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communicating arteries
Multiple small arteries run between the anterior and posterior pancrea-
ticoduodenal arcades, either via the pancreaticoduodenal groove or Portal vein Veins directly draining body and tail
through the substance of the gland. The largest and most consistent of
these is the communicating artery (sometimes known as the middle
pancreaticoduodenal arcade), which passes between the main and
accessory pancreatic ducts and connects the anterior pancreaticoduode- Veins directly
nal arterial arcade and the posterior superior pancreaticoduodenal draining head
artery (Yamaguchi et al 2001; Fig. 69.6C; see also Fig. 65.4). This artery and neck
gives rise to the majority of small arteries that supply the major duo-
denal papilla (Mirjalili and Stringer 2011).
Splenic vein
Other arterial arcades in the head of the pancreas
Kirk’s arcade is formed by a right branch of the dorsal pancreatic
artery that emerges on to the anterior surface of the head of the Inferior
gland and anastomoses with a branch of either the gastroduodenal mesenteric
or the anterior pancreaticoduodenal arcade (Woodburne and Olsen vein
1951). It supplies blood to the ventral surface of the head and neck of
the gland.
Gastrocolic venous trunk
splenic artery
The splenic artery arises from the coeliac trunk and runs behind the Superior mesenteric vein
superior border of the pancreas to the splenic hilum (see Fig. 69.6A).
It gives multiple small branches along its course that penetrate and Inferior pancreaticoduodenal
supply the pancreatic parenchyma. Prominent among these are the vein
dorsal pancreatic artery (see below); great pancreatic artery (arteria
Superior pancreaticoduodenal veins
pancreatica magna), arising approximately two-thirds of the way along
(anterior and posterior)
the gland; and the artery to the tail of the pancreas (arteria caudae
pancreatis), arising near the tail. These branches lie on or within the Fig. 69.7 Venous drainage of the pancreas. (Adapted from Drake RL,


posterior aspect of the gland and often anastomose with the transverse Vogl AW, Mitchell A (eds), Gray’s Anatomy for Students, 2nd ed, Elsevier,
pancreatic artery. Anatomical variations are not unusual; the dorsal, Churchill Livingstone. Copyright 2010.)
great or transverse pancreatic arteries may be dominant in any one
individual (Wu et al 2011).
veins (the gastrocolic trunk of Henle) or the right gastroepiploic vein
Dorsal pancreatic artery alone, to drain into the superior mesenteric vein at the inferior border
The dorsal pancreatic artery commonly arises from the initial 2 cm of of the neck of the pancreas (Mourad et al 1994, Lange et al 2000). The
the splenic artery, although it may take origin from the common hepatic posterior superior pancreaticoduodenal vein drains cranially into the
or superior mesenteric artery or the coeliac trunk (Horiguchi et al portal vein. Both anterior and posterior inferior pancreaticoduodenal
2008). The artery is short and gives off numerous branches, including veins usually drain directly into the superior mesenteric vein. Veins
a terminal left branch near the inferior border of the gland. Several from the body and tail of the gland drain directly into the splenic vein.
right-sided branches run to the head of the pancreas, passing either A transverse (or inferior) pancreatic vein may be present, running along
behind or in front of the superior mesenteric vein to supply the poste- the inferior border of the pancreas to join the inferior mesenteric vein.
rior or anterior surface of the pancreatic head, respectively; they anas- A few pancreatic veins communicate with systemic veins in the retro-
tomose with arteries of the pancreaticoduodenal arcade (Tsutsumi et al peritoneum (veins of Retzius); these may form retroperitoneal varices
2014). The terminal left branch anastomoses with the transverse pan- in portal hypertension.
creatic artery.
Lymphatic drainage
The length and course of the dorsal pancreatic artery depend prima-
rily on its site of origin. When it arises from the splenic artery, common The lymphatic drainage of the pancreas is extensive (see Fig. 64.14B),


hepatic artery or coeliac trunk, the artery runs inferiorly on the dorsal which, in part, explains the poor prognosis of pancreatic cancer. Lym-
surface of the pancreas, whereas if it arises from the superior mesenteric phatic vessels commence within the connective tissue septa within the
artery, it runs superiorly. The artery uniformly terminates near the infe- gland and join to form larger lymphatics that follow local arteries (Deki
rior border of the pancreas close to the confluence of the splenic and and Sato 1988, O’Morchoe 1997). Lymphatics from the tail and body
superior mesenteric veins (Bertelli et al 1998). drain mostly into nodes along the splenic artery and inferior border of
the gland, and from there to pre-aortic nodes between the coeliac trunk
Transverse pancreatic artery and superior mesenteric artery. Lymphatics from the neck and head
The transverse pancreatic artery, also called the inferior pancreatic drain more widely into nodes along the pancreaticoduodenal, superior
artery, commonly originates from the left terminal branch of the dorsal mesenteric and hepatic arteries, and, ultimately, into pre-aortic nodes
pancreatic artery. It runs to the left on the posterior surface of the (Donatini and Hidden 1992). There is no evidence of lymphatic chan-
gland close to its inferior border, gives multiple branches to the body nels within the pancreatic islets.
and tail, and anastomoses with other pancreatic branches of the
splenic artery.
INNERVATION OF THE PANCREAS
The transverse pancreatic artery may occasionally originate from the
gastroduodenal artery or the anterior superior pancreaticoduodenal
artery, crossing the anterior surface of the pancreatic head to reach the The pancreas has a rich autonomic nerve supply (Love et al 2007).
inferior border of the neck of the gland and then the tail. In such cases, Parasympathetic afferents convey sensory information from pancreatic
it may be the dominant artery to the pancreatic body, and its injury or ducts, acini and islets via the vagus nerve. Preganglionic vagal efferents
deliberate ligation during pancreaticoduodenectomy may cause ischae- have their cell bodies in the dorsal motor nucleus of the vagus and


mia of the remnant pancreas. reach the pancreas via hepatic, gastric and coeliac branches of the
nerve. They synapse with postganglionic parasympathetic pancreatic
arterial segmentation of the pancreas neurones, which are distributed singly or clustered in ganglia in the
interlobular connective tissue, lobules and islets. Pancreatic ganglia
Available with the Gray’s Anatomy e-book are most abundant in the head and neck of the gland. The ganglia
contain neurones that are dominantly cholinergic but nitrergic, pepti-
dergic and dopaminergic neurones are also present. These pancreatic
Venous drainage of the pancreas
neurones receive input not only from vagal efferents but also from
Multiple veins drain the pancreas into the portal, superior mesenteric enteric neurones from the stomach and duodenum, sympathetic
and splenic veins (Mourad et al 1994; Fig. 69.7). Although variations efferents and other pancreatic neurones. Their nerve fibres ramify in
are common, the anterior superior pancreaticoduodenal vein typically the interacinar spaces and supply acinar cells and islets, modulating
joins either the confluence of the right gastroepiploic and right colic both exocrine and endocrine secretion (see Fig. 69.10). A network of


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The pancreas may be divided into two arterial ‘segments’ that are sepa-
rated by a relatively avascular plane; there is disagreement on the defini-
tion of these segments. One view is that the two segments are separated
by a plane passing to the left of the superior mesenteric artery, such that
the head and neck are supplied by branches of the gastroduodenal and
superior mesenteric arteries, and the body and tail are supplied by
branches of the splenic artery (Busnardo et al 1988). An alternative
view holds that the anterior segment consists of the superior part of the
pancreatic head, neck, body and tail of the gland (derived from the
dorsal pancreatic bud), and the posterior segment consists of the infe-
rior part of the head and the uncinate process (derived from the ventral
pancreatic bud) (Sakamoto et al 2000). In both schemes, the main
pancreatic duct crosses between the segments. Currently, segmental
anatomy is of limited practical surgical significance.


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interstitial cells (of Cajal) provides an additional link between auto- pancreatic islets, forming the endocrine component, are embedded
nomic nerves and pancreatic acini. (Figs 69.8–69.10).
Visceral afferents transmit pain and other sensory information to cell
bodies in the sixth to twelfth thoracic dorsal root ganglia via the coeliac
Exocrine pancreas
plexus and thoracic splanchnic nerves. The cell bodies of preganglionic
sympathetic nerves are located in the intermediolateral columns of the
spinal cord (T6–12); their axons travel in the thoracic splanchnic nerves The exocrine pancreas is a branched acinar gland (see Fig. 2.6), sur-
and synapse in the coeliac and superior mesenteric ganglia. Postgangli- rounded and incompletely lobulated by delicate loose connective
onic sympathetic nerves innervate the blood vessels, ganglia and ducts tissue. Individual acini are composed of roughly spherical clusters of
within the pancreas, causing vasoconstriction and inhibiting exocrine pyramidal cells that secrete digestive enzymes, water and bicarbonate.
secretion. A narrow intralobular duct lined by flattened or cuboidal centro-acinar
Perineural invasion is relatively common in pancreatic cancer and cells originates from within each secretory acinus. Intralobular ducts
not only adversely affects prognosis but may also be a factor in the pain unite to form larger interlobular ducts lined by taller cuboidal and,
associated with this disease (Bapat et al 2011). eventually, columnar epithelium. The latter are surrounded by connec-
tive tissue septa, containing smooth muscle, autonomic nerves and fat.
Referred pain Neuroendocrine cells are present among the columnar ductal cells, and
Pain arising in the pancreas is poorly localized. In common with other mast cells are numerous in the surrounding connective tissue. A network
foregut structures, the majority of pain arising from the pancreas is of intralobular arteries, arterioles and capillaries form capillary net-
referred to the epigastrium. Inflammatory or infiltrative processes works around the terminal ducts, acini and the richly vascularized


arising from the gland rapidly involve the tissues of the retroperito- endocrine islets (Love et al 2007).
neum that are innervated by somatic nerves; pain is then localized to
the lower thoracic spine. Intractable pain from chronic pancreatitis or Acinar cells Acinar cells have a basal nucleus surrounded by abun-
inoperable pancreatic tumours can be temporarily controlled by dant basophilic rough endoplasmic reticulum and an apical region
thermal or chemical ablation of the coeliac plexus. containing dense eosinophilic secretory zymogen granules. A promi-
nent supranuclear Golgi complex is associated with large, membrane-
bound granules containing the protein constituents of pancreatic
MICROSTRUCTURE secretion, including enzymes that are only active after release. Gangli-
onic neurones and cords of undifferentiated epithelial cells are also
The pancreas is composed of exocrine and endocrine tissues. The main found within the acini. The structure of the exocrine pancreas and its
tissue mass is exocrine, forming 98% of the pancreas, in which functional regulation are summarized in Figure 69.8.
SPHINCTERIC TONE BICARBONATE IONS AND WATER TRANSPORT (Ductal and centro-acinar cells)
Neural control Parasympathetic fibres Neural control Mainly vagal cholinergic fibres
Sympathetic fibres Hormonal control Mainly secretin (duodenum and jejunum)
Pancreatic islet
Islet hormones modulate
acinar secretion via local
capillaries
Insulo-acinar
portal system
Acinar secretion is
controlled by duodenal
neuroendocrine
cell secretion
Adrenergic
Acinar cell vasoconstrictor
terminals
Centro-acinar cell
Secretion of granule contents
(including proteases, esterase, Intercalated
amylase and lipase) duct cell
Postganglionic
parasympathetic
neurone
Zymogen granule
(enzyme storage)
Preganglionic
cholinergic fibres
Cholinergic
nerve terminal
ENZYME SECRETION (Acinar cells)
Neural control Mainly vagal cholinergic fibres
Hormonal control Mainly duodenal cholecystokinin (CCK)


Fig. 69.8 The microstructure of the exocrine pancreas and the mechanisms by which its secretion is controlled. Pancreatic stellate cells (see text) are
not shown.


