ANATOMY OF GALLBLADDER
INTRODUCTION
Understanding the anatomy of gall bladder and the extra hepatic biliary system is essential to all surgeons. Caring for patients with hepato-biliary and other disorders. This concept is underscored by the recognition that these organs are in juxtaposition to a number of major vascular structures as well as other viscera of both, gastrointestinal and genitourinary tracts. For the sake of ease we can study it under the following major headings,
A. Embryology or developmental Anatomy.
B. Histology or microscopic Anatomy.
C. Surface anatomy.
D. Gross or Macroscopic Anatomy.
E. Developmental anomalies.
DEVELOPMENTAL ANATOMY
Knowledge of the developmental anatomy is essential because gall bladder and biliary anomalies are not uncommon and the failure to recognise such a congenital problem can result in significant peri-operative morbidity.
When the embryo is 3 mm in size the liver primodium appears in the middle of the third week (approximately 25 days) as an out growth of the endodermal epithelium at the distal end of the foregut. This outgrowth known as the hepatic diverticulum or liver bud, consists of the rapidly proliferating cells strand which penetrate the septum transversum, that is the mesodermal plate between the pericardial cavity and the stalk of the yolk sac. At this stage embryo is 32 days old approximately and 5 mm in size. While the hepatic cell strands continue to penetrate in the septum, the connection between the hepatic diverticulum and the foregut [duodenum] narrows, thus forming the bile duct. A small ventral outgrowth is formed by the bile duct and this out growth gives rise to the gall bladder and cystic duct. The embryo is now approximately 36 days old and of 9 mm in size. Initially the gall bladder is a hollow organ, but as a result of proliferation of its epithelial lining it becomes temporarily solid. The definite lumen develops by re-canalisation of the epithelium. The intra and extra hepatic ducts also go through a solid stage in their development.
During further development, the epithelial liver cords intermingle with the vitelline and the umbilical veins forming the hepatic sinusoids. The liver cords differentiate into parenchyma and form the lining of the biliary ducts.
As a result of its continuous rapid growth, the liver becomes too large for the confines of the septum transversum and begins gradually to protrude into the abdominal cavity. As the embryo grows older the mesoderm of the septum between the ventral abdominal wall and the liver becomes stretched and very thin, thus forming a membrane called the falciform ligament. The umbilical vein originally found in the mesoderm of the septum now occupies a position in the free, caudal margin of the falciform ligament. The umbilical vein, originally found in the mesoderm of the septum, now occupies a position in the free, caudal margin of the falciform ligament. Similarly, the mesoderm or the septum between the liver and the foregut [stomach and the duodenum] becomes stretched and membranous, thereby forming the lesser omentum. [ gastrohepatic and gastroduodenal ligament ]. In the free margin of the lesser omentum are found the bile duct, the portal vein and the hepatic artery.
MICROSCOPIC ANATOMY
HISTOLOGY OF THE GALL BLADDER
The gall bladder is a blind pear shaped diverticulum of the common hepatic duct, to which it is connected by cystic duct. Occasionally, embryonic bile duct, Lushka’s duct are seen in the connective tissues that open into bile duct of liver. These embryonic remnants never communicate with the lumen of this organ. The gall bladder is approximately 3 inches (8 cm) in length and 1.5 inches (4 cm) in diameter but is capable of considerable distension. Its wall is composed of three layers:
1. The mucous membrane.
2. The muscularis.
3. The adventitia (serosa).
1. Mucous Membrane
When empty the mucosa is thrown into folds, or rugae, and thus is irregular in section, often with the appearance of simple glands. All epithelial cells are similar, tall columnar cells, with basely located nuclei. Electron microscopy a fine microscopic apical border cilia lining the apical membrane of ductular cells with lateral borders nearest the lumen exhibiting the zonula occuludens, and basal borders showing folds. A fine basal lamina and a lamina propria of delicate, reticular connective tissue support the cells with numerous small blood vessels provided by cystic artery and cystic veins, with some of the venous blood being returned to the sinusoids of the liver. Occasional small lymph nodules are present, with a few mucous glands at the neck of the gall bladder. These glands occur more frequently in individuals with chronic inflammation of this organ along with abnormal folds of the epithelium. Rokitansky Aschoff sinuses. The later are not glands and may extend as far as the perimuscular connective tissue layer.
