Anatomy - Gastrointestinal Flashcards
Anatomy - Gastrointestinal
1
Q
How is the abdominal cavity separated from the thorax?
A
By the diaphragm (it has apertures that allows structures to pass between the thorax and abdomen)
2
Q
Pelvic cavity
A
- Inferior to abdominal cavity
- continuous with abdominal cavity
3
Q
Which organs does the abdominal cavity contain?
A
Those in:
- gastrointestinal tract
- hepatobiliary system
- urinary system
- endocrine system
- also contains the spleen and the great vessels and their branches
4
Q
Which organs are in the gastrointestinal tract?
A
- stomach
- small intestine
- large intestine
5
Q
Which organs are in the hepatobiliary system?
A
- liver
- gallbladder
6
Q
Which organs are involved in the urinary system?
A
- kidneys
- ureter
7
Q
Which organs are involved in the endocrine system (in the abdomen)?
A
- pancreas
- adrenal glands
8
Q
Spleen- what type of organ is it?
A
A haematopoietic and lymphoid organ
9
Q
What are the anterior, lateral and posterior walls of the abdomen composed of?
A
- skin
- subcutaneous tissue
- muscles + their associated aponeuroses
10
Q
Aponeuroses
A
Flat tendons
11
Q
How many lumbar vertebrae contribute to the posterior wall of the abdominal cavity?
A
Five
12
Q
What are the functions of the abdominal wall?
A
- protect the abdominal viscera
- increase the intro-abdominal pressure (e.g. for defamation and childbirth)
- maintain posture and move the trunk
13
Q
What is the internal aspect of the abdominal wall lined with?
A
a serous membrane called parietal peritoneum
14
Q
Boundaries of the abdominal cavity
A
- xiphisternum
- costal margin
- iliac crests
- anterior superior iliac spines (ASIS)
- pubic tubercles
- pubic symphysis (a fibrocartilaginous joint)
15
Q
How can the anterior abdominal wall be described in clinical practice?
A
four quadrants - upper right and left and lower right and left
nine regions
16
Q
Which two invisible lines outline the four quadrants?
A
- vertical line running down the midline through the lower sternum, umbilicus and pubic symphysis
- horizontal line running across the abdomen through the umbilicus
17
Q
Why do the nine regions allow us to be more precise when describing pateint’s pain or location of tenderness, mass, swelling, or injury upon examination?
A
regions are smaller than the four quadrants
18
Q
How is the abdomen divided into nine regions?
A
four imaginery lines:
- right and left midclavicular lines which extend vertically from the midclavicular point to the mid-inguinal point
- subcostal line
- intertubercular line
19
Q
Subcostal line
A
horizontal line drawn through the inferior-most parts of the right and left costal margins (through the 10th costal cartilage)
20
Q
Intertubercular line
A
horizontal line drawn through the tubercles of the right and left iliac crests and the body of L5
21
Q
Three middle regions
A
superior: epigastric region
middle: umbilical region
inferior: hypogastric region
22
Q
Three right side regions of anterior abdominal wall
A
superior: right hypochondriac region
middle: right lumbar region
inferior: right iliac region
23
Q
Three left side regions
A
superior: left hypochondriac region
middle: left lumbar region
inferior: left iliac region
24
Q
In clinical practice, what is the other term for left and right iliac region?
A
left and right iliac FOSSA
25
Other landmarks in the abdomen
- transpyloric plane
- transumbilical plane
- intercristal plane
- McBurney's point
26
Transpyloric plane
- horizontal line passing through the tips of right and left 9th costal cartilages
- lies in between the superior border of manubrium and pubic symphysis
- transects the pylorus of stomach, gallbladder, pancreas and hila of kidneys
27
Transumbilical plane
- unreliable landmark
- position varies depending of the amount of subcutaneous fat present
- in slender individual it lies approximately at the level of L3
28
Intercristal plane
- horizontal line drawn between the highest points of right and left iliac crests
- cannot be palpated from anterior aspect of abdominal wall
- used to guide procedures on the back e.g. lumbar puncture
29
McBurney's point
- surface marking of the base of the appendix
- lies two thirds of the way along a line drawn from the umbilicus to the right anterior superior iliac spine
30
What are the four pairs of muscles of the anterolateral abdominal wall?
