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Flashcards in Abdomen III Deck (68)
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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