2. Muscularis
There is no submucosa in the gall bladder and external to the mucosa is a layer of smooth muscle, irregular in thickness and orientation of its component bundles. In any section, smooth muscle will be cut in all possible planes, for the muscularis is a meshwork of interlacing bundles of smooth muscle fibres between which are collagenous, reticular and some elastic fibres.
3. Adventia or Serosa
The gall bladder lies on the inferior surface of the liver and its outer coat of dense fibroconnective tissue blends in some regions with that of the Glisson’s capsule. Elsewhere, the adventitia is covered by peritoneum. The neck of the gall bladder continues into cystic duct, and here mucous membrane is thrown into a spiral fold with a core containing smooth muscle. This is termed spiral valve of Heister.
HISTOLOGY OF EXTRA HEPATIC BILIARY PASSAGES
Extrahepatic Ducts
These all are lined by a tall columnar epithelium that secretes mucus. There is a layer of sub epithelial connective tissue with preponderance of elastic fibres and a marked lymphoid tendency. Many lymphocytes and occasional granulocytes are found migrating through the epithelium into the lumen. In the subepithelial layer, there may be accumulations of tubuloacinar glands, mostly mucous in types and blood vessels and nerves are prominent. In the common bile duct, there is also a layer of smooth muscles, at first composed of isolated bundles of smooth muscle fibres but, near the duodenum, forming a complete investment of oblique and transverse fibres. This layer, particularly the circular fibres, is thickened at the termination of the common bile duct (the sphincter of Boyden) and around the ampulla of the conjoined bile and pancreatic ducts just proximal to the ampullary opening into the duodenum (the sphincter of Oddi). At the opening into the duodenum (the ampulla of Vater), the mucosa shows a valve-like fold protruding into the lumen. Because the common bile duct traverses the lesser omentum, it is covered by peritoneum.
SURFACE ANATOMY
Although the mobile abdominal viscera are inconstant in position the surface marking of the fundus of the gall bladder is of clinical value.
SURFACE MARKING OF THE FUNDUS OF THE GALL BLADDER
This projects below the inferior border of the liver [it extend along a line which passes from the right tenth costal cartilage to left fifth rib at the mid clavicular line] at the point where the linea semilunaris crosses the tip of the ninth costal cartilage in the transpyloric plane.
SURFACE MARKING OF THE COMMON BILE DUCT
The position of the bile duct is indicated on the anterior abdominal surface by a line starting 5 cm above the transpyloric plane and 2 cm right of the median plane and descending vertically for 7.5 cm.
MACROSCOPIC ANATOMY
INTRODUCTION
The biliary apparatus collects bile from the liver, stores it in the gall bladder, and transmits it into the second part of the duodenum. The apparatus consists of:
(i) The Right and the Left Hepatic Ducts
(ii) The Common Hepatic Duct
(iii) The Gall bladder
(iv) The Cystic Duct
(v) The Bile Duct
(i) RIGHT AND LEFT HEPATIC DUCTS:
DIAMETERS: RIGHT – 3 mm, LEFT 5 mm
The right and the left hepatic ducts emerge at the porta hepatis from right and left lobes of the liver in the shape of ‘V’. Left hepatic duct has a greater propensity for dilatation as a consequence of distal obstruction. The right hepatic duct has a very short extra hepatic course and it is about 1 cm long.
ARRANGEMENTS:
The arrangement of structures at the porta hepatis, from behind forwards, is the branches of the portal vein, hepatic artery and hepatic ducts.
(ii) COMMON HEPATIC DUCT:
SIZE: About 4 cm [1.5 inches] long.
