Download 9/30/09 Abdomen Continued Ureters: They are muscular ducts

9/30/09
Abdomen Continued
Ureters:
They are muscular ducts. They muscular part is important because they push the urine down (in supine
position). They have a narrow lumen. Their job is to carry urine from the kidneys to the urinary bladder.
The expanded end of the urine is referred to as the renal pelvis and located in the sinus of each kidney.
Each papillae drains urine into a minor calyces, several minor calyces unite to form a major calyce, the
major calyce unite to form the renal pelvis, which is the expanded end of the ureter. The abdominal
part of the ureter adheres to the parietal peritoneum but it is retroperitoneal. The ureters run
inferiomedially right along the transverse processes of the lumbar vertebrae. They then each (right and
left) cross the external iliac arteries just inferior where the below arteries bifurcate.
The adrenal glands (suprarenal) lie on the superiomedial border of each kidney. Each adrenal gland is
enclosed in the renal fascia holding in them in close approximation to the kidney and fixing their
position. They are a little different in shape. The right renal gland is more triangular than the left. The
right renal gland is anterior to the diaphragm and contacts the IVC and the liver. The left adrenal gland is
in close association with the spleen, stomach, pancreas, and diaphragm.
Blood Flow:
The renal arteries left and right arise off of the abdominal as soon as the aorta pierces off right where it
comes off of the diaphragm. The kidneys receive 20-25% of Cardiac Output at rest and thus, the most
active tissue in the body. Each of those arteries enters the hilum (a doorway) and divides into 5
segmental arteries. The right renal artery is lower than the left renal artery due to space (this is because
the liver is on the right so everything on right may be a little lower). The left renal vein is longer than the
right renal vein. Each renal vein drains its blood into the IVC.
The arterioblood flow associated with the adrenal glands:
The adrenal glands have a profuse blood supply from 3 different sources because they are ductless
glands and deposit directly into the bloodstream:
1.) superior suprarenal arteries, which arise off of the inferiophrenic artery
2.) the middle suprarenal arteries, which arise off of the abdominal aorta
3.) the inferiorsuprarenal arteries, which arise off of the renal arteries
Each of the glands is drained by a suprarenal vein. The arteries for the abdominal part of the ureters are
from renal arteries, the testicular arteries, and abdominal aorta. The nerves are from the renal plexus
and consist of sympathetic and parasympathetic fibers.
Diaphragm:
The diaphragm is a muscular tendonous partition that separates the thorax from the abdomen. It is the
primary or principle muscle of inspiration and forms the convex floor of the thorax and concave roof of
the abdomen. Only the domes of the diaphragm move during inspiration because only the peripheral
parts are attached the inferior thoracic cage and the lumbar vertebrae, which makes it fixed in position.
The right dome of the diaphragm is higher than the left due to the liver. The levels of the domes of the
diaphragm depend on posture, phase in respiratory cycle. The diaphragm is composed of a peripheral
muscular part and a central aponeurotic part or tendous part called the central tendon. The muscle
fibers radiate toward the central tendon and they are divided into 3 sections. The sternal part of the
muscle fibers is attached to the xipoid process of the sternum. The costal part of muscle fibers attached
to inferior 6 ribs. The lumbar part of muscle fibers is attached to the lumbar vertebrae. The central
tendon of the diaphragm is the tendon of all muscular fibers of the diaphragm. It is fused with the
inferior surface of the fibrous pericardium. The central tendon has NO bony attachment.
The diaphragmatic apertures are the openings that allow structures to pass through to the abdomen.
There are 3 to be discussed. The renalcaval foramen through which the IVC passes is located within the
central tendon of the diaphragm. It is between T8 & T9 and the IVC is attached to margin to the edge of
the foramen. As a result of that  when the diaphragm contracts, the venocaval foramen enlarges and
gets wider and this facilitates venous return. The esophageal hiatus is the aperture in the right dome of
the diaphragm and about the level of T10. This is in muscle fiber not in tendon. The esophagus is
constricted with the diaphragm contracts (you can’t swallow when inspiring). Vagal trunks and gastric
vessels pass through the esophageal hiatus. The aortic hiatus is behind the diaphragm and therefore
blood flow through the aorta is not affected by diaphragmatic movements. The thoracic duct and the
azygous vein also pass through the aortic hiatus.
