Anatomy - GI COPY COPY Flashcards
What is this structure and what does it do?
-Hepatic portal vein
-All products of digestion, except lipids, are transported to the liver from the gut through the hepatic portal vein
Where is the liver and when is it palpable?
-Right upper guadrant
-Epigastrium
-Below right costal margin during inspiration
What surface of the liver is this?
-Diaphragmatic surface
-Anteriosuperior
-Related to inferior diaphragm surface
What surface of the liver is this?
-Visceral surface
-Posterioinferior
-Related to other organs
Regions of liver not covered by visceral peritoneum:
-Bare area of liver
-Region where gallbladder in contact with liver
-Porta hepatis
What does this show?
Liver areas not covered by visceral peritoneum
Label the diagram:
Label the structure:
What does it do?
-Falciform ligament
-Separates the left and right lobes
-Connects anterior surface of the liver to internal aspect of anterior abdominal wall
What are these and what do they all receive?
-8 functional segments of liver
-Each have their own branch of hepatic artery and portal vein
-Have their own hepatic duct
Label this diagram:
What enters the liver at the porta hepatis?
-Right and left hepatic arteries
-Right and left portal veins
-Right and left cystic ducts
how does venous blood exit the liver?
-2 or 3 large hepatic veins
-Within liver - not visible
-Unite with IVC posterior to liver
Difference between hepatic veins and hepatic portal veins:
-HPV - receive nutrient rich blood from gut from superior and inferior mesenteric veins and splenic vein
-HV - venous blood leaves liver via IFC
What is the nerve innervation to the liver?
-Hepatic plexus
-Parasympathetic fibres from vagus
-Also sympathetic fibres
-Follow paths of hepatic vessels and biliary tree ducts
What is the liver anatomically related to?
-Diaphragm connection via triangular and coronary ligaments
-Anterior abdominal wall via falciform
-Stomach and duodenum via lesser omentum
What does this show the entrance to and what is it in relation to?
-Entrance of lesser sac
-Portal triad on free edge of lesser omentum
-Form anterior boundary of epiploic foramen -> entrance to lesser sac
What 2 things are hidden?
-Hepatorenal recess - between right kidney and posterior surface of right liver side
-Left and right subphrenic recess - either side of falciform ligament - between anterosuperior surface of liver and diaphragm
What is this?
-Round ligament of the liver (ligamentum teres)
-Remnant of umbilical vein (blood from placenta to foetus)
What is this?
-Ligamentum venosum
-Remains of ductus venosus (diverted blood from umbilical vein to IVC)
Label this diagram:
-Gallbladder on posteroinferior side of liver
-Body lies in gallbladder fossa
-Fundus extends to inferior liver border
What is this the surface marking of?
-Fundus of gall bladder
-9th costal cartilage
-Midclavicular line intersects 9th costal cartilage
Explain the pathway of bile in the liver:
-Produced by hepatocytes
-Excreted into small channels called bile canaliculi
-Canaliculi drain into bile ducts
-Bile ducts converge into right and left hepatic ducts
Pathway of the bile duct:
-Runs in free edge of lesser omentum
-Posterior to superior duodenum
-Posterior to pancreas head
-Enters duodenum
Vasculature of gall bladder:
-Cystic artery (arises from right hepatic)
-Cystic vein (directly into liver or HPV)
Innervation of gall bladder and pain referrals?
-Parasympathetic and sympathetic
-Visceral afferents return to CNS with sympathetic
-Visceral pain enters spinal cord T5-T9 (epigastric pain)
-Pain referred to right shoulder
-Inflammation irritates diaphragm
-Diaphragm innervated by phrenic (C3,4,5)
-C3,4,5 also receives somatic sensory info from right shoulder skin
-Parietal peritoneum irritation
-Right hypochondrium pain
What is hepatomegaly and what can cause it? palpable?
-Enlargement of the liver
-Causes:
-Hepatitis (liver inflammation from various causes)
-Malignancy
-Heart failure
-Inferior border palpable inferior to right costal margin
What are liver metastases?
-Most cancers of liver are from cancer elsewhere in the body
-Venous blood from the gut passes to the liver so bowel cancer often metastasises in the liver
What is cirrhosis of the liver?
Causes?
-‘Scarring’ of the liver
-Causes:
-Chronic excess alcohol consumption
-Chronic hepatitis B or C infection
-Build up of fat in the liver
-Hepatocytes destroyed and replaced with fibrous tissue
-Liver shrunken, hard and nodular
-Impairs function - leads to liver failure
What level does the coeliac trunk leave the aorta?
T12
Label this diagram:
What does it show?
Coeliac axis
Label this diagram:
Describe:
-Most duodenum is retroperitoneal
-C-shape that sups pancreas
-Fourth part meets jejunum at duodenal flexure
What lies anterior and posterior to the duodenum?
