Abdomen III Flashcards
Layers of the posterior abdominal wall (posterior to anterior)
(1) Bony Layer- Iliac bone (iliac fossa/crest), lumbar vertebras, last 2 ribs
(2) Muscles- Psoas major/minor, Iliacus and Quadratus lumborum
(3) Fascia [named according to muscles]
(4) Visceral layer- kidneys, ureters, suprarenal glands, abdominal aorta and IVC [retroperitoneal structures]
(5) Partial Peritoneal layer
Lumbar plexus is formed inside of what? What does this mean for its branches?
Inside the psoas major, so its branches are related to the posterior abdominal muscles.
Fascia of the posterior abdominal wall
Psoas fascia, iliac fascia and thoracolumbar fascia
Function of Iliacus
Flexes hip and stabilizes hip joint; acts with psoas major
Function of Psoas major
- Flexes hip (in conjunction with Iliacus)
- Flexes vertebral column laterally
- Used to balance trunk in sitting position
- Also used to flex the trunk
Function of Psoas minor
Flexes pelvis on vertebral column
Function of Quadratus lumborum
Extends and laterally flexes vertebral column. Fixes 12th rib during inspiration
Lateral regions of the diaphragm are raised into…
Right and Left copula. The right is higher than the left due to the liver
What is the insertion of the diaphragm?
The central region which is called the central tendon. It is close to the heart/pericardium.
Innervation of diaphragm
Phrenic nerve (C3, 4, 5)
Origin of the diaphragm
(1) Sternal Part- Xiphoid Process
(2) Costal part- Lower 6 costal cartilages
(3) Vertebral (lumbar) part- 2 crura and 5 ligaments
The Right Crus of the Vertebral origin of the diaphragm
Right crus- larger, longer, and stronger than left and arises from the bodies of the upper 3 lumbar vertebrae.
Some fibers run up to form the esophageal hiatus by encircling the esophagus. Makes extra valve like constriction around esophagus. (MORE IMPORTANT OF THE TWO)
Others run down to form the suspensory ligament of the duodenum.
The Left Crus of the Vertebral origin of the diaphragm
Arises from bodies of upper 2 lumbar vertebrae
The Median arcuate ligament of the Vertebral origin of the diaphragm
Unites crura across aorta, forming aortic hiatus
The Medial arcuate ligament of the Vertebral origin of the diaphragm
Tendinous arch across the upper part of psoas major. 2, (1 on each side)
The lateral arcuate ligament of the Vertebral origin of the diaphragm
Tendinous arch across the quadratus lumborum 2, (1 on each side)
What tubes pierce the diaphragm?
I 8(ate) 10 Eggs At 12 (noon)
Inferior Vena Cava- T8 (via caval hiatus)
Esophagus- T10 (via esophageal hiatus)
Aorta- T12 (via aortic hiatus)
Lumbar Plexus and its Branches
Nerve Plexus which forms inside the psoas major via union of the ventral rami of the upper 3 lumbar nerves and part of the 4th lumbar nerve.
Branches are closely related to the posterior abdominal wall muscles and all have both muscle and sensory function (except for lateral cutaneous)
(1) Subcostal nerve (T12)
(2) Iliohypogastric nerve (L1)
(3) Ilioinguinal nerve (L1)
(4) Genitofemoral nerve (L1, 2)
(5) Lateral femoral cutaneous nerve (L2, L3)
(6) Femoral nerve (L2, 3, 4)
(7) Obturator nerve (L2, 3, 4)
Relationships and differences with/between the Subcostal nerve, Iliohypogastric nerve, and Ilioinguinal nerve.
All run in front of the quadratus lumborum muscle and pierce transverse abdominal muscle to run between it and internal oblique muscle.
-BUT Iliohypogastric and Ilioinguinal pierce internal oblique to run between it and external oblique.
Iliohypogastric= sensory to posterolateral gluteal skin (in addition to its muscle functioning)
What is unique to the Ilioingunal nerve?
It is the only one that accompanies the spermatic cord (or round ligament of uterus), continues through inguinal canal and emerges through the superficial ring. Sensory to skin over root of penis or labia
Characteristics of the Genitofemoral nerve.