COURSE:
The main right and left hepatic ducts near the right end of the porta hepatis as the common hepatic duct unite near the right end of the porta hepatis as the common hepatic duct which descends about 3 cm before being joined on its right at an acute angle by the cystic duct to form the main bile duct. It makes up the left border of the triangle of Calot.
ARRANGEMENTS:
The common hepatic duct lies to the right of the hepatic artery and anterior to the portal vein.
(iii) GALL BLADDER:
“ A reservoir for bile” Shown in figure 1.
NUMBER: Single
COLOUR: Slate Blue
SHAPE: Piriform or pear-shaped sac.
DIMENSIONS: It is a hollow organ. 7-10 cm long, 3 cm broad at its widest.
CAPACITY: 30-50 ml
POSITION:
It is normally present in the Right hypochondrium. It is partly sunk in a fossa in the right hepatic lobe’s inferior surface. It extends forwards from a point near the right end of the porta hepatis to the inferior hepatic border. Its upper surface is attached to the liver by connective tissue, else where it is completely covered by peritoneum continued from hepatic surface. Occasionally it is completely invested by peritoneum and even connected to the liver by short mesentery. It typically lies in close proximity to the duodenum, pylorus, and hepatic flexure of the right colon and right kidney.
PARTS:
For descriptive purposes it is divided into the following:
(a) Fundus
(b) Body
(c) Neck
(d) Infundibulum
(a) FUNDUS:
The fundus is rounded blind expanded end, projects down forwards and to the right, extending beyond the inferior border to contact the anterior abdominal wall behind the ninth right costal cartilage, where the lateral edge of the right rectus abdominis crosses the costal margin. It is generally the least well vascularised portion of the gall bladder and therefore it is more susceptible to ischemic changes, including perforation.
RELATIONS:
ANTERIORLY: Anterior abdominal wall.
POSTERIORLY: The transverse colon near its commencement. [These relations change when the gall bladder is lower, as it is often in slender Females]
(b) BODY:
The body is directed up, back and to the left, near the right end of the porta, it is continuous with the bladder neck.
RELATIONS:
ABOVE: Liver.
BELOW: Transverse colon.
POSTERIORLY: Upper end of the second segment of the duodenum.
(c) NECK:
The neck [cervix] is narrow, curving up and forwards and then abruptly back and downwards, to become the cystic duct, at which transition there is a constriction. The neck is attached to the liver by loose connective tissues containing the cystic artery. The mucosa of the neck is obliquely rigid, forming a spiral groove.
RELATIONS:
SUPERIORLY: Liver
INFERIORLY: First part of the duodenum.
(d) INFUNDIBULUM:
Also known as the Hartman’s pouch which is a small bulbous diverticulum. From the right side of the neck a small recess may project down and back towards the duodenum. It has been widely regarded as a constant feature, but Davies and Harding [1942] have shown that it is always a Sequa of pathological states, especially dilatation, when it is large the cystic duct arises from its upper left aspect and not from what appears to be gall bladder’s apex. Gallstones lodged in the pouch may cause adhesions with the duodenum or bile duct, and may perforate into any one of them.
(iv) CYSTIC DUCT:
SHAPE: ‘S’ Shaped
SIZE: 3-4 cm [1.5 inches approximately]
COURSE:
It passes back, down and to the left from the neck of the gall bladder, joining the common hepatic duct to form the bile duct. It is adherent to the common hepatic duct for a short distance before joining it, usually near the porta hepatis but sometimes lower, in which case the cystic duct lies along the lesser omentum’s right edge. It’s mucosa bears five to 12 cresentric folds like those in the gall bladder’s neck. They project obliquely in regular succession, appearing like a “Spiral valve” [of Heister]. The function of the spiral valve is believed to be strengthening of the wall and assisting in keeping the lumen open. When the duct is distended, the spaces between the folds dilate and externally it appears twisted like the neck of the gall bladder.