-Anterior to third part:
-Superior mesenteric artery
-Posterior to first part:
-Bile duct
-Hepatic portal vein
-Gastroduodenal artery
What is this and what does it do?
-Major duodenal papilla
-Point at which bile and digestive pancreatic secretions enter duodenum
What supplies blood to the duodenum?
-First half:
-Branches of coeliac trunk
-Gastroduodenal
-Second half:
-Branches of superior mesenteric artery
-Inferior pancreaticoduodenal artery
What drains blood from the duodenum?
Tributaries of hepatic portal vein that follow arteries
Where does the pancreas lie?
-Horizontally on posterior abdominal wall (lesser sac)
-Level of L1
-Retroperitoneal (no capsule so bumpy)
-Head cupped by C-shaped duodenum
-Tail extends to hilum of spleen
What forms the pancreas?
Dorsal and ventral pancreatic buds that fuse during development
Label the parts of the pancreas:
What lies embedded in the upper border of the pancreas and posterior?
-Upper border - splenic artery
-Posterior - splenic vein
Label the two structures:
Where do they lie?
Within the substance of the pancreas
What are the functions of the pancreas?
-Endocrine and exocrine functions
-Synthesises and secreted insulin (high blood glucose) and glucagon
-Produces pancreatic juice with digestive enzymes
-Transported in main pancreatic duct and accessory pancreatic duct to duodenum
-Communication between ducts
What does the duodenum receive?
-Bile from gallbladder via bile duct
-pancreatic juice from pancreas via main and accessory pancreatic ducts
Label this diagram:
What does it show?
-Bile duct and main pancreatic duct merge at hepatopancreatic ampulla
-Ampulla opens up to second part of duodenum at major duodenal papilla (halfway down duodenum in internal wall)
What surrounds the hepatopancreatic ampulla and what is its function?
-Smooth muscle
-Sphincter of Oddi
-Contraction prevents reflux of duodenal contents into bile and main pancreatic ducts
Label this diagram:
What does it show?
Minor pancreatic duct empties pancreatic juice into duodenum at minor duodenal papilla, proximal to major duodenal papilla
What is the blood supply to the pancreas?
-Splenic artery, major branch of coeliac trunk runs along upper border of pancreas to give rise to pancreatic arteries
-Gastroduodenal artery gives rise to superior pancreaticoduodenal arteries
-Superior mesenteric gives rise to inferior pancreaticoduodenal arteries
What veins drain the pancreas?
-Veins follow arteries
-Splenic vein drains pancreas and unites with superior mesenteric vein
-Forms portal vein posterior to neck of pancreas
Describe the spleen:
-Haematopoietic and lymphoid organ
-LUQ
-Protected by ribs 9-11
What are the two surfaces of the spleen?
-Diaphragmatic surface adjacent to diaphragm
-Visceral surface in contact with stomach, left kidney and colon (vessels enter and exit at hilum on visceral surface)
Describe the 4 borders of the spleen:
-Superior - notched
-Inferior - smooth
-Anterior - notched
-Posterior - smooth
Describe the vasculature to and from the spleen:
-Splenic artery supplies blood to the spleen - embedded in the superior border of the pancreas
-Separates into 5 branches at the hilum
-Splenic vein runs posterior to the pancreas and unites with the superior mesenteric vein to form the hepatic portal vein
Label this diagram:
Describe parietal peritoneum:
Innervation?
-Lines abdominal wall
-Can be seen with naked eye
innervated by somatic nerves that supply overlying muscles and skin of abdominal wall
Describe visceral peritoneum:
+nerves
-Adhered to surface of viscera and not seen with naked eye
-Innervated by visceral sensory nerves:
-Convey painful sensations back to CNS
-Along path of sympathetic nerves that innervate the organ/structure is covers
Describe pain from parietal and visceral peritoneum:
-Parietal:
-Sharp
-Severe
-Well localised to abdominal wall
-Visceral:
-Can be severe
-Dull
-Diffuse
-Can be perceived as nausea or distension
What lies in between the two layers of peritoneum?
-Peritoneal cavity
-Healthy abdomen - thin film of peritoneal fluid lies in cavity
-Allows viscera to slide freely alongside each other
What relationship do the visceral and parietal peritoneum have?
They are continuous with each other
How can abdominal viscera be described in terms of peritoneum?
-Intraperitoneal - almost completely covered by peritoneum (e.g. stomach)
-Retroperitoneal - posterior to peritoneum, only covered on anterior surface e.g. pancreas and abdominal aorta)
Label this diagram:
What does it mean to be secondarily retroperitoneal?
Organs that were intraperitoneal in early development but came to be stuck down onto the posterior abdominal wall
What are common features of mesenteries, omenta, ligaments and folds?
-All composed of peritoneum and connect organs to each other and abdominal wall
-May carry blood vessels, nerves and lymphatics to viscera
-Contain variable amount of fat - some are very fatty
What are mesenteries?
