SPLEEN

Greater Sac.

” Being developed in the dorsal mesogastrium, the spleen projects into the greater sac surrounded by peritoneum of the original leaf leaf of the dorsal mesogastrium.”.

The normal spleen weighs approximately 150g(and decreases its size with age.

D i.e. Greater Sac

B. i.e. Phrenicocolic ligament

B. i.e. Presacral area

D. i.e. Derives nerve supply from coeliac plexus

Phrenicocolic ligament & Left colic flexure prevent downward displacement of enlarged spleen

Spleen develops from cephalic part of dorsal mesogastrium and so projects into the greater sac. Notching of superior bordr is an evidence of its multiple nodular origin.

Spleen lies obliquely along the long axis of 10^th rib and derives its nerve supply from celiac plexus.

D i.e. Vascular sinus

Ans. is ‘b’ i.e., Hilum of spleen 

• Accessory spleen is the most common congenital anomaly of spleen.
• “Over 80% of accessory spleens are found in the region of splenic hilum and vascular pedicle” – Schwartz

Ans. is ‘b’ i.e., 2 

 Dorsal mesogastrium

The visceral surface of the spleen is related to the fundus of the stomach, the anterior surface of the left kidney, the splenic flexure of the colon and the tail of the pancreas.

• The spleen is the largest single mass of lymphoid tissue in the body.
• It lies just beneath the left half of the diaphragm close to the 9th, 10th, and 11th ribs.
• The long axis lies along the shaft of the 10th rib, and its lower pole extends forward only as far as the midaxillary line. The spleen is surrounded by peritoneum which passes from it at the hilum as the gastrosplenic omentum (ligament) to the greater curvature of the stomach (carrying the short gastric and left gastroepiploic vessels).
• The peritoneum also passes to the left kidney as the splenorenal/lienorenal ligament (carrying the splenic vessels and the tail of the pancreas).
• The phrenicocolic ligament is not attached to the spleen but supports its anterior end.
• Ligamentum teres is related to the liver and represents the obliterated left umbilical vein.

Relations of spleen:

Anteriorly: The stomach, tail of the pancreas, and left colic flexure. The left kidney lies along its medial border.

Posteriorly: The diaphragm; left pleura (left costodiaphragmatic recess); left lung; and  9^th, 10^th, and 11^th rib.

Accessory spleen may be found at :-

i) Hilum of spleen (most common site).

ii) Tail of pancreas.

iii) Derivatives of dorsal mesogastrium:- Greater omentum, gastrophrenic ligament, gastrosplenic ligament, linorenal ligament.

iv) Broad ligament of uterus (in males) and spermatic cord (in female); both left side.

Spleen develops in cephalic part of dorsal mesogastrium from its left layer during 6^th week of intrauterine life into a number of nodule which soon fuse to form a lobulated spleen.

Notching of superior border is an evidence of its multiple origin.

The nodules which fail to fuse form accessory/supernumerary -spleen or spleniculi.

These may be found at :

i) Hilum of spleen (most common site).

ii) Tail of pancrease.

iii) Derivatives ofdorsal mesogastrium :- Greater omentum, gastrophrenic ligament, gastrosplenic ligament, linorenal ligament.

iv) Broad ligament of uterus (in males) and spermatic cord (in female); both left side.

 Dorsal mesogastrium

Ans. is `b^‘ i.e., Red pulp 

Histology of spleen

• Spleen has a capsule which is mainly composed of collagen with some elastin. Trabeculae are septae pass inwards from the capsule. Spleen is mainly composed of two parts :

1. White pulp : The white pulp of the spleen is formed of mass of T and B lymphocytes surrounding central artery, arranged as lymphoid nodule. Each nodule is also called Malpigian bodies. Marginal zone surrounds the white pulp and contains antigen presenting cells as macrophages.
2. Red pulp : Red pulp is made up of a mesh of leaky sinusoids (vascular sinuses) through which the red cells are squeezed. Adjacent blood spaces contain blood cells and arranged in cords called splenic cords of billorth.

Ans. is ‘a’ i.e., White pulp