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Cell types Secretion
A (Alpha cells) Glucagon
B (Beta cells) Insulin
D (Delta cells) Somatostatin, gastrin
F cells Pancreatic polypeptide
Pancreatic acinus Pancreatic duct
Neuroendocrine cells (white) are incorporated
into exocrine pancreatic tissue
Fig. 69.10 The microstructure and control of function of the endocrine pancreas.
telsi
citaercnaP
Acinus Islet Fig. 69.9 Microstructure of the pancreas. The exocrine tissue consists of
acini with pyramid-shaped columnar cells arranged in spherical clusters.
Acinar secretions drain into intralobular ducts, which, in turn, join larger
interlobular ducts, present in connective tissue septa containing blood
vessels. Interspersed between the acini are islets of Langerhans, which
appear as clusters of pale-staining cells surrounded by a network of
capillaries, seen as narrow clear spaces. Adipocytes may also be present.
Haematoxylin and eosin. (Courtesy of Dr Mukul Vij, Global Hospital, Chennai,
India.)
Small duct Large duct
Stimulation of
insulin synthesis
and secretion
Ganglion cell Preganglionic
Discontinuous
vagal fibre
tight junctions
Secretomotor terminals
Sympathetic Parasympathetic
Fenestrated Neuroinsular Gap junction
capillaries complex
Postganglionic
sympathetic
vasomotor
terminal
Direct receptor Indirect stimulation via
stimulation vagus and gastrointestinal
by glucose hormones after ingestion
Gap junction
Somatostatin released
by D cell inhibits glucagon
(and B cell insulin) release
locally...
...and also passes
into vessels to exert
distant effects
Neural modulation of
endocrine cell activity


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Key references
Stellate cells Pancreatic stellate cells are myofibroblast-like cells dis- ACUTE PANCREATITIS
tributed in the exocrine part of the pancreas, mainly in the peri-acinar
space, where their long cytoplasmic processes encircle the base of the
acinus, and in perivascular and periductal regions of the pancreas. They Available with the Gray’s Anatomy e-book
are usually in a quiescent state but, when activated, they have been
implicated in the pathogenesis of chronic pancreatitis and pancreatic
cancer (Omary et al 2007, Masamune and Shimosegawa 2013). CHRONIC PANCREATITIS
Endocrine pancreas
Available with the Gray’s Anatomy e-book
Pancreatic islets (of Langerhans) constitute the endocrine component
of the pancreas. The human pancreas may contain more than a million PANCREATIC TUMOURS
islets distributed throughout the gland but most numerous in the tail.
Each islet consists of a highly vascularized cluster of polyhedral cells
arranged in a trabecular pattern, closely approximated to a dense Available with the Gray’s Anatomy e-book
network of fenestrated capillaries, which enables bidirectional transport
of substrates between the islet cells and the circulation (In’t Veld and
Marichal 2010). Islets are also supplied by autonomic nerve fibres, PANCREATIC TRANSPLANTATION
which travel with the blood vessels and end blindly in the pericapillary
space. True synaptic contact between these nerve fibres and islet cells
has not been demonstrated, though their role in islet function has been Available with the Gray’s Anatomy e-book
suggested (Rodriguez-Diaz et al 2012). Specialized staining techniques
are necessary to distinguish various islet cells, designated alpha, beta,
delta, epsilon and pancreatic polypeptide (PP) or F cells. Beta cells
secrete insulin and are the most abundant (nearly 50% in human
islets), followed by glucagon-secreting alpha cells (30–40%). Delta cells Bonus e-book images
and PP cells are less common and secrete somatostatin and pancreatic
polypeptide, respectively. Epsilon cells secrete ghrelin. Unlike mouse


islets, where beta cells form the core of the islet and are surrounded by Fig. 69.5 E–G Variations in the ductal anatomy of the pancreas.
alpha cells, human islets do not show cell-type specific localization. The
various cell types are uniformly distributed along the microvasculature Fig. 69.11 An intraoperative photograph taken during
and have extensive interlinkages with other islet cells. Their general pancreaticoduodenectomy.
organization is shown in Figure 69.10.
KEY REFERENCES
Busnardo AC, DiDio LJ, Thomford NR 1988 Anatomicrosurgical segments Nagai H 2003 Configurational anatomy of the pancreas: its surgical rele-
of the human pancreas. Surg Radiol Anat 10:77–82. vance from ontogenetic and comparative-anatomical viewpoints.
A description explaining the segmental vascularity of the pancreas and the J Hepatobil Pancreat Surg 10:48–56.
watershed area near the neck of pancreas. A well-illustrated description of the arrangement of vascular and other
structures around the duodenum and head of pancreas, with explanations
In’t Veld P, Marichal M 2010 Microscopic anatomy of the human islet of
based on the embryological development of the pancreas, foregut and midgut.
Langerhans. Adv Exp Med Biol 654:1–19.
A detailed description of the human islet of Langerhans. Omary MB, Lugea A, Lowe AW et al 2007 The pancreatic stellate cell: a star
on the rise in pancreatic diseases. J Clin Invest 117:50–9.
Kamisawa T, Okamoto A 2008 Pancreatographic investigation of pancreatic A detailed review of the pancreatic acinar cell, which is the focus of research
duct system and pancreaticobiliary malformation. J Anat 212:125–34. into its possible role in a multitude of pancreatic disorders.
A review of the pancreatic ductal system.
Saisho Y, Butler AE, Meier JJ et al 2007 Pancreas volumes in humans from
Kimura W 2000 Surgical anatomy of the pancreas for limited resection. birth to age one hundred taking into account sex, obesity, and presence


J Hepatobil Pancreat Surg 7:473–9. of type-2 diabetes. Clin Anat 20:933–42.
A beautifully illustrated description of the surgical anatomy of the pancreas. A description of pancreatic volumes and the ratio of parenchymal and fat
components in humans, with an account of how it changes with age and
Kimura W, Nagai H 1995 Study of surgical anatomy for duodenum-
gender.
preserving resection of the head of the pancreas. Ann Surg
221:359–63. Woodburne RT, Olsen LL 1951 The arteries of the pancreas. Anat Rec
A detailed description of the vascular anatomy of the head of the pancreas 111:255–70.
and duodenum. One of the earliest comprehensive reviews of pancreatic arterial anatomy.


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Acute inflammation of the pancreas occurs in response to a variety of
pancreatic insults, including gallstone obstruction of the hepatopancre-
atic ampulla, which causes reflux of bile and pancreatic juice into the
pancreatic duct. This precipitates intraparenchymal activation of inac-
tive digestive enzymes, leading to cell injury, an inflammatory cascade
and destruction of pancreatic tissue.
The regional anatomy of the pancreas explains most of the clinical D
complications of acute pancreatitis. Irritation of the stomach contrib-
utes to gastric stasis and vomiting; inflammation of the superior
mesenteric plexus may contribute to paralytic ileus; and vascular inflam-
mation may cause superior mesenteric or portal vein thrombosis, arte-
rial bleeding or pseudoaneurysms, and ischaemia of the transverse
colon. Haemorrhagic fluid may accumulate in the loose retroperitoneal E
B
tissues around the pancreas and track laterally to the flanks (Grey
Turner’s sign), down to the inguinal ligaments (Fox’s sign), or via the
lesser omentum and ‘bare area’ of the liver to the falciform ligament CC
and the skin around the umbilicus (Cullen’s sign), manifesting as
AA
diffuse bruising.
Peripancreatic acute fluid collections frequently resolve spontane-
ously as the inflammation in the pancreas subsides. Accumulation of
fluid anterior to the pancreas, just beneath the posterior wall of the
lesser sac, can result in a ‘pseudocyst’ containing amylase-rich fluid and
debris but lacking a true epithelial lining (Banks et al 2013). A large Fig. 69.11 An intraoperative photograph taken during
pseudocyst bulges forwards into the lesser sac in contact with the pos- pancreaticoduodenectomy. This patient had coeliac artery stenosis and
terior wall of the stomach, lesser omentum and gastrosplenic ligament. consequently hypertrophied pancreaticoduodenal arcade arteries
(A) provided the arterial supply to the liver. The pancreatic head and
If it does not resolve spontaneously, the pseudocyst can be drained
duodenum were resected, preserving the arcade. Note the cut stump at
internally through the posterior wall of the stomach by endoscopic or


the proximal body of the pancreas (B) and the exposed portal/superior
open surgery, or externally by means of a percutaneous drain inserted
mesenteric vein (C). The arcade communicates with the hepatic artery (E)
under radiological guidance.
to supply the liver (D). (Courtesy of Mohamed Rela, Global Hospitals,
Sustained injury to the pancreas can cause permanent damage,
Chennai, India.)
leading to parenchymal fibrosis and calcification within the paren-
chyma and the pancreatic ducts. This often causes chronic pain, diabe- and Nagai 1995). Stenosis of the coeliac artery is common in elderly
tes mellitus and pancreatic exocrine insufficiency with steatorrhoea and individuals with atherosclerosis. Here, the arterial blood supply to the
malnutrition. Fibrosis can involve the bile duct in the head of the pan- liver is provided by the superior mesenteric artery through hypertro-
creas, leading to obstructive jaundice, and/or the splenic vein, causing phied arteries of the anterior and posterior pancreaticoduodenal
splenic vein thrombosis and ‘left-sided’ portal hypertension. arcades. Care should be taken to avoid ligation of these branches during
The vast majority of pancreatic tumours are ductal adenocarcinomas pancreatic surgery since this could cause hepatic ischemia (Fig. 69.11).
derived from exocrine ductal epithelium. Up to two-thirds of such The pancreas is usually transplanted along with the kidney (this is
tumours are located in the head of the pancreas. Tumours in the head termed a simultaneous pancreas–kidney transplant) in patients with
of the pancreas often obstruct the pancreatic segment of the bile duct end-stage renal disease caused by diabetes mellitus. In selected patients,
early in the course of disease, leading to obstructive jaundice. The the pancreas alone can be transplanted to treat poor glycaemic control
appearance of a dilated common bile duct and main pancreatic duct and hypoglycaemia unawareness (White et al 2009).
on cross-sectional imaging (the ‘double duct’ sign) is a characteristic Donor pancreas is recovered from deceased donors, usually as part
sign in tumours of the pancreatic head. Advanced tumours may invade of a multi-organ recovery procedure. The entire pancreas, along with


