Gastrointestinal Anatomy Flashcards
If a patient is presenting with abdominal pain what could there be a problem with
Small or large intestines
Stomach
Liver
Gall bladder
Pancreas
Kidneys
Great vessels
Muscles of abdominal wall
How is the abdominal cavity separated from the thoracic cavity
It is separated by the diaphragm
How do things pass from the thoracic cavity to the abdominal cavity
Through apertures in diaphragm
What is the abdominal cavity continuous with
It is continuous with the pelvic cavity
What does the abdominal cavity contain
The abdominal cavity contains the organs from the
Gastrointestinal tract
Hepatobiliary system
Urinary system
Endocrine system
And the spleen and great vessels
What are the anterior, lateral and posterior walls of the abdomen composed of
Skin
Subcutaneous tissue
Muscle
Associated aponeuroses
5 lumbar vertebrae on the posterior wall
What are the functions of the abdominal wall
Protect abdominal viscera
Increase intra-abdominal pressure
Maintain posture and move the trunk
What is the internal aspect of the abdominal wall lined with
The internal abdominal wall is lines with parietal peritoneum
What are the bony landmarks which define the boundaries of the abdominal cavity
Xiphisternum
Costal margin
Iliac crests
Anterior superior iliac spines
Pubic tubercles
Pubic symphysis
How is the abdomen spit into the four quadrants
There is a vertical line which runs down the midline through the lower sternum, umbilicus and pubic symphysis
There is a horizontal line that runs across the abdomen through the umbilicus
What are the names of the four quadrants of the abdomen
Right upper and right lower
Left upper and left lower
Why is the abdomen divided further into 9 regions not just the four quadrants
Dividing the abdomen further than the four quadrants into 9 regions allows us to be more precise when describing the location of pain/injury
How is the abdomen divided into the 9 regions
2 mid Clavicular lines left and right which run down from the mid Clavicular points vertically down to the mid-inguinal point
The subcostal line which runs horizontally through the left and right costal margins through the 10th costal cartilage
The intertubercular line which is a horizontal line which through the tubercles of the left and right iliac crests and the body of L5
What are the 3 central of the 9 regions of the abdomen from superior to inferior
Epigastric region
Umbilical region
Hypogatric region
What are the 3 right of the 9 regions of the abdomen from superior to inferior
Right hypochondriac region
Right lumbar region
Right iliac region
What are the 3 left of the 9 regions of the abdomen from superior to inferior
Left hypochondriac region
Left lumbar region
Left iliac region
What can the right and left iliac region also be known as
The right and left iliac fossa
What is the transpyloric plane
This is a horizontal line that passes through the tips of the right and left 9th costal cartilages. It lies between the superior border of the manubrium and the pubic symphysis. It transects the pylorus of the stomach, the gallbladder, the pancreas and the hila of the kidneys
What is the intercristal plane
This is a horizontal line drawn between the highest point of the right and left iliac crests which is used for a guide for procedures such as lumbar puncture
What is the transumbilical plane
This is an unreliable landmark as it position differs depending on how much fat is present but is usually the level of L3
What is McBurney’s point
This is the surface marking of the base of the appendix which lies 2/3 of the way along a line drawn from the umbilicus to the right superior iliac spine
What are the 4 pairs of muscles which make up the anterolateral abdominal wall
The external obliques
The internal obliques
The transversus abdominis
The recuts abdominis
Where is the recuts abdominis found
The recuts abdominis is located right and left either side of the midline
Where does the recuts abdominis make attachments
The recuts abdominis is attached to the sternum and costal margin superiorly and the pubis inferorly
What surrounds the rectus abdominis
It is surrounded by an aponeurotic rectus sheath
What is found lateral to the recuts abdominis
3 sheets of muscles
What is the most superficial sheet of muscle and what orientation are its fibres
The most superficial sheet of muscle is the external oblique and the fibres run medially and inferiorly towards the midline
What sheet of muscle lies deep to the external oblique and what is the orientation of its fibres
The muscle which lies deep to the external oblique is the internal oblique which fibres are orientated perpendicular to the external oblique ones and so run medially to superiorly
What muscle lies deep to the internal oblique and what orientation are its fibres
The transversus abdominis lie deep to the internal obliques and its fibres are orientated horizontally
What happens to the 3 sheets of muscle anteriorly
They become aponeurotic which is a flat tendon
How do the sheets of muscles become an aponeurosis
The fibres fuse with each other and then in the midline they fuse with the aponeuroses of the opposite side and form a seam called the linea alba
What forms the Rectus sheath which encloses the rectus abdominis
The aponeuroses of the external oblique, internal oblique and the transversus abdominis
What is the rectus abdominis muscles comprised of
It is comprised of muscle segments which are interspersed with horizontal tendinous bands.
What happens to the rectus abdominis when they hypertrophy with exercise
They bulge on either side which can then be seen on the anterior abdominal wall as bulges which is known as the six-pack
What forms the rectus sheath on the anterior wall
The external oblique aponeurosis and the anterior layer of the internal oblique aponeurosis
What forms the posterior wall of the rectus sheath
The posterior layer of the internal oblique aponeurosis and the transversus abdominis aponerurosis
Where is the transversalis fascia located
Deep to the transversus abdominis
What lies deep to the transversalis fascia
The parietal peritoneum
Where does the inferior part of the external oblique aponeurosis attach
It attaches to the anterior superior iliac spine laterally and the pubic tubercle medially
What does the attachments of the external oblique aponeurosis form
The inguinal ligament
What is found above the inguinal ligament
The inguinal canal
What is the anterolateral abdominal wall supplied by
The musculophrinic artery
The superior epigastric artery
The inferior epigastric artery
What is the musculophrenic artery a branch of
The internal thoracic artery
What is the superior epigastric artery a continuation of
The internal thoracic artery
What is the inferior epigastric artery a branch of
The external iliac artery
What is the anterolateral abdominal wall innervated by
The muscle and skin of the anterolateral abdominal wall are innervated by
Thoraco-abdominal nerves T7-T11 which are somatic nerves which are a continuation from the intercostal nerves T7-T11 and contain both sensory and motor fibres
The subcostal nerve which originates from T12 spinal nerve
The iliohypogastric and ilioinguinal nerve which are both branches of the L1 spinal nerve
What is a hernia
A hernia is a protrusion of tissue or organ from one region to another through an opening or defect
What is meant by a laparotomy
It is a surgical opening in the anterior abdominal wall which is done when good access to the abdomen is needed. This procedure is done via an midline sagittal incision is made to avoid damage to nerves and muscles, which are spit rather than cut.
Why is key hole or laparoscopy better then open surgery
Less post-operative pain
Faster wound healing
Smaller risk of infection
Smaller risk of post-operative hernia
What is an abdominal aortic aneurysm
This is an abnormal swelling of the wall of the aorta, over time it will become weak and prone to rupture. An aneurysm may be detected on abdominal examination, rupture carries high mortality rates
What is the peritoneum
The peritoneum is a serous membrane that lines the abdominal wall and covers the viscera within it
What are the two types of peritoneum
Parietal and visceral
Where does the parietal peritoneum line
The parietal peritoneum lines the abdominal wall and can be seen with the naked eye
What is the parietal peritoneum innervated by
It is innervated by the same somatic nerves which innervate the muscles and skin of the anterolateral abdominal wall
What is the pain like from the parietal peritoneum
Sharp, severe and well localised
What does the visceral peritoneum cover
The abdominal viscera and Cannot be seen by the naked eye as it is adhered to the surface of the viscera
What is the visceral peritoneum innervated by
It is innervated by visceral sensory nerves which conveys painful sensation to the CNS along the sympathetic nerves that innervates the organ/structure it covers
What is pain from the visceral peritoneum usually like
Can be severe, dull and will diffuse so hard to pinpoint
How is pain from the visceral peritoneum usually perceived
As nausea or distension
What is found between the parietal and visceral peritoneum
The peritoneal cavity
What is found in the peritoneal cavity
Filled with peritoneal fluid
Why is peritoneal fluid important
It allows the viscera to slide freely alongside each other
What is meant by intraperitoneal viscera
Intraperitoneal viscera is almost completely covered by peritoneum
What is an example of intraperitoneal viscera
The stomach
What is meant by retroperitoneal viscera
Retroperitoneal viscera is posterior to the peritoneum and so is only covered by peritoneum on the anterior surface
What is an example of retroperitoneal viscera
Pancreas
Why are some organs described as secondarily retroperitoneal
They are described as secondary retroperitoneal as the organs were intraperitoneal in early development but came to be stuck down onto the posterior abdominal wall
What do mesenteries, omerta, ligaments and folds all have in common in the abdominal cavity
They are all composed of peritoneum and connect organs to each other and the abdominal wall
They contain amounts of fat
They may all carry blood vessels, nerves and lymphatics
What are the mesentries
They are folds in the peritoneum that contain fat
What is the role of the mesenteries
They suspend the small intestines and parts of the large intestines from the posterior abdominal wall
What is found within the mesenteries
Arteries that supply the intestines which branch from the abdominal aorta and the veins that drain the gut which are from the portal venous system
What are the greater and lesser omenta
They are folds in the peritoneum that are usually fatty
What is the function of the greater and lesser omenta
They connect the stomach to other organs
Where is the greater omentum located
It hangs from the greater curvature of the stomach and lies superficial to the small intestine
What is the lesser omenta role
The lesser omenta connects the stomach and the duodenum to the liver
What can be found in the free edge of the lesser omenta
The hepatic artery, the hepatic portal vein and the bile duct
What do the hepatic artery, the hepatic portal vein and the bile duct make up
The portal triad
What are ligaments within the abdominal cavity
The ligaments are folds of peritoneum that connect organs to each other or the abdominal wall
What is the falciform ligament
This connects the anterior surface of the liver to the anterior abdominal wall
What are the coronary and triangular ligaments
They connect they superior surface of the liver to the diaphragm
What are peritoneal folds and how are they created
They are raised from the internal aspect of the lower abdominal wall and are cremated by the structures they overlie
Where can the median umbilical fold be found
It can be found In the midline
What does the median umbilical fold represent
It represents the remnant of the urachus which was an embryological structure that connected the bladder to the umbilicus
Where can the medial umbilical fold be located
They are found lateral to the median umbilical fold
What does the medial umbilical fold represent
It represents the remnants of paired umbilical arteries which returned venous blood to the placenta
Where are the lateral umbilical folds located
They are located lateral to the medial umbilical folds
What is found deep to the lateral umbilical folds
Deep to these folds are the epigastric arteries which supply the anterior abdominal wall
What is the lesser sac
The lesser sac is the space that lies posterior to the stomach and anterior to the pancreas
What is the lesser sac also known as
The omental bursa
What is the greater sac
The remaining part of the peritoneum cavity
How do the greater and lesser sacs communicate
They do this via the passageway that lies posterior to the free edge of the lesser omentum the epiploic foramen
What is the epiploic foramen also known as
The omental foramen
Where does the gastrointestinal system develop from
Then embryonic gut tube
Where is the embryonic gut tube located
Lies in the midline of the abdominal cavity
What holds the embryonic gut suspended
The dorsal mesentary
What is the function of the ventral mesentary
This connects the stomach to the anterior abdominal wall, and is where the liver grows
What does the ventral mesentary become anteriorly and posteriorly
It becomes the falciform ligament anteriorly and posteriorly it becomes the lesser omentum
How does development cause the formation of the lesser sac and some organs to become retroperitoneal
During development the organ grow, migrate and rotate to finally end up in their final position however when this happens they pull the peritoneal attachments with them which then causes the lesser sac and some organs to be pushed to the posterior and be retroperitoneal
What is peritonitis
Infection and inflammation of the peritoneum which may be localised or generalised
What can peritonitis be caused by
Inflammation of the organ or rupture of a hollow viscus
Why can peritonitis be life threatening
It can be life-threading because if the intestine is ruptured and faecal matter and bacteria contaminate the peritoneum, the bacteria can diffuse and cause sepsis
What are peritoneal adhesions
Peritoneal adhesions are fibrous connections between the parietal and visceral peritoneum
Why do we get peritoneal adhesions
We get them as when the peritoneum becomes irritated it begins to produce fibrin which cause the adhesion of the 2 layers which then become fibrous and can cause pain
What does peritoneal adhesions increase the risk of
Twisting of the intestine as it can no longer move freely
What is ascites
It is an increased volume of peritoneal fluid
Why does ascites occur
It occurs secondary to an already existing pathology such as heart or liver failure
Where does the oesophagus pass through the diaphragm
The oesophagus passes through the oesophageal hiatus
What level of the vertebral column does the oesophagus pass though the diaphragm
Level of T10
What does the hiatus around the oesophagus function as
It functions as a sphincter
What does the hiatus sphincter around the oesophagus prevent
It prevents the reflux of the stomach back into the oesophagus
How long is the abdominal part of the oesophagus
2cm
What supplies the distal oesophagus
Branches of the left gastric artery
Where does the venous blood drain to from the distal oesophagus
The distal oesophagus drains its venous return into the azygos system via the oesophageal veins and the portal venous system via the left gastric veins
What type of anastomoses is at the site of the distal oesophagus
Portosystemic anastomoses
What is the shape and function of the stomach
The stomach is a j-shaped sac that expands to accommodate food and fluid, through chemical and mechanical breakdown
What does the stomach break food down into
Chyme
What are the 4 parts of the stomach
Cardia
Fundus
Body
Pyloric antrum
What is the cardia
The cardia is the part of the stomach which is continuous with the distal oesophagus
What is the fundus
The fundus is the most superior of the stomach this is usually full of gas
What is the largest part of the stomach
The body
What is the location of the pyloric part of the stomach
The pyloric part of the stomach is distal to the body
What is the pyloric part of the stomach
This is the inferior part of the stomach which is wide but tapers off towards the pyloric canal which leads into the pyloric sphincter
What is the role of the pyloric sphincter
Regulates the passage of chyme into the duodenum
What is the right border of the stomach also known as
The lesser curvature
What is the left border of the stomach also known as
The greater curvature
Where does the stomach lie in the abdomen
The stomach lies in the left upper quadrant but position could vary
What is the stomach covered with
Visceral peritoneum
What is the anterior of the surface of the stomach close to
The anterior surface is close to the anterior abdominal wall, diaphragm and the left lobe of the liver
What does the posterior surface of the stomach become
The anterior surface of the lesser sac
Where is the lesser sac found
The lesser sac is found posterior to the stomach
What are the contents of the lesser sac
Pancreas, left kidney and spleen
What does the lesser omentum connect
The lesser curvature of the stomach to the liver
What does the free edge of the lesser omentum contain
The hepatic artery, hepatic portal vein and the bile duct
What is posterior to the free edge of the lesser omentum
Entrance to the lesser sac
Where can the greater omentum be located
The greater omentum hangs down from the greater curvature of the stomach
Where do the arteries branch from that supply the stomach
The coeliac trunk
Where does the coeliac trunk, branch from
The coeliac trunk branches from the anterior aspect of the abdominal aorta
At what level does the coeliac trunk branch from the abdominal aorta
The level of T12
What does the coeliac trunk supply
The abdominal viscera that is derived from the embryological foregut
What does the foregut comprise of
The foregut comprises of the stomach, the first half of the duodenum, the liver, the gallbladder and the pancreas
What other structure does the coeliac trunk supply that isn’t of foregut origin
The coeliac trunk also supplies the spleen which is of mesodermal origin
How many arteries does the coeliac trunk branch into
3
What are the 3 branches of the coeliac trunk
The left gastric artery
The common hepatic artery
The splenic artery
What of the 3 branch arteries of the coeliac trunk is the smallest
The left gastric artery
Where do the left and right gastric arteries run along
The lesser curvature of the stomach
What happens to the left and right gastric arteries
The left and right gastric arteries anastomoses with each other
Where does the right gastric artery branch from
The common hepatic artery
Where do the left and right gastro-omental arteries run
They run along the greater curvature of the stomach
What happens to the left and right gastro-omental arteries
They anastomoses together
Where does the left gastro-omental artery branch from
The splenic artery
Where does the right gastric-omental artery branch from
This artery branches from the gastroduodenal artery which is a branch of the common hepatic artery
Where can you find the left and right gastric veins
Running along side the left and right gastric artery’s in the lesser curvature of the stomach
Where can you find the left and right gastro-omental veins
They run along side the left and right gastro-omental arteries in the greater curvature of the stomach
Where do the left and right gastric and the left and right gastro-omental veins drain into
They all drain into the hepatic portal vein
What is the hepatic portal vein
This is a large vein which carries nutrient rich venous blood from the GI tract to the liver
What carries parasympathetic fibres to the stomach
The vagus nerve
What does parasympathetic stimulation to the stomach stimulate
Peristalsis and gastric secretion
What nerve carries sympathetic fibres to the stomach
The greater splanchnic nerve
Where is the greater splanchnic nerve formed and from what
The greater splanchnic nerve is formed of preganglionic fibres that leave the spinal cord between T5 and T9
What happens to the greater splanchnic nerve after it leaves the spinal cord
It passes through the sympathetic trunk without synapsing
Where does the greater splanchnic nerve synapse and what does this cause
The greater splanchnic nerve synapses in prevertebral ganglia around the trunk of the coeliac trunk become postganglionic fibres which travel to the stomach to inhibit peristalsis and gastric secretion
What is a hiatus hernia
The abdominal oesophagus and upper part of the stomach herniate through the oesophagus hiatus (Appature in the diaphragm) and into the throax.
What symptoms could present in a hiatus hernia
If the contents of the stomach reflux into the oesophagus the patient could experience heartburn and acid reflux
What is a gastric ulcer
A gastric ulcer develops when the mucosal lining of the internal wall of the stomach breaks down exposing the mucosa to the acidic contents of the stomach
What normally causes a gastric ulcer
It is normally due to an infection caused by helicobacter pylori which erodes the mucosal lining and exposing the muscular wall to gastric acids and enzymes
What could a gastric ulcer cause if left untreated
The erosion could continue through the wall and nearby blood vessels and can result in a catastrophic intra-abdominal bleed
What is pyloric stenosis
This is a congenital malformation characterised by the hypertrophy of the circular smooth muscle of the pyloric sphincter.
Who is more prone to get pyloric stenosis
More common in baby boys
When does pyloric stenosis usually present
Approximately 6 weeks after birth
What is the typical presentation of pyloric stenosis
Vomiting which is sometimes projectile after feeding but the baby doesn’t seem unwell and will continue to take feeds. However they will become dehydrated with continuous vomiting
What are the symptoms of gastric cancer
Some symptoms are non-specific but can include abdominal discomfort, early satiety (felling full quickly), loss of appetite, nausea, weight loss, difficulty swallowing and indigestion
What are the 3 parts of the small intestine
The duodenum, the jejunum and the ileum
What is the duodenum continuous with
The pylorus of the stomach
What is the shape of the duodenum
Shot and curved into a c-shape round the head of the pancreas
Is the duodenum intrapertioneal or retroperitoneal
Most of the duodenum is retroperitoneal
What is found on the internal wall of the duodenum half way along
Major duodenal papilla
What is the major duodenal papilla
It is the opening of the bile duct and the main pancreatic duct into the duodenum
Where does the first half of the duodenum develop embryologically
The foregut
What is the first half of the duodenum supplied by
The coeliac trunk
Where does the second half of the duodenum develop embryologically
The midgut
What artery supplies the second half of the duodenum
It is supplied by branches of the superior mesenteric artery
What is the jejunum continuous with superiorly
The duodenum
Are the jejunum and ileum intraperitoneal or retroperitoneal
They are both intraperitoneal
How are the jejunum and the ileum suspended fro the posterior abdominal wall
By the mesentery of the small intestine
What is embedded in the mesentery
The blood vessels that supply the small intestine from the superior mesenteric artery
Where is the jejunum located within the abdomen
Left upper quadrant
Where is the ileum located in the abdomen
Right Lower quadrant
Where are the jejunum and the ileum derived from embryologically
The midgut
What are the jejunum and ileum the site of and how are they adapted for this
Nutrient absorption
They have a large surface area, the mucosa is folded known as plicae circulares, the folds hold villi and each epithelial cell on the luminal surface have microvilli
How can you differentiate between the jejunum and the ileum
They are had the differentiate just upon looking at them however on the internal surfaces the plicae circulares is more pronounced in the jejunum and the ileum has peyers patches which are large submucosal lymph nodules
What is a blind-ended diverticulum, where does it occur and what is it called
A blind-ended diverticulum is the embryological remnant of the connection which was resent between the midgut loop and the yolk sac. It occurs approximately one meter from it termination and is known as meckels diverticulum
What can meckels diverticulum be confused with if it becomes inflamed
Appendicitis
What is the terminal ileum continuous with
The caecum
Where does the ileum and caecum join
At the ileocaecal junction in the right iliac fossa region
What is the function of the large intestines
The large intestine reabsorbs water from faecal material which forms semi-solid faeces
What sections make up the large intestine
The caecum, the appendix, the ascending colon, the transverse colon, the descending colon, the sigmoid colon, the rectum and anal canal
The outer muscle layer is formed of 3 bands known as what
The Taeniae coil
What does the inner circular muscle layer form
It forms bulges called haustra or haustrations
The large intestine has fatty tags called what
Epiploic appendages or appendices epiploicae
What do the epiploic appendages mark
They mark the point at which blood vessels penetrate the intestinal wall
What is the caecum
First part of the large intestine, it is a distended blind ended pouch
What is the caecum covered by
Peritoneum
Does the caecum have a mesentery
No
What is the appendix
The appendix is a Small diverticulum that protrudes from the caecum
What does the appendix contain
Lymphoid tissue
What is the surface marking of the base of the appendix
McBurney’s point
How is the appendix connected to the caecum
By a small mesentery called the mesoappendix
What is the ascending colon continuous with
The caecum
Where is the ascending colon located in the abdomen
It runs vertically on the right side of the posterior of the abdominal wall in the right paracolic gutter
Is the ascending colon intraperitoneal or retroperitoneal
Retroperitoneal
What is the ascending colon an example of
It is an example of secondary retroperitoneal organ
How does the ascending colon become continuous with the transverse colon
The ascending colon makes a 90 degree turn left into the right upper quadrant and so becomes the transverse colon
What is the bend of the ascending colon called
The hepatic flexure
What is the hepatic flexure also known as
The right colic flexure
Where does the transverse colon run
The transverse colon runs horizontally in the upper abdomen, but sometimes hangs inferiorly
Is the transverse colon intraperitoneal or retroperitoneal
Intraperitoneal
Is the transverse colon suspended
Yes it is suspended from the posterior abdominal wall by the transverse mesocolon
What does the transverse colon become continuous with
The transverse colon does a 90 degree turn in the left upper quadrant and becomes continuous with the descending colon
What is the 90 degree turn that the transverse colon makes
The turn is called the splenic flexure
What is the splenic flexure also known as
The left colic flexure
What is the splenic flexure tethered to
The splenic flexure is tethered to the diaphragm
How is the splenic flexure tethered to the diaphragm
By the phrenicocolic ligament
What does the transverse colon mark
The transverse colon marks the transition point between the embryological midgut and hindgut
What of the transverse colon is midgut and what is hindgut
The proximal two thirds of the transverse colon are mid gut and the distal third is the hindgut
What is the descending colon continuous with superiorly and inferiorly
The transverse colon superiorly
The sigmoid colon inferiorly
Where does the descending colon run in the abdomen
The descending colon runs vertically down the left side posteriorly along the abdominal wall in the left laracolic gutter
Is the descending colon intraperitoneal or retroperitoneal
Retroperitoneal
What is the descending colon an example of
It is an example of a secondary retroperitoneal organ
Where is the sigmoid colon found
The sigmoid colon is found id the lower left quadrant of the abdomen
What is the sigmoid colon continuous with superiorly and inferiorly
The descending colon superiorly
The rectum inferiorly
As the sigmoid colon approaches the midline it makes a 90 degree turn to where
Into the pelvis
What is the 90 degree turn called that the sigmoid colon makes
The rectosigmoid junction
Does the sigmoid colon have a mesentery
Yes called the sigmoid mesocolon
Is the sigmoid colon intraperitoneal or retroperitoneal
Intraperitoneal
Where does the rectum descend into
The pelvis from the rectosigmoid junction
Is the rectum intraperitoneal or retropertioneal
Retroperitoneal
What is the function of the rectum
The function of the rectum is to store faeces unto it is convenient to defecate
What is the rectum continuous with inferiorly
The anal canal
What artery branches off the aorta to supply the midgut
The superior mesenteric artery
At what level does the superior mesenteric artery leave the aorta
The level of L1
What are the structures of the midgut that the superior mesenteric artery supply
The midgut- second half of the duodenum, the small intestine and the large intestine as far as the proximal two thirds of the transverse colon. And it also supplies some of the pancreas
What branch of the abdominal aorta supplies the hindgut
The inferior mesenteric artery
What level does the inferior mesenteric artery leave the aorta
The level of L3
What structures does the inferior mesenteric artery supply
The hindgut- the distal third of the transverse colon, the descending colon, the sigmoid colon, the rectum and the upper part of the anal canal
What are the major branches of the superior mesenteric artery
Jejunal branch- several branches to the jejunum
Ileal branch- several branches to the ileum
Ileocolic artery- supplies the caecum, appendix and the ascending colon
Right colic artery- supplies the ascending colon
Middle colic artery- supplies the transverse colon
Where are the jejunal and ileal branches located
In the mesentery of the small intestine
All the major branches of the superior mesenteric artery anastomose with each other to form loops of arteries called
Arcades
What runs from the arcades and what do they supply
From the arcades are vasa recta which are straight vessels which supply the intestinal wall
What are the major branches of the inferior mesenteric artery
The left colic artery- supplies the transverse colon and the descending colon
Sigmoid branches- supply the sigmoid colon
Superior rectal artery- the terminal branches of the inferior mesenteric artery which supply the upper rectum
What happens to the middle colic artery of the SMA and the left colic artery of the IMA
They anastomose along the distal third of the transverse colon and the splenic flexure to for the marginal artery
What happens to the left colic and the sigmoid arteries
They anastomose
What is the lower rectum supplied by
The Lower rectum is supplied by branches from the internal iliac arteries from the pelvis
Where does venous blood from the gut ultimately drain to
The inferior vena cava to be returned to the heart
Before reaching the inferior vena cava where does the venous blood go to
The liver
Why does the venous blood go to the liver before the inferior vena cava
The venous blood from the gut contains loads of nutrients which has been absorbed
How does venous blood rich with nutrients reach the liver
Through the portal venous system
Where is the inferior mesenteric vein be found
Along side the inferior mesenteric artery
What does the inferior mesenteric vein drain
The venous blood from the hind gut
Where does the inferior mesenteric vein ascend
On the left side of the abdomen
Where does the inferior mesenteric vein drain into
The splenic vein
Where can you find the superior mesenteric vein
Along side the superior mesenteric artery
What does the superior mesenteric vein drain
The midgut
Where does the superior mesenteric vein ascend
It acsends in the right side of the abdomen
What does the superior mesenteric vein unite with and what does this form
The superior mesenteric vein unites with the splenic vein close to the liver posterior to the neck of the pancreas and forms the hepatic portal vein
What happens when the venous blood enters the liver via the hepatic portal vein
After the nutrients have been absorbed out of the blood, the venous blood enters small hepatic veins which unite within the liver to form 2/3 large hepatic veins which then enter the inferior vena cava to return the venous blood to the heart
What fibres innervate the midgut and hindgut and what do they stimulate
Parasympathetic fibres innervate the midgut and hindgut and they stimulate peristalsis and secretions
What nerve carries parasympathetic inner actions to the foregut and midgut
The vagus nerve
What nerve carries parasympathetic innervations to the hindgut
The pelvic splanchnic nerve
How are the pelvic splanchnic nerves formed
Where do the pelvic splanchnic nerves originate from
They are formed by the axons of the parasympathetic neurons in the sacral spinal cord, the cell bodies of preganglionic parasymathetic neurons lie in the sacral spinal cord in S2-S4. They leave the spinal cord and form the pelvic splanchnic nerves. Th preganglionic axons then synapse with a second neuron in a ganglion close to the viscera
Where do the sympathetic fibre that innervate the gut originate from
The preganglionic sympathetic fibres pass from the spinal cord between T5 and T12 and pass through the sympathetic trunk without synapsing via the greater, lesser and least splanchnic nerves
What nerve carries sympathetic innervation to the foregut and where do they originate from
They greater splanchnic nerves innervate the foregut which originate from T5-T9
What nerve carries sympathetic innervation to the midgut and where does it originate
The lesser splanchnic nerve innervates the midgut whcih originates from T10-T11
What nerve carries sympathic innervation to the hind gut and where does it originate
The least splanchnic nerve innervates the hind gut which originates from T12
The sympathetic fibres in the preganglionic fibres synapse where
Within ganglia that lie in the abdomen around the aorta, coeliac trunk, SMA and IMA
The postganglionic fibres carrying sympathetic fibres from the visceral nerves then innervate the gut causing what
Inhibition of peristalsis and secretions
The gut can also be innervated by visceral sensory fibres what do these do
They convey sensory information back to the CNS which doesn’t reach our conscious perception
If we receive sensory information from the abdomen which reaches out conscious perception what does this mean
It is caused due to ischaemia, distension or spasm
Painful sensations from the foregut return to the CNS via what segments in the spinal cord
T5-T9
Painful sensations from the midgut return to the CNS via what segments of the spinal cord
T10-T11
Painful sensations from the hindgut return to the CNS via what segments in the spinal cord
T12
Information from the dermatomes of the foregut is received by which spinal segments
T5-T9
Information from the dermatomes of the midgut is received by which spinal segments
T10-T11
Information from the dermatomes of the hindgut is received by which spinal segments
T12
Pain from the abdominal viscera is referred to the body wall so epigastric pain is suggested as pathology of what
Foregut pathology
Pain from the abdominal viscera is referred to the body wall so central/umbilical pain is suggested as pathology of what
Midgut pain
Pain from the abdominal viscera is referred to the body wall so lower/suprapubic pain is suggested as pathology of what
Hindgut pain
What is an appendicitis
Inflammation of the appendix
Where is the pain of an appendicitis usually felt
In the umbilical region of the abdomen
Why is the pain felt in the umbilical region of the abdomen
The pain is felt here due to the peritoneum becoming irritated and so sending sensations through visceral sensory afferents which return to the spinal segment T10 and send the sensation to the CNS
Where does the pain become more localised after awhile
The pain becomes more localised as the adjacent parietal peritoneum becomes involved, which causes severe pain in the right iliac fossa region of the abdomen
What could be presenting symptoms of a appendicitis
Pain diffuse from the umbilical region of the abdomen to the right iliac fossa region
Tenderness which is maximal over McBurney’s point
What can a rupture do the appendix cause
Peritonitis
How is an appendicitis resolved
Via an appendectomy performed usually laparoscopically unless rupture is suspected
What is mesenteric ischaemia
Mesenteric ischaemia is where the mesenteric vessels become occluded by a thrombus
What can ischemia of the intestines cause
Infarction
Why can mesenteric ischaemia be a surgical emergency
Because the intestine need to become revascularized and an secretions of necrotic intestine must be removed but mortality is high
What are the 2 types of inflammatory bowel disease
Crohn’s disease and ulcerative colitis
What Is Crohn’s disease characterised by
Inflammation of the gut mucosa
Where typically does Crohn’s disease affect
Typically the small intestine but can affect anywhere in GI tract
What could a patient with Crohn’s disease present with
Abdominal pain, diarrhoea, bloody stools, weight loss and tiredness
What does ulcerative colitis affect
The colon and rectum
How is ulcerative colitis characterised
The mucosa of the colon and rectum become inflamed and ulcerated
Patients with ulcerative colitis could present with what symptoms
Abdominal pain, bloody diarrhoea, weight loss and tiredness
What are the main symptoms of colon cancer
Change in bowel movements
Blood in the stool
Abdominal pain
Bloating
How would colon cancer be investigated to give a diagnosis
A colonoscopy to visualise the colon and take biopsies of any masses
What is Volvulus
This is twisting of the gut
Where is twisting of the gut most often seen
In the sigmoid colon
Why is twisting of the gut most often seen in the sigmoid colon
Because the other parts of the gut are suspended with a mesentery and so aren’t mobile
What can twisting of the gut cause
Obstruction and infraction
Where is the liver located in the abdomen
Lies in the upper right quadrant and epigastrium
What is the liver protected by inferiorly
The ribs
Where does the liver move to during inspiration
It moves inferiorly
Which part of the liver can be felt upon palpation of the abdomen
The lowermost part of the liver just under the right costal margin, will be palpable
How do products of digestion get transported to the liver
Via the hepatic portal vein
What is not transported to the liver via the portal vein
Lipids
What does the liver produce
Bile
Where is bile transported to from the liver for storage
The gallbladder
What is the function of bile
Bile emulsifies lipids within the chyme entering the duodenum from the stomach
What are the 2 surfaces of the liver
The diaphragmatic surface and the visceral surface
What is the diaphragmatic surface of the liver
The surface which lies anterosuperior related to the inferior surface of the diaphragm
What is the visceral surface of the liver
This is the surface that lies posteroinferior and is related to other organs
What regions on the liver is not covered by peritoneum
The bare area of the liver- which is a region on the posterior surface that lies in contact with the diaphragm
The region where the gallbladder sits in contact with the liver
The region of the porta hepatis which is where the hepatic blood vessels and ducts of the biliary system enter and exit the liver
How many lobes does the liver have
2 anatomical lobes the right and left
Which lobe of the liver is the largest
The right
How are the 2 anatomonical lobes of the liver separated
By the falciform ligament
What is the role of the falciform ligament
This ligament connects the anterior surface of the liver to the internal aspect of the anterior abdominal wall
What are the 2 accessory lobes of the liver called
The caudate and the quadrate
Where are the 2 accessory lobes located
The posteroinferior surface of the liver
Internally how many segments is the liver organised into
8
What is each organisational segment supplied by
It’s own branch of the hepatic artery, portal vein and hepatic duct
What is the liver supplied by
The right and left hepatic arteries
Where do the left and right hepatic arteries arise from
The coeliac trunk
What does the common hepatic artery give rise to
The gastroduodenal artery
After the gastroduodenal artery what does the common hepatic artery become
The hepatic artery proper
What does the hepatic artery proper become
The hepatic artery proper bifurcates into the left and right hepatic arteries
Where do the hepatic arteries enter the liver
The porta hepatis
What is the portal triad made up of
Bile duct
Portal vein
Hepatic artery
How does venous blood exit the liver
Via 2/3 hepatic veins
What do the hepatic veins unite with
The inferior vena cava
Where do the hepatic portal veins and inferior vena cava unite
Posterior to the liver
What is the difference between the hepatic portal veins and hepatic veins
Hepatic portal veins carry nutrient-rich blood from the gut to the liver from the superior and inferior mesenteric veins and splenic vein
Hepatic vein carry venous blood from the liver to the inferior vena cava
What is the liver served by
The hepatic plexus
What is the hepatic plexus composed of
Parasympathetic fibres from the vagus nerve
Sympathetic fibres
Where is pain from the liver felt and why
Pain from the liver would be referred to the epigastric region due to it been a foregut derivative
What is the liver connected to and how
The diaphragm via the coronary and triangular ligaments
The anterior abdominal wall via the falciform ligaments
The stomach and duodenum by the lesser omentum
Where does the portal triad run
In the free edge of the lesser omentum
What does the portal triad and the free edge of the lesser omentum form
The anterior boundary of the epiploic foramen
What is the epiploic foramen
The entrance to the lesser sac
Where is the lesser sac located
The posterior of the stomach
What is the hepatorenal recess
This is a recess that lies between the right kidney and the posterior visceral surface of the right side of the liver to which fluid flows into the space when in the supine position
What is the left and right subphrenic recess
This recess lies on the left and right side of the falciform ligament between the anterosuperior surface of the liver and diaphragm
Where does the liver develop from embryologically
The embryological foregut
Where does the liver grow from embryologically
The liver grows from a tissue bud that develops in the ventral mesentery which is a peritoneal fold in the upper abdomen that connects the stomach to the anterior abdominal wall. As the liver continues to grow and migrate to the right side of the abdomen, the peritoneal attachments are pulled with it. The remains of the ventral mesentery form the lesser omentum and the falciform ligament. The peritoneal attachments of the liver anchor it to the surrounding structures such as the diaphragm
What does the free edge of the falciform ligament contain
The round ligament of the liver
What is the round ligament of the liver known as
The ligament teres
What is the round ligament of the liver a remnant of
The umbilical vein
In a foetus what was the function of the umbilical vein
Carries oxygenated blood from the placenta to the foetus
Where is the ligamentum venosum located
This is a embryological remnant on the posterior surface of the liver, in the groove between the caudate lobe and left lobe of the liver
What is the ligament venosum
It is the remnant of the ductus venosus
What is the function of the ductus venosus in a foetus
This diverts blood from the umbilical vein to the inferior vena cava shunting oxygen rich blood to the heart bypassing the liver
What is the function of the gallbladder
Store and concentrate bile
Where is the gallbladder located
On the posteroinferior surface of the liver close to the duodenum
How many parts does the gallbladder have
3 parts
What are the 3 parts of the gallbladder
The body, fundus and neck
What is the main part of the gallbladder and where is it located
The body and is located in the gallbladder fossa on the visceral surface of the liver
What dose the neck of the communicate with
The cystic duct
What is the fundus of the gallbladder
The fundus is the rounded end of the gallbladder which extends to the inferior border of the liver
What is the surface marking of the fundus of the gallbladder
Tip of the 9th costal cartilage at the point where the mid Clavicular line intersects the right costal margin
What makes bile in the liver
Hepatocytes continuously produce liver
Where is bile excreted frirst
Into the small channels known as the bile canaliculi
Where do the canaliculi drain into
The bile ducts
What do the bile ducts form
They converge to form the left and right hepatic ducts which exit the liver
Where do the left and right hepatic ducts exit the liver
The hepatic ducts exit the liver at the porta hepatis
What do the left and right hepatic ducts form
They converge to form the common hepatic duct
What does the common hepatic duct receive
The cystic duct from the gallbladder
What does the common bile duct become after the cystic duct
The bile duct or common bile duct
Where does the bile duct run
In the free edge of the lesser omentum posterior to the superior part of the duodenum and posterior to the head of the pancreas which then enters the duodenum
What happens if bile isn’t needed for digestion
It enters the gallbladder via the cystic duct and then when needed it flows from the gallbladder via the cystic duct to the bile duct and duodenum
What is the spinal fold
Lies at the junction between the gallbladder neck and the cystic duct
What is the blood supply to the gallbladder
Blood supply is via the cystic artery
Where does the cystic artery arises from where
From the right hepatic artery
What drains the gallbladder
The cystic veins
Where do the cystic veins pass into
They either pass directly into the liver or join the hepatic portal vein
What is the gallbladder innervated by
Parasympathetic and sympathetic fibres
Where does visceral pain from the gallbladder enter the spinal cord
The visceral pain from the gallbladder runs along the visceral afferents and enters the spinal cord at T5-T9
Where is pain from the gallbladder felt in the abdomen
The epigastrium
Why might gallbladder pain be felt in the right shoulder
Gallbladder pain maybe referred to the right shoulder because gallbladder pathology could irritate the diaphragm which in innervated by the phrenic nerve C3-C5 which also receives somatic sensory information from the skin of the right shoulder
If gallbladder pathology irritates the parietal peritoneum where would the pain be felt
The pain would be well localised to the right hypochondrium
What is hepatomegaly
Enlargement of the liver
What can cause hepatomegaly
Hepatitis, malignancy and heart failure
Why does cancer of the bowel travel to the liver
Cancer of the bowel travels to the liver within the venous blood from the gut via the hepatic portal vein
What is cirrhosis of the liver
Known as scarring of the liver
What can cirrhosis caused by
Can be caused by excess alcohol consumption, chronic infection with hepatitis B or C or a build up of fat on the liver
What happens When a liver becomes cirrohosis
Hepatocytes are destroyed and replaced with fibrous tissue, the liver becomes shrunken, hard and modular which can lead to dysfunction of the liver and liver failure
What is portal hypertension
High blood pressure in the portal venous system
Why does portal hypertension occur
The blood flow through the liver and portal vein is obstructed
Why could the portal vein become obstructed
Due to cirrhosis
What are portosystemic anastomoses
They are communications between the veins draining into the systemic circulation and veins draining into the portal circulation
What are gallstones most commonly composed of
Cholesterol
When might gallstones provide symptoms
When the gallstones migrate into the biliary tree and get lodged there
What is biliary colic
Biliary colic is a term used to describe severe pain caused by the contraction of the gallbladder against the gallstone in the cystic duct
What happens if the gallstone remains stuck in the cystic duct
The flow of bile will become blocked and the gallbladder will become inflamed
What is inflammation of the gallbladder known as
Cholecystitis
What is a cholecystectomy
The removal of the gallbladder
What does the left gastric artery supply
The distal oesophagus and the lesser curvature of the stomach
What does the common hepatic artery supply
Supplies the liver, stomach and duodenum
What does the splenic artery supply
Supplies the stomach, pancreas and spleen
What regulates gastric emptying into the duodenum
The pyloric sphincter
Is the duodenum intraperitioneal or retroperitoneal
Most is retroperitoneal
How many parts is the duodenum divided into
4
What are the 4 parts of the duodenum
Superior
Descending
Inferior
Ascending
Where on the duodenum would you find the bile duct, gastroduodenal artery and the hepatic portal vein
Posterior to the first part/superior of the duodenum
Where on the duodenum would you find the superior mesenteric artery be found
Anterior to the thrird part/inferior part
Where does the duodenum join with the jejunum
At the fourth part/ascending part of the duodenum unites with the jejunum at the duodenojejunal flexure
What is found halfway along the duodenum
The major duodenal papilla
What does the major duodenal papilla mark
The point at which bile and digestive pancreatic secretions enter the duodenum
Where is the first part of the duodenum derived from
The foregut
What is the first half of the duodenum supplied by
A branch of the coeliac trunk via the gastroduodenal artery
Where is the second half of the duodenum derived from
The mid gut
What supplies the second half of the duodenum
Branches of the superior mesenteric artery via the inferior pancreaticoduodenal artery
Where do the veins from the duodenum drain into
The hepatic portal vein
Where is the pancreas located in the abdomen
Lies horizontally on the posterior abdominal wall across the right and left upper quadrant
At what level does the pancreas lie at
Level of L1
Is the pancreas intrperitoneal or retroperitoneal
Retroperitoneal
Where does the pancreas develop from embryologically
The dorsal and ventral pancreatic buds which during development fuse together
How many parts make up the pancreas
4
What are the 4 parts of the pancreas
The head, the neck, the body and the tail
Where does the duodenum touch the pancreas
Cupped around the head
Where does the tail extend to in the abdomen
The hilum of the spleen
What does the pancreas form part of
The posterior wall of the lesser sac
Where is the splenic artery located
In the upper border of the pancreas to the posterior
Where are the main pancreatic duct and the accessory pancreatic duct found
In the substance of the pancreas
What 2 functions does the pancreas have
An endocrine and exocrine function
What is the endocrine function of the pancreas
Synthesises and secretes insulin and glucagon
Why is insulin released from the pancreas
In response to high blood levels of glucose
What is the exocrine function of the pancreas
Produces pancreatic juices which contain digestive enzyme which gets transported to the duodenum via the main and accessory pancreatic duct
What does the duodenum receive from the liver and gallbladder
Bile via the bile duct
What does the duodenum receive from the pancreas
Pancreatic juice via the main and accessory pancreatic ducts
What do the bile duct and main pancreatic duct become
They merge and become the hepatopancreatic ampulla
Where does the hepatopancreatic ampulla open into
The second part of the duodenum at the major duodenal papilla
What surrounds the hepatopancreatic ampulla
Surrounded by smooth muscle
What is the smooth muscle around the hepatopancreatic ampulla known as
The spinchter of oddi
What does contraction of the sphincter of oddi prevent
Reflux of duodneal contents into the bile and main pancreatic ducts
Where does the accessory pancreatic duct empty the pancreatic juice into
The duodenum at the minor duodenal papilla proximal to the major duodenal papilla
What branches supply the pancreas
The coeliac trunk and the superior mesenteric artery
Where does the splenic artery run
Runs from the coeliac trunk along the upper border of the pancreas which gives rise to pancreatic arteries
Where does the superior pancreaticoduodenal arteries arise from
This artery arises from the gastroduodenal artery which comes off the common hepatic artery from the coeliac trunk
Where does the inferior pancreaticoduodenal arteries arise from
The superior mesenteric artery
What vein drains the pancreas
The splenic vein
What veins unite to form the hepatic portal vein
The splenic vein and the superior mesenteric vein
What is the spleen
The spleen is a haematopoietic and lymphoid organ
Where is the spleen located in the abdomen
Found in the left upper quadrant of the abdomen
What protects the spleen
Ribs 9 to 11
What is the spleen cover in
Parietal peritoneum
What are the functions of the spleen
Breakdown of red blood cells
Storage of red blood cells and platelets
Immune responses
Production of IgG
What are the 2 surfaces of the spleen
The diaphragmatic surface and the visceral surface
What is the diaphragmatic surface of the spleen
The surface which lies adjacent to the diaphragm
What is the visceral surface of the spleen
The surface which lies in contact with the stomach, left kidney and colon
Where is the Hilum located
On the visceral surface
How many borders does the spleen have
4
What are the 4 borders of the spleen
Anterior, superior, posterior and inferior
What is a characteristic of the anterior and superior borders of the spleen
They are typically notched
What is a characteristic of the posterior and inferior borders of the spleen
They are smooth
Is the spleen palatable
No, if it is it must be enlarged at least 3 times its normal size
What is the spleen supplied by
The splenic artery which is a branch of the coeliac trunk
How many branches does the splenic artery divide into before it enters the hilum of the spleen
5 branches
What is the venous drainage of the spleen
The splenic vein
Where does the splenic vein run
It runs posterior to the pancreas
Where a duodenal ulcers most commonly found
In the first part of the duodenum
Why might a duodenal ulcers cause severe intra-abdominal bleeding
The ulcer will erode through the duodenal wall and then through the gastroduodenal artery which is posterior to the first part of the duodenum causing it to bleed
What is pancreatitis
Inflammation of the pancreas
What causes acute pancreatitis
Excess alcohol intake or impact ion of gallstones in the hepatopancreatic ampulla
What happens in gallstone pancreatitis
The Impactation of the gallstones prevents the pancreatic juice from leaving the pancreas and will so build up and cause a break down of the pancreas itself known as autolysis
Where is pain felt during pancreatic cancer
Back
When pancreatic cancer affects the head of the pancreas what can it cause
Obstruct the flow of bile in the bile duct which leads to an accumulation of bile pigments in the blood
What does a build up of bile pigments in the blood cause
Jaundice
What is the cause of diabetes mellitus
Cause by the insulin producing cells in the pancreas no longer produce insulin or don’t produce enough
What is a result of the pancreas not producing enough insulin
Sustained high blood glucose levels
What can diabetes be caused by
Pancreatitis
What is splenomegaly
Enlargement of the spleen
What can cause enlargement of the spleen
Infection by mononucleosis or malaria
Haematological malignancy eg-leukaemia
Portal hypertension
When the spleen is enlarged where does it migrate towards
The midline of the right iliac fossa
Why does the spleen move to the right iliac fossa and not the left
The phrenicocolic ligament prevents descent
How is a splenic haemorrhage resolved
Splenectomy - removal of the spleen
If a patient has a splenectomy what are they more prone to
Bacterial infections
What does the mucosa in the upper nasal cavity contain
Olfactory receptors
What do the axons of the olfactory receptors form
The olfactory nerves CN I
How are the left and right nasal cavities seperated from what
Each other By a thin midline septum
The oral cavity by the hard plate
The brain by bone
What does the nasal cavity communicate with
The nasopharynx posteriorly and the paranasal sinuses
What is the midline nasal septum composed of
Cartilage anteriorly and two thin plates of bone posteriorly
What does the perpendicular plate of the ethmoid bone form
The superior part of the posterior septum
What does the vomer form
The inferior part of the posterior septum
What is found on the lateral wall of the nasal cavity
3 projections of bone
What are the 3 projections of bone in the nasal cavity
Superior conchae
Middle conchae
Inferior conchae
What is the space inferior to the conchae in the nasal cavity
The space is the meatuses
The superior meatus lies inferior to the superior conchae
The middle meatus lies inferior to the middle conchae
The inferior meatus lies inferior to the inferior conchae
As air is inspired through the meatus what happens
It is warmed, humidified and filtered
How is the nasal cavity is seperated from the cranium
By the cribriform plate
Why does the cribriform plate have many tiny holes
So the axons of the olfactory nerves can travel to the brain
Where are olfactory receptors located
In the spheno-ethmoidal recess in the upper nasal cavity between the superior conchae and the cribriform plate
What are the paranasal sinuses
Cavities within the skull bones
Where are the frontal sinuses located
Lie in the anterior part of the frontal bone
Where are the ethmoid air cells located
Lie within the ethmoid bone which is superior to the nasal cavity and medial to the orbits
Where are the sphenoid sinuses located
Within the sphenoid bone
Where are the maxillary sinuses located
In the maxillae of the facial skeleton
How do the paranasal sinuses communicate with the nasal cavity
Via small ducts/channels
Where does the frontal sinus drain
Into the middle meatus
Where does the sphenoid sinus drain
Into the spheno-ethmoidal recess
Where does the ethmoid air cells drain
Into the superior and middle meatus
Where do the maxillary sinus drain
Into the middle meatus
Why can’t the maxillary sinuses drain when the head is up right
Because the opening of the maxillary sinus lies superomedially in the middle meatus
What does thenasolacrimal duct drain
Drains the fluid (tears) that lubricates the anterior surface of the eye
Where does the nasolaracrimal duct open into
The inferior meatus
Why do we get a runny nose when we cry
Because excess fluid runs down the nasolacrimal duct
What is the middle ear
A small cavity within the temporal bone that is modified for hearing
What is within the middle ear
3 tiny bones which transmit sound waves to the inner ear
What is the auditory tube also known as
The Eustachian tube
What is the role of the Eustachian tube
The Eustachian tube connects the middle ear to the nasopharynx
Where is the opening of the Eustachian tube
Lateral wall of the nasopharynx
What is the opening of the Eustachian tube surrounded by
Budge of tonsillar tissue
What does the Eustachian tube allow
It allows air t pass into the middle ear so that the pressure on either side of the tympanic membrane which lies between the middle ear and the external ear is equal which is important for optimal conduction of sound waves
What is the nasal cavity is supplied by
Several branches of the maxillary artery
Where does the maxillary artery arise from
The external carotid artery
What is the most common site of bleeding from the nose
The anastomotic network which supplies the nasal septum
What is the sensory innervation of the nose
Branches of the trigeminal nerve CN V
What is the palate
The palate seperates the nasal cavities from the oral cavity
What is the palate composed of
Bone anteriorly which is the hard plate and muscle posteriorly which is the soft plate
What does the palate form
The roof of the oral cavity
What is the hard palate composed of
2 bones
The palatine bone of the maxilla
Horizontal plate of the palatine bone
Why is the hard palate functionally important
Prevents food and liquids entering the nasal cavity
We push our tongue up against the hard palate during the first phase of swallowing forcing food into the oropharynx
We push our tongue up against the hard palate to articulate certain sounds
What is formed if the palate does not form properly during embryological development
A cleft palate
What does a cleft palate cause
Difficulty with eating, swallowing and speech
Where is the soft palate located
Posterior to the hard palate
What is the midline conical projection called
The uvula
Where is the uvula located
Hangs from the posterior border of the soft palate
What is the soft palate composed of
Several muscles
What happens to the muscles of the soft palate during swallowing
They contract with elevates the soft palate which closes of the nasopharynx from the oral cavity which prevents reflux of food and liquid into the nasal cavity
What is the muscles of the soft palate innervated by
The vagus nerve
What are the boundaries of the oral cavity
Superiorly the hard and soft palate
Inferiorly the soft tissue and muscles of the floor of the mouth
Laterally by the cheeks
What does the oral cavity contain
Tongue
Teeth
Gums
Openings of the salivary ducts
What is the oral cavity continuously
Oropharynx
What could a dental abscess cause
Sepsis or spread the infection to the deep tissues of the face
How many teeth do adults have
32 in total
16 embedded in the maxilla
16 embedded in the mandible
What teeth are in the upper and lower jaw
4 incisors
2 canines
4 premolars
6 molars
What are teeth composed of
Inner pulp containing blood vessels and nerves
Dentin which surrounds the pulp
Enamel an outer hard coating
What causes erosion of enamel and dentin
Bacteria and food which are high in sugars and acids
Is the dentin and enamel are eroded what could this cause
Decay, inflammation and infection in the pulp
An infection of the inner pulp could spread to where
May spread to the bone which will lead to abscess formation
What is the tongue essential for
Chewing, swallowing and speech
What is on the superior surface of the tongue
Papillae
What do some of the papillae do
Detect taste via taste buds
What is the tongue composed of
Intrinsic and extrinsic muscles
Where are the intrinsic muscles of the tongue located
The intrinsic muscles lie entirely within the tongue and are pair bilaterally and fuse in the midline
What is the function of the intrinsic muscles of the tongue
They change the shape of the tongue
Where are the extrinsic muscles of the tongue located
They are attached to the tongue but originate outside from the mandible and the hyoid bone
What is the function of the extrinsic muscles of the tongue
They move the tongue
What innervates the muscles of the tongue
The hypoglossal nerve CN XII
How many nerves supply sensory innervation to the tongue
3
What are the 3 never which provide sensory innervation to the tongue
Taste- is found in the anterior 2/3 of the tongue and is served by the facial nerve CN VII
General sensation such as touch, pain and temp- is found in the anterior 2/3 of the tongue served by the trigeminal nerve CN IX
Taste and general sensation of the posterior 1/3 of the tongue is served by the glossopharyngeal nerve CN IX
What is the oral cavity supplied byt
It is supplied by the lingual, maxillary and facial arteries which are branches of the external carotid artery
What is the soft palate innervated by
There vagus nerve
What is the tongue innervated by
The hypoglossal nerve CN XII
The facial nerve CN VII
The trigeminal nerve CN V
The glossopharayngeal nerve CN IX
Where are the pharyngeal tonsils located
In the roof and posterior wall of the nasopharynx
What are pharyngeal tonsils also known as
The adenoids
Where are the tubal tonsils located
They surround the opening of the Eustachian tube on the lateral wall of the nasopharynx
Where are palatine tonsils located
On the lateral wall of the oropharynx
What are the palatine tonsils also known as and where can they be seen
They are known as the tonsils
They are visible on either side of the oropharynx when the mouth is open
Where are the lingual tonsils found
They are found in the posterior tongue which are just collections of lymphoid tissues
What is epistaxis
Nosebleed
What is used to stop a nosebleed
Apply pressure
Bleeding could be cauterised
Nasal tampon
What can happen if the nose is hit via blunt trauma
The nasal bones/septum may be broken which could also fracture the cribriform plate
What is sinusitis
Inflammation or infection of the mucosa lining the paranasal sinuses
Why might sinusitis be problematic in the maxillary sinuses
They do not drain freely unless laying down on one side
Where might pain be felt from inflammation of the maxillary sinuses
Pain in the cheek due to the sensory nerve that supplies the check runs in the roof of the maxillary sinus
What happens if the bone of the hard palate do not develop or fuse in the midline
A cleft palate with be formed allowing communication between the nasal and oral cavities
What would be the result of injury to the right hypoglossal nerve
Would result in atrophy and weakness/paralysis of the ipsilateral side of the tongue
What is the result of hypoglossal nerve palsy
Te tongue would deviate to the affected side then the patient protrudes their tongue
How do mouth cancers present
Ulcers, lumps, patches of discolouration
What structures could oral cancers affect
The oral mucosa, tonsils, tongue and salivary glands
What is tonsillitis
Inflammation of the tonsils
Which tonsils are most commonly affected in tonsillitis
The palatine tonsils
What can inflammation of the tonsils cause
May obstruct the opening to the Eustachian tube which can result in accumulation of fluid in the middle ear
How can recurrent tonsillitis be treated
Tonsillectomy
