Abdomin

Abdomen

Lumbar plexus
It is formed from the ventral rami of the 1st , 2nd, 3rd and part of the 4th lumbar nerves as well as branch from T12 nerves . It is located in the posterior abdominal wall , deep within psoas muscles .
Branches :
1.iliohypogastric(L1) 2. Ilioinguinal(L1) 3. Genitofemoral (L1,L2)
4. lat.cutaneous nerve of the thigh (L2,L3) 5. Obturator (L2,L3,L4)
6. accessory obturator (L3.L4) 7. Femoral (L2,L3,L4).
Branches 1. 2. 4. 7. emerge from lat. border of psoas m. Branches 5. 6. emerge from med. border of the m. Branch 3. emerge from ant. surface of the m.

Abdominal aorta

It enters the abdomen in front of the lower part of the body of T12 vertebra through the aortic hiatus. It descends ant. to lumbar vertebrae, to the left of IVC and to the right of left sympathetic trunk. It is only 13 cm long , it terminates by dividing into Rt & Lt common iliac arteries at the lower part of L4 vertebra . branches in sequence are :
inferior phrenic artery (T12 )
celiac trunk ( L1 )
suprarenal artery ( L1 )
1st lumbar artery ( L1 )
Superior mesenteric artery ( L1 )
Renal artery ( L2 )
Testicular ( ovarian ) artery ( L2 )
2nd lumbar artery ( L2 )
Inferior mesenteric artery ( L3 )
3rd lumbar artery ( L3 )
4th lumbar artery ( L4 )
Median sacral artery ( L4 )
Common iliac artery ( L4 )
2. , 5. , 9. , 12. , are unpaired ( single ) branches , the remaining are paired .
Inferior vena cava
It drains blood from the body below the diaphragm to right atrium of the heart . it is formed by the union of common iliac veins behind right common iliac artery . it ascends on the right side of aorta. The right sympathetic trunk lies behind the right margin of the vein. The IVC penetrates the diaphragm at the level of 8th thoracic vertebra & drains into the right atrium of the heart .
The inferior vena cava receives the following tributaries :
Hepatic veins
Right suprarenal vein ( left one drains to left renal vein )
renal veins
Right testicular or ovarian vein ( left drains to left renal vein )
Right inferior phrenic vein ( left one drains to left renal vein )
Four lumber veins (left 2nd lumbar drains to left renal vein )
Two common iliac veins
Median sacral vein


The kidneys
The kidneys are retroperitoneal organs, they lie on either sides of vertebral column in the paravertebral gutter.

The superior poles of the kidneys reach the upper border of the body of T12 vertebra, while the inferior poles lie at the level of L3.
The kidneys are 10 x 5 x 2.5 cm in size.
The left kidney is longer than the right kidney. The right kidney is slightly lower than the left kidney due to the mass of the liver above it.
Each kidney has 2 surfaces, anterior and posterior:
Anterior surface slightly faces lateraly.
Posterior surface slightly faces medialy.
Each kidneys has 2 borders, medial and lateral:
Lateral border directed posterioly and it is convex.
Medial border directed anteriorly, this border is indented, exhibiting a hilum for the entrance and exit of the renal blood vessels and renal pelvis (which continues as ureter).
The hilum is surrounded by a space called renal sinus (which is a fat filled space around the renal blood vessels and the renal pelvis).

Renal fascia and renal fat:

The kidney is surrounded by perirenal fat, then renal fascia then pararenal fat.The renal fascia extends superiorly covering the suprarenal gland and it extends inferiorly and medially along the ureter giving periureteric fascia.