the adjacent duodenum, causing gastric outlet obstruction and/or the the duodenal C loop (attached to the head of pancreas) and spleen
portal or superior mesenteric veins posterior to the neck of the pancreas. (closely related to the tail of the pancreas), is recovered to prevent
A tumour in the body or tail of the gland often grows to a large size damage to the vascular arcades in the pancreaticoduodenal groove and
before presenting as an abdominal mass or with back pain and weight minimize handling of the pancreas during organ recovery (Abu-Elmagd
loss (Yeo et al 2002). Tumours of the uncinate process can cause et al 2000). The arterial supply for the pancreas graft is based on the
early involvement of the superior mesenteric vessels and duodenum splenic artery and the superior mesenteric artery, both of which should
(O’Sullivan et al 2009). Peripancreatic and pre-aortic lymph nodes may be carefully preserved during the donor operation. Both arteries are
be involved, together with hepatic nodes, in pancreatic head tumours, reconstructed to a Y-shaped deceased donor iliac artery graft to enable
and splenic hilar nodes may be involved in pancreatic tail tumours. a single arterial anastomosis in the recipient. The venous drainage is
Surgery for pancreatic head tumours usually involves combined through the portal vein. The pancreas graft is implanted heterotopically
resection of the pancreatic head and duodenum (pancreaticoduodenec- in the pelvis (not in its normal anatomical position, i.e. the upper
tomy) because of their shared blood supply. The resectability of the retroperitoneum). The reconstructed artery is anastomosed to the exter-
tumour depends on the presence and extent of major vascular involve- nal iliac artery. The portal vein of the graft can be anastomosed to either
ment, particularly the portal vein and superior mesenteric vessels. An the iliac vein or the superior mesenteric vein of the recipient. Though
accessory or replaced right hepatic artery (p. 1166) running cranially on portal and systemic venous drainage each has its own supporters, there
the posterior surface of the pancreatic head and behind the supraduo- is no evidence regarding the superiority of one technique versus the


denal segment of the bile duct is at risk of injury during such procedures other (Bazerbachi et al 2012). Drainage of the pancreas exocrine secre-
(Turrini et al 2010). Recognition of this variation and preservation of tions is into the ileum through a duodeno-ileal anastomosis or into the
the artery are essential to maintain the arterial supply to the right lobe recipient urinary bladder through a duodeno-cystic anastomosis. Com-
of the liver. In distal or total pancreatectomy, spleen-preserving resec- plications of the procedure are primarily a result of the damage the
tions are generally undertaken if the underlying pathology does not delicate pancreas sustains during the organ recovery, storage and trans-
involve the splenic vein lying in the groove on the posterior surface of plantation process. Complications include graft pancreatitis, graft
the gland, taking care to control the multiple small pancreatic venous necrosis leading to bleeding, thrombosis of vascular anastomoses and
tributaries. In duodenum-preserving resection of the pancreatic head, sepsis (Delis et al 2004, Troppmann 2010). However, in the majority of
which is sometimes undertaken for chronic pancreatitis and benign patients, pancreas transplantation provides the potential for an insulin-
pancreatic tumours, it is important to preserve an adequate duodenal free life and retards the development of diabetes-related complications
blood supply from the pancreaticoduodenal arterial arcades (Kimura (Gruessner et al 2012).


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REFERENCES
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Banks PA, Bollen TL, Dervenis C et al 2013 Classification of acute Kamisawa T, Suyama M, Fujita N et al 2010a Pancreatobiliary reflux and the
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by international consensus. Gut 62:102–11.
Kamisawa T, Takuma K, Tabata T et al 2010b Clinical implications of acces-
Bapat AA, Hostetter G, Von Hoff DD et al 2011 Perineural invasion and sory pancreatic duct. World J Gastroenterol 16:4499–503.
associated pain in pancreatic cancer. Nat Rev Cancer 11:695–707.
Kimura W 2000 Surgical anatomy of the pancreas for limited resection.
Bazerbachi F, Selzner M, Marquez MA et al 2012 Portal venous versus sys- J Hepatobil Pancreat Surg 7:473–9.
temic venous drainage of pancreas grafts: impact on long-term results. A beautifully illustrated description of the surgical anatomy of the pancreas.
Am J Transplant 12:226–32.
Kimura W, Nagai H 1995 Study of surgical anatomy for duodenum-
Bertelli E, Di Gregorio F, Bertelli L et al 1995 The arterial blood supply of
preserving resection of the head of the pancreas. Ann Surg 221:
the pancreas: a review. I. The superior pancreaticoduodenal and the
359–63.
anterior superior pancreaticoduodenal arteries. An anatomical and
A detailed description of the vascular anatomy of the head of the pancreas
radiological study. Surg Radiol Anat 17:97–106, 1–3.


and duodenum.
Bertelli E, Di Gregorio F, Bertelli L et al 1996a The arterial blood supply
of the pancreas: a review. II. The posterior superior pancreaticoduode- Lange JF, Koppert S, van Eyck CH et al 2000 The gastrocolic trunk of Henle
nal artery: an anatomical and radiological study. Surg Radiol Anat in pancreatic surgery: an anatomo-clinical study. J Hepatobili Pancreat
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Bertelli E, Di Gregorio F, Bertelli L et al 1996b The arterial blood supply of Love JA, Yi E, Smith TG 2007 Autonomic pathways regulating pancreatic
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Bertelli E, Di Gregorio F, Bertelli L et al 1997 The arterial blood supply of Mirjalili SA, Stringer MD 2011 The arterial supply of the major duodenal
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Mourad N, Zhang J, Rath AM et al 1994 The venous drainage of the pancreas.
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Bertelli E, Di Gregorio F, Mosca S et al 1998 The arterial blood supply of
Nagai H 2003 Configurational anatomy of the pancreas: its surgical rele-
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J Hepatobil Pancreat Surg 10:48–56.
Burgard G, Gilly F, Braillon G et al 1991 Anatomic basis of the surgical A well-illustrated description of the arrangement of vascular and other
approach to the retropancreatic common bile duct. Surg Radiol Anat structures around the duodenum and head of pancreas, with explanations
13:352–3. based on the embryological development of the pancreas, foregut and
Busnardo AC, DiDio LJ, Thomford NR 1988 Anatomicrosurgical segments midgut.
of the human pancreas. Surg Radiol Anat 10:77–82.
Omary MB, Lugea A, Lowe AW et al 2007 The pancreatic stellate cell: a star
A description explaining the segmental vascularity of the pancreas and the
on the rise in pancreatic diseases. J Clin Invest 117:50–9.
watershed area near the neck of pancreas.
A detailed review of the pancreatic acinar cell, which is the focus of research
Caglar V, Songur A, Yagmurca M et al 2012 Age-related volumetric changes into its possible role in a multitude of pancreatic disorders.
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O’Morchoe CC 1997 Lymphatic system of the pancreas. Microsc Res Tech
Anat 34:935–41.
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Deki H, Sato T 1988 An anatomic study of the peripancreatic lymphatics.
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Purvis NS, Mirjalili SA, Stringer MD 2013 The mucosal folds at the pancrea-
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CHAPTER
70
Spleen
The spleen is a large, encapsulated, complex mass of vascular and lym- 1993, Üngör et al 2007). The average adult weight is dependent on the
phoid tissue situated in the upper left quadrant of the abdominal cavity volume of contained blood; emptied of blood, it weighs between 70
between the fundus of the stomach and the diaphragm. It is mainly and 120 g, whereas in vivo its weight ranges from 150 to 350 g (Naka-
concerned with phagocytosis and immune responses. Although docu- mura et al 1989, Petroianu 2011, Skandalakis et al 1993).
mented for more than 3,000 years, there are many aspects of the spleen The shape of the spleen is also variable and mostly determined by
that remain poorly understood. It plays important roles in immuno- its relations to neighbouring structures during development; it often
logical defence, metabolism and maintenance of circulating blood ele- appears as a slightly curved wedge. The superolateral aspect is shaped
ments (Petroianu 2011, Tarantino et al 2013; Table 70.1). In the fetus, by the left dome of the diaphragm, and the inferomedial aspect mostly
it is also a major site of haemopoiesis and can resume this role post- by the neighbouring stomach, left kidney and splenic flexure of the
natally in certain pathological conditions (Üngör et al 2007). However, colon. In the fetus, the spleen is lobulated (Ch. 60; Coetzee 1982, Faller
it is not essential for life; if the spleen is removed, many of its functions 1985, Gupta et al 1976, Petroianu 2011, Scothorne 1985, Skandalakis
can be assumed by the liver and other tissues of the mononuclear et al 1993, Üngör et al 2007); the adult spleen usually only retains a
phagocytic system. notch on its anterior border, although additional surface notches may
The most common clinical manifestations of splenic disorders are persist (Mikhail et al 1979).


splenomegaly and a decrease in the number of cellular elements in the A splenic lobule that fails to coalesce with the developing spleen can
blood (cytopenias). Other clinical manifestations include infections, persist as a supernumerary or accessory spleen (also known as a sple-
lassitude and abdominal discomfort (Coetzee 1982, Oguro et al 1993, nunculus; Gupta et al 1976). This fully functional island of splenic
Petroianu 2011, Tarantino et al 2013). Chronic splenomegaly in chil- tissue is found in approximately 10% of individuals and may be located
dren may be associated with growth retardation (Petroianu 2003, in any part of the abdomen, or even outside it, but is most commonly
Petroianu 1996). The most serious long-term consequence of removal present near the splenic hilum within the gastrosplenic ligament or
of the spleen is severe sepsis, which carries a 2% mortality in otherwise greater omentum (Faller 1985, Petroianu 2011; Fig. 70.1).
healthy adults and an even greater risk of death in children, the elderly, A normal adult spleen is not palpable on abdominal examination.
and patients with chronic diseases. In living supine healthy adults, it is most frequently located between
the tenth and twelfth ribs, with its long axis along the eleventh rib
(Gupta et al 1976, Mirjalili et al 2012). Its posterior border is approxi-
GROSS ANATOMY mately 4 cm from the midline at the level of the tenth thoracic vertebral
spine and it extends about 3 cm anterior to the mid-axillary line. In the
The size and weight of the spleen vary with age and sex, and can also absence of long peritoneal ligaments, it has to triple in size before it
vary slightly in the same individual under different conditions. The becomes palpable below the left costal margin (Mikhail et al 1979,
adult spleen is usually 9–14 cm long, 6–8 cm wide and 3–5 cm thick, Üngör et al 2007).
and fits comfortably in the individual’s cupped hand. It reaches its


largest dimension in puberty and diminishes thereafter (DeLand 1970,
Jakobsen and Jakobsen 1997). Although its weight increases during RELATIONS
puberty, it is comparatively largest in the young child and tends to
diminish in size and weight in old age (Coquet et al 2010, DeLand The spleen has superolateral diaphragmatic and inferomedial visceral
1970, Jakobsen and Jakobsen 1997, Scothorne 1985, Skandalakis et al surfaces (Fig. 70.2), anterosuperior and posteroinferior borders, and
Table 70.1 Summary of splenic functions
Superior pole Gastric impression Segmental branches
General functions Specific functions (posterior extremity) of splenic artery
Haematological and immunological Haemopoiesis
Maturation of blood elements Anterosuperior
Immunoglobulin activation border (notched)
Recirculation of T and B lymphocytes
Production Leukocytes
Peptides
Immunoglobulins (mainly IgM)
Opsonins
Tuftsin
Properdin
Complement factors
Stem cells
Storage Leukocytes
Platelets
All metals
Clearance Microorganisms Vein leaving hilum
Parasites
Circulating antigens Renal impression
Altered circulating cells
Circulating foreign bodies Posteroinferior border
Synthesis Precursor of hepatic functions
Inferior pole
Metabolism Lipids
Cholesterol
Bilirubin
Amino acids
Pancreatic
Control Bone marrow Colic impression impression
Mononuclear phagocytic function
Somatic growth
1188 Fig. 70.2 The visceral surface of the spleen.