-Folds of peritoneum containing fat
-Suspend small intestine and parts of large intestine from posterior abdominal wall
-Arteries supplying intestine
(abdominal aorta branches) and veins draining gut (portal venous system) embedded in mesenteries
Label this diagram:
What are the greater and lesser omenta?
-Folds of peritoneum that are usually fatty and connect stomach to other organs
-Greater omentum - hangs from the greater curvature of stomach and lies superficial to small intestine
-Lesser omentum - connects stomach and duodenum to the liver, portal triad embedded within its free edge
Label this diagram:
What are ligaments (abdomen)?
-Folds of peritoneum that connect organs to each other or to abdominal wall
-Falciform ligament (anterior liver surface to anterior abdominal wall)
-Coronary and triangular ligaments (superior surface of liver to diaphragm)
What are peritoneal folds?
-Raised from internal aspect of lower abdominal wall
-Created by structures they overlie, like carpet running over a cable
Describe the median umbilical fold:
-Lies in midline
-Represents remnant of urachus (embryologically connected the bladder to umbilicus
Label this diagram:
Describe the lateral umbilical folds:
-Lateral to the median umbilical fold
-Represent remnants of paired umbilical arteries (returned venous blood to placenta in foetal life)
Describe the lateral umbilical folds:
not embryologically
-Lateral to medial umbilical folds
-Inferior epigastric arteries lie deep to these peritoneal folds
-Supply anterior abdominal walls
What is the peritoneal cavity divided into?
-Smaller lesser sac (omental bursa) is a space that lies posterior to the stomach and anterior to pancreas
-Larger greater sac is the remaining part of the peritoneal cavity
How do the greater and lesser sac communicate with each other?
-Passageway that lies posterior to the free edge of the lesser omentum
-Called epiploic foramen (omental foramen)
What is this?
Where does the gastrointestinal system develop from?
-Embryonic gut tube
-Lies in midline of the abdominal cavity, suspended from the posterior abdominal wall by dorsal mesentery
What passes through the dorsal mesentery?
Major branches of the abdominal aorta that supply the developing gut tube
What is the ventral mesentery and what does it become?
-Connects stomach to anterior abdominal wall
-As liver grows within it, anterior part becomes falciform ligament
-Posterior part becomes lesser omentum
What does growth, migration and rotation of organs during development cause?
-Pull their peritoneal attachments with them
-Responsible for formation of lesser sac
-Some organs are ‘pushed’ onto the posterior abdominal wall and become retroperitoneal
Through what does the oesophagus pass through to reach the stomach and at what level?
-Oesophageal hiatus
-Level T10
What prevents reflux of stomach contents into the oesophagus?
-The muscle around the oesophageal hiatus
-Acts as a sphincter
How long is the abdominal segment of the oesophagus?
Less than 2cm
What supplies blood to the distal oesophagus?
Supplied by branches from left gastric artery
What is the venous drainage of the distal oesophagus?
-Towards both the systemic system of veins (via oesophageal veins draining into azygous vein)
-Also to portal venous system (via left gastric veins)
What is the distal oesophagus a site of and why?
-Portosystemic anastomoses
-Drains into systemic and portal venous system
What does the stomach do?
Chemically and physically breaks down food into chyme
What part of the stomach is the oesophagus continuous with?
Cardia of the stomach
Describe the most superior part of the stomach:
-Fundus of the stomach
-Superior to level of oesophagus entry
-Usually filled with gas
What is the largest part of the stomach?
Body
Describe the part of the stomach distal to the body:
-Pyloric part of the stomach
-Pyloric antrum is wide and tapers towards the pyloric canal which is narrow
-Pyloric sphincter is part of the pyloric canal
What regulates the passage of chyme from the stomach into the duodenum?
-Pyloric sphincter
-Formed of circular smooth muscle
What are the right and left borders of the stomach called?
-Right - Lesser curvature
-Left - Greater curvature
Where is the stomach positioned and what covers its surface?
-Left upper Quadrant (can be variable)
-Visceral peritoneum
What is the anterior surface of the stomach related to (3)?
-Anterior abdominal wall
-Diaphragm
-Left lobe of liver
What does the posterior surface of the stomach form?
Anterior wall of the lesser sac
What lies posterior to the stomach and what forms its posterior wall (4)?
-Lesser sac
-Posterior wall of lesser sac:
-Pancreas
-Stomach
-Left kidney
-Spleen
What connects the lesser curvature of the stomach to the liver?
Lesser omentum
What does the free edge of the lesser omentum contain?
-Hepatic artery
-Hepatic portal vein
-Bile duct
PORTAL TRIAD
What is posterior to the free edge of the lesser omentum?
-Entrance to the lesser sac
-Epiploic foramen
What hangs from the greater curvature of the stomach?
Greater omentum
What is this and at what level does it leave the abdominal aorta?
-Coeliac trunk
-one of 3 large unpaired vessels that leave the anterior aspect of the abdominal aorta to supply the abdominal viscera derived from embryological foregut
-T12
What comprises the foregut?
-Stomach
-First half of duodenum
-Liver
-Gallbladder
-Pancreas
Why is the spleen different from other organs in a similar area?
-Develops in dorsal mesentery
-Supplied by coeliac trunk
-Mesodermal in origin
What does the coeliac trunk divide into?
Which vessel is the smallest?
-Splenic artery
-Left gastric artery
-Common hepatic artery
-Left gastric artery is a much smaller calibre vessel than the other two
What vessels run along the lesser curvature of the stomach adn where do they originate?
-Left and right gastric arteries
-They anastomose with each other
-Left gastric = coeliac trunk
-Right gastric = common hepatic artery
What vessels run along the greater curvature of the stomach and where do they originate?
-Right and left gastro-omental arteries
-They anastomose with each other
-Left gastro-omental = splenic artery
-Right gastro-omental = gastroduodenal artery (branch of common hepatic)
What is the venous drainage of the foregut?
-Left and right gastric veins
-Left and right gastro-omental veins
-Splenic vein
-Accompany their correspondent arteries
-Ultimately drain into the hepatic portal vein
Describe the parasympathetic innervation to the stomach:
-Vagus nerve conveys parasympathetic fibres to stomach
-Parasympathetic stimulation promotes peristalsis and gastric secretion
Describe the parasympathetic innervation to the stomach:
-Vagus nerve conveys parasympathetic fibres to stomach
-Parasympathetic stimulation promotes peristalsis and gastric secretion
Describe sympathetic innervation to the stomach:
-Sympathetic fibres are conveyed to the stomach via the greater splanchnic nerve
-GSN is formed of preganglionic sympathetic fibres that leave spinal cord segments T5-T9
-Pass through sympathetic trunk without synapsing
-Synapse in prevertebral ganglia around coeliac trunk
-Postganglionic fibres travel to stomach and inhibit peristalsis and secretion
Label the 3 sections of the small intestine:
What part of the stomach is the duodenum continuous with?
Pylorus
Describe the duodenum:
Retro or intraperitoneal?
-Short and curved
-C-shaped around head of pancreas
-Most of its length is retroperitoneal
What lies approximately halfway down the internal wall of duodenum?
What is its function?
-Major duodenal papilla
-Opening of the bile duct and main pancreatic duct into the duodenum
What does the first half of the duodenum develop from and how does its vasculature relate to this?
-First half develops from embryological foregut
-Supplied by arterial branches from coeliac trunk
-Duodenal branch and superior pancreaticoduodenal artery
What does the second half of the duodenum develop from and how does this relate to its vasculature?
-Second half develops from embryological midgut
-Supplied by branches from artery of the midgut
-This artery is superior mesenteric artery
-Inferior pancreaticoduodenal artery
Are the jejunum and ileum retroperitoneal or intraperitoneal?
Intraperitoneal
What are suspended from the posterior abdominal wall by mesentery?
Jejunum and ileum
What blood vessels supply the small intestine and where do they lie?
-Vessels from superior mesenteric artery
-Embedded within mesentery
Where does the small intestine lie and what is the jejunum and ileum derived from embryologically?
-Centre of abdomen
-Jejunum lying in left upper
-Ileum lies in right lower
-Derived from embryological midgut
What is the small intestine function?
What adaptations does it have for this function?
-Nutrient absorption
-Vast surface area:
-Long
-Mucusa folded (plicae circulares)
-Villi
-Microvilli on luminal surface of each epithelial cell
What are these called?
How can the ileum and jejunum be differentiated?
-Difficult to differentiate based on external appearance
-Some internal differences:
-Plicae more pronounced in jejunum
-Internal ileum characterised by Peyer’s patches (large submucosal lymph nodules)
What are these?
-Peyer’s patches
-Large submucosal lymph nodules
-In ileum of small intestine
What is present in the ileum of some people?
-Bears a blind-ended diverticulum
-Approx 1m from termination
-Meckel’s diverticulum
-Embryological remnant of connection between midgut loop to yolk sac
What is this?
What is the terminal ileum continuous with and what does this form?
-Continuous with caecum (first part of large intestine)
-At ileocaecal junction
-In right ileac fossa
What is this?
Ileocaecal junction/valve
What is the function of the large intestine?
Reabsorbs water from faecal material to for semi-solid faeces
Where in the abdomen does the large intestine lie?
Peripherally
What is the large intestine composed of?
-Caecum
-Appendix
-Ascending colon
-Transverse colon
-Descending colon
-Sigmoid colon
-Rectum
-Anal canal
Is the large intestine intraperitoneal or retroperitoneal?
Some sections are intra and some are retro
Describe the external appearance of the large intestine:
-Outer longitudinal muscle layer organised into three bands
-These are called teniae coli
-inner circular muscle layer forms ‘bulges’ called haustra
-Bears fatty tags called epiploic appendages
Label this diagram:
Describe the first part of the large intestine:
-Caecum
–Distended, blind-ended ‘pouch’
-Covered by peritoneum but has no mesentery
Describe this:
What does it connect to and what via?
-Appendix
-Small diverticulum that arises from caecum
-Contains lymphoid tissue
-Varies in length and tip position
-Connected to caecum by mesentery - mesoappendix
What is this?
-McBurney’s point
-Surface marking for base of appendix
Label the structure:
Where does it lie?
-Ascending colon
-Runs vertically on right side of posterior abdominal wall in right paracolic gutter
-
Is the ascending colon intraperitoneal or retroperitoneal?
Secondarily retroperitoneal
What does the ascending colon do in the RUQ?
-90 degree turn left
-Continuous with transverse colon
-‘bend’ in colon called hepatic flexure or right colic flexure
How is the transverse colon suspended?
-Suspended from posterior abdominal wall
-By transverse mesocolon
Is the transverse colon intraperitoneal or retroperitoneal?
Intraperitoneal
What does the transverse colon do in the LUQ?
-90 degree turn inferiorly
-Continuous with descending colon
-‘bend’ called splenic flexure or left colic flexure
How is the splenic flexure suspended?
-Tethered to diaphragm by phrenicocolic ligament
What does the transverse colon mark the transition of and why is this significant?
-Between embryological midgut and hindgut
-Proximal 2/3 develop from midgut
-Distal 1/3 develop from hindgut
-Supplied by different blood vessels and nerves
Label the structure:
Where does it lie?
-Descending colon
-Left paracolic gutter
Is the descending colon intraperitoneal or retroperitoneal?
Secondarily retroperitoneal
Describe this structure:
-Sigmoid colon
-As it approaches midline, makes 90 degree turn inferiorly into pelvis
-‘bend’ called rectosigmoidal junction
What is this?
What is its significance?
-Sigmoid mesocolon
-Sigmoid mesentery
-Sigmoid is intraperiotoneal
What are these and their function?
-Rectum descends into the pelvis from rectosigmoidal junction
-Rectum stores faeces until it is convenient to defecate
-Rectum continuous inferiorly with anal canal
Is the rectum intra or retroperitoneal?
Retroperitoneal
What main arteries supply the gastrointestinal tract?
-Coeliac tract
-Superior mesenteric artery
-Inferior mesenteric artery
What is the artery of the midgut?
Superior mesenteric artery
Describe the SMA and what it supplies:
-Artery or midgut
-Leaves aorta at level L1
-Branches to midgut structures:
-Second half of duodenum
-Small intestine
-Large intestine as far as proximal 2/3
-Parts of pancreas
Describe IMA and what it supplies:
-Artery of hindgut
-Leaves aorta at level of L3
-Smaller calibre vessel than other 2
-Branches to hindgut structures:
-Distal 1/3 of transverse colon
-Descending and sigmoid colon
-Rectum
-Upper anal canal
What are the major branches of the SMA (5)?
-Middle colic = transverse colon
-Ileocolic = caecum, appendix, ascending colon
-Right colic = ascending colon
What are the major branches of the IMA?
One is missing from the diagram
-Left colic = transverse colon and descending colon
-Sigmoid branches = sigmoid colon
-Superior rectal = terminal branch of IMA, supplies upper rectum
-Lower rectum supplied by vessels originating from internal iliac arteries in pelvis
What anastomoses form from the IMA?
-Branch of left colic artery and middle colic artery (from SMA) anastomose along distal 1/3 of transverse colon and splenic flexure
-Forms marginal artery
-Branches of left colic and sigmoid anastomose
What does venous blood from the gut ultimately drain into and how?
-Inferior vena cava
-Contains absorbed nutrients
-First enters liver via portal venous system
-Returned to heart via IVC
Label this diagram:
What does it show?
Venous drainage of the gut
What is the venous drainage of the hindgut?
-Inferior mesenteric vein
-Accompanies IMA
-Ascends left side of abdomen and drains into splenic vein from spleen
What is the venous drainage of the midgut?
-Superior mesenteric vein
-Accompanies SMA
-Ascends and unites with splenic vein close to liver (posterior to pancreas neck)
-Forms hepatic portal vein
What are the final veins carrying venous blood to and from the liver?
-Hepatic portal vein into liver
-After nutrients removed from blood, enters small hepatic veins
-These unite within liver to form two or three large hepatic veins that enter IVC as it passes posterior to liver
What do parasympathetic fibres innervating the midgut and hindgut stimulate and are they the same?
-Peristalsis and secretions
-Parasympathetic fibres travel to midgut and hindgut via different nerves
What innervates the parasympathetic fibres of foregut and midgut?
Vagus nerve
What innervates the parasympathetic fibres of the hindgut?
-Pelvic splanchnic nerves
-Formed by the axons of parasympathetic neurons that lie in the sacral spinal cord
Describe the formation of pelvic splanchnic nerves:
-Cell bodies of preganglionic parasympathetic neurons lie in sacral segments S2 - S4
-Axons of these neurons leave spinal cord and form pelvic splanchnic nerves
-Preganglionic axons synpase with second neuron in ganglion
-Parasympathetic ganglia are located very close to (or within) walls of viscera
Describe general sympathetic innervation of gut:
-Preganglionic sympathetic fibres from T5-T12 pass through sympathetic trunk
-WITHOUT SYNAPSING
-Via greater, lesser and least splanchnic nerves
Describe the sympathetic innervation from 3 splanchnic nerves:
-Greater splanchnic - carries fibres from T5-T9 - innervates foregut
-Lesser splanchnic - carrier fibres from T10-T11 - innervates midgut
-Least splanchnic - carries fibres from T12 - innervates hindgut
Where do preganglionic fibres from the 3 splanchnic nerves synpase?
What do the postganglionic sympathetic fibres form in the gut and what do they do?
-Synapse in ganglia that lie in:
-Abdomen
-Clustered around aorta and coeliac trunk, SMA and IMA
-Postganglionic sympathetic fibres form visceral nerves that innervate gut
-These fibres inhibit peristalsis and secretions
-They are visceral motor fibres
What do visceral sensory fibres from the gut do?
-Convey visceral sensory information from the gut to the CNS
-Usually does not reach consciousness
-Painful sensations caused by ischaemia, distension or spasm do reach or conscious perception
Where do visceral sensory fibres from gut run?
-Visceral sensory fibres from foregut, midgut and hindgut travel to CNS alongside sympathetic fibres that innervate that part of the gut
-Painful sensations from the:
-Foregut enter spinal cord segments T5-T9
-Midgut enter spinal cord segments T10-11
-Hindgut enter spinal cord segment T12
Describe what regions of the spinal cord receive somatic sensory information from the abdominal wall:
-T5-T9 receive info from dermatomes T5-T9 (upper abdomen and epigastrium)
-T10-T11 receive info from dermatomes T10-T11 (umbilical region)
-Segment T12 receive information from dermatome T12 (suprapubic regio)
Describe the referral of pain from abdominal viscera?
Why is this?
-Regions of the spinal cord receive both somatic sensory information from the abdominal wall and visceral sensory information from abdominal viscera so the pain from viscera is perceived to be from the abdominal wall
-Epigastric pain suggests foregut pathology
-Central abdomen/umbilical suggests midgut pathology
-Lower abdominal/suprapubic suggests hindgut pathology
What is inferior to the abdominal cavity?
-Pelvic cavity
-Continuous with it
Organs of what systems are contained within the abdominal cavity?
-GI tract
-Hepatobiliary system
-Urinary system
-Endocrine system
-Spleen
-Great vessels
How many lumbar vertebrae contribute to the posterior wall of the abdominal cavity?
5
what composes the anterior, lateral and posterior walls of the abdomen?
-Skin
-Subcutaneous tissue
-Muscle and their associated aponeuroses (flat tendons)
What are the 3 functions of the abdominal wall?
-Protect abdominal viscera
-Increase intra-abdominal pressure
-Maintain posture and move the trunk
What lines the internal aspect of the abdominal wall?
-Serous membrane
-Parietal peritoneum
-Like the pleura of the lungs
Label this diagram:
What are the bony landmarks that define the boundaries of the abdominal cavity?
-Xiphisternum
-Costal margin
-iliac crests
-Anterior Superior Iliac Spines
-Pubic tubercles
-Pubic symphysis
Label this diagram:
What does it show?
Bony landmarks of the abdominal cavity
What is the basic system of describing areas on the anterior abdominal wall?
-Four quadrants
-Vertical line through midline from lower sternum, umbilicus and pubic symphysis
-Horizontal line runs across abdomen through umbilicus
Label the 4 quadrants of the anterior abdominal wall:
What is the more specific system of describing areas of the anterior abdominal wall and what lines are drawn to create them?
-Nine regions
-Right and left midclavicular lines extending from midclavicular point to mid-inguinal point (halfway between ASIS and pubic tubercle)
-Subcostal line - horizontal line drawn through inferior-most parts of right and left costal margins (through 10th costal margin)
-Intertubercular line - horizontal line through tubercles of right and left iliac crests and body of L5
label the 9 regions of the anterior abdominal wall:
What is the transpyloric plane?
-Horizontal line
-Passes through tips of right and left 9th costal cartilages
-Between superior border of manubrium and pubic synthesis
-Transects pylorus of stomach, gallbladder, pancreas and hila of kidneys
What is this?
Transpyloric plane
What is the transumbilical plane?
-Unreliable landmark
-In slender individuals, lies at level L3 approximately
What is this?
Transumbilical plane
What is the intercristal plane?
-Horizontal line
-Between highest points of right and left iliac crests
-Guides procedures on back
What is this?
Intercristal plane
What is McBurney’s point?
-Surface marking for base of appendix
-Lies 2/3 way along line drawn from umbilicus to right ASIS
What is this?
What muscles compose the anterior abdominal wall?
-4 pairs
-External oblique (diagonal)
-Internal oblique (diagonal)
-Transversus abdominis (horizontal)
-Rectus abdominis (rectus = straight)
Label the muscles of the anterolateral abdominal wall:
Where do the rectus abdominis muscles lie and connect?
-Lie either side of midline
-Attached to sternum and costal margin superiorly
-Pubic inferiorly
-Surrounded by aponeurotic rectus sheath
What is this?
Rectus abdominis
What is this and what does it do?
-Rectus sheath
-Encloses rectus abdominis
Describe this muscle:
-External oblique
-Most superficial
-Run medially and inferiorly towards midline
Describe this muscle:
-Internal oblique
-Deep to EO
-Orientated perpendicular to EO (medially and superiorly)
Describe this muscle:
-Transversus abdominus
-Deep to IO
-Horizontal fibres
What happens to the muscles of the anterior abdominal wall anteriorly?
-Become aponeurotic
-Fibres of aponeuroses fuse with each other in midline
-Fuse with aponeuroses of other side forming a tough midline raphe (seam) called the linea alba
-Also form rectus sheath
Label this diagram:
What lie either side of the linea alba?
-Rectus abdominis muscles
-Composed of muscle segments interspersed with horizontal tendinous bands
-When they hypertrophy with exercise, they bulge either side of the tendinous bands and are seen as a ‘six-pack’
What forms the rectus sheath?
AS THEY APPROACH MIDLINE:
-Aponeurosis of IO splits into anterior and posterior layers
-Aponeurosis of EO and anterior layer of IO form anterior rectus sheath wall
-Posterior rectus sheath formed of posterior layer of IO aponeurosis and transversus abdominus aponeurosis
Label this diagram of what forms the rectus sheath:
What is this and what is its positioning?
-Transversalis fascia
-Lies deep to transversus abdominis
-Deep to this is parietal peritoneum
What is this?
-Inguinal ligament
-Inferior part of external oblique aponeurosis is attached to ASIS laterally and pubic tubercle medially
-Forms inguinal ligament
-Just above it is inguinal canal
What is the blood supply the anterolateral abdominal wall?
-Musculophrenic artery (branch of internal thoracic)
-Superior epigastric (continuation of internal thoracic artery, descends into rectus sheath)
-Inferior epigastric (branch of external iliac artery, ascends in rectus sheath and anastomoses with superior epigastric
-Accompanied by deep veins and network of superficial veins
Label the diagram of the blood supply to the anterolateral abdominal wall:
What is the innervation of the muscles and skin of the anterolateral abdominal wall?
-Thoraco-abdominal nerves T7-T11 - continuation of intercostal nerves of respective vertebrae, somatic containing sensory and motor fibres
-Subcostal nerves - original from T12 spinal nerve (runs along border of 12th rib)
-Iliohypogastric and ilioinguinal nerves - branches of L1 spinal nerve
Label these nerves:
Label these nerves:
What forms the first part of the respiratory tract?
Left and right nasal cavities
What do mucosa in the upper part of the nasal cavity contain and what do these form?
-Olfactory receptors
-Axons of these receptors form the olfactory nerves (CNI)
The left and right nasal cavities are separated from:
-Each other by a thin midline septum - formed of cartilage and bone
-Oral cavity inferiorly by hard palate
-Brain superiorly by bone
What do the nasal cavities communicate with?
-Nasopharynx posteriorly
-Paranasal sinuses (cavities within the skull bones)
What is this and what is it made up of?
-Nasal septum
-Formed of cartilage anteriorly and two thin plates of bone posteriorly
What forms the nasal septum?
-Cartilage anteriorly
-Perpendicular plate of ethmoid bone superior part of posterior septum
-Vomer forms inferior part of the posterior septum
What makes up the lateral wall of the nasal cavity?
-Three projections of bone:
-Superior
-Middle
-Inferior
CONCHAE or TURBINATES
What are inferior to the turbinates and what happens in them?
-Spaces inferior to them are meatuses
-Superior meatus lies inferior to superior concha etc.
-As inspired air travels through the meatuses it is warmed, humidified and filtered
What separates the nasal cavity from the cranium and brain?
Describe it:
-Cribriform plate
-Delicate section of bone perforated with tiny holes
-Axons of olfactory neurons pass through these perforations to form olfactory nerves which travel to the brain
What is this and what is located here?
-Sphenoethmoidal recess
-Olfactory receptors
Where are olfactory receptors located?
-Speno-ethmoidal recess in the upper nasal cavity
-between the superior concha and the cribriform plate
What are these?
-Paranasal sinuses
-Cavities within the skull bones and are named according to the bones within they are located
Where do each of the paranasal sinuses lie?
Frontal - anterior part of frontal bone
Ethmoid - ethmoid bone superior to nasal cavity and medial to orbits
Sphenoid - sphenoid bone
Maxillary - maxillae of facial skeleton
What do the paranasal sinuses communicate with?
The nasal cavity via small ducts/ channels
what do each of the paranasal sinuses communicate with and via what?
Frontal -> Middle meatus
Sphenoid -> spheno-ethmoidal recess
Ethmoid air cells -> Superior and middle meatuses
Maxillary -> middle meatus
Describe the communication of the paranasal sinuses with the nasal cavity:
Describe the opening of the maxillary sinus and its drainage:
-Lies superomedially
-Cannot drain freely when the head is upright
What other structure does the nasal cavity receive?
EYE
-Nasolacrimal duct
-Drains fluid which lubricate the anterior surface of the eye
-Duct opens into the inferior meatus
-Reason why you get a runny nose when you cry as excess fluid drains down nasolacrimal duct
Other than the nasolacrimal duct, what other structure does the nasal cavity communicate with?
-Also communicates with the middle ear
-Auditory tube connects middle ear to the lateral wall of the nasopharynx - surrounded by a slight bulge of tonsilar tissue
What is this and what does it do?
-Auditory tube (eustachian tube)
-Allows air to pass into the middle ear so that pressure on either side of the tympanic membrane is equal
-Important for optimal conduction of soundwaves
What is the arterial supply of the nasal cavity?
-Supplied by several arteries including branches of the maxillary artery which is a terminal branch of the external carotid artery
-Anastomotic network formed supplies nasal septum which is often site of nosebleed
What does this show?
Anastomotic blood vessels of the nasal septum
What is the innervation of the nose?
Sensory innervation of the nose is via branches of the trigeminal nerve
What separates the nasal and oral cavities?
-The palate
-Anteriorly composed of bone - hard palate
-Posteriorly muscle - soft palate
-Forms the roof of the oral cavity
What makes up the hard palate?
-Composed of two bones
-Palatine bone of the maxilla
-Horizontal plate of the palatine bone
Why is the hard palate functionally important?
-Prevents food or fluid entering nasal cavity
-Push tongue against it during first phase of swallowing to force food and fluid backwards into oropharynx
-Push tongue against it ti articulate certain sounds
What does the soft palate have that projects?
-Midline conical projection called the uvula
-Hangs from the posterior border of the soft palate and seen at back of mouth
What is the soft palate composed of and what is its function?
-Several muscles
-Contract during swallowing which elevates the soft palate
-nasopharynx is closed off from the oral cavity to prevent reflux of food into the nasal cavity
What innervates the muscles of the soft palate?
Vagus nerve
What are the boundaries of the oral cavity?
Superior - hard and soft palate (roof)
Inferior - soft tissues and muscles (floor)
Laterally - cheeks (contain buccinator muscle)
What does the oral cavity contain?
-Tongue
-Teeth
-Gums
-Openings of salivary ducts
What are the basics of the number and type of teeth?
-Adults have 32 teeth
-16 embedded in the maxilla (upper jaw)
-16 embedded in the mandible
-In upper and lower jaw:
-4 incisors
-2 canines
-4 premolars
-6 molars
What are the teeth composed of?
-An inner pulp containing blood vessels and nerves
-Dentin surrounding pulp
-Outer, hard coating of enamel
What is the tongue essential for?
Normal chewing, swallowing and speech
What does the tongue bear on its surface and what do they do?
-Papillae on its superior surface
-Some detect taste (taste buds)
Where does the tongue lie?
-Anterior part lies in oral cavity
-Posterior part (root) extends into the oropharynx
What does this show?
-Vallecula
-Space between the posterior tongue and anterior aspect of the epiglottis
What is the tongue composed of?
-Intrinsic and extrinsic muscles
-Intrinsic: Lie entirely within the tongue, paired bilaterally and fuse in midline - change shape of tongue
-Extrinsic: Attached to the tongue but originate outisde it (mandible and hyoid) - move the tongue
What innervate the muscles of the tongue?
Hypoglossal (CNXII)
Describe the sensory innervation to the tongue:
-Taste in anterior 2/3 = VII
-General sensation in anterior 2/3 = V
-Taste and general sensation in posterior 1/3 = IX
What is the blood supply to the oral cavity?
Lingual, maxillary and facial arteries which are branches of the external carotid artery
What is the innervation of the oral cavity?
-Complex
-Muscles of soft palate = vagus
-Tongue innervated by four cranial nerves (V, VII, IX, XII)
What is the location of each of the palatine tonsils?
-Pharyngeal - roof and posterior nasopharynx wall
-Tubal - surround auditory tube opening on nasopharynx lateral wall
-Palatine - lateral wall of oropharynx (visible)
-Lingual - posterior tongue