- external oblique
- internal oblique
- transversus abdominis
- rectus abdominis
anteriorly, these muscles becomes aponeurotic - the aponeuroses fuse with each other and, in the midline, they fuse with the aponeuroses of the opposite side forming a tough midline raphe called LINEA ALBA.
Aponeuroses of these sheets also form the rectus sheath
31
External oblique (EO)
- diagonally orientated fibres
- most superficial
- fibres run medially and inferiorly, towards the midline
- lateral to rectus abdominis
32
Internal oblique (IO)
- diagonally orientated fibres
- lies deep to the EO
- fibres are orientated perpendicular to those of EO (they run medially and superiorly)
- lateral to rectus abdominis
33
Transversus abdominus
- horizontally orientated fibres
- deep to IO
- lateral to rectus abdominis
34
Rectus abdominus
- rectus = straight
- lie either side of the midline
- attached to sternum and costal margin superiorly and to pubis inferiorly
- surrounded by aponeurotic rectus sheath
35
Aponeurosis
a thin sheath of connective tissue that helps connect your muscles to your bones (flat tendon)
36
Midline Raphe
seam
37
Linea Alba
white line
38
What else does the rectus sheath do?
it encloses the rectus abdominis
39
Right and Left Rectus Abdominis muscles
- lie either side of the linea alba
- comprised of muscle segments interspersed with horizontal tendinous bands
- when muscle segments hypertrophy with exercise, they bulge either side of the tendinous bands and can be seen on anterior abdominal wall as bulges 'six-pack'
40
True or false? The rectus abdominis lies within the rectus sheath
true
41
True or false? The anterior and posterior walls of the rectus sheath are formed by aponeuroses of EO, IO and transversus abdominis
true
42
What happens to the aponeurosis of IO as it approaches the midline?
it splits into anterior and posterior layers
43
What forms the anterior wall of the rectus sheath?
EO aponeurosis and anterior layer of IO aponeurosis
44
What forms the posterios wall of the rectus sheath?
posterior layer of IO aponeurosis and transversus abdominis aponeurosis
45
Transversalis fascia
lies deep to transversus abdominis
46
Where is the parietal peritoneum?
deep to the transversalis fascia
47
Inguinal ligament
formed from the attachment of the most inferior part of the external oblique aponeurosis to the anterior superior iliac spine laterally, and the pubic tubercle medially
48
Inhuinal canal
just above the inguinal ligament
49
Which arteries supply the anterolateral abdominal wall?
- musculophrenic artery (branch of internal thoracic artery)
- superior epigastric artery
- inferior epigastric artery
These vessels are accompanied by deep veins, an extensive network of superficial veins found in the anterolateral abdominal wall
50
Superior epigastric artery
- continuation of the internal thoracic artery
- descends in the rectus sheath
51
Inferior epigastric artery
- branch of external iliac artery
- ascends in the rectus sheath
- anastomoses with superior epigastric
52
What are the muscles and skin of the anterolateral abdominal wall innervated by?