Spleen
1188.e1
07
RETPAHC
Spleens in men are proportionally heavier than those in women. In
pathological conditions, the spleen may expand and retain blood;
weights rarely exceed 700 g but gigantic spleens exceeding 10 kg have
been reported (Coquet et al 2010, DeLand 1970, Jakobsen and Jakobsen
1997, Skandalakis et al 1993). Splenomegaly compresses and displaces
adjacent organs, causing abdominal discomfort, dyspepsia, respiratory
restriction and difficulty walking (Coetzee 1982, Petroianu 2011).
Fig. 70.1 A supernumerary spleen located in the greater omentum
(arrow). Supernumerary spleens are usually isolated and may be
connected to the spleen or splenic pedicle by thin vessels.


Spleen
1189
07
RETPAHC
of the spleen is a long fissure pierced by the splenic vessels, nerves and
Central tendon lymphatics, and lies on the visceral surface closer to the posteroinferior
border (Petroianu 2011).
The anterosuperior border separates the diaphragmatic surface
from the gastric impression and is usually convex. Inferiorly, it may
bear one or two notches that have persisted from the lobulated form
of the spleen in early fetal life (p. 1064). However, the notch may be
Left cupola of diaphragm absent and is not a completely reliable guide to identification of the
spleen during clinical examination. The posteroinferior border sepa-
rates the renal impression from the diaphragmatic surface and is more
Tail of pancreas
rounded and blunt than the anterosuperior border. The superior pole
corresponds to the posterior extremity and usually faces the vertebral
column. The inferior pole is longer and less angulated than the superior
pole and connects the anterosuperior and posteroinferior borders
Phrenicocolic ligament anteriorly; it is related to the colic impression and often lies adjacent
Splenic flexure to the splenic flexure and phrenicocolic ligament (Petroianu 2011).
The inferior pole of the spleen is particularly at risk of injury from
blunt abdominal trauma or during surgical procedures on the stomach,
pancreatic tail, left kidney, left suprarenal gland and left colon. Excessive
traction of the stomach, transverse colon or greater omentum may tear
the splenic capsule and superficial parenchyma by way of their perito-
neal attachments, causing bleeding that may be difficult to control
(Merchea et al 2012).
SPLENIC LIGAMENTS
Fig. 70.3 The posterior relations (‘bed’) of the spleen. (Adapted from
The spleen develops between the two leaves of the dorsal mesogastrium
Drake, RL, Vogl, AW, Mitchell, A (eds), Gray’s Anatomy for Students, 2nd
(see Figs 60.6–60.7) and so is almost entirely invested in visceral peri-
ed, Elsevier, Churchill Livingstone. Copyright 2010.)


toneum that is firmly adherent to its capsule (Üngör et al 2007). The
dorsal mesogastric attachments persist as peritoneal ligaments. Thus,
the superior pole of the spleen is connected to the stomach via the
1 2 gastrosplenic ligament, and to the posterior abdominal wall by a vari-
ably developed phrenicosplenic ligament. The inferior pole of the
spleen is connected to the posterior abdominal wall by the splenorenal
ligament and to the splenic flexure of the colon. The phrenicocolic liga-
ment lies just inferior to the lower pole (Fig. 70.5). Each of these liga-
ments is made up of two layers of peritoneum containing fat, blood
and lymphatic vessels and nerves (Petroianu 2011, Skandalakis et al
1993). The phrenicosplenic ligament runs between the spleen and the
peritoneum of the undersurface of the diaphragm. The anterior layer of
the splenorenal ligament is continuous with the peritoneum of the
posterior wall of the lesser sac over the left kidney, and with the poste-
rior layer of the gastrosplenic ligament at the splenic hilum. The poste-
rior layer of the splenorenal ligament is continuous with the peritoneum
over the inferior surface of the diaphragm and anterior surface of the
left kidney. The terminal portions of the splenic artery and vein, and,
more inferiorly, the tail of the pancreas, lie between the two peritoneal
layers of the splenorenal ligament. The tail of the pancreas may be
injured during dissection when ligating and dividing the splenic vessels,
3 4 5 6 resulting in bleeding, local pancreatitis and pancreatic fistula formation
(Petroianu 2011, Skandalakis et al 1993).
Fig. 70.4 The gross appearance of the spleen in situ. An intra-abdominal
image of the spleen (1) and its relation with the stomach (4), liver (3), The gastrosplenic ligament is continuous with the phrenicosplenic
colon (6), diaphragm (2) and greater omentum (5). ligament, the splenic capsule, the gastric serosa and the greater
omentum. It contains the short gastric and superior polar arteries, and


the left gastroepiploic artery, all of which arise from the splenic artery,
and their corresponding veins. During splenectomy or mobilization of
superior and inferior poles. The convex, smooth diaphragmatic surface the fundus of the stomach, the short gastric vessels must not be ligated
faces mostly superiorly and laterally, although the posterior part may too close to the stomach in order to avoid the risk of local gastric
face posteriorly (Mirjalili et al 2012). The diaphragmatic surface is sepa- necrosis, perforation and their consequences.
rated from the left pleural costodiaphragmatic recess, lower lobe of the The phrenicocolic ligament connects the splenic flexure of the colon
left lung and the tenth to twelfth left ribs by the underside of the left to the diaphragm and runs inferior and lateral to the lower pole of the
dome of the diaphragm (Figs 70.3–70.4); splenic inflammation or spleen. It is continuous with the peritoneum of the lateral end of the
surgery may lead to a left-sided basal pleural effusion and left lower transverse mesocolon at the end of the pancreatic tail, and the spleno-
lobe atelectasis (Petroianu 2011). renal ligament at the hilum of the spleen (Merchea et al 2012,
The visceral surface is irregular, faces inferomedially towards the Skandalakis et al 1993). When the phrenicocolic ligament is being
abdominal cavity and is marked by gastric, renal and colic impressions. divided, particularly when electrocautery is used, the colon is at risk
The gastric impression faces anteromedially and is broad and concave of injury.
where the spleen lies adjacent to the posterior aspect of the fundus,
upper body and upper greater curvature of the stomach. It is separated Mobile spleen The length of the peritoneal ligaments associated
from the stomach by a peritoneal recess, limited by the gastrosplenic with the spleen vary; longer ligaments afford the spleen greater mobil-
ligament. The renal impression is slightly concave and lies on the pos- ity, which can stretch its vascular pedicle. This facilitates surgical mobi-
teroinferior part of the visceral surface, separated from the gastric lization but may render the spleen more susceptible to injury from


impression above by a ridge of splenic tissue and the splenic hilum. It shear forces during trauma.
faces inferomedially and slightly backwards, and is related to the upper A floating or wandering spleen is characterized by excessive mobility
lateral area of the anterior surface of the left kidney and sometimes to and migration of the organ outside the left hypochondrium. In such
the superior pole of the left suprarenal gland. The colic impression is cases, the spleen may undergo torsion or cause bladder or rectal symp-
usually flat; it lies at the inferior pole of the spleen and is related to the toms from local pressure; imaging usually confirms the diagnosis (Fig.
splenic flexure of the colon and the phrenicocolic ligament. The hilum 70.6). If surgical treatment is necessary, the spleen is freed from local


Spleen
1189.e1
07
RETPAHC
Operating on a normal-sized spleen is a relatively straightforward
procedure for most surgeons. Mobilization of the spleen requires divi-
sion of the phrenicocolic, gastrosplenic and phrenicosplenic ligaments.
Undue traction on the phrenicocolic ligament during mobilization of
the splenic flexure may tear the splenic capsule, causing bleeding
(Merchea et al 2012). This is less likely if the phrenicocolic ligament is
retracted laterally rather than inferiorly and medially (Merchea et al
2012). The anterosuperior border and anterior diaphragmatic surface
of the spleen are often adherent to the greater omentum and care must
be taken when retracting the latter. The diaphragmatic surface of
the spleen is occasionally adherent to the peritoneum on the undersur-
face of the diaphragm; these adhesions may follow inflammation of
the spleen or be congenital in origin (Petroianu 2011, Skandalakis
et al 1993).


SPlEEn
1190
8
nOITCES
A Phrenicosplenic ligament 1988, Liu et al 1996, Pandey et al 2004, Sylvester et al 1995). Almost
always, the splenic artery arises from the coeliac trunk, in common with
Outline of spleen the left gastric and common hepatic arteries. However, it may originate
from the common hepatic artery or the left gastric artery, or rarely
directly from the aorta either in isolation or as a splenomesenteric trunk
(Cortés and Pellico 1988, García-Porrero and Lemes 1988, Liu et al
1996, Pandey et al 2004, Torres 1998, Trubel 1985).
From its origin, the artery runs a little way inferiorly before turning
Inferior diaphragmatic
peritoneum to the left behind the stomach to run horizontally posterior to the upper
border of the body and tail of the pancreas. Multiple loops or even coils
Origin of splenorenal
ligament of the artery appear above the superior border of the pancreas (McFee
et al 1995, Pandey et al 2004). The splenic artery courses anterior to
Posterior peritoneal layer
of lesser sac the left kidney and left suprarenal gland, and runs in the splenorenal
ligament behind or above the tail of the pancreas. In its course, it gives
off numerous branches to the pancreas (dorsal pancreatic, greater pan-
Splenocolic ligament
creatic artery, and arteries to the tail) and, near its termination, it gives
Phrenicocolic ligament
off the short gastric arteries and the left gastroepiploic artery (Gürleyik
et al 2000, Liu et al 1996, Mikhail et al 1979, Pandey et al 2004, Skan-
Pancreaticocolic ligament
dalakis et al 1993, Trubel et al 1985, Trubel et al 1988). Additional
branches include a posterior gastric artery in 40% of individuals and
small retroperitoneal branches.
Lateral colonic The splenic artery varies between 8 and 32 cm in length and its
peritoneal fold calibre usually exceeds that of the common hepatic and left gastric


arteries, ranging from 3 to 12 mm. Splenic artery blood flow is approxi-
mately 3 ml/sec/100 g, corresponding to approximately 7% of cardiac
output (Cortés and Pellico 1988, García-Porrero and Lemes 1988,
Nakamura et al 1989, Pandey et al 2004, Petroianu 2011, Skandalakis
et al 1993, Torres 1998, Trubel et al 1985).
B The splenic artery usually divides into two, or occasionally three,
branches before entering the hilum of the spleen. The superior and
inferior branches are sometimes known as superior and inferior polar
arteries; as they enter the hilum they divide into four or five segmental
arteries that each supply a segment of splenic tissue. There is relatively
Anterior border of spleen little arterial collateral circulation between segments, which means that
occlusion of a segmental vessel often leads to infarction of part of the
spleen (Cortés and Pellico 1988, García-Porrero and Lemes 1988,
Gupta et al 1976, Liu et al 1996, Mikhail et al 1979, Pandey et al 2004,
Torres 1998, Trubel al 1985, Trubel et al 1988). Segmental arteries
Gastrosplenic ligament
divide within the splenic trabeculae and give rise to follicular arterioles,
which are surrounded by a thick lymphoid sheath of white pulp. These
Peritoneal reflection
at splenic hilum feed the sinusoids of the red pulp. There is considerable communica-
tion between arterioles (García-Porrero and Lemes 1988, Liu et al 1996,
Mikhail et al 1979, Skandalakis et al 1993, Sow et al 1991, Trubel
et al 1988).
The superior pole of the spleen gains an additional arterial supply,
distinct from the splenic hilar vessels, from the short gastric arteries
in the gastrosplenic ligament. These vessels connect the superior pole
of the spleen to the gastric fundus and preserve viability of this region
of the spleen after ligation of the splenic pedicle (García-Porrero


