THE SPLEEN. 1151 
is triangular in form, and looks downwards and inwards, and is in contact with the 
splenic Flesaite of the colon and the costo-colie ligament (vide p: L033)! 
The anterior border (margo anterior) of the spleen i is sharp and prominent, and 
intervenes between the gastric and diaphragmatic surfaces. Its leading character- 
istic 1s that it is 
irregularly notched. 
The posterior border 
(margo posterior) 
separates the renal / 
from the diaphrag- / 
matic surface. It 
is important to 
know that,if in the 
living subject the 
finger is drawn 
along the last in- 
tercosta] space, it 
will indicate with 
tolerable accuracy 
on the surface of 
the body the posi- 
tion and direction 
of the posterior 
border,  “Vhe.,;in- 
ferior border (margo 
inferior) of the 
spleen intervenes 
Hilus 
_ Anterior 
> basal angle 
Pancreatic impression 
between the dia- Internal basal angle Posterior basal angle 
A PaO 1 a AS) ~ “oe ny ‘ T 
phragmatic surface Fic. 786.—THE SPLEEN—VISCERAL ASPECT. 
and the basal sur- 
face. The other margins of the spleen are those which separate the visceral areas 
from each other, and “they have been already noticed. 
A marked feature of the typically- formed spleen is the great prominence of the 
anterior basal angle. It forms the most anteriorly placed part of the organ. 
Peritoneal Relations of the Spleen.—The spleen i is almost completely enveloped 
by peritoneum, and two folds of peritoneum, viz. the gastro-splenic omentum and 
the leno-renal ligament, pass from it. Both of these folds are attached in the 
neighbourhood of the hilus. The lieno-renal ligament proceeds backwards to the 
anterior surface of the left kidney (p. 1049); the gastro-splenic omentum connects 
the spleen with the fundus of the stomach (p. 1054). 
Accessory Spleens.—Small globular masses of splenic tissue are not infrequently found in 
the neighbourhood of the spleen. These are termed accessory spleens. 
Blood- vessels, Lymphatics, and Nerves of the Spleen.—The large splenic artery gains the 
spleen by passing between the two layers of the lieno-renal ligament. It breaks up into several 
branches which enter the organ through the hilus. Some tw igs proceed from the splenic artery 
to the stomach, which they gain by insinuating themselves between the two layers of the gastro- 
splenic omentum. The splenic vein is formed? in the leno-renal ligament by the union ah the 
branches which emerge from the hilus of the organ. It joins the superior mesenteric vein to 
form the vena porte. 
The splenic plexus of nerves is an offset from the coeliac part of the solar plexus, and acecom- 
panies the arteries into the spleen. 
The lymphatic vessels leave the spleen at the hilus, and accompany the great vessels. There 
are no lymphatic channels within the spleen, although they are present in its capsule (Mall). 
Structure of the Spleen.—In our study of the structure of the spleen we have to 
consider—(1) the tunica propria, (2) the trabecular framework, (3) the spleen pulp, 
and (4) the distribution of the blood-vessels and the Malpighian corpuscles. 
Tunica propria (tunica albuginea).—Subjacent to the serous coating furnished by the 
peritoneum the spleen is provided with a strong capsule termed the tunica propria. This 
is formed of fibrous tissue, with a large proportion of elastic fibres and a certain amount of 
involuntary muscular tissue. It is therefore highly distensible, and perhaps feebly con- 
tractile. To the outer surface of this capsule the peritoneum is inseparably attached. 
