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Name these vessels
- Common hepatic artery branches off;
- - Gastroduodenal artery which gives rise to the Right gastro-omental (gastro-epiploic) artery
- - Superior pancreaticoduodenal arteries
- - Right gastric artery
- Esophageal branch of left gastric artery
- From the splenic artery;
- - Short gastric arteries
- - Left gastro-omental (gastro-epiploic) artery
- Cisterna chyli
- Thoracic duct
- Lymphatic Drainage of GI Tract;
- Lymphatic follicles lie in mucous membrane of digestive tract from tonsils to anus. From these folicles, lymphatic vessels through muscle wall of gut to;
- - EPI- group of nodes; that lie directly on the gut
- - PARA- group of nodes; lie at the margin of gut along the mesenteric border
- - INTERMEDIATE group of nodes; lying along the arteries supplying the gut
- - PRE-AORTIC group of nodes; finally the lymph is conveyed to lymph nodes lying in front of the aorta
Basic principle of abdominal viscera innervation;
- A given organ is innervated by branches of a visceral nerve plexus; The branches follow the artery that supplies the organ;
- The visceral nerve plexus consists of four main components:
- – Sympathetic fibers
- – Parasympathetic fibers
- – Sympathetic ganglia
- – Visceral sensory fibers
Describe the visceral efferent fibres for the gut
- Presynaptic sympathetic fibres: are carried in thoracic splanchnic nerves, lumbar splanchnic nerves, and sacral splanchnic nerves
- Presynaptic parasympathetic fibres are carried in vagus nerves, which supply as far as proximal 2/3 of transverse colon
- Presynaptic parasympathetic fibres are carried in pelvic splanchnic nerves (S2, S3, S4) to terminal 1/3 of transverse colon, descending colon, sigmoid colon, rectum, anal canal
What are the functions of sympathetic and parasympathetic efferent supply?
- Sympathetic supply:
- - Inhibitory to smooth muscle of gut
- - Causes contraction of smooth muscle sphincters
- - Causes contraction of smooth muscle of blood vessels
- Parasympathetic supply:
- - Causes contraction of smooth muscle of gut
- - Enhances secretion from glands
Describe the visceral afferent fibres for the gut (minus the rectum)
Visceral afferent fibres for abdominal esophagus, stomach, small intestine and colon accompany sympathetic fibres to sensory ganglia of lower thoracic spinal nerves and upper two lumbar spinal nerves
Describe the visceral afferent fibres for the rectum
Visceral afferent fibres for rectum accompany parasympathetic fibres in pelvic splanchnic nerves to sensory ganglia of S2, S3, S4 spinal nerves
Describe the autonomic nerve supply to the non-rectal/proximal gut
- We have a sympathetic chain/trunk, from which splanchnic nerves branch. Some of these lumbar splanchnic nerves make up;
- – Prevertebral autonomic plexuses ;. i.e. celiac, superior mesenteric, inferior mesenteric = Presynaptic Sympathetic Fibres
- – fibres passing downward and medially into pelvis to take part in formation of the superior hypogastric plexus
- The presynaptic parasympathetic fibres also originate superiorly.
- – Fibres from anterior vagal trunk pass to distal part of esophagus, stomach, liver, and celiac plexus
- – Fibres from the posterior vagal trunk enter the celiac and superior mesenteric plexuses and run with their arteries to the parasympathetic ganglia in the wall of the gut
- This parasympathetic innervation is only far as the proximal two thirds of transverse colon
Which nerves contribute to the superior mesenteric plexus? What organs does this plexus innervate?
- The superior mesenteric plexus has:
- (a) sympathetic nerves from the thoracic splanchnic nerves (some pass via the celiac plexus) and
- (b) parasympathetic fibres from the vagus nerves.
- The superior mesenteric ganglion (sympathetic) lies among the plexus. The nerve fibres from the superior mesenteric plexus innervate the organs supplied by the superior mesenteric artery
- - i.e. the midgut.
Where are the sympathetic and parasympathetic nerve fibres around the inferior mesenteric artery derived from?