and Lemes 1988, Gürleyik et al 2000, Liu et al 1996, Petroianu 2011,
Petroianu and Petroianu 1994, Petroianu et al 1989, Skandalakis et al
1993, Torres 1998, Trubel et al 1988).
Veins
Fig. 70.5 The peritoneal connections of the spleen. A, The posterior
Blood from the parenchyma of the spleen is collected by trabecular
peritoneal connections, seen as if the spleen has been removed, with the
veins. They join to form segmental veins that drain individual splenic
folds fixed in their ‘normal’ positions. B, The anterior peritoneal connections,
segments. In general, there are no anastomoses between intrasegmental
seen with the spleen in place, as if the stomach and greater omentum have
venous tributaries. Segmental veins join to form two (superior and
been removed, with the folds fixed in their ‘normal’ positions. (Adapted from
inferior) or three (superior, middle and inferior) ‘lobar’ veins that Drake, RL, Vogl, AW, Mitchell, A (eds), Gray’s Anatomy for Students, 2nd
ed, Elsevier, Churchill Livingstone. Copyright 2010.) emerge from the length of the splenic hilum and unite to form the
splenic vein within the splenorenal ligament (see Fig. 70.2; Fig. 70.8).
Communicating veins may interconnect lobar veins (DeLand 1970,
Gupta et al 1980, Liu et al 1996, Par et al 1965, Sow et al 1991).
adhesions and returned to the left hypochondrium, the surgeon short- The splenic vein runs medially below the splenic artery and posterior
ening and suturing its ligaments to the diaphragm (McFee et al 1995, to the tail and body of the pancreas (see Fig. 69.4 D–G) (Gürleyik et al
Petroianu 2011, Üngör et al 2007). 2000, Par et al 1965). It crosses the posterior abdominal wall anterior


to the left kidney, renal hilum and abdominal aorta, separated from the
left sympathetic trunk and left crus of the diaphragm by the left renal
VASCULAR SUPPLY AND LYMPHATIC DRAINAGE
vessels, and from the abdominal aorta by the superior mesenteric artery
and left renal vein (Gupta et al 1976, Gupta et al 1980, Liu et al 1996,
Arteries
Par et al 1965). It ends posterior to the neck of the pancreas, where it
joins the superior mesenteric vein to form the portal vein. Along its
The spleen is supplied by the splenic artery, one of the most tortuous course it receives the short gastric veins, left gastroepiploic veins, retro-
arteries in the body (Fig. 70.7). The pathophysiology of the tortuosity peritoneal veins (Retzius’s retroperitoneal venous plexus), pancreatic
of this vessel, which may become more pronounced with advancing veins, posterior gastric vein, left gastric vein (occasionally) and the
age, is not understood, although several theories have been proposed inferior mesenteric vein. Approximately 60% of portal vein blood flow
(Borley et al 1995, Cortés and Pellico 1988, García-Porrero and Lemes is derived from the gut and the remainder from the spleen and pancreas


Spleen
1190.e1
07
RETPAHC
2
7 1
55
6 4
S
33 33
A
A
3
2
1
4
B
Fig. 70.6 A mobile enlarged spleen located in the left side of the pelvis.
A, A computed tomography (CT) scan showing the abnormal location of
B
an enlarged spleen (S). B, A surgical view of the same spleen, which
appears congested due to partial obstruction of its venous drainage at
the splenic hilum (arrow). Note the lack of restraining peritoneal ligaments.
C
Fig. 70.7 A, A three-dimensional reconstructed contrast-enhanced CT
scan. Key: 1, spleen; 2, liver; 3, kidneys; 4, splenic vein; 5, superior polar
vein; 6, portal vein; 7, aorta. B, A splenic digital subtraction arteriogram
showing the splenic artery (1) and its branches. Note the primary division
of the splenic artery (2) into superior (3) and inferior branches (4). C, An
excised spleen demonstrating the hilar vessels.


SPlEEn
1190.e2
8
nOITCES
Portal vein Splenic vein Spleen
A
Superior mesenteric vein
Portal vein Splenic vein
B
Fig. 70.8 A, A splenoportogram. B, An axial oblique CT slice showing the
portal and splenic veins.


Spleen
1191
07
RETPAHC
(Dawson et al 1986, Gupta et al 1980, Gürleyik et al 2000, Liu et al Fibrous framework
1996, Oguro et al 1993, Par et al 1965).
Obstruction to portal or splenic venous drainage leads to reversed
The serosa of the peritoneum covers the entire spleen, except at its
venous flow through the splenic vein and its tributaries, resulting in
hilum and where the peritoneal ligaments are attached. The connective
splenomegaly and widespread varices (Petroianu 1988, Petroianu 1992,
tissue capsule, deep to the serosa, is approximately 1.5 mm thick and
Petroianu 2011, Petroianu et al 1989, Re et al 1985, Skandalakis et al
contains abundant type I collagen fibres and some elastin fibres. It is
1993).
composed of an outer and inner lamina in which the directions of the
collagen fibres differ, so increasing its strength. Numerous trabeculae
Lymphatic drainage
extend from the capsule into the substance of the spleen, where they
branch to form a connective tissue scaffold (Faller 1985, Scothorne
Lymphatic drainage begins in the white pulp. Lymphatics travel with 1985). The largest trabeculae enter at the hilum and divide into branches
the blood vessels towards a lymphatic subcapsular plexus, which drains in the splenic pulp, providing conduits for the splenic vessels and nerves
via larger lymphatic channels to lymph nodes at the splenic hilum and (see Fig. 70.10; Figs 70.11–70.12). Within the spleen, these branches
around the tail of the pancreas (Fig. 70.9). From here, lymph drains to become continuous with a delicate network of type III (reticular) col-
suprapancreatic, infrapancreatic and omental lymph nodes, and from lagen fibres that pervades both red and white pulps and is maintained
there to coeliac nodes and the cisterna chyli. by fibroblasts within its interstices (Gupta et al 1976, Krieken and Velde


1988, Scothorne 1985).
INNERVATION White pulp
The spleen is innervated by both components of the autonomic nervous
In an adult, white pulp accounts for between 5% and 20% of the splenic
system; the sympathetic supply is dominant. Postganglionic sympa-
tissue. Branches of the splenic artery radiate out into the parenchyma
thetic nerves from the coeliac plexus and parasympathetic nerves from
of the spleen from the hilum, ramifying within trabeculae. In their
the vagal trunks travel with the splenic vessels (see Fig. 70.9). Sympa-
terminal few millimetres, their connective tissue adventitia is replaced
thetic fibres innervate arteries at least to the trabecular level and have
by a sheath of T lymphocytes, the peri-arteriolar lymphatic sheath
the potential to influence blood flow within the human spleen (Kudoh
(PALS). This is expanded in places by aggregations of B lymphocytes,
et al 1979). Unlike in some animals, the motor innervation of the
lymphoid follicles measuring 0.25–1 mm in diameter and visible to the
human splenic capsule is largely vestigial; it contains minimal quanti-
naked eye on the freshly cut surface of the spleen as white semi-opaque
ties of smooth muscle and therefore does not contract. In contrast, the
dots, in contrast to the surrounding deep reddish purple of the red pulp.
capsule and parenchyma are innervated by sensory fibres that convey
Follicles are usually situated near the terminal branches of arterioles
pain. Mild to moderate splenomegaly is often painless but splenic
and typically protrude to one side of a vessel, which consequently
inflammation from infection, infarction (e.g. sickle cell disease, emboli-
appears eccentrically placed within the follicle. Arterioles branch later-
zation) or abrupt distension of the capsule (e.g. haematoma) may cause
ally within follicles to form a series of parallel terminal arterioles, peni-
severe pain, intensified by inflammation of the overlying parietal peri-
cillar arterioles (Krieken and Velde 1988, Scothorne 1985; see Figs


toneum. Referred pain from the splenic pulp is poorly localized to the
70.10–70.12).
epigastrium (Petroianu 2011).
Like peri-arteriolar sheaths, follicles are centres of lymphocyte aggre-
gation and proliferation. After antigenic stimulation, they become sites
MICROSTRUCTURE of intensive B-cell proliferation, developing germinal centres similar to
those found in lymph nodes; antigen presentation by follicular den-
dritic cells is involved in this process. Germinal centres regress when
The spleen contains the largest single mass of lymphoid tissue in the
the stimulus abates. Follicles tend to atrophy with advancing age and
body in direct continuity with the circulation. Splenic parenchyma
may be absent in the very elderly (Krieken and Velde 1988, Petroianu
is divided into two principal regions – white pulp and red pulp –
2011, Scothorne 1985; see Figs 70.10–70.12).
named according to the appearance of the cut surface of a fresh spleen
(Fig. 70.10).
Red pulp
The red pulp constitutes up to 90% of the total splenic volume and is
a unique filtration device that enables the spleen to clear particulate
material from the blood as it perfuses the organ (Krieken and Velde
T 1988, Petroianu 2011, Scothorne 1985; see Fig. 70.11). It contains large
numbers of venous sinusoids that ultimately drain into tributaries of
the splenic vein. The sinusoids are separated from each other by a
C fibrocellular network of small bundles of collagen fibres, the reticulum,
numerous reticular fibroblasts and splenic macrophages. Seen in two
dimensions, these intersinusoidal regions appear as strips of tissue, the
W splenic cords (see Figs 70.11–70.12), whereas in reality they form a
three-dimensional continuum around the venous spaces (Chen 1978,
Krieken and Velde 1988, Scothorne 1985, Weiss 1983).
Venous sinusoids are elongated ovoid vessels, approximately 50 µm
R
in diameter, supported externally by circumferential and longitudinal


reticular fibres (Krieken and Velde 1988, Scothorne 1985, Weiss 1983),
and lined by a characteristic, discontinuous endothelium that is unique
T T
to the spleen. The long, narrow endothelial cells are aligned with the
long axis of the sinusoid; they are also called stave cells because they
W resemble the planks in a barrel (see Fig. 70.12). Stave cells are attached
to their neighbours at intervals along their length by short stretches of
intercellular junctions that alternate with intercellular slits that allow
T
blood cells to squeeze into the lumen of the sinusoid from the sur-
rounding splenic cords. A discontinuous basal lamina is present on the
abluminal aspect of the sinus.
Large, stellate fibroblasts – reticular cells – lie around the sinusoids.
They synthesize the matrix components of the reticulum, including
Fig. 70.10 A section through the spleen. White pulp (W) is present as
ovoid areas of basophilic tissue. Red pulp (R) lies between white pulp collagen and proteoglycans, and their cytoplasmic processes help to
tissue and consists of splenic sinusoids and intervening cellular cords. compartmentalize the reticular space. Blood from the open ends of the
Part of the capsule (C) is seen top right, from which trabeculae (T) capillaries that originate from penicillar arterioles percolates through
extend into the splenic tissue. (Courtesy of Mr Peter Helliwell and the reticular spaces within the splenic cords. Macrophages in the spaces
the late Dr Joseph Mathew, Department of Histopathology, Royal remove blood-borne particulate material, including ageing and damaged
Cornwall Hospitals Trust, UK.) erythrocytes. If the number of damaged erythrocytes increases, the


Spleen
1191.e1
07
RETPAHC
Gastrosplenic ligament
Short gastric vessels
Superior polar vessel
Phrenicosplenic ligament
Spleen
Left gastric artery Lymph nodes of the
splenic hilum
Posterior vagal trunk Segmental artery
Sympathetic nerves
Segmental vein
Common
Division of the
hepatic artery
splenic artery
Portal vein Inferior polar vessels
Splenic artery
Splenic vein
Inferior mesenteric vein Phrenicocolic ligament
Superior mesenteric vein
Fig. 70.9 The lymph nodes related to the spleen. The pancreas has been rendered partially transparent to visualize the major blood vessels lying
posteriorly. The greater curvature of the stomach has been reflected superiorly to expose its posterior surface and the peritoneal lining of the posterior
wall of the lesser sac removed. (Courtesy of Dr Andy Petroianu and Dr Iriam Starling.)
In malignant neoplasms of the greater curvature of the stomach,
distal pancreas or distal transverse colon, it may be necessary to remove
the spleen and tail of the pancreas to achieve a radical resection. In
leukaemias and lymphomas, lymphadenopathy of splenic hilar nodes
may be found along with splenomegaly during staging investigations
(Petroianu 2011).


