Abdomen Flashcards
Appendix: Gross anatomy
- Arises approximately 2-3cm inferior to the ilioceacal valve, at the convergence of the teni coli.
- Variable length 2-20cm
- Has a mesentery – mesoappendix
- Variable position of the tip: retrocaecal, pelvic, pre or post-ileal
Appendix: Neurovasculature
- Arterial: Appendicular artery a branch of the ilicolic artery
- Venous: Similar named veins draining into the portal system
- Lymphatics: Superior mesenteric group
- Innervation: Superior mesenteric
Appendix: Relations
- Anterior: Parietal peritoneum, loops of small bowel
- Posterior: Iliacus and psoas muscles, femoral nerve
- Medial: Terminal ilium
- Lateral: iliacus and psoas muscles
- Superior: ileocecal valve
- Inferior: lateral third of the inguinal ligament
Appendix: Variants
- Position
- retrocecal (65-70%)
- pelvic (25-30%)
- pre- or post-ileal (5%)
- promontory
- paracaecal
- subcecal
- Variants
- additional arterial supply from accessory appendicular artery
- duplex appendix: very rare
- agenesis of the appendix
Biliary Tree: Description:
The biliary tree is the system of biliary vessels of the liver and abdomen
Location:
Intrahepatic and within the free edge of the lesser omentum
Biliary tree: Gross Anatomy
Dividable into intrahepatic and extrahepatic ducts
Each liver segment has its own biliary drainage duct, where biliary canaliculi unite to form segmental ducts. There ducts join to form:
- Right posterior duct
- Right anterior duct
- Right hepatic duct
- Left hepatic duct
Biliary Tree: Course
The right and left hepatic duct unite to form the common hepatic duct, segment I drains directly here also. The common hepatic duct then leaves the liver parenchyma.
The common hepatic duct is joint by the cystic duct of the gallbladder arfter ~2-3cm, they unite to form the common bile duct.
The common bile duct runs in the free edge of the lesser omentum, behind the head of the pancreas to join with the main pancreatic duct forming the ampulla of Vater draining into the D2 via the sphincter of oddi.
Biliary Tree: Neurovasculature
Blood supply:
- Right and left hepatic artery
- Cystic artery
- Branches of the common hepatic artery
- Posterior pancreaticoduodenal artery branches
- Gastroduodenal artery
Venous:
- Into the portal system
Lymphatics:
- Porta hepatis nodes
- Coeliac nodes
Innervation:
- Coeliac plexus
Biliary Tree: Relations
At the porta hepatis:
The common hepatic duct lies in front and is to the right of the hepatic artery, the portal vein is between the two
Biliary Tree: Variants
Cystic duct:
- Duplication
- Low insertion
- High insertion
- Cystic artery posterior to the right hepatic duct
Common hepatic duct:
- Triple confluence
- Aberrant hepatic duct
- Non-union of the left and right hepatic ducts
CBD:
- May pass behind through or around the pancreatic head
- Variable location of the ampulla
- CBD may drain separately from the main pancreatic duct
- Pancreatic divisum
Extrahepatic Biliary Tree: Description
The extra hepatic biliary tree is the system responsible for the drainage and storage of bile from the liver to the D2 segment of the duodenum.
Extrahepatic biliary tree: Gross Anatomy
The left and right intrahepatic ducts join to form the common hepatic duct which leaves the liver parenchyma at the porta hepatis anterior to the hepatic artery and to the right of the portal vein.
The common hepatic duct joins the cystic duct to form the common bile duct.
The common bile duct initially travels in the free edge of the lesser omentum, then courses posterior to the duodenum and the pancreas joining the main pancreatic duct to form the ampulla of Vater.