Posterior abdominal Wall:
Posterior abdominal wall is composed mainly of muscles and fascia attached to the vertebrae. In
addition to being attached to the vertebrae, they are also attached to the hip bones and the ribs. The
PAW (posterior abdominal wall) also contains fat, nerves, lymph nodes, and blood vessels.
Muscles:
There are 3 paired of muscles in the posterior abdominal wall. The Psoas Major runs from the
transverse process of the lumbar vertebrae to the lesser trochanter of the femur. It is a hip flexor. The
Quadriatus lumborum runs from the lumbar vertebrae to the iliac crest and it extends and laterally
flexes the vertebral column. The Iliacus runs from the superior 2/3 of the iliac fossa (is in the front) to
the lesser trochanter of the femur. It is a flexor at the hip joint.
Fascia:
The posterior abdominal wall is covered with a continuous layer of fascia that lies between the
peritoneum and the muscles that were just mentioned. The fascia is sometimes referred to by name,
but the names are taken by the location of the muscles (the Quadriatus Lumborum fascia, etc.).
Somatic Nerves:
The subcostal nerves, which arise from the ventral rami of T12 supply the muscles and skin of the
anteriorlateral abdominal wall. Lumbar nerves form the lumbar vertebrae supply muscles of the skin and
back.
The lumbar plexus is located in the Psoas muscle formed by the ventral rami of L1-L4. Major nerves of
the lumbar plexus include the obturator nerve formed by ventral rami of L2-L4 and innervates the
medial thigh muscles (adductors).
The femoral nerve also from L2, L3, L4. The femoral nerve supplies the extensors at the knee.
The lumbosacral trunk L4 & L5 also called the lumbarsacral trunk descend into the pelvis to participate
in the sacral plexus along with the ventral rami of S1 through S4.
Both sympathetic and parasympathic nerves are distributed to the abdominal viscera by ganglia
associated with the anterior surface of the abdominal aorta. The sympathetic portions are referred to as
splanic nerves. The parasympathetic portion are vagal.
Blood Flow:
The arteries associated with the abdominal wall are mostly from the abdominal aorta. The abdominal
aorta runs from T12-L4. At L4 the abdominal aorta bifurcates to form the common iliac arteries. The
arterial branches of the abdominal aorta are described as visceral or parietal and also paired on
unpaired. Unpaired visceral arteries include the celiac trunk along with SMA (superiormesenteric artery)
& IMS (inferiomesenteric artery). Paired visceral arteries include the suprarenal arteries and the renal
arteries and the gonadal arteries. Paired parietal include the inferior phrenics and the lumbar arteries.
An unpaired parietal would be the mediansacral artery, a small artery that arises from where the
abdominal aorta bifurcates into right and left common iliac. Veins here are all part of the IVC. There are
several collateral routes available for venous return in the event that the IVC is obstructed. An example
would be venous return through the lateral thoracic veins, which connect with the circumflex iliac veins,
and then to the axillary veins.
Lympathics:
Lymph nodes lie along the IVC, aorta, and iliac vessels. The common iliac lymph nodes receives lymph
from the lower limbs and pass lymph through the lumbar lymph nodes. Lymph from the GI tract as well
as the liver, spleen, and pancreas drain into the preaortic lymph nodes and they are located all along
the aorta where arteries arise. The lumbar lymph nodes received lymph from the posterior abdominal
wall, kidneys, ureters, gonads, uterus, uterine tubes, descending colon, and areas within the pelvis.
Lymph from the lumbar lymph nodes drain into the cysternokali, which is a thin walled sac at the
inferior end of the thoracic duct and is located just in front of the bodies of L1 & L2. The thoracic duct
ascends through the aortic hiatus (behind the diaphragm) to the thoracic duct. The thoracic duct
receives all lymph from all areas inferior to the diaphragm and returns lymph to the vascular system at
the junction of the left subclavian vein and the left internal jugular vein. Approximately 75% of the
lymph returns to the body through the thoracic duct.
Test for Friday:
Do not forget ostieology bones of pectoral girdle, markings on scapula and pectoral girdle…the
olecranon, trochlea, elblow, know joints, structure of joint determines stability (glenohumeral joint
versus others)…all of the muscles with the digits and toes…know femoral triangle, popliteal fossa,
anticuboial fossa, superficial and deep veins of arm, deltopectoral triangle