SPlEEn
1192
8
nOITCES
A B
C D
Fig. 70.11 The microstructure of the spleen (haematoxylin and eosin staining). A, Red pulp covered by the splenic capsule (arrow). B, Trabeculae
(arrows) inside the red pulp. Trabecular arterioles (1) and venules (2), containing erythrocytes, are also shown. C, Red pulp (1), marginal or perifollicular
zone (2), and white pulp (3) containing a follicular arteriole surrounded by a peri-arteriolar lymphatic sheath (arrow). D, Red pulp containing several
sinusoid capillaries (*) with discontinuous endothelial cells and surrounded by macrophages containing phagocytosed particles within their cytoplasm
(arrows).
Capsule
Venous drainage
Sinusoids in red pulp
Trabeculae
Closed circulation
Open circulation
Stave cell
Reticular fibres
White pulp
Fig. 70.12 The main features of splenic structure, not to scale. The capsule, trabeculae, reticular fibres and cells, the perivascular lymphoid sheaths and
follicles (white pulp), and the cellular cords and venous sinusoids of the red pulp are shown. The ‘open’ and ‘closed’ theories of splenic circulation are
illustrated; it is likely that most of the circulation is of the open form. The venous sinusoids are lined by specialized endothelial ‘stave’ cells; the
intercellular gaps of these have been over-emphasized for clarity.


1193
07
RETPAHC
Key references
reticular cells proliferate and the red pulp expands, causing the spleen removing abnormal and effete cells, blood cell particles, bacteria, para-
to enlarge (Kudoh et al 1979, Scothorne 1985). sites and foreign antigens.
Perifollicular zone
IMAGING
The perifollicular (marginal) zone lies at the interface between the
white and red pulp; it is the site where blood is delivered into the red Available with the Gray’s Anatomy e-book
pulp and where many lymphocytes leave the circulation to migrate to
their respective T- and B-lymphocyte aggregations in the white pulp.
These lymphocytes are more loosely arranged than they are in the white
SPLENOMEGALY
pulp, and are held in a dense network of reticular fibres and cells. The
arterioles leaving the white pulp are also surrounded by a small aggrega-
tion of macrophages: the peri-arteriolar macrophage sheath (Krieken Available with the Gray’s Anatomy e-book
and Velde 1988, Petroianu 2011, Scothorne 1985; see Fig. 70.11C).
Splenic microcirculation SPLENIC TRAUMA
Segmental splenic arteries ramify in the trabeculae (trabecular arteries) The spleen is one of the most frequently damaged organs in blunt
before tapering to become arterioles that pass through the white pulp abdominal trauma (Table 70.2, Fig. 70.15). It is particularly prone to
and give off penicillar arterioles (García-Porrero and Lemes 1988, injury during rapid deceleration or compression, and its peritoneal liga-
Gupta et al 1976, Scothorne 1985). These exit the white pulp and ments render it vulnerable to shearing injuries of the parenchyma and
traverse the perifollicular marginal zone before entering the red pulp. splenic vessels. Fractures of the lower left ribs may be associated with
Evidence supports a dominantly ‘open’ circulation in humans, in which blunt injuries (Buntain et al 1988). Traction on peritoneal ligaments or


blood empties into and percolates slowly through the reticular tissue adhesions may lead to inadvertent capsular tears during surgical proce-
of the splenic cords before re-entering the vascular lumen through slits dures such as splenic flexure mobilization. There is insufficient evidence
in the walls of the venous sinusoids (Cavalli et al 1982, Chen 1978; see to know whether enlarged spleens are at a significantly greater risk of
Fig. 70.12). From the venous sinusoids, blood collects in venules that trauma (Skandalakis et al 1993), but this is frequently postulated.
unite to form small veins that run within the trabeculae and drain into
segmental splenic veins (Cavalli et al 1982, Chen 1978, Petroianu 2011,
Scothorne 1985). Some blood probably takes an alternative, ‘closed’ SPLENECTOMY
route and enters the venous sinusoids directly from arterioles and capil-
laries in the marginal zone. Either way, the blood is exposed to macro-
Available with the Gray’s Anatomy e-book
phages and the filtering mechanism of the spleen responsible for
Bonus e-book images
Fig. 70.1 A supernumerary spleen located in Fig. 70.8 A, A splenoportogram. B, An axial Fig. 70.15 Splenic trauma. A, A CT scan
the greater omentum. oblique CT slice showing the portal and showing multiple splenic tears. B, Suture
splenic veins. repair of a ruptured spleen. C, Complete
Fig. 70.6 A mobile enlarged spleen located splenic rupture. D, Subtotal splenectomy
in the left side of the pelvis. A, A computed Fig. 70.9 The lymph nodes related to the after treatment of the patient illustrated
tomography (CT) scan showing the spleen. in C.
abnormal location of an enlarged spleen.
B, A surgical view of the same spleen, Fig. 70.13 Splenic imaging. A, An ultrasound Fig. 70.16 Partial splenectomy and
which appears congested due to partial scan with colour Doppler. B, A magnetic autotransplantation. A, Partial splenectomy


obstruction of its venous drainage at the resonance scan. C, A radioisotope scan preserving the superior pole supplied by the
splenic hilum. (99mTc sulphur colloid). short gastric vessels. B, Partial splenectomy
preserving the inferior pole supplied by the
Fig. 70.7 A, A three-dimensional Fig. 70.14 Examples of different pathologies left gastroepiploic vessels. C, A splenic
reconstructed contrast-enhanced CT scan. causing splenomegaly. A, Portal segment removed after total splenectomy
B, A splenic digital subtraction arteriogram hypertension. B, Gaucher’s disease. and sliced into 1–2 cm cubes. D, The
showing the splenic artery and its branches. C, Myelofibrosis. D, Thalassaemia. same slices in C sutured on to the greater
C, An excised spleen demonstrating the E, Sarcoma. F, Lymphoma. omentum.
hilar vessels.
KEY REFERENCES
Coetzee T 1982 Clinical anatomy and physiology of the spleen. South Afr Skandalakis PN, Colborn GL, Skandalakis LJ et al 1993 The surgical anatomy
Med J 61:737–46. of the spleen. Surg Clin North Am 73:747–68.
A classic reference paper on splenic anatomy and physiology. One of the most complete descriptions of splenic anatomy.
García-Porrero JA, Lemes A 1988 Arterial segmentation and subsegmenta- Sylvester PA, Stewart R, Ellis H 1995 Tortuosity of the human splenic artery.
tion in the human spleen. Acta Anat 131:276–83. Clin Anat 8:214–18.
A detailed description of the relation between the arterial distribution and A description of the tortuosity of the splenic artery, demonstrating its
spleen segmentation. importance in anatomical and surgical approaches.
Liu DL, Xia S, Xu W et al 1996 Anatomy of vasculature of 850 spleen speci-
mens and its application in partial splenectomy. Surgery 119:27–33.
A detailed description of the vascular anatomy of the spleen and its role in
surgical procedures on the spleen.


Spleen
1193.e1
07
RETPAHC
Imaging demonstrates the gross morphology and vascular supply of the
spleen, and can also be used to assess splenic function. Imaging modali-
ties include ultrasound (US), computed tomography (CT), magnetic
resonance imaging (MRI), arteriography, splenoportography and scin-
tigraphy (Buntain et al 1988, Merran et al 2007, Nakamura et al 1989,
Spleen
Xu et al 2009; see Figs 70.7–70.8; Fig. 70.13). Cross-sectional imaging
is particularly useful for assessing tumours and infiltrations of the
spleen. Percutaneous drainage of splenic and perisplenic fluid collec-
tions is routinely performed under image guidance, and percutaneous
splenic biopsy is being increasingly utilized in diagnosis. Arteriography
Splenic
is essential for selective embolization and the insertion of an arterial
artery
stent to treat splenic artery aneurysm. Scintigraphy can be used to
investigate splenic phagocytic function by quantifying the uptake of
radioactive labelled agents (e.g. 99mtechnetium sulphur colloid or heat-
damaged erythrocytes) (Hermann and Winkel 1977, Merran et al 2007,
Splenic
Petroianu 2011, Xu et al 2009). vein
The numerous causes of splenomegaly may broadly be classified into
haematological (e.g. lymphoproliferative, myeloproliferative, erythro- A
cyte disorders); vascular (e.g. portal hypertension); infectious (e.g. viral,
bacterial, other); autoimmune; and infiltrative (e.g. storage disorders
and tumours) (Cavalli et al 1982, Petroianu 1988, Petroianu 2011, Re
et al 1985; Fig. 70.14).
Contrast-enhanced CT imaging is particularly useful in the assess- Thoracic
aorta
ment of splenic trauma. The majority of splenic injuries from blunt
abdominal trauma are successfully treated by conservative manage-
Liver
ment. Extensive burst injuries with persistent bleeding or major injuries
to the hilar vessels may require splenectomy but various repair tech-


niques are available. With hilar injuries, a subtotal splenectomy, pre- Spleen
serving the short gastric vessels and superior pole only, is one option.
Minor intraoperative capsular tears may be controlled by the topical
Kidneys
application of haemostatic agents and sutures, although direct suture
repair is challenging because the splenic pulp is fragile. Arteriography
and embolization are additional techniques that can be used to control
bleeding or treat vascular lesions (Petroianu 2011).
Most surgical procedures performed on the spleen should start with
ligation of the splenic artery at the superior border of the pancreatic B
tail. This can be difficult in patients with portal hypertension, splenic
artery aneurysm, retroperitoneal fibrosis, regional lymphadenopathy or
inflammatory conditions. After splenic artery ligation, the spleen
becomes softer because most of its contained blood returns to the cir-
culation. Despite the interruption of splenic artery inflow, the superior
pole of the spleen continues to be perfused by the short gastric arteries,
and the inferior pole may be supplied retrogradely via the left gastroepi-
ploic artery. Ligation and division of the splenic vein should be the last
step before removal of the spleen to maximize autotransfusion of blood
from the spleen (Liu et al 1996, Petroianu 2011, Petroianu and Petroi-
anu 1994, Petroianu et al 1989, Skandalakis et al 1993, Sow et al 1991).
In partial or subtotal splenectomy, the vessels that supply the part
Liver
of the spleen to be removed are ligated and divided close to the organ.
The devascularized region turns dark blue, demarcating it from the
Spleen
residual viable splenic tissue; the organ is then divided in this plane
(Christo and DiDio 1997, Gürleyik et al 2000, Liu et al 1996, Petroianu
and Petroianu 1994, Sow et al 1991). Wedge excision leaves two flaps
of splenic capsule that can be sutured or stapled to cover the remaining
raw parenchyma, after suture of any visible bleeding vessels (Petroianu