Emerges on the front of the psoas muscle and descends on its anterior surface. It divides into a genital branch, which enters the inguinal canal through the deep inguinal ring to reach spermatic cord and supply cremaster muscle and a femoral branch, which supplies the skin of the femoral triangle.
Characteristics of the Lateral femoral cutaneous nerve
Emerges from the lateral side of the psoas muscle and runs in front of Iliacus.
Characteristics of the Femoral nerve
Emerges from the lateral border of the psoas major and descends in the groove between the psoas and iliacus. Enters the femoral triangle deep to the inguinal ligament and lateral to the femoral vessels.
Characteristics of the Obturator nerve
Descends along the medial border of the psoas muscle. It runs forward on the lateral wall of the pelvis and enters the thigh through the obturator foramen.
Where is the kidney positioned?
It is a retroperitoneal organ which lies on the posterior abdominal wall opposite T12 to L3 vertebrae in the erect position.
Right vs Left Kidney
The right lies a little lower than the left because of the large size of the right lobe of the liver. Therefore the right kidney is related to rib (posteriorly) whereas the left kidney is related to ribs 11/12
Location of Hilum of Kidney and its associated structures
Hilum is found on the medial border. The Ureter, renal vessels and nerves enter and leave via this area. They are arranged anterior to posterior in order of VAP (renal Vein, renal Artery, and Pelvis of ureter)
Main structures of the kidney
Consists of the medulla and the cortex, containing 1 to 2 million nephrons (per kidney).
- CORTEX- forms outer part of kidney and also projects into the medullary region between the renal pyramids (as renal columns)
- MEDULLA- forms the inner part of the kidney and consists of 8-12 renal pyramids. The apexes of the pyramids are called renal papilla and open into the minor calyx
- MINOR CALYCES- receive urine from the collecting tubules and empty into 2-3 MAJOR CALYCES, which in turn empty into the RENAL PELVIS OF THE URETER
Blood Supply of the Kidney
-Renal arteries arise from the side of the abdominal aorta (opposite the upper border of L2)
Right vs Left renal artery
Right is longer than left and passes posterior to IVC
How does the Renal Artery Divide
The renal artery gives the inferior suprarenal artery, then enters the hilum of the kidney and divides into 5 segmental arteries (end arteries).
Characteristics of the Right and Left Renal VEINS
- Both open directly into the IVC
- Left renal vein is longer than right and passes anterior to the aorta below the origin of Superior Mesenteric Artery (SMA)
What veins does the left renal vein receive?
3 veins
(1) Left suprarenal vein
(2) Left gonadal (testicular or ovarian) vein
(3) May give rise to Inferior Hemiazygos vein
Location and path of the Ureter
It is a retroperitoneal muscular tube that begins with the renal pelvis and extends from the kidney to the urinary bladder
Sites of Kidney Stone constriction of the Ureter
3 potential areas
(1) Ureto-pelvic junction -where it joins the renal pelvis
(2) Pelvic inlet- where it crosses the pelvic brim over the distal end of the common iliac artery
(3) Ureterovesicular junction- where it enters the wall of the urinary bladder. This is the narrowest point of the whole ureter
Suprarenal gland
Also known as the adrenal glands
Retroperitoneal organ on top of kidney
It has a cortex that produces three types of steroid hormones and medulla (derived from embryonic neural crest cells)- secretes epinephrine and norepinephrine as well as catecholamines.
Arteries and veins of the Suprarenal gland (adrenal gland)
It receives arteries from 3 sources:
(1) Superiorly from the inferior phrenic artery
(2) At the center/middle from the Abdominal Aorta
(3) Inferiorly from the renal artery
It is drained via the suprarenal vein which empties into the IVC on the RIGHT and into the LEFT RENAL VEIN on the LEFT
At what vertebrate does the Abdominal Aorta bifurcate and what does it bifurcate to?
L4, Bifurcates to Right and Left common Iliac
Describe the branches of the AA which come off the anterior midline
They are unpaired visceral and head to the Alimentary tract (foregut, midgut and hindgut)
(1) Celiac (T12)
(2) Superior Mesenteric Artery [SMA] (L1)
(3) Inferior Mesenteric Artery [IMA] (L3)
Describe the branches of the AA which come off the Lateral section
They are paired visceral and head to the Urogenital/ Endocrine organs
(1) Suprarenal (L1) Gives suprarenal gland its blood supply
(2) Renal (L1)
(3) Gonadal (Testicular or Ovarian- L2) Runs laterally on the psoas major muscle and across the ureter
Describe the branches of the AA which come off the Postero-lateral section
They are paired parietal (segmental) and head to the diaphragm body wall.