Relations of the kidneys:

They have the same relations except anteriorly.
Each kidney is bounded medially by the psoas muscles.
Laterally by the Transversus abdominis muscles.
Posterioly:
Diaphragm (behind the superolateral part of the kidney).
Quadratus lumborum muscle.
Subcostal nerves and vessels.
Iliohypogastric and ilioinguinal (behind lower part of kidney).
Anterior relations of kidneys are different except that, the suprarenal glands cap the superomedial surface of each kidney.
Anterior relations of right kidney: The 2nd part of duodenum is anterior to the medial border (hilum), lateral to the duodenum the superior 2/3 of the kidney is in contact with the right lobe of liver, while over the inferior 1/3 we have the right colic flexure laterally and the coils of jejunum medially.
Anterior relations of left kidney: Across the hilum lies the pancreas, superolaterally the spleen, between the spleen, pancreas and suprarenal gland, the stomach makes contact with the upper part of the left kidney. Inferior to area of contact of pancreas, the left kidney is in relation to the left colic flexure laterally and to coils of jejunum medially.
The ureter: : It is a muscular tube, 25 cm in length, half of it is abdominal & half is pelvic. It is covered by the periureteric fascia (from renal fascia). The abdominal part of ureter descends from renal pelvis (located posteroinferiorly in the hilum) on the psoas muscle until crossing the bifurcation of the common iliac artery where it enter the pelvis.
Relation of the ureters:
Each ureter is crossed obliquely by testicular (or ovarian) vessels.
The right ureter is also crossed anteriorly by the right colic & the ileocolic vessels, while the left ureter is crossed by the left colic vessels.


Blood supply of abdominal Ureter: branches from the renal and testicular (or ovarian) arteries.
Nerves of the ureter: derived from renal & testicular plexuses.
Lymphatics of ureter: lumbar and Common iliac nodes.

Blood vessels of the kidney: The renal arteries arise from aorta at the level of upper border of L2, pass to the hilum o f the kidneys anterior to the crura of the diaphragm and the psoas muscles.
The right renal artery is longer than the left and it is a little lower than the left, it passes behind inferior vena cava, the head of pancreas and the 2nd part of duodenum.
The left renal artery lies behind the left renal vein, body of pancreas and the splenic vein.
Extrarenally each renal artery gives off:
suprarenal artery to the lower part of suprarenal gland.
Ureteric branches to the ureter.

The renal veins: they emerge from the hilum of kidneys; they lie anterior to renal arteries.
The left renal vein is longer than the right, it passes in front of aorta just below superior mesenteric artery to end in the inferior vena cava. The left renal vein receives :
Left suprarenal vein.
Left inferior phrenic vein.
Left testicular (ovarian) vein.
Left 2nd lumbar vein.
The right renal vein lies behind the 2nd part of duodenum, it ends in the right side of the inferior vena cava.

Lymphatics of kidneys:

The lymphatic vessels of the kidney follow the renal vein to the lumbar L.Ns..
Nerves of the kidneys:
The kidneys are supplied by autonomic from renal plexus. It is derived from Lesser (T10,T11) and Least (T12) thoracic splanchnic nerves.
Suprarenal Gland:
They are endocrine gland, situated on the superomedial aspect of the kidneys. They are 4x2.5x1 cm in size. Each gland has a hilum on its anterior surface from this furrow emerges the central suprarenal vein.
The right suprarenal gland:
It is triangular in form, lies in front of the diaphragm & it makes contact anteriorly with inferior vena cava medially & liver laterally.
The left suprarenal gland:
It is semilunar in shape, lies anterior to diaphragm. Anteriorly it is in relation with the cardia of the stomach superiorly & with pancreas inferiorly.
The two glands are separated by celiac arterial trunk.
The two glands are enclosed within the renal fascia but are separated from the kidneys by perirenal fat.
Arterial supply:suprarenal arteries are derived from the inferior phrenic artery, abdominal aorta and renal artery.
Suprarenal veins:
There is only single suprarenal vein (central vein), which emerges from the hilum on the anterior surface of the gland. On left side it drains to left renal vein. On right side it drains directly to inferior vena cava.


Lymphatics of suprarenal gland:
They follow the vessels of the gland to end in the upper nodes of the lumbar chain.
Nerves of suprarenal glands:
From celiac plexus & splanchnic nerves.