2011, Petroianu 1993, Petroianu et al 1989, Petroianu 1988; Fig. 70.16).
If total splenectomy is required to treat splenic trauma, autotrans-
plantation of splenic tissue into the greater omentum or mesentery of
the bowel can preserve useful splenic function (see Fig. 70.16). Approxi- C
mately 20% of the original splenic mass needs to be transplanted and
venous drainage of this tissue must be to the portal venous system to Fig. 70.13 Splenic imaging. A, An ultrasound scan with colour Doppler.
maintain the metabolic and immunological functions of the splenic B, A magnetic resonance scan. C, A radioisotope scan (99mTc sulphur
tissue (Oguro et al 1993, Petroianu 2011). colloid). Contrast-enhanced CT imaging, digital subtraction angiography
Total splenectomy has numerous potential consequences. Intraop- and a splenoportogram are shown in Figures 70.7–70.8.
eratively, bleeding or damage to the pancreas, stomach or colon may
occur. Early postoperative complications include left-sided basal pul-
monary atelectasis and pleural effusion, subphrenic abscess, transient
leukocytosis and thrombocytosis with the risk of thrombotic complica-
Table 70.2 Buntain’s classification of splenic injury
tions. In the longer term, there is an increased risk of infection (espe-
cially from encapsulated bacteria), which may be fatal (Petroianu 2011). Grade Description of injury
Conservative management of splenic trauma and partial splenec-
Grade I Subcapsular haematoma or localized capsular disruption without significant
tomy now enable splenic function to be preserved in situations where injury to the parenchyma
splenectomy would once have been routinely performed. Furthermore, Grade II Single or multiple capsular and parenchymal disruptions that do not involve
most surgical procedures on the spleen can now be performed laparo- the hilar vessels
scopically, which readily affords inspection of the spleen from all per- Grade III Deep fractures in the hilum involving the vessels


spectives (Poulin and Thibaut 1993, Sow et al 1991). Grade IV Shattered or fragmented spleen or hilar avulsion
(Reproduced from Buntain WL, Gould HR, Maull KI. Predictability of splenic salvage by computed
tomography. J Trauma. 1988; 28:24–34.)


SPlEEn
1193.e2
8
nOITCES
A
B C D
E F
Fig. 70.14 Examples of different pathologies causing splenomegaly. A, Portal hypertension. B, Gaucher’s disease. C, Myelofibrosis. D, Thalassaemia.
E, Sarcoma. F, Lymphoma.


Spleen
1193.e3
07
RETPAHC
A B
Tear
C D
Fig. 70.15 Splenic trauma. A, A CT scan showing multiple splenic tears. B, Suture repair of a ruptured spleen. C, Complete splenic rupture. The splenic
hilum has been clamped to control bleeding. D, Subtotal splenectomy after treatment of the patient illustrated in C.
A
B
C D
Fig. 70.16 Partial splenectomy and autotransplantation. A, Partial splenectomy preserving the superior pole supplied by the short gastric (‘splenogastric’)
vessels (arrow). B, Partial splenectomy preserving the inferior pole supplied by the left gastroepiploic vessels (arrow). C, A splenic segment removed
after total splenectomy and sliced into 1–2 cm cubes. D, The same slices in C sutured on to the greater omentum.


SPlEEn
1193.e4
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nOITCES
REFERENCES
Borley NR, Mc Farlane JM, Ellis H 1995 A comparative study of the tortuos- Nakamura T, Moriyasu F, Ban N et al 1989 Quantitative measurement of
ity of the splenic artery. Clin Anat 8:219–21. abdominal arterial blood flow using image-directed Doppler ultra-
Buntain WL, Gould HR, Maull KI 1988 Predictability of splenic salvage by sonography. J Clin Ultrasound 17:261–8.
computed tomography. J Trauma 28:24–34. Oguro A, Taniguchi H, Koyama H et al 1993 Relationship between liver
Cavalli G, Re G, Casali AM et al 1982 The microvascular architecture of function and splenic blood flow. Ann Nucl Med 7:251–5.
spleen in congestive splenomegaly. Pathol Res Pract 174:131–46. Pandey SK, Bhattacharya S, Mishra RN et al 2004 Anatomical variations of
Chen L-T 1978 Microcirculation of the spleen. Science 201:157–9. the splenic artery and its clinical implications. Clin Anat 17:497–502.
Christo MC, DiDio LJ 1997 Anatomical and surgical aspects of splenic Par MM, Barry P, Autissier JM et al 1965 Considérations sur la morphologie
segmentectomies. Ann Anat 179:461–74. de la veine splénique et de ses affluents. Soc Nac Med 1:539–47.
Coetzee T 1982 Clinical anatomy and physiology of the spleen. South Afr Petroianu A 1988 Treatment of portal hypertension by subtotal splenectomy
Med J 61:737–46. and central splenorenal shunt. Postgrad Med J 64:38–41.
A classic reference paper on splenic anatomy and physiology. Petroianu A 1993 Subtotal splenectomy and portal variceal disconnection
in the treatment of portal hypertension. Can J Surg 36:251–4.
Coquet B, Sandoz B, Savoie PH et al 2010 Anthropometric characterization


of spleen in children. Surg Radiol Anat 32:25–30. Petroianu A 1996 Subtotal splenectomy in Gaucher’s disease. Eur J Surg
162:511–13.
Cortés JA, Pellico LG 1988 Arterial segmentation in the spleen. Surg Radiol
Anat 10:323–32. Petroianu A 2003 Subtotal splenectomy for treatment of retarded growth
and sexual development associated with splenomegaly. Minerva Chir
Dawson DL, Molina ME, Conner CES 1986 Venous segmentation of the
58:413–14.
human spleen. Am Surg 52:253–6.
Petroianu A 2011 The Spleen. London: Bentham Science.
DeLand FH 1970 Normal spleen size. Radiology 97:589–92.
Petroianu A, Ferreira VL, Barbosa AJA 1989 Morphology and viability of the
Faller A 1985 Splenic architecture reflected in the connective tissue structure
spleen after subtotal splenectomy. Braz J Med Biol Res 22:491–5.
of the human spleen. Experientia 41:164–7.
Petroianu A, Petroianu S 1994 Anatomy of gastrosplenic vessels in patients
García-Porrero JA, Lemes A 1988 Arterial segmentation and subsegmenta-
with schistosomal portal hypertension. Clin Anat 7:80–3.
tion in the human spleen. Acta Anat 131:276–83.
A detailed description of the relation between the arterial distribution and Petroianu A, Simal CJR, Barbosa AJA 1992 Impairment of phagocytosis by
spleen segmentation. mammalian splenic macrophages by 99mTc sulphur colloid. Med Sci
Res 20:847–9.
Gupta CD, Gupta SC, Arora AK et al 1976 Vascular segments in the human
Poulin EC, Thibaut C 1993 The anatomical basis for laparoscopic splenec-
spleen. J Anat 121:613–16.
tomy. Can J Surg 36:484–8.
Gupta SB, Gupta SC, Gupta CD 1980 Venous segments in the human spleen.


Re G, Casali A, Cavalli D et al 1985 Morphological bases of splenic circula-
Indian J Med Res 72:465–9.
tion in congestive splenomegaly. Haematologica 70:283–90.
Gürleyik E, Gürleyik G, Bingöl K et al 2000 Perfusion and functional
Scothorne RJ 1985 The spleen. Histopathology 9:663–9.
anatomy of the splenic remnant supplied by short gastric vessels.
Excerpta Med 179:490–3. Skandalakis PN, Colborn GL, Skandalakis LJ et al 1993 The surgical anatomy
of the spleen. Surg Clin North Am 73:747–68.
Hermann HJ, Winkel K 1977 Scintigraphy of the spleen. Lymphology
One of the most complete descriptions of splenic anatomy.
10:115–19.
Jakobsen SS, Jakobsen US 1997 The weight of normal spleen. Forensic Sci Sow ML, Dia A, Ouedraogo T 1991 Anatomic basis for conservative surgery
Int 88:215–23. of the spleen. Surg Radiol Anat 13:81–7.
Krieken JH, Velde J 1988 Normal histology of the human spleen. Am J Surg Sylvester PA, Stewart R, Ellis H 1995 Tortuosity of the human splenic artery.
Pathol 12:777–85. Clin Anat 8:214–18.
A description of the tortuosity of the splenic artery, demonstrating its
Kudoh G, Hoshi K, Murakami T 1979 Fluorescence microscopic and enzyme
importance in anatomical and surgical approaches.
histochemical studies of the innervation of the human spleen. Arch
Histol Jpn 42:169–80. Tarantino G, Scalera A, Finelli C 2013 Liver-spleen axis: intersection between
Liu DL, Xia S, Xu W et al 1996 Anatomy of vasculature of 850 spleen speci- immunity, infections and metabolism. World J Gastroenterol 19:
mens and its application in partial splenectomy. Surgery 119:27–33. 3534–42.


A detailed description of the vascular anatomy of the spleen and its role in Torres RR 1998 The true splenic blood supply and its surgical applications.
surgical procedures on the spleen. Hepato-Gastroent 45:885–8.
McFee RB, Musacchio T, Gorgescu D et al 1995 Wandering spleen with Trubel W, Turkof, E, Rokitansky A et al 1985 Incidence, anatomy and ter-
torsion in a geriatric patient. Dig Dis Sci 40:2656–9. ritories supplied by the posterior gastric artery. Acta Anat 124:26–30.
Merchea A, Dozois EJ, Wang JK et al 2012 Anatomic mechanisms for splenic Trubel W, Rokitansky A, Turkof, E et al 1988 Correlations between posterior
injury during colorectal surgery. Clin Anat 25:212–17. gastric artery and superior polar artery in human anatomy. Anat Anz
167:219–23.
Merran S, Cohen PK, Servois V 2007 Scanographie de la rate: anatomie
normale, variantes et pièges. J Radiol 88:549–58. Üngör B, Malas MA, Sulak O et al 2007 Development of spleen during fetal
period. Surg Radiol Anat 29:543–50.
Mikhail Y, Kamel R, Nawar NN et al 1979 Observations on the mode of
termination and parenchymal distribution of the splenic artery with Weiss L 1983 The red pulp of the spleen. Clin Haematol 12:375–93.
evidence of splenic lobation and segmentation. J Anat 128:253–8. Xu WL, Li SL, Wang Y et al 2009 Role of color Doppler flow imaging
Mirjalili SA, McFadden SL, Buckenham T et al 2012 A reappraisal of adult in applicable anatomy of spleen vessels. World J Gastroenterol 15:
abdominal surface anatomy. Clin Anat 25:844–50. 607–11.