(v) BILE DUCT:
The bile duct is formed near the porta hepatis, by the junction of the cystic and common hepatic ducts. According to its course it has 4 parts,
(a) Supra duodenal portion
(b) Retro duodenal portion
(c) Infra duodenal portion
(d) Intra duodenal portion
DIMENSIONS: ABOUT 7.5 cm long and 6 mm in diameter.
COURSE:
The bile duct runs downwards and backwards, first in the free margin of the lesser omentum [Supra duodenal portion] then behind the first part of the duodenum [retro duodenal portion] and lastly behind or embedded in the head of the pancreas [infra duodenal portion]. Near the middle of the left side of the second part of the duodenum it comes in contact with pancreatic duct and accompanies it in the wall of the duodenum, where the two ducts unite to form the hepato-pancreatic ampulla or ampulla of Vater. The common channel is believed to be quite important in the pathogenesis of the gall stone pancreatitis. The distal constricted end of ampulla opens at the summit of the major duodenal papilla [8-10 cm distal to pylorus]. The opening is guarded by the sphincter of the ampulla [of Oddi]. The intramural part of the bile duct before it enters the ampulla of Vater is surrounded by the sphincter of the bile duct [of Boyden] [Intra duodenal portion]
RELATIONS
A. SUPRA DUODENAL PART [IN THE FREE MARGIN OF THE LESSER OMENTUM]
1. ANTERIORLY: Liver
2. POSTERIORLY: Portal vein and epiploic foramen.
3. TO THE LEFT: Hepatic artery.
B. RETRO DUODENAL PART:
1. ANTERIORLY: First part of the duodenum
2. POSTERIORLY: Inferior vena cava
3. TO THE LEFT: Gastro duodenal artery
C. INFRA DUODENAL PART:
1. ANTERIORLY: A Groove in the upper and lateral parts of the posterior surface of the head of the pancreas.
4. POSTERIORLY: Inferior vena cava
BLOOD SUPPLY OF BILIARY APPARATUS:
1. Cystic artery is the chief source of blood supply and is distributed to gall bladder, cystic duct, and hepatic duct upper part of the bile duct.
2. Several branches from the posterior superior pancreaticoduodenal artery supply the lower part of the bile duct.
3. Right hepatic artery forms a minor source of supply to the middle part of the bile duct.
4. Accessory cystic artery may arise from the common hepatic artery or from one of its branches.
COURSE:
The cystic artery usually arise from the right hepatic artery passes behind the common hepatic and cystic duct in the Calot’s triangle and reach the upper surface of the neck of the gall bladder, where it divides into superficial and deep branches. Occasionally, the cystic artery arises from the hepatic artery proper, and rarely from the gastroduodenal artery. Then it passes in front of, or behind, the bile duct or the common hepatic duct, to reach the upper surface of neck of gall bladder.
VENOUS DRAINAGE
1. The superior surface of gall bladder drains directly into the hepatic veins through the gall bladder fossa.
2. Rest of gall bladder drains by one or two cystic veins, which commonly enter the liver, either directly or after joining the veins draining the hepatic duct and upper part of the bile duct. Only rarely the cystic vein opens into the right branch of portal vein.
3. The lower part of the bile duct drains into the portal vein.
LYMPHATIC DRAINAGE
1. Lymphatics from the gall bladder cystic duct, hepatic duct and upper part of the bile duct pass to the cystic node and the node of the anterior border of the epiploic foramen; these are the most constant members of the upper hepatic nodes. The cystic nodes lie in the angle between the cystic and the common hepatic ducts; it is constantly enlarged in the cholecystitis.
2. The lower part of the bile duct drains into the lower hepatic and the upper pancreaticosplenic nodes.
NERVE SUPPLY:
The cystic plexus of nerves, supplying the territory of the cystic artery is derived from the hepatic plexus, which receives fibres from the coeliac plexus, left and right vagus and the right phrenic nerves. The nerve plexus supplies the lower part of the bile duct over the superior pancreaticoduodenal artery.