The ampulla of Vater drains into D2 via the major duodenal papillae
Extrahepatic Biliary Tree: Neurovasculature
Arteries:
- Cystic
- Right hepatic
- Posterior superior pancreaticoduodenal artery
Venous:
- Drains to portal vein
Lymphatics:
- Porta hepatis
- Coeliac
Extrahepatic Biliary Tree: Variants
Cystic duct:
- Low insertion
- Medial insertion
- Parallel course
- Cystic artery anterior to the cystic duct
Common hepatic duct:
- Triple confluence
- Aberrant hepatic duct
- Non-union of the right and left hepatic ducts
Common bile duct:
- Partially covered posteriorly
- Completely covered
- Completely uncovered
- Lateral to pancreatic head
Caecum: Description
- The caecum is the first section of the large bowel
- Location: typically located in the right iliac fossa, considered and intraabdominal segment of large bowel
- Function: Receive the contents of the small bowel, dilates to accommodate this contents and gas production
Caecum: Gross Anatomy
- Sac like structure
- Diameter typically from 3-9cm
- Covered in visceral peritoneum typically has a short mesentery
- 3 teni coli
- Haustral folds of the bowel wall between the teni
- Vermiform appendix has its origin at the base of the ceacum
- Fat containing ileocecal valve (one was between the ilium and the caecum)
Caecum Neurovasculature
Arterial supply:
- Anterior and posterior caecal arteries from the colic artery from the ileocolic trunk of the superior mesenteric artery
Venous drainage:
- Anterior and posterior caecal veins into the portal system via the superior mesenteric vein
Innervation:
- Superior mesenteric plexus and vagal trunks
Lymphatics:
- Local mesenteric nodes
- Superior mesenteric nodes
Caecum: Relations
- Posterior: iliacus muscle, psoas muscle, femoral nerve, lateral femoral cutaneous nerve
- Anterior: anterior abdominal wall, parietal peritoneum
- Lateral: iliacus
- Medial: terminal ilium
- Inferior: appendix, lateral third of the inguinal ligament
- Superior: large bowel continues as the ascending colon
Caecum: Variants
- May be on a long mesentery
- Absence of a mesentery
- Location anywhere in the intraabdominal cavity
Duodenum: Description
- The duodenum is the first part of the small intestine
- Location: between the pylorus of the stomach and the jejunum, in the anterior pararenal space
- Function: Alkalinisation of chym, mixing of bile with chyme, sensing of chyme to produce gastrointestinal reflexes
Duodenum: Gross Anatomy
- D1 (5 cm)
- commences at the pylorus and passes backward, upward, and to the right, beneath the quadrate lobe to the body of the gall-bladder
- intraperitoneal for first 2-3 cm
- D2 (7.5 cm)
- descends along the right margin of the head of the pancreas, generally to the level of the upper border of the body of L3
- pancreatic duct and CBD enter the descending duodenum through the major duodenal papilla (ampulla of Vater)
- also contains the minor duodenal papilla, the entrance for the accessory pancreatic duct
- junction between the embryological foregut and midgut lies just below the major duodenal papilla
- D3 (10 cm)
- takes a second bend, and passes from right to left across the vertebral column
- D4 (2.5 cm)
- ascends and ends opposite L2
- unites with the jejunum, forming the duodendojejunal flexure
- DJ flexure is surrounded by a peritoneal fold containing muscle fibres (ligament of Treitz)
Duodenal Segments
- D1 from the pylorus of the stomach courses to the right, features duodenum bulb
- D2 from the D1 segment descending approximately 3-4cm, features major and minor duodenal papilla
- D3 from D2 turn to the left around the pancreatic head course
- D4 from D3 continues to course to the left however also ascends to the ligament of Treitz, after the small bowel continues as the jejunum
Duodenal Relations
- D1
- anteriorly - gallbladder, quadrate lobe of liver
- posteriorly - common bile duct, portal vein, gastroduodenal artery
- superiorly - epiploic foramen
- inferiorly - pancreatic head
- D2
- anteriorly - transverse mesocolon
- posteriorly - right kidney, right ureter, right adrenal gland
- superiorly - liver, gallbladder (variable)
- inferiorly - loops of jejunum
- laterally - ascending colon, hepatic flexure, right kidney
- medially - pancreatic head
- D3
- anteriorly - small bowel mesentery root, SMA, SMV
- posteriorly - right psoas muscle, right crus of diaphragm, right ureter, gonadal vessels, aorta and IVC
- superiorly - pancreatic head / uncinate process
- inferiorly - loops of jejunum
- D4
- superiorly - stomach
- inferiorly - loops of jejunum
- posteriorly - left psoas muscle, aorta, left renal vessels
Duodenum: Neurovasculature
Arterial supply:
- Duodenal cap (first 2.5cm) - supraduodenal artery (branch of gastroduodenal artery)
- Remaining D1 to mid D2 - superior pancreaticodudenal artery (branch of gastroduodenal artery)
