and Iliacus?
Psoas Major – L1-L4 spinal nerves
Iliacus – Femoral nerve (L2-4)
What is the lumbar plexus?
A nerve network from anterior rami of L1 to L4 spinal nerves
Supplies anterolateral abdominal muscles & skin of inguinal & pubic regions
Which nerves supply the lower abdominal wall & inguinal region?
Iliohypogastric nerve (L1)
Ilioinguinal nerve (L1)
what are the branches & functions of the genitofemoral nerve?
Genital branch – Supplies skin over scrotum/labia majora & cremaster muscle in males
Femoral branch – Sensory to upper anterior thigh
Which nerves supply sensory and motor functions to the lower limb?
Lateral cutaneous nerve of thigh (L2-3) – Sensory to lateral thigh
Femoral nerve (L2-4) – Motor to quadriceps
Obturator nerve (L2-4) – Motor to adductors
Where do the gonadal arteries originate?
Branch from the abdominal aorta
Begin at the aortic hiatus and divide at L4 into left & right common iliac arteries
Where do the gonadal veins drain?
Right gonadal vein → IVC
Left gonadal vein → Left renal vein
Where does the IVC form?
At L5 from the union of left & right common iliac veins
Cause & Effect of Renal Vein Entrapment Syndrome
SMA compresses the left renal vein
Can lead to renal vein entrapment syndrome
Causes left testicular pain (testicular varicocele) in males