- The sympathetic fibres: come from lumbar splanchnic nerves which pass from the lumbar part of the sympathetic trunk (cell bodies in the L1 and L2 spinal segments of the lateral horn of the grey matter of the spinal cord) to the plexus of nerves surrounding the abdominal aorta.
- The parasympathetic fibres: come from the pelvic splanchnic nerves (S2-S4) which enter the inferior hypogastric plexus and ascend in the hypogastric nerves to plexus of nerves around the inferior mesenteric artery.
Describe the autonomic nerve supply to the rectum
- Parasympathetic supply to Large Intestine
- The vagal trunks give parasympathetic supply to the gut as far as the proximal two thirds of transverse colon. Parasympathetic supply to terminal part of transverse colon, descending colon, sigmoid colon and rectum is from the PELVIC SPLANCHNIC NERVES
- Presynaptic parapsympathetic fibres: arise from the pelvic splanchnic nerves which arise from the sacral plexus and carry fibres from ventral rami of S2, S3, S4 spinal nerves.
- - they also run to inferior hypogastric, superior hypogastric and inferior mesenteric plexuses
- The vagal trunks and pelvic splanchnic nerves are often referred to as the "craniosacral parasympathetic outflow from CNS"
What dermatomes do different parts of the gut refer pain to?
- Visceral pain from foregut structures (e.g. stomach and proximal duodenum) is generally felt in the epigastrium,
- from midgut structures (e.g . ileum and appendix) in the umbilical region
- hindgut structures (e.g. descending colon and rectum) in the suprapubic region
Describe the anatomy of the superior abdominal wall;
Name the 3 apertures, the level and the contents
- Diaphragm: forms the superior boundary separating the abdominal cavity from the thoracic cavity.
- It consists of two parts, a central tendinous part into which the circumferentially arranged muscle fibers attach.
- The diaphragm is anchored to the lumbar vertebrae by musculotendinous crura, which blend with the anterior longitudinal ligament of the vertebral column;
- - the right crus is the longest and broadest of the crura and is attached to the bodies of vertebrae LI to LIII, and the intervening intervertebral discs; similarly, the left crus is attached to vertebrae LI and LII and the associated intervertebral disc.
- There are 3 arcuate ligaments;
- - The crura are connected across the midline by a tendinous arch (the mediaN arcuate ligament), which passes anterior to the aorta
- - MediaL and lateral arcuate ligaments; one on each side
- 3 apertures include;
- - Vena caval foramen: (T8) containing inferior vena cava and right phrenic nerve
- - Esophageal hiatus: (T10) containing Oesophagus and vagus nerves
- - Aortic hiatus: (T12) containing thoracic aorta and thoracic duct
- Through the L and R crura: Azygos or hemiazygos veins, and Thoracic splanchnic nerves
Name the components of the posterior abdominal wall
- Bones: lumbar vertebrae and the sacrum, (ribs)
- Muscles: include
- – Psoas major
- – Psoas minor
- – Quadratus lumborum
- – Iliacus
- – Diaphragm
What is meant by the "retroperitoneal space"?
- Retroperitoneal space: a potential space between transversalis fascia and parietal peritoneum; it is the posterior portion of extraperitoneal fat (or fascia)
- Transversalis fascia: is continuous with diaphragmatic fascia superiorly, psoas and quadratus fascia posteriorly, and renal fascia medially.
- - renal fascia: has 2 layers and divides retroperitoneal space into perirenal fat and pararenal fat.
- Fibrous capsule of the kidneys
Describe how the renal fascia relates to other features
- Anterior: layer passes over aorta and IVC.
- Posterior: layer fuses with psoas fascia.
- Superiorly: both layers fuse and continue with diaphragmatic fascia.
- Inferiorly: the anterior layer disappears in extraperitoneal fat, and the posterior layer continues with iliac fascia.
- Left and right lobes = Diaphragmatic view
- Attachment of falciform ligament; Separates the two lobes on the diaphragmatic surface
- - Ligamentum teres; in its lower free margin
- Coronary ligament: upper layer and lower layer
- Left triangular ligament
- Hilum; or "Porta hepatis". Structures include;
- - Hepatic portal vein and artery proper
- - Common hepatic and bile duct
- Fissures for ligamentum teres
- Fissures for ligamentum venosum
- - These ligaments separate the L and R lobes of the liver on the visceral surface
- Caudate (Posterior) and Quadrate (anterior) lobes: Visible from the visceral surface.