- Mid-D2 to ligament of Trietz - inferior pancreaticoduodenal arteries (branch of SMA)
Venous drainage:
- Duodenal cap (first 2.5cm) - prepyloric vein (drains to portal vein)
- Remaining duodenum - superior pancreaticoduodenal vein (drains to portal vein) and inferior pancreaticoduodenal vein (drains to SMV)
Lymph drainage:
- Coeliac Nodes
- Superior Mesenteric Nodes
Nerve supply:
- Sympathetic nerve fibres via coelic and superior mesenteric trunks
- Parasympathetic nerve fibres via anterior and posterior vagal trunks
- Enteric nervous system
Duodenal variants
- Duodenal diverticulum - most commonly occurs in D2 or D3
- Duodenal duplication - most commonly occurs at the medial wall of D2 or D3
- appears as a cystic structure that does not communicate with the lumen
- Malrotation
- Duodenal atresia
- Third part can cross as low as L4
Jejunum: Description
The Jejunum is the proximal 2/5 of the small intestine
Jejunum: Gross Anatomy
- Approximately 3m in length
- More valvuae conniventes than the ileum
- Normal wall thickness 3mm
- The ileum has a smaller diameter 2.5cm vs 3cm jejunum
Jejunum: Relations
The jejunum lies in the free edge of the mesentery
Jejunum Neurovasculature
Arterial supply:
- Jejunal branches from the superior mesenteric artery
Venous:
- Jejunal veins draining into the SMV–>; portal
Lymphatic drainage:
- Superior mesenteric nodes
Innervation:
- Superior mesenteric plexus (vagus)
Ileum
The ileum is the final part of the small intestine
Gross anatomy:
- 2-4m in length
- Separated from the caecum by the ileocaecal value
- Relations etc at the same as for the jejunum
Differences between the jejunum and ileum:
Location:
- jejunum: upper left part of the peritoneal cavity
- ileum: lower right part of the peritoneal cavity
Gross appearance:
- jejunum: greater calibre (3 cm), thicker walls and more vascular
- ileum: lesser calibre (2 cm), thinner walls and less vascular
interior:
- jejunal folds (valvulae conniventes) are thicker (2-3 mm) than ileal folds (1-2 mm)
- jejunal folds are also more numerous and deeper than ileal folds
Mesentery:
- jejunum: less fat, longer vasa recta, fewer arterial arcades
- ileum: more fat, more arterial arcades, shorter vasa recta
Immunology:
- presence of aggregated lymphoid follicles (Peyer patches), more prominent in the ileum
Gall Bladder Description:
The gallbladder is a pear shaped musculomembranous sac that is part of the extrahepatic biliary system.
- Location: Within the gallbladder fossa
- Function: The storage and concentration of bile
Gallbladder Gross Anatomy
Gross anatomy:
- Typically 7 to 10 cm in length and 2.5 cm wide. Holding about 30ml of bile.
- Drains bile via the cystic duct, which joins the common hepatic duct to form the common bile duct
- The gallbladder is attached to the gallbladder fossa by connective tissues and vessels
- The under surface of the gallbladder is covered by peritoneum
Dividable into:
- Fundus
- Body
- Neck
Layers:
- Serosa
- Muscularis externa
- Lamina Propria
- Mucosa
Gallbladder: Relations
- Superior: Visceral surface of the liver
- Inferiorly: D2 segment of the duodenum
- Anteriorly: 9 th costal cartilage
- Posteriorly: Right kidney, distal D1
- Medial: D1, free margin of the lesser omentum and the epiploic foramen
- Laterally: the right lobe of the liver
Gallbladder: Neurovasculature
Blood supply:
- Cystic artery from the right hepatic artery
- Direct venous drainage into the liver
Innervation:
- Sympathetic: coeliac plexus
- Parasympathetic: via the anterior vagal trunk
Lymphatics:
- Drains into the portal nodes then to the coeliac nodes
Gallbladder: Variants
- Morphology
- Phrygian cap: the fundus is sometimes folded back upon itself
- Hartmann pouch (infundibulum): neck is focally dilated and probably pathological / related to cholelithiasis
- Number
- accessory gallbladder
- gallbladder bifid / duplication / triplication
- cystic duct may also be duplicated / tripled
- gallbladder agenesis
- gallbladder bifid / duplication / triplication
- accessory gallbladder
- Location
- left-lobe > intrahepatic > retrohepatic
- Cystic duct
- low cystic duct insertion - into the distal-third of the CHD
- medial cystic duct insertion - into the left, not the right, side of the CHD
- parallel cystic duct course - courses parallel to the CHD for at least 2cm
- cystic duct empties into the right posterior hepatic duct
Left kidney: Description
The kidneys are paired retropenritoneal organs. Function: production of urine, water and electrolyte homeostatsis, hormone production Location: Perirenal space, long axis parallel to psoas, lies on quadratus lumborum
Left Kidney: Gross Anatomy
- 9-14cm long, left usually larger than the right
- Bean shaped
- Fibrous capsule
- Divided in the superior, mid and inferior poles
- The parenchyma consists of cortex and medulla.