(1) Subcostal- (T12)
(2) Inferior Phrenic- (Supplies the Diaphragm- T12)
(3) Lumbar- (Pass behind the psoas major and quadratus Lumborum– L1-4)
Median sacral artery
Arises from the back of the Aorta just above the bifurcation. Descends in front of sacrum to supply the rectum and anal canal. Gives the 5th pair of lumbar arteries
Common Iliac Arteries
The terminal branches of the abdominal aorta, pass downward and laterally to end opposite the lumbosacral disc by dividing into external and internal iliac arteries (1 of each on each side – 2 of each in total)
IVC formation and path
- It is formed on the right side of L5 by the union of the two common iliac veins, below the bifurcation of the aorta. It is longer than the abdominal aorta and ascends along the right side of the aorta.
- Passes through the opening for the IVC in the central tendon of the diaphragm at the level of T8 and enters the right atrium of the heart
Tributaries of IVC
(1) It is formed by the union of the external and internal iliac veins
(2) Receives the right gonadal and right suprarenal veins (these usually drain into the left renal vein on the left side)
(3) Receives Hepatic veins
(4) Receives Right and Left Renal Veins
(5) Receives 3rd and 4th Lumbar veins and Inferior Phrenic Veins
(6) Azygos vein may arise from the back of IVC at L2. Otherwise it is formed by the union of ascending lumbar vein and subcostal vein.
Cisterna Chyli
- It is the lower dilated lymphatic sac at the end of the thoracic duct. Lies just to the right and posterior to the aorta.
- Lymph from the intestinal and lumbar lymph trunks flows in here. Most common drainage duct of the body’s lymphatics.
- It narrows superiorly to give the thoracic duct which passes the aortic opening of the diaphragm to reach the thorax and drains at the junction between THE LEFT SUBCLAVIAN AND INTERNAL JUGULAR VEIN (Jugular subclavian junction). THORACIC DUCT IS ON LEFT SIDE
Nerve which lies on the psoas major
Genitofemoral nerve
Nerve (lateral) to psoas major between the psoas and Iliacus
Femoral nerve
Nerve (medial) to psoas major going to the adductor compartment of the thigh
Obturator nerve (round, white and glistening)– Dr. D style
Nerves in order on the quadratus lumborum
Subcostal, Iliohypogastric, and Ilioinguinal nerves
Nerve on the Iliacus
Lateral Femoral Cutaneous Nerve
Suprarenal gland blood supply
Inferior phrenic, middle suprarenal (aorta) and renal arteries
Draw the branches of the Aorta
—- DRAW—-
What innervates the Psoas major
Ventral Rami of first four lumbar nerves
What innervates the Psoas minor
Ventral Rami of first lumbar nerve
What innervates the quadratus lumborum?
Ventral rami of T12 and first four lumbar nerves
L4 of lumbar plexus is also shared by the…
Sacral plexus
Ilio-inguinal is the only nerve to touch the
Anterior Superior Iliac Spine
Both gondadal arteries branch from where? The Gonadal veins branch from where?
Arteries- AA
Veins- Right= IVC, Left = Renal vein
External Iliac supplies the…
Lower limbs
What does external iliac become after crossing the inguinal ligament?
Femoral artery
Liver pushes this up…
and this down…
Right cupola up,
Right kidney down
Renal artery comes out of aorta at what vertebrate level?
L4
Left renal veins runs where?
Anterior to the aorta and left renal artery
Which artery supplies the adrenal gland?
Renal arteries
Difference between gonadal vein and ureter
Ureter is more medial/anterior and crosses pelvis
Ventral mesentery gives us what?
Falciform Ligament and Lesser Omentum
Mneumonic for Lumbar Plexus
Some (Subcostal nerve) Idiotic (Iliohypogastric) Insensitive (Ilioinguinal) Guys (Genitofemoral) Lead (Lateral femoral cut.) Females (Femoral) On (Obturartor)
