Anatomy: Abdomen - Spleen

spleen

(left hypochondrium = protection of lower thoracic cage)

most frequently injured

spleen

(lymphocyte (WBC) proliferation + immune surveillance/respon

Prenatally: hematopoietic (blood-forming) organ

Postnatally: identifying, removing, + destroying old RBCs & broken-down platelets; recycling iron + globin

useful, but NOT a vital organ

splenic hilum

splenic branches of the splenic artery + vein enter/leave

• rests on Left Colic Felxure

• associated posteriorly with left 9th - 11th ribs; separated by diaphragm + costodiaphragmatic recess

• varies in size, weight, + shape;

normally: approx. 12 cm long, 7 cm wide (weighs 7 ounces)

the volume of blood that passes through the spleen’s capillaries and sinuses

• normally contains large quantity of blood

• expelled periodically into circulation by action of smooth muscle in its capsule + trabeculae

• dense, irregular, fibroelastic connective tissue

(can expand + contract)

• capsule is thickened at the splenic hilum

• Internal trabeculae (deep aspect of the capsule) carry blood vessels to/from the parenchyma (splenic pulp) = substance of the spleen

causes:

• punctures by fractured rib (left 9th-12th)

• sudden, marked increase in intra-abdominal pressure = thin capsule + overlying peritoneum of spleen burst

- rupture = intraperitoneal hemorrhage and shock

• 
  **Sub-total (partial) splenectomy: **(when possible); followed by rapid regeneration

- total splenectomy: (usually no serious effects); most functions are assumed by other reticuloendothelial organs (e.g., the liver and bone marrow)

• greater susceptibility to certain bacterial infections

CONDITIONS IN WHICH THE SPLEEN MUST BE REMOVED:

Warm autoimmune hemolytic anemia:

• Spleen recognizes RBC as foreign bodies and attacks them

spleen is diseased (ex. granulocytic leukemia) may enlarge 10X or more its normal size

• sometimes accompanies hypertension

• occurs in some forms of hemolytic or granulocytic anemias (RBCs or WBCs destroyed at abnormally high rates); splenectomy may be life-saving

• not usually palpable in the adult; if it is, enlarged 3x

• common (10%) + usually small

• 1+ small accessory spleens may form near splenic hilum

• embedded partly or wholly in tail of pancreas (b/t layers of gastrosplenic ligament, in infracolic compartment in mesentery, or in close proximity to ovary or testis)

• if not removed during splenectomy, symptoms that indicated removal of the spleen (e.g., splenic anemia) may persist

relationship of the costodiaphragmatic recess to the spleen is clinically important

• *potential space descends to level of 10th rib in midaxillary line

• keep in mind for needle biopsy, or injecting radiopaque material into spleen for visualization of the portal vein (splenoportography)

• material may enter the pleural cavity, causing pleuritis

inject below rib 10 level