- The renal sinus consists of the renal pelvis, calyces, vessels, nerves, lymphatics and fat
- The renal cortex lie peripheral
- The medulla consists of 10-14 hilum facing pyramids, separated by renal columns
- Each pyramid drains into minor calyces via a papilla, which inturn 3-4 join to form the major calyces, of which 2-3 join to drain into the renal pelvis
Left kidney: Neurovasculature
- Arterial: right and left renal arteries from the abdominal aorta level L1
- Venous: Right and left renal veins into the inferior vena cava
- Innervation: Renal plexus
- Lymphatics: Peri-renal and para-aortic
Right Kidney: Relations
- Anterior: Hepatic flexure, liver
- Posterior: Diaphragm, quadratus lumborium
- Superior: right adrenal gland, liver
- Inferior: Right ureter
- Medial: duodenum, inferior vena cava
Left Kidney: Relations
- Anterior: Splenic flexure, stomach, lesser sac
- Posterior: quadratus lumborum
- Superior: Spleen
- Inferior: Left ureter
- Medially: Jejunum and pancreas
Kidney: Variants
Horseshoe, agenesis, cross fused renal ectopia, pancake, pelvic kidney, colomn of bertin, dromedary hump, accessory renal arteries, duplex collecting system, retrocaval ureter
Ureters: Description
The ureters are paired fibro-muscular tubes between the kidneys and urinary bladder.
Function: transport of urine
Location: Proximally in the pararenal space of the retroperitoneum
Ureters: Gross Anatomy
Gross anatomy:
Length: ~25cm in adults, 3mm in diameter
Divided into three parts:
- Abdominal ureter
- Pelvis ureter
- Intravesicular ureter
Ureters: Course
- Runs along the medial aspect of the psoas major
- ureter lies anteriorly and slightly medial to the tips of the L2-L5 transverse processes
- Enters the pelvis anteriorly to the sacroiliac joint at the bifurcation of the common iliac vessels (at the pelvic brim) and then courses anteriorly to the internal iliac artery down the lateral pelvic sidewall
- At the level of the ischial spine it turns forward and medially to enter the posterolateral wall of the bladder
- then runs an oblique 1-2cm course before opening into the bladder at the internal ureteric orifice
- in the male
- ureter crosses above the seminal vesicles and is crossed by the ductus deferens
- in the female
- ureter runs medial and forward on the lateral aspect of the cervix and upper part of the vagina to reach the fundus of the bladder
- here it is crossed by the uterine artery
- Constrictions of the ureter are the most common sites of stone obstruction
- pelvi-ureteric junction (PUJ)
- as the ureter enters the pelvis and crosses over the common iliac artery bifurcation
- vesicoureteric junction (VUJ)
Ureters: Relations
- Abdominal ureter
- posteriorly
- psoas muscle, genitofemoral nerve, common iliac vessels, tips of L2-L5 transverse processes
- anteriorly
- right ureter: descending duodenum (D2), gonadal vessels, right colic vessels, ileocolic vessels
- left ureter: gonadal artery, left colic artery, loops of jejunum, sigmoid mesentery and colon
- medially
- right ureter: IVC
- left ureter: abdominal aorta
- posteriorly
- Pelvic ureter
- posteriorly
- sacroiliac joint, internal iliac artery
- inferiorly
- male: seminal vesicle
- female: lateral fornix of the vagina
- anteriorly
- male: ductus deferens
- female: uterine artery (in the broad ligament)
- medially
- female: cervix
- posteriorly
Ureters: Neurovasculature
Arterial:
- Renal arteries
- Direct branches from the aorta
- Superior and inferior vesicular arteries
Venous:
Same veins – highly variable
Lymphatics:
Para-aortic
Internal and external iliac
Innervation: renal plexus and hypogastric plexus
Ureters: Variants
- Duplex collecting system
- bifid ureter
- ectopic insertion
- ureterocoele
Pancreas:Description
The pancreas is a mixed endocrine/exocrine organ of the gastrointestinal system
Location: anterior pararenal space
Function: Production of digestive fluid, control of metabolism
Pancreas: Gross Anatomy
Linear organ
Divided into:
- Head – thickest part, attached to the c loop of the duodenum, uncinated process extends posteriorly
- Neck – Thinnest part, lies anterior to the SMA and SMV, portal confluence
- Body - main part lies to the left of the SMA, SMV
- Tail – lies within the layers of the splenorenal ligament
Pancreatic secretions are drained by a system of pancreatic ducts that converge on the main pancreatic duct in the majority of individuals. This joins with the common bile duct forming the ampulla of Vater which typically drains into the 2 nd part of the duodenum by the sphincter of oddi.