- Inferior vena cava:* hepatic veins which take blood from the liver drain it to the IVC
- Round ligament of the liver
- Coronary ligament; there is an upper and lower layer
- Attachment of lesser omentum; hepatic artery, bile duct, portal vein in its right free margin
How are the viscera (i.e. organs) arranged retroperitoneally?
- Three “subregions”:
- – Liver & esophagus
- – Pancreas & duodenum
- – Kidney, suprarenal gland & ureter
Name the important relations of the duodenum
- D1: anterior to gastroduodenal artery, portal triad and IVC
- D2: pancreas medially, transverse colon anteriorly, right kidney posteriorly
- D3: crosses IVC and aorta and crossed by SMA and SMV
- D4: ascends to lateral border L1/2 with IMV laterally (green dashed line)
Name the important relations of the pancreas
- Head: anterior to IVC and posteriorly indented by common bile duct
- Uncinate process: between mesenteric vessels and aorta
- Neck: anterior to origin of portal vein
- Body: anterior to splenic vein (splenic artery snakes along upper border)
- Tail: lies in splenorenal ligament with splenic vessels
Describe the anatomy of the ureter
- Function: ureters are muscular tubes that transport urine from the kidneys to the bladder. The ureters descend retroperitoneally on the medial aspect of the psoas major muscle
- Three parts: and blood supply (just take out that it is segmental)
- - Abdominal; the renal arteries supply the upper end; the middle part may receive branches from the abdominal aorta, the testicular or ovarian arteries, and the common iliac arteries*
- – Pelvic; in the pelvic cavity, the ureters are supplied by one or more arteries from branches of the internal iliac arteries.
- – Ureterovesical
- At three points along their course the ureters are constricted/narrowings
- – Ureteropelvic junction
- – Crossing iliac artery
- – Ureterovesical junction
Describe the anatomy of the adrenal glands
- Also retroperitoneal organ; and enclosed by the renal fascia. Right (pyramid) and left (semilunar and larger) shaped differently
- Arterial supply: arises from three primary sources;
- - superior suprarenal arteries: as the bilateral inferior phrenic arteries pass upward from the abdominal aorta to the diaphragm, they give off multiple branches (superior suprarenal arteries) to the suprarenal glands;
- - Middle suprarenal artery: a middle branch to the suprarenal glands usually arises directly from the abdominal aorta;
- - Inferior suprarenal arteries: inferior branches from the renal arteries pass upward to the suprarenal glands.
- Venous drainage: consists of a single vein leaving the hilum of each gland.
- - right side, the right suprarenal vein is short and almost immediately enters the inferior vena cava;
- - left side, the left suprarenal vein passes inferiorly to enter the left renal vein (think direction of blood flow).
Label this axial abdominal CT scan.
Give the name of the nerves
- Iliohypogastric nerve (L1): Skin overlying iliac crest, upper inguinal, and hypogastric regions; internal oblique and transversus abdominis muscles
- Ilioinguinal nerve (L1): Skin of lower inguinal region, mons pubis, anterior scrotum or labium majus, and adjacent medial thigh; inferiormost internal oblique and transversus abdominis
- Subcostal nerve: (T12) Muscles of anterolateral abdominal wall (including most inferior slip of external oblique) and overlying skin, superior to iliac crest and inferior to umbilicus
- Lateral cutaneous nerve of the thigh: it supplies skin on the anterolateral surface of the thigh
- Genitofemoral nerve: In females, sensory to anterior labia majora;
- - in males, motor to cremaster muscle, sensory to anterior aspect of scrotum and adjacent thigh
- - Femoral branch supplies skin over lateral part of femoral triangle;
Which nerves convey pain from the ureter?
- His pain (ureteric colic) is from obstruction of the ureter by the stone.
- Sympathetic afferent (sensory) fibres from the ureter enter the spinal cord at T11-L1 spinal level. This visceral pain is referred to skin regions innervated by somatic sensory nerves from these ipsilateral spinal segments (the flank and inguinal region).
- The correct answer is: Sympathetic fibres