Parasympathetic nerves are motor to musculature of the gall bladder and bile ducts, but inhibitory to the sphincters of the bile duct. Gall bladder pain via vagus is referred to stomach.
Sympathetic nerves (T 7-9) are vasomotor and motor to sphincters. Pain via sympathetic nerves is referred to the inferior angle of the scapula.
Pain via the phrenic nerve is referred to the right shoulder.
ANATOMIC RELATIONSHIP IN LAPAROSCOPIC CHOLECYSTECTOMY:
A thorough knowledge of the anatomy of the extrahepatic biliary tree and its frequent anatomic variants is essential for performance of safe laparoscopic cholecystectomy. The surgeon should have an appreciation of for the distortion in the anatomy as a result of retraction on the gallbladder and how the direction of the retraction alters the spatial relationship between the cystic duct and the common bile duct. Good exposure will enable the surgeon to identify anatomic variants and optimise identification of structures. The hepatocystic or "Calot's triangle" is of key significance to the surgeon during laparoscopic cholecystectomy because a number of important structures lie close to 20.
ANOMALIES
a. ANOMALIES OF THE GALL BLADDER
b. ANOMALIES OF THE DUCTS
c. ANOMALIES OF BLOOD VESSELS
I. ANOMALIES OF GALL BLADDER:
SIGNIFICANCE:
Anomalies of the gall bladder per se are generally of minimal clinical significance. In rare circumstances they may be associated with more severe lesions, including cardiac malformations and polycystic kidneys and a variety of musculoskeletal defects. Anomalies of the gall bladder are as follows.
(i)ABNORMAL NUMBER:
a. HYPOPLASIA OR AGENESIS OF GALL BLADDER
It is due to the failure of the distal end of cystic duct to expand. There is a high incidence of common bile duct stones and duct dilatation in patients with agenesis of gall bladder. Autopsy incident of absent gall bladder is 0.03 %- 0.06% with an equal male to female ratio but clinical cases are more common among the females when the ratio is about 21-12. Shah and Askari has reported two case in Pakistan in 1989 21.
b. DOUBLE GALL BLADDER: With two or combined cystic ducts. Double gallbladder has been reported by Esper et al 22. Double gallbladder is shown in figure 2.
(ii) ABNORMAL SHAPE:
a. PHRYGIAN CAP OR FOLDED FUNDUS.
In which the gall bladder fundus is constricted and turned back on itself and appears segmental on contrast studies. Its incidence is 2-6%. Figure 3.
b. BILOBULATED GALL BLADDER.
This is an exaggerated form of the above.
c. HOUR GLASS GALL BLADDER
(iii) DIVERTICULUM OF THE GALL BLADDER
(iv)ABNORMAL POSITION OF THE GALL BLADDER
a. INTRAHEPATIC GALL BLADDER.
It is the most common anomaly. It is so common that it is typically not even considered to be abnormal. While of no specific pathologic concern, a true intra hepatic gall bladder may present some technical difficulties for the surgeon at the time of either open or laparoscopic cholecystectomy.
b. TRANSPOSITION OR LEFT SIDED GALL BLADDER:
It is found under the left lobe of the liver or in between the two lobes of the liver or in between the two lobes.
c. FALCIFORM LIGAMENT:
Occasionally, the gall bladder may lie to the left of the falciform ligament. This anomaly results from a failure during the rotational phase of embryonic development.
d. ABDOMINAL WALL
e. RETRODISPLACEMENT:
Fundus extends backwards into the free margin of the lesser omentum.
f. RETROPERITONEAL
(v) TRABECULATED GALL BLADDER:
This leads to impaired function of gall bladder.
(vi) ABNORMAL MESENTERY
a. ABSENT MESENTERY
b. LONG MESENTERY OR FLOATING GALL BLADDER:
A common anomaly occurs when the gall bladder is attached to the liver by a large mesentery. This variant may predispose to torsion of the gall bladder a rare but reported occurrence. It occurs in 5% of the cases.
(vii) ATRESIA OF GALL BLADDER:
Initially the gall bladder is a hollow organ, but, as a result of proliferation of its epithelial lining, it becomes temporarily solid. The definitive lumen develops by recanalisation of the epithelium when this fails to occur, the gall bladder remains atretic and does not develop. Agenesis was reported by Gardezi, 2 in a series of 910 cases 23.
(viii) MISCELLANEOUS:
a. PRESENCE OF ECTOPIC HEPATIC TISSUE WITHIN THE WALL OF GALL BLADDER
b. PRESENCE OF ECTOPIC PANCREATIC TISSUE WITHIN THE WALL OF GALL BLADDER
c. PRESENCE OF ECTOPIC TISSUE WITHIN THE WALL OF GALL BLADDER
II. ANOMALIES OF THE DUCT:
SIGNIFICANCE:
Anomalies of the cystic duct and bile duct are of much greater clinical significance than the defect of the gall bladder. Over 50 percent of all patients undergoing a biliary tract procedure will have either a ductal or an arterial anomaly. Failure to recognise the abnormalities of the cystic duct –common bile duct junction is a commonly reported cause of inadverent bile duct injury during cholecystectomy. These are as follows
B. ANOMALIES OF THE CYSTIC DUCT:
1. ABSENCE OF CYSTIC DUCT:
Here neck of gall bladder directly opens into the common bile duct.
2. TWO CYSTIC DUCTS
When double gall bladder is present.
3. LOW INSERTION OF THE CYSTIC DUCT:
Cystic duct runs parallel to the common bile duct unusually long distance before joining this structure. The cystic duct opens in common bile duct near the Ampulla of Vater. This occurs in up to 25 percent of patients.
4. HIGH INSERTION OF THE CYSTIC DUCT:
The cystic duct may join the common hepatic duct either in the confluence or in proximal part in 2 percent.
5. Cystic duct drain in the right hepatic duct.
6. Cystic duct drains into the left hepatic duct.
7. Cystic duct drains into the anterior wall of the common bile duct.
8. Cystic duct opens into the posterior wall of the common bile duct.
9. The spiral cystic duct runs down and behind the common hepatic duct to enter on its medial aspect in 35%.
10. The cystic duct may also run a parallel course with the bile duct both being enclosed in the common fibrous sheath. 5-7%
11. Long cystic duct entering the common duct close to the duodenum.
Anomalies are shown in figure 4, and 5.
A. ANOMALIES OF HEPATIC DUCT:
1. ACCESSORY HEPATIC DUCT:
It may emerge more often from the right lobe to join the main hepatic duct or, rarely, the gall bladder itself. Also known as bile duct of Lushka and about 1-2 mm in diameter. It is present in 1% of the cases. If these are overlooked during removal of the gall bladder, persistent leakage of bile results from the bed. (As shown in figure no 6)
EXTRA-HEPATIC BILIARY ATRESIA
The extra-hepatic duct go through a solid stage in the development. If the lumen fails to reopen, the ducts will appear as narrow fibrous cords. The gall bladder and the hepatic duct proximal to the atresia are then considerably distended and severe, steadily increasing jaundice will become obvious after birth.
B. CHOLEDOCHAL CYST:
Cystic disease may involve any portion of the intrahepatic or extrahepatic biliary tract. This is heterogenous congenital disorder. These lesions are present in fewer than 1 in 50,000 live births. It is more in females. Excision of the cyst as the treatment of choice. The highest rates are seen in Chinese and Japanese population. About 60% of the cases are diagnose in first 10 years of life. Female to male ratio is 4:1 24. Whereas Khattak et al has described this ratio as 3.2:1 25. Both show female predominance.
They are classified as:
TYPE I- cystic dilatation of the common bile duct.
TYPE II single bile duct diverticulum
TYPE III cystic dilatation of the intraduodenal portion of the bile duct [choledochocele].
TYPE IV A combination of extra hepatic and intra hepatic cystic cysts.
TYPE IV B multiple cysts with the extra hepatic ducts.
TYPE V multiple diffuse dilatations of the intra hepatic ducts. Caroli,s disease.
D. ANOMALIES OF THE COMMON BILE DUCT
1. DIFFERENT WAYS OF OPENING OF COMMON BILE DUCT AND MAIN PANCREATIC DUCT INTO THE DUODENUM
These are as follows,
a. Both ducts may open independently into the ampulla of Vater.
b. Both ducts may not join, but each may separately enter and discharge on the eminence of the duodenal papilla.
c. Both ducts may join together extraduodenally to form a common channel and then open into the duodenum.
2. ABSENT COMMON BILE DUCT
The right and left hepatic ducts join the gall bladder and the duct draining the gall bladder takes the course of normal common bile duct to the duodenum. It is very rare.
3. ACCESSORY BILE DUCT:
4. ABNORMAL OPENING OF THE COMMON BILE DUCT:
In 6% patients, the common bile duct runs a longer course terminating either in the angle between the 2nd and 3rd part or in the third part of the duodenum.
5 ATRESIA OF THE COMMON BILE DUCT:
Occasionally atresia is limited to a small portion of the bile duct only.
III ANOMALIES OF BLOOD VESSELS:
SIGNIFICANCE:
Arterial anomalies are also quite common and need to be recognised during surgery on the biliary tract to minimise the chance of intra-operative complications. It includes
A. ANOMALIES OF HEPATIC ARTERY
B. ANOMALIES OF CYSTIC ARTERY
A. ANOMALIES OF HEPATIC ARTERY:
Due to anomalous origin or the mis identification of the right hepatic artery can be injured during cholecystectomy.
1. ANOMALOUS ORIGIN
a. Right hepatic artery arising from the superior mesenteric artery, this is most common and it occurs in up to 20% of patients.
b. In 5% of the patients two hepatic arteries are seen and from common hepatic and other from the superior mesenteric artery.
c. Common hepatic artery coming off from the superior mesenteric artery.
d. The left hepatic artery arising from the left gastric artery.
e. Double hepatic arterial system with one arising from common hepatic and other arising from superior mesenteric artery.
2. ANOMALOUS COURSE:
a. The right hepatic artery lying anterior to the common hepatic duct –it is of particular importance during performance of biliary tract surgery.
b. CATERPILLAR TURN OR MOYNIHAN'S HUMP: It is the most dangerous anomaly. It occurs when the hepatic artery takes a tortuous course in front of the origin of the cystic duct or the right hepatic artery is tortuous, and the cystic artery is short. This tortuosity is known as Moynihan’s hump. The presence of the "caterpillar hump" right hepatic artery should be suspected when an unusually large "cystic artery" is viewed through the laparoscope 26.
ANOMALIES OF CYSTIC ARTERY
The cystic artery arises from the hepatic artery within the hepatocystic triangle in approximately 80% of the individuals 27. As it crosses the hepatocystic triangle, the cystic artery often supplies the cystic duct with one or more of its branches. Although generally over looked in the open cholecystectomy these branches can cause severe bleeding during laparoscopic cholecystectomy. Anatomic variations of the cystic artery are recognised in 50% of the individuals 28. (As show in figure 7).
a. ACCESSORY CYSTIC ARTERY: It arises from the gastroduodenal artery.
b. Cystic artery can be on occasion be a branch from the
-Left hepatic artery
-Main hepatic artery
-Coeliac axis
c. In 15 percent of the cases the cystic artery cross in front of the common hepatic duct and cystic duct.
d. In 20% of the cases double cystic arteries are seen one or both of which may arise from the right hepatic artery or one may have an abnormal origin 29 like,
- other from gastroduodenal or hepatic artery
- other from the hepatic artery and crossing the common hepatic duct anteriorly
e Two cystic arteries arising from the right hepatic artery. Right hepatic artery is adherent to the cystic duct and neck of the gall bladder. Posterior cystic artery is very short.