Pancreas: Neurovasculature
Arterial supply:
- Branches from the Splenic Artery
- Superior Pancreaticoduodenal Artery (Gastroduodenal Artery)
- Inferior Pancreaticoduodenal Artery (SMA)
Venous drainage:
- Drains to the SMV and splenic veins and ultimately portal vein
Lymphatic drainage:
- Coeliac / Superior Mesenteric Nodes
Nerve supply:
- Spinal Cord Segment T6 to T10
- Vagal Trunks
Pancreas: Relations
- Head/Uncinate process
- Lodged within the curve of the duodenum
- Posterior: aorta, IVC, CBD, right renal vessels, right crus of the diaphragm, SMA, SMV
- uncinate process passes posterior to the SMV and SMA
- Anterior: small bowel
- Neck
- Antero-superiorly: pylorus
- Posterior: commencement of the portal vein
- Body
- Anterior: lesser sac
- Posterior: splenic vein, left kidney, left renal vessels, left suprarenal gland
- Superior: splenic artery
- Tail
- Extends to the splenic hilum
- Lies within the lienorenal ligament
Pancreas: Variants
Pancreas Divisum: MPD drains at minor duodenal papilla (incomplete: communication with duct of Wirsung vs complete: no communication with duct of Wirsung)
Annular Pancreas: ventral pancreatic bud fails to rotate resulting in ring of pancreatic tissue around second part of duodenum
Agenesis of Dorsal Pancreas: failure of the dorsal pancreatic bud to form the body and tail of the pancreas
Ectopic Pancreas: gastric antrum, proximal duodenum, ileum, Meckel’s diverticulum
Bifid tail of pancreas / fishtail pancreas: rare branching anomaly of pancreatic tail and duct system
Pancreatic Duct: Gross Anatomy
Main pancreatic duct (Wirsung) – runs the length of the pancreas terminates at the ampulla of Vater, formed by the fusion of the dorsal and ventral ducts.
Accessory pancreatic duct (Santorini) – Variant, usually connects to the main duct, runs in the head of the pancreas drains to the minor duodenal papilla. Ruminant of the dorsal duct.