CHAPTER
71
Suprarenal (adrenal) gland
The suprarenal (adrenal) glands lie immediately superior and slightly shape, flattened in the anteroposterior plane and marginally larger than
anterior to the upper pole of each kidney (see Figs 74.5, 62.8). Golden the right. The bulk of the right suprarenal sits on the apex of the right
yellow in colour, each gland possesses two functionally and structurally kidney and usually lies slightly higher than the left gland, which lies
distinct areas: an outer cortex and an inner medulla. The glands are on the anteromedial aspect of the upper pole of the left kidney.
surrounded by perinephric fat enclosed within the renal fascia, and At birth, the glands are proportionately larger and are approximately
separated from the kidneys by a small amount of fibrous tissue. one-third the size of the ipsilateral kidney. The cortex of each gland is
The dimensions of the suprarenal glands in adults in vivo have been expanded by a well-developed ‘fetal zone’, responsible for producing
measured from axial computed tomography (CT) scans (Vincent et al dehydroepiandrosterone (DHEA), the substrate for placental oestrogen,
1994). The mean maximum width of the body of the suprarenal gland in the fetus. The suprarenal cortex (specifically the fetal zone) reduces
is 61 mm (right) and 79 mm (left), and the mean width of each limb in size immediately after birth and the medulla grows comparatively
of the gland (medial and lateral) is approximately 30 mm. No indi- little. By the end of the second postnatal month, the weight of the
vidual suprarenal limb should measure more than 5 mm in transverse suprarenal has reduced by more than 50%. The glands begin to grow
section. In adults, each suprarenal gland weighs approximately 5 g (the again by the end of the second year and regain their weight at birth by
medulla contributes about one-tenth of the total weight) and has a puberty. There is little further weight increase in adult life.
volume of approximately 3–6 cm3 (Wang et al 2013). Small accessory suprarenal nodules, composed mainly of cortical


The glands are macroscopically slightly different in external appear- tissue (also known as ‘adrenal rests’), may occur in the areolar tissue
ance (Fig. 71.1). The right is pyramidal in shape and has two well- near the suprarenal glands. They are also occasionally found in the
developed lower projections (limbs), giving a cross-sectional appearance spermatic cord, epididymis or testis in boys (Altin et al 1992), and
similar to a three-pointed star. The left gland is more semilunar in ovary or broad ligament of the uterus in girls. Ectopic suprarenal tissue
may cause diagnostic confusion and is rarely the site of neoplastic
change.
A
Area related to stomach RIGHT SUPRARENAL GLAND
The right suprarenal gland lies posterior to the inferior vena cava, sepa-
rated from it by only a thin layer of fascia and connective tissue. It also
Suprarenal vein lies posterior to the right lobe of the liver and anterior to the right crus
Hepatic area
of the diaphragm and superior pole of the right kidney (Fig. 71.2). Its
inferior surface or base overlaps the anterosuperior aspect of the upper
pole of the right kidney, with the two lower projections (limbs) of the
gland straddling the renal tissue. The anterior surface has two distinct
facets: a narrow medial facet that lies posterior to the inferior vena cava,
and a triangular lateral facet that lies in contact with the bare area of
Area
the liver. The lowest part of the anterior surface may be covered by the
related
to pancreas peritoneal reflection of the inferior layer of the coronary ligament,
Area related to which also represents the upper recess of the hepatorenal pouch (see
inferior vena cava Fig. 63.2). Here, the gland lies posterior to the lateral border of the
Suprarenal vein second part of the duodenum. Below the apex, near the anterior border
of the gland, the right suprarenal vein emerges from the hilum to join
the inferior vena cava. This vein is short, which makes surgical resection
Right Left
of the gland or mobilization of the inferior vena cava potentially haz-
ardous. It may be inadvertently avulsed from the inferior vena cava
B during surgery or, occasionally, by high-energy deceleration injuries.


The posterior surface of the gland is divided into upper and lower areas
by a curved transverse ridge. The large upper area is slightly convex and
abuts the diaphragm, whereas the small lower area is concave and lies
in contact with the superior aspect of the upper pole of the right kidney.
Area The medial border of the gland is thin and lies lateral to the right coeliac
related to ganglion and the right inferior phrenic artery where the artery runs over
diaphragm the right crus of the diaphragm.
LEFT SUPRARENAL GLAND
The left suprarenal gland is closely applied to the left crus of the dia-
phragm, separated from it by a thin layer of fascia (see Fig. 71.2). The
medial aspect is convex longitudinally, whereas the lateral aspect is
concave because it is moulded by the medial surface of the upper pole
Area related to Area related Suprarenal vein of the left kidney. The superior border is sharply defined while the
right kidney to left kidney
inferior surface is more rounded. The upper part of the anterior surface
is covered by the peritoneum of the posterior wall of the lesser sac,
Right Left which separates it from the stomach and sometimes from the postero-
1194 Fig. 71.1 The suprarenal glands. A, Anterior aspect. B, Posterior aspect. inferior border of the spleen. A small lower part of the anterior surface


Suprarenal (adrenal) gland
1195
17
RETPAHC
Right lobe of liver Inferior vena Left crus of Pancreas Inferior phrenic arteries
cava diaphragm
Superior suprarenal arteries
Right suprarenal gland
Left suprarenal gland
A
Left kidney
Right suprarenal Right crus of Left suprarenal Left kidney
gland diaphragm gland Inferior vena cava Inferior suprarenal artery
Right kidney
Middle suprarenal artery
Abdominal aorta
Liver Right kidney Right suprarenal Left suprarenal Left kidney
gland gland Fig. 71.3 The arterial supply and venous drainage of the suprarenal
glands. (With permission from Drake RL, Vogl AW, Mitchell A (eds), Gray’s
Anatomy for Students, 2nd ed, Elsevier, Churchill Livingstone. Copyright
2010.)
the capsule before penetrating the gland to form a subcapsular arterial
plexus, from which fenestrated sinusoids pass around clustered glomer-
ulosa cells and between the columns in the zona fasciculata to a deep
plexus in the zona reticularis. Venules from this plexus pass between
medullary chromaffin cells to medullary veins, which they enter
between prominent bundles of smooth muscle fibres. Some relatively
large arteries bypass this indirect route and pass directly to the medulla
(Fig. 71.4). The arterial supply of the suprarenal gland is prone to
considerable variation (Manso and DiDio 2000, Dutta 2010); only the
main variants will be described here.
Superior suprarenal arteries
The superior suprarenal artery usually arises from the ipsilateral inferior
phrenic artery and passes to the gland as four or five small branches; it
may occasionally arise from the abdominal aorta.
Middle suprarenal arteries
The middle suprarenal artery is usually single, but may be multiple or
absent. It often arises from the lateral aspect of the abdominal aorta at
around the level of the superior mesenteric artery and ascends slightly
over the crura of the diaphragm to anastomose with the other suprar-
enal arteries on the surface of the gland. The right middle suprarenal
B
artery passes behind the inferior vena cava close to the right coeliac


ganglion, whereas the left middle suprarenal artery passes close to the
Fig. 71.2 Magnetic resonance imaging (MRI) of the suprarenal glands. A,
left coeliac ganglion, splenic artery and the superior border of the pan-
Axial T1 weighted MRI. B, Coronal T2 weighted MRI. (Courtesy of Dr
creas. The middle suprarenal artery may originate from either the ipsi-
Louise Moore, Chelsea & Westminster Hospital.)
lateral inferior phrenic or renal artery.
Inferior suprarenal arteries
is not covered by peritoneum and lies adjacent to the pancreas and The inferior suprarenal arteries often contribute most of the arterial
splenic artery. The hilum faces inferiorly from the lower part of the supply to the gland. One or two arteries usually arise from the ipsilateral
medial aspect. The left suprarenal vein emerges from the hilum and renal artery, but the inferior suprarenal arteries may originate from
runs inferomedially to join the left renal vein. The posterior surface of either the abdominal aorta or the ipsilateral gonadal artery.
the gland is divided by a ridge into a lateral area adjoining the kidney
and a smaller medial area that lies in contact with the left crus of the Veins
diaphragm. The medial border lies lateral to the left coeliac ganglion Medullary veins emerge from the hilum to form a suprarenal vein,
and the left inferior phrenic and left gastric arteries, which ascend on which is usually single. The right vein is very short, and passes directly
the left crus of the diaphragm. and horizontally into the posterior aspect of the inferior vena cava. An
accessory right suprarenal vein is occasionally present and runs from
the hilum superomedially to join the inferior vena cava above the right
VASCULAR SUPPLY AND LYMPHATIC DRAINAGE
suprarenal vein. The short course renders the right suprarenal vein(s)
vulnerable to injury or even avulsion from the inferior vena cava during
Arteries
surgery if undue traction is applied. The left suprarenal vein is longer
The suprarenal glands have one of the highest arterial flow rates per and descends medially, anterolateral to the left coeliac ganglion, then


gram of tissue (up to 5 ml/g/min) (Williams and Leggett 1989). Each passes posterior to the pancreatic body and usually drains into the left
gland is supplied by superior, middle and inferior suprarenal arteries, renal vein; it may receive the left inferior phrenic vein (Loukas et al
whose main branches may be multiple (Fig. 71.3). They ramify over 2005). Since the venous drainage from each gland is usually via a single


SuPRAREnAl (AdREnAl) glAnd
1196
8
nOITCES
Capsule
Zona
glomerulosa
Zona
Cortex
Secretes: fasciculata
Mineralo-
Zona
corticoids
reticularis
(including
aldosterone)
Medulla
Capsular
artery
Capsule
Secrete: Zona
glomerulosa
Glucocorticoids
(including cortisone)
Sex hormones
(including dehydroepi-
androsterone) Cortical
sinusoid
Zona
fasciculata
Preganglionic sympathetic terminal
Zona Medullary
reticularis arteriole
Secretes:
Adrenaline
Medullary
capillary
Medulla Medullary
Preganglionic sympathetic terminal vein
Secretes:
Noradrenaline
Fig. 71.4 The gross sectional appearance, microstructure, vasculature and ultrastructure of the suprarenal gland. Brief functional summaries are
included.


Suprarenal (adrenal) gland
1197
17
RETPAHC
C
ZG
Cx
M
ZF
ZR
Fig. 71.5 A cross-section through an adult suprarenal gland showing the cortex (Cx) and highly vascular medulla (M). The cortex is shown at higher
magnification to demonstrate the outer capsule (C), the zona glomerulosa (ZG), zona fasciculata (ZF) and zona reticularis (ZR). The boundaries between
zones are indistinct and variable. (Courtesy of Mr Peter Helliwell and the late Dr Joseph Mathew, Department of Histopathology, Royal Cornwall
Hospitals Trust, UK.)
vein, infarction of the gland is more likely to be caused by damage to sympathetic neurones). A smaller proportion of postganglionic sympa-
a suprarenal vein than to one of the suprarenal arteries. thetic nerve fibres innervate cortical blood vessels. Other nerve fibres
Understanding variant suprarenal venous anatomy is important to containing a variety of neurotransmitters have been identified within
avoid bleeding during minimally invasive adrenalectomy, particularly the suprarenal cortex and may be involved in modulating steroid
in patients with large tumours and phaeochromocytomas. Cadaver hormone secretion. The cell bodies of afferent nerve fibres arising in
studies have shown little variation in suprarenal venous anatomy but the suprarenal medulla are almost all located in dorsal root ganglia,
suggest that variants are more commonly found on the right (Cesme- although some lie in vagal ganglia; their precise function is unknown
basi et al 2014). However, a small clinical series showed that there may (Mravec 2005).
be a higher rate of suprarenal vein variants in patients with phaeochro-
mocytoma (Parnaby et al 2008).
Anticipating variant suprarenal venous anatomy is key to minimiz- MICROSTRUCTURE
ing bleeding during laparoscopic adrenalectomy, particularly in patients
with large tumours or phaeochromocytomas. Sholten et al (2013) In section, the suprarenal gland has an outer cortex, which is yellowish
reported variant suprarenal veins in 13% of individuals undergoing in colour and forms the main mass, and a thin medulla, forming about