- thoraco-abdominal nerves T7-T11
- the subcostal nerve
- iliohypogastric and ilioinguinal nerves
53
Thoraco-abdominal nerves T7-T11
- continuation of intercostal nerves T7-T11
- these somatic nerves contain sensory and motor fibres
54
Subcostal nerve
originates from T12 spinal nerve (runs along inferior border of 12th rib)
55
Iliohypogastric and Ilioinguinal nerves
bracnhes of the L1 spinal nerve
56
Hernias
- abnormal protrusion of tissues or organs from one region into another through an opening/defect
- hernia of anterior abdominal wall may occur if the muscles are weak or have been incised during surgery
- segment of the small intestine may protrude through a defect in the wall, forming a visible and palpable lumo under the skin
57
Laparotomy
- surgical opening of anterior abdominal wall
- used for when good access to the abdomen is needed
- midline sagittal incision of linea alba involves minimal risk to nerves and muscles
- ideally, muscles are split rather than cut
- keyhole surgery is performed where possible (laparoscopy) as it is associated with less post-operative pain, faster wound healing and a smaler risk of wound infection and post-operative hernia
58
Peritoneum
serous membrane that lines the abdominal wall and covers the viscera within it
59
Peritoneum
serous membrane that lines the abdominal wall and covers the viscera within it
60
Parietal Peritoneum
- Lines abdominal wall
- can be seen with naked eye
- innervated by somatic nerves that supply overlying muscles and skin of the abdominal wall
- pain from parietal peritoneum is usually sharp, severe, and well localised to abdominal wall
61
Visceral peritoneum
- covers the abdominal viscera
- adhered to surface of the viscera and cannot be seen with the naked eye
- innervated by visceral sensory nerves (these nerves convery 'painful' sensations back to CNS along the path of the sympathetic nerves that innervate the organ/structure it covers
- pain can be severe and is usually dull and diffuse
- 'painful' sensations may be percieved as nausea or distension
62
Peritoneal cavity
- lies between the parietal and visceral peritoneum
- in a healthy abdomen a thin film of peritoneal fluid lies here
63
What is the purpose of the peritoneal fluid?
allows the viscera to slide freely alongside each other
64
True or false? The two layers of peritoneum are continuous with each other
True - arrangement of the two layers mirrors the arrangement of the of the parietal and visceral pleura
65
How can the abdominal viscera be described as?
- Intraperitoneal: almost completely covered by peritoneum e.g. stomach
- Retroperitoneal: posterior to the peritoneum, hence only covered by peritoneum on their anterior surface e.g. pancreas and abdominal aorta
66
'secondarily retroperitoneal'
- some retroperitoneal organs are described as this
- these organs were intrperitoneal in early development but came to be stuck down onto the posterior abdominal wall
67
Features of mesenteries, omenta, ligaments and folds
- composed of peritoneum and connect organs to each other and to the abdominal wall
- may carry blood vessels, nerves, nerves and lymphatics to the viscera
- they contain a variable amount of fat
68
Mesenteries
- folds of peritoneum that contain fat and suspend the small intestine and parts of the large intestine from the posterior abdominal wall
- arteries that supply the intestine (from abdominal aorta) and veins that drain the gut (tributaries of the portal venous system) are embedded into the mesenteries
69
Two Omenta
greater and lesser
70
Greater Omentum
- usually fatty and connect stomach to other organs
- hangs from the greater curvature of the stomach
- lies superficial to the small intestine
71
Lesser Omentum
- usually fatty and connect stomach to other organs
- connects stomach and duodenum to the liver
- hepatic artery, hepatic portal vein and bile duct are embedded within its free edge
72
The Portal Triad
- hepatic artery
- hepatic portal vein
- bile duct
73
Ligaments
- folds of peritoneum that connect organs to each other or to the abdominal wall
- falciform ligament
- coronary and triangular ligaments
74
Falciform ligament
connects the anterior surface of the liver to the anterior abdominal wall
75
Coronary and Triangular ligaments
connect the superior surface of the liver to the diaphragm
76
Peritoneal folds
- raised from the the internal aspect of the lower abdominal wall
- created by the structures they overlie
- somtimes they are difficult to see
- median umbilical fold
- medial unbilical fold
- lateral umbilical folds
77
Median umbilical fold
- lies in the midline and represents the remnant of the urachus
78
Urachus
an embryological structure that connected the bladder to the umbilicus
79
Medial umbilical folds
- lateral to the median umbilical fold
- these represent the remnants of the paired umbilical arteries, which returned venous blood to the placenta in foetal life
80
Lateral umbilical folds
- lateral to medial umbilical folds
- inferior epigastric arteries lie deep to these peritoneal folds
- they supply the anterior abdominal wall
81
Lateral umbilical folds
- lateral to medial umbilical folds
- inferior epigastric arteries lie deep to these peritoneal folds
- they supply the anterior abdominal wall
82
How is the peritoneal cavity divided into two regions of unequal size?
- smaller lesser sac (omental bursa)
- larger greater sac - the remaining part of the peritoneal cavity
The sacs communicate with each other via a passageway that lies posterior to the free edge of the lesser omentum - the epiploic foramen (also called the omental foramen)
83
Smaller lesser sac
a space that lies posterior to the stomach and anterior to the pancreas
84
True or false? The viscera of the abdominal cavity do not develop in the locations that we see them in the adult
true
85
Where does the gastrointestinal system develop from?
the embryonic gut tube which lies in the midline of the abdominal cavity, suspended from the posterior abdominal wall by the dorsal mesentery
86
True or false? Major branches of the abdominal aorta that supply the developing gut tube travel through the dorsal mesentery
true
87
Ventral mesentery
- connects the stomach to the anterior abdominal wall
- as the liver grows within it, the anterior part od the ventral mesentery becomes the falciform ligaments and the posterior becomes the lesser omentum
88
What happens to the organs after they grow, migrate and rotate towards their final position during development?
they 'pull' their peritoneal attachments with them
89
True or false? Growth, migration, and rotation of organs during development is responsible for the formation of the lesser sac and results in some organs being 'pusched' onto the posterior abdominal wall and becoming retroperitoneal
true
90
Peritonitis
- infection and inflammation of the peritoneum
- it may be localised or generalised
- may be caused by inflammation of an organ or rupture of a hollow viscus
- rupture of the intestine allows faecal matter and bacteria to contaminate the peritoneum
- because the peritoneum has a large surface area and is semi-permeable, peritonitis can lead to sepsis and is hence a life-threatening condition.
- extremely painful
91
Peritoneal Adhesions
- in healthy abdomen a thin layer of peritoneal fluid allows the abdominal viscera to slide freely alongside each other
- adhesions are pathological fibrous connections between the parietal and visceral peritoneum
- when the peritoneum is irritated it produces fibrin which causes the parietal and visceral peritoneum to adhere to each other.
- these connections may become fibrous
- can cause chronic abdominal pain and they increase the risk of volvulus (twisting) of the intestines, because it can no longer move freely
92
Ascites
An increased volume of peritoneal fluid.
An ascitic drain can be used to remove the fluid and relieve symptoms, but fluid will usually reaccumulate.
93
Oesophageal Hiatus
place at which oesophagus passes through the diaphragm at the level of T10
94
What does the muscle aroung the oesophogeal hiatus function as?
- sphincter
- prevents reflux of stomach contents into the oesophagus
95
The abdominal segment of the oesophagus is less than how many cm long?
The abdominal segment of the oesophagus is less than 2 centimetres long
96
What artery supplies the distal oesophagus?
bracnhes from the left gastric artery
97
What is the venous drainage of the distal oesophagus?
venous drainage is towards both the systemic system of veins (via oesophageal veisn that drain into the azygos vein) and to the portal venous system (via the left gastric veins)
- therefore the distal oesophagus is a site of PORTOSYSTEMIC ANASTOMOSES
98
What shape is the stomach
J shaped sac
99
What does the stomach chemically and mechanically break food down into?
chyme
100
What are the four parts of the stomach?
- cardia
- fundus
- body
- pyloric antrum
101
Cardia of the stomach
- the oesophagus travels through the diaphragm at the level of T10 and is continuous with the cardia of the stomach
102
Fundus of the stomach
- most superior part of the stomach
- llies superior to the level of entry of the oesophagus and is usually filled with gas
103
Body of the stomach
- largets part of the stomach
- inferior to cardia and fundus
104
Pyloric Antrum
- distal to the body
- wide and tapers towards the pyloric canal (which is narrow and contains the pyloric sphincter)
105
Pyloric sphincter
- formed of circular smooth muscle
- regulates the passageway of chyme into the duodenum
106
What is the right border of the stomach called?
lesser curvature
107
What is the left border of the stomach called?
greater curvature
108
Where does the stomach lie?
the left upper quadrant (but its size and position is variable)
109
What is the stomach covered with?
visceral peritoneum
110
What is the anterior surface of the stomach related to?
- The anterior abdominal wall
- diaphragm
- left lobe of the liver
111
What does the posterior surface of the stomach form?
The anterior wall of the lesser sac
112
True or false? The lesser sac and the structures that form it’s posterior wall lie posterior to the stomach
True
These include the pancreas, left kidney and spleen
113
What is the lesser omentum connected to?
The lesser curvature to the liver
114
What does the free edge of the lesser omentum contain?
- hepatic artery
- hepatic portal vein
- bile duct
115
What is posterior to the free edge of the lesser omentum?
The entrance to the lesser sac
116
Where does the greater omentum hang from?
The greater curvature
117
True or false? The stomach is supplied by arteries that branch from the coeliac trunk
True
118
What is the coeliac trunk?
One of the three large unpaired vessels that leave the anterior aspect of the abdominal aorta (level of T12) to supply abdominal viscera that are derived from the embryo logical foregut
119
What does the foregut comprise of?
- stomach
- first half of the duodenum
- liver
- gallbladder
- pancreas
120
Where does the spleen develop and what is it supplied by?
- develops in the dorsal messengers
- supplied by coeliac trunk
(Mesodermal in origin)
121
What are the branches of the coeliac trunk?
- left gastric artery
- common hepatic artery
- splenic artery
122
True or false? The left gastric is a much smaller calibre vessel than the common hepatic and splenic arteries
True
123
Where do the left and right gastric arteries run along?
The lesser curvature of the stomach (and anastomose with each other)
124
Where does the left gastric artery arise from?
The coeliac trunk
125
Where does the right gastric artery usually arise from?
The common hepatic artery
126
Where to the left and right gastrointestinal-omental (gastropiploic) arteries run along?
The greater curvature of the stomach and anastomose wit each other
127
Where does the left gastro-omental artery arise from?
The splenic artery
128
Where does the right gastro-omental artery arise from?
The gastroduodenal artery (a branch of the common hepatic artery)
129
What does the right and left gastric veins and the left gastric-omental veins drain into?
The hepatic portal vein
130
What is the hepatic portal vein?
A large vein that carries nutrient-rich venous blood from the GI tract to the liver
131
What nerve innervates the stomach?
- The vagus nerve (conveys parasympathetic fibres to the stomach)
- sympathetic fibres via the greater splanchnic nerve
132
What does parasympathetic stimulation of the stomach stimulate?
Promotes peristalsis and gastric secretion
133
What is the greater splanchnic nerve formed from?
Preganglionic sympathetic fibres that leave the spinal cord segments T5-T9
(Passes through the sympathetic trunk without synapsids)
134
Where do the sympathetic fibres from the greater splanchnic nerve synapse?
They synapse in the prevertebral ganglia around. The coeliac trunk.
The postganglioic fibres travel to the stomach and inhibit peristalsis and secretion
135
Hiatus hernia
- abdominal oesophageal and upper part of the stomach may herniate through the oesophageal hiatus into the thorax
- if contents of the stomach reflux in to the oesophageal the patient may experience heartburn and acid reflux
136
Gastric uLcer
- mucous lines the internal wall of the stomach and protects the mucosa from the acidic stomach contents
- a gastric (stomach) ulcer develops when the mucosal lining of the stomach breaks down
- this is normally due to infection with Helicobacter pylori, which erodes the mucosal lining, exposing the muscular wall to gastric acid and enzymes
- erosion through the wall and into nearby blood vessels can result in catastrophic intra-abdominal bleeding
137
Pyloric stenosis
- congenital malformation characterised by hypertrophy of the circular smooth muscle of the pyloric sphincter
- more common in baby boys than girls and typically presents at approximately six weeks after birth
- typical presentation is of vomiting (sometimes projectile) after feeds, but baby does not appear unwell and is hungry and willing to take more feeds
- with continued vomiting babies with pyloric stenosis becomes dehydrated and stop gaining weight
- can be treated surgically
138
Gastric cancer
- primary cancer of the stomach may present late as some of the symptoms are non-specific
- e.g. abdominal discomfort, early satiety, loss of appetite, nausea, weight loss, difficulty swallowing and indigestion
139
What are the three parts of the small intestine that are continuous with each other?
- duodenum
- jejunum
+ ileum
140
What is the duodenum?
- continuous with the pylorus of the stomach
- short and curved into a c-shape around the head of the pancreas
- most of the length of the duodenum is retroperitoneal
141
What is found approximately halfway along the internal wall of the duodenum?
The major duodena, papilla
142
What is the duodenal papilla?
Opening of the bile duct and the main pancreatic duct into the duodenum
143
Embryology of the duodenum
- first half develops from embryological foregut (supplied by arterial branches from coeliac trunk)
- second half develops from the embryological midgut (supplied by branches from the artery of the midgut SMA)
144
Jejunum
- continuous with the duodenum
- lies in the left upper region
- derived from embryological midgut
145
True or false? Both the jejunum and ileum are intraperitoneal and are ‘suspended’ from the posterior abdominal wall by the mesentery of the small intestine
True
146
Where are the blood vessels that supply the small intestine (from the SMA) embedded within?
The mesentery
147
Where does the small intestine lie in the abdomen?
Central
148
Where is the ileum in the abdomen?
Right lower region
149
What is the ileum derived from?
Embryological midgut (so is the jejunum)
150
True or false? The jejunum and ileum are the sites of nutrient absorption
True
Therefore have a vast surface area
151
The folds in the small intestine
- small intestine is long
- the mucosa is folded (pilcae circulates)
- the mucosal folds bear villi
- there are microvilli on the luminal surface of each epithelial cell
152
Where is the jejunum in the abdomen?
left upper region
153
Internal differences between the jejunum and ileum
- pilcae more pronouned in the jejunum
- internal ileum characterised by PEYER'S patches
154
Plicae
circular folds
155
Peyer's patches
large submucosal lymph nodules
156
Meckel's diverticulum
- a blind-ended diverticulum approximately one meter from termination in some people
- embryological remnant of the connection that was present between the midgut loop to the yolk sac
- if inflammed it may mimic appendicitis
157
True or false? The terminal ileum is continuous with the caecum
true - at the ileocaecal junction in the right iliac fossa
158
Caecum
- the first part of the large intestine
- distended blind-ended pouch
- covered by peritoneum but no mesentery
159
Role of the large intestine
reabsorbs water from faeca, meterial to form semi-solid faeces
160
Where is the large intestine?
lies peripherally in the abdomen
161
What is the large intestine composed of?
- caecum
- appendix
- ascending colon
- transverse colon
- descending colon
- sigmoid colon
- rectum
- anal canal
162
True or false? Some parts of the large intestine are retroperitoneal and some are intraperitoneal
true
163
What is the outer longitudinal muscle layer of the large intestine orginised into?
- three bands
- the taeniae coli
164
What do the inner circular muscle layer form in the large intestine?
- 'bulges' called huastra (or haustrations)
165
Epiploic appendages (appendices epiploicae)
- fatty tags on large intestine
- mark point at which blood vessels penetrate the intestinal wall
166
Appendix
- small diverticulum that arises from caecum
- contains lymphoid tissue
- surface marking of base of appendix is McBurney's point
- varies in length and position of tip is variable
- connected to caecum by small mesentery the mesoppendix
167
Mesoappendix
mesentery connecting appendix and caecum together
168
Ascending colon
- continuous with caecum
- runs vertically on right side of posterior abdominal wall in right paracolic gutter
- retroperitoneal (secondarily retroperitoneal organ)
169
Right Paracolic Gutter
space between the ascending colon and the lateral abdominal wall
170
Hepatic flexture (right colic flexture)
bend between ascending and transverse colon
171
Transverese colon
- continuous with ascednign colon
- runs horizontally in upper abdomen but often hangs inferiorly
- intraperitoneal
- suspended from posterior abdominal wall by transverse mesocolon
172
Splenic flexture (left colic flexture)
- bend between transverse colon and descending colon
- tethered to diaphragm by PHRENICOCOLIC ligament
173
Phrenicocolic ligament
tethers the splenic flexture to the diaphragm
174
What does the transverse colon mark?
- the transition point between the embryological midgut and embryological hindgut
- the proximal 2/3 develop from the midgut
- the distal 1/3 develops from the hindgut
- therefore these two parts of the transverse colon are supplies by different blood vessels and nerves
175
Descending colon
- continuous with the transverse colon superiorly and sigmoid inferiorly
- runs vertically on left side of posterior abdominal wall in left paracolic gutter
- retroperitonela (secondarily retroperitoneal organ)
176
Sigmoid colon
- left lower quadrant
- names due to its sinuous shape
- continuos with descending colon and rectum inferiorly
- has a mesentery (the sigmoid mesocolon)
- intrapertioneal
177
Rectosigmoid junction
as sigmoid approaches midline it makes a 90 degree turn inferiorly into the pelvis
178
Rectum and Anal canal
- rectum descends inferiorly into pelvis from rectosigmoid junction
- retroperitoneal
- rectum stores feaces until convenient to defecate
- continuous inferiorly with anal canal
179
Which large unpaired arteries leaving the abdominal aorta supply the gastrointestinal tract?
- coeliac trunk
- superior mesentery artery
- inferior mesentery artery
180
Ceoliac trunk
- leaves aorta at T12
- gives rise to branches that supply the foregut
181
Structures in the foregut
- oesophagus
- stomach
- first half of duodenum
- liver
- gallbladder
- bile ducts
- pancreas
- spleen
182
Superior mesenteric
- midgut
- leaves aorta at L1
- branches can also supply parts of the pancreas
183
Structures in the midgut
- second half of duodenum
- small inestine
- large intestine up to and including first 2/3 of transverse colon
184
Inferior mesenteric
- hindgut
- leaves aorta at L3
- smaller calibre vessel
185
Structures in the hindgut
- distal third of the transverse colon
- descending colon
- sigmoid colon
- rectum
- upper part of anal canal
186
Major branches of the SMA
- jejunal branches
- ileal branches
- ileocolic artery
- right colic artery
- middle colic artery
187
What do the jejunal branches supply?
jejunum
188
What do the ileal branches supply?
ileum
189
What does the ileocolic artery supply?
- caecum
- appendix
- ascending colon
190
What does the right colic artery supply?
ascending colon
191
What does the middle colic artery supply?
transverse colon
192
True or false? The jejunal and ileal bracnhes are embedded in the mesentery of the small intestine
true - they anastomose with each other forming 'loops' of arteries called ARCADES
193
Arcades
- loops of arteries formed from anastomoses
- from these run the vasa reca (straight vessels) which supply the intestinal wall
194
Major branches of the IMA
- left colic artery
- sigmoid branches
- superior rectal artery
195
What does the left colic artery supply?
- transverse colon
- descending colon
196
What do the sigmoid branches supply?
sigmoid colon
197
What does the superior rectal artery supply?
upper rectum (it is the terminal branch of the IMA)
198
Marginal artery
formed from the anastomoses of middel colic artery and left colic artery in teh splenic flexture
199
True or false? branches of the left colic and sigmoid arteries anastomose too
true
200
What supplies the lower rectum?
blood vessels that originate from internal iliac arteries in pelvis
201
Why does blood enter the liver before reaching the vena cava?
venous blood from gut contains absorbed nutrients
202
Veins in small and large intestine
- inferior mesenteric vein
- superior mesenteric vein
- hepatic portal vein
203
Inferior mesenteric vein
- accompanies IMA and drains the hindgut
- ascends on the left side of the abdomen
- typically drains into the splenic vein from spleen
204
Superior mesenteric vein
- accompanies SMA and drains midgut
- ascends and unites with splenic vein close to liver to form hepatic portal vein
205
Hepatic portal vein
- enters liver
- after nutrients are removed from blood it enters small hepatic veins which untie within the liver to form two or three large hepatic veins that enter the IVC as it passes posterior to the liver
206
True or false? The midgut and hindgut are innervated by parasympathetic fibres
true - they stimulate peristalsis and secretions
207
What are the foregut and midgut innervated with parasympathetic fibres from?
Vagus nerve
208
What is the hindgut innervated with parasympathetic fibres from?
Pelvic splanchnic nerves
209
Pelvic Splanchnic nerves
- formed by axons of parasympathetic neurons that lie in the sacral spinal cord
- cell bodies of preganglionic parasympathetic neurons lie in sacral segments S2-S4
- axons of these neurons leave the spinal cord and form pelvic splanchnic nerves
- preganglionic axons synapse with a second neuron in a ganglion very close to or within the walls of the viscera
210
True or false? The pelvic splanchnic nerves also convey parasympathetic fibres to pelvic viscera
true
211
Where do the preganglionic sympathetic fibres passing through the sympathetic trunk arise from?
T5-T12 (they pass through via the greater, lesser and least splanchnic nerves)
212
Greater splanchnic nerves
T5-T9 (innervates forgut)
213
Lesser splanchnic nerves
T10-T11 (innervates midgut)
214
Least splanchnic nerves
T12 (innervates hingut)
215
Where do the preganglionic fibres in the splanchnic nerves synapse?
within the ganglia that lie in the abdomen, clustered around the arota and coeliac trunk, SMA, IMA
216
What do the postganglioic fibres form?
visceral nerves that innervate the gut (these are the fibres tht inhibit peristalsis and secretions)
(these are visceral motor fibres)
217
True or false? The gut is also innervated by visceral sensory fibres
true
218
Visceral sensory fibres
- convey visceral sensory information from gut to CNS
- such information does not reach conscious perception but pain caused by ishcaemia, distension or spasm do
- fibres from foregut, midgut and hindgut travel to CNS alongside sympathetic ifbres that innervate that part of the gut
219
Where do painful sensations from the foregut enter the spinal cord?
segments T5-T9
220
Where do painful sensations from the midgut enter the spinal cord?
segments T10-T11
221
Where do painful sensations from the hindgut enter the spinal cord?
segments T12
222
True or false? Regions T5-T12 can also recieve somatic sensory information from the abdominal wall
true
- T5-T9 recieve information from dermatomes T5-T9 (upper abdomen and epigastric)
- T10-T11 recieve informaiton from dermatomes T10-T11 (umbilical region)
- T12 recieves information from dermatome T12 (suprapubic region)
223
Pain from the abdominal viscera is referred to?
the body wall
224
Epigastric pain suggests?
foregut pathology
225
Central abdominal/umbilical pain suggests?
midgut pathology
226
Lower abdominal/suprapubic pain suggests?
hindgut pathology
227
Appendicitis
- inflammation of appendix
- pain typically begins in umbilical region and is poorly localised
- result of irritation of visceral peritoneum
- as inflammation progresses adjacent parietal peritoneum becomes involved causing localised pain in right iliac fossa
- therefore history: diffuse umbilical pain that moves to right iliac fossa
- tenderness maximal over McBurney's point
- rupture can lead to peritonitis
- removal usually performed laproscopically
228
True or false? Symptoms of appendicitis varies depending on where the tip lies?
true
229
Mesenteric ischaemia
- occlusion of mesenteric vessels by thrombus
- resultsin ischaemia of intestine which may progress to infarction
- acute mesenteric ischaemia is a surgical emergency
- gut must be revascularised and any sections of necrotic intestine must be removed
- mortality high
230
Inflammatory Bowel Disease
- two types: Crohn's disease and ulcerative colitis