Smaller ducts – clusters of exocrine pancreastic cells for acini which are connected to:
intercalated ducts
Intralobular ducts join to the main pancreatic duct in a herringbone pattern
Pancreatic Duct Variants
- Pancreatic divisum – most common variant, failure of fusion of the dorsal and ventral ducts. As a result the majority of pancreastic secretions are drained via the minor papilla, believed to increase the risk of pancreatitis. Types;
- 1 no connection
- 2 Absent ventral duct
- 3 Inadequate connection
- Santorrinicele – cystic dilation of the of the dorsal duct in the setting of pancreatic divisum
- Meandering main pancreatic duct – maybe z-type or loop type
- Ansa pancreatica – loop like connection between the main and accessory ducts
- Anomalous pancreaticobiliary junction – union of the pancreatic duct and the common bile duct outside of the duodenal wall
Right Adrenal Gland: Description
Paired retroperitoneal endocrine organs
Function: Production of multiple hormones
Location: Enclosed within the pararenal fascia superior to each kidney
Right adrenal gland: Gross Anatomy
Right pyramid shaped, left spoon shaped
Body with a medial and lateral limbs
Outer cortex and inner medulla
Cortex has 3 zones:
- Glomerulosa
- Fasciculata
- Reticularis
Right adrenal gland: Relations
- Superior – Right crus
- Inferior – upper pole of the right kidney
- Lateral – right lobe of the liver
- Medial – right crus
- Anterior – inferior vena cava
- Posterior – upper pole of the right kidney
Left adrenal glands: Relations
- Superior – left crus
- Inferior – upper ple of the left kidney
- Lateral – spleen
- Medial – left crus
- Anterior – pancreas
- Posterior – upper pole of the left kidney
Right Adrenal Gland: Neurovasculature
Arterial supply:
- Superior adrenal artery - Branch of the Inferior Phrenic Artery
- Middle adrenal artery - Branch of Abdominal Aorta
- Inferior adrenal artery - Branch of Renal artery
Venous drainage:
- Mainly by single adrenal vein
- Left adrenal vein drains into the left renal vein
- Right adrenal vein drains into the IVC
Lymphatic drainage:
- Para-aortic Lymph Nodes
Nerve supply:
- Splanchnic nerves from the Coeliac and Renal Plexuses
Right adrenal gland variants
- Horseshoe adrenal gland: solitary adrenal gland that is present in the midline
- Pancake adrenal gland: takes on a flattened appearance, often in the presence of a pelvic kidney or renal agenesis
- Adrenal gland hypoplasia/agenesis
- Accessory adrenal glands: often near adrenal glands but may be found anywhere in the abdomen, pelvis or scrotum
Segmental Anatomy of the liver: Descriptions
The liver can be divided into 8 functionally independent segments using the Couinaud classification
system.
Segmental anatomy of the liver: Gross anatomy
Each segment has its own dual blood inflow, lymphatic and biliary drainage
Each segment is a wedge pointed at the porta hepatis
The segement are divided in to a superior and inferior group by a horizontal plane drawn at the level of the bifurcation of the portal vein.
The segments are divided right to left by vertical planes following the hepatic veins.
Segments of the liver
Segment 1 – caudate lobe special in this system as is can receive supply from the left and right portal system, location – around the vena cava, divided into medial caudate process and lateral papillary process. Drains directly into the IVC
Segment 2 and 3 – to the left of the left hepatic vein, superior and inferior to the portal vein bifurcation
Segement 4 – between the left and middle hepatic veins, divided into A for part above the bifurcation of the portal vein and B for below
5 and 6 – Both inferior to the portal bifurcation, 5 between the middle and the right hepatic veins, 6 to the right of the right hepatic vein
7 and 8 - both above the portal vein bifurcation, 7 to the right of the right hepatic vein, 8 between
the right and middle hepatic veins
Segmental anatomy of the liver: Variants
- Right or left supply to the caudate
- Hepatic vein duplication
- Reidels lobe
- Beavertail liver
Liver: Description
Large metabolic organ in the right upper quadrant of the abdomen
Function:
- Detoxification
- Glycogen storage
- Hormone production
- Production of plasma proteins
- Storage of vitamins
Liver Gross Anatomy
- Wedge shaped organ that lies below the right hemidiaphragm
- Dividable into four lobes based on surface anatomy
- Right lobe, left lobe, caudate lobe and quadrate lobe
- Dividable into 8 independently resectable segments
- Two surfaces diaphragmatic and visceral
- Predominantly covered with peritoneum bar a bare area on the superior aspect
- Capsule called Glisson’s capsule
Liver: Ligaments
- Falciform ligament / ligamentum terres / ligamentum venosum
- Lesser omentum
- Coronary ligaments left and right
- Triangular ligaments
Liver:Relations
- Superior – right hemidiaphragm
- Inferior – Gallbladder/portahepatis/right adrenal gland and kidney/hepatic flexure
- Medial – duodenum
Liver: Neurovasculature
Arterial supply:
- Hepatic artery
Venous:
- Hepatic veins draining into the IVC
Special circulation:
- Portal vein
Lymphatics:
- Portahepatis to coeliac nodes
- Superior surface can drain to mediastinum
Nerves:
- Coeliac plexus T7-T9 (Sympathetic) and vagal trucks (parasympathetic ) phrenic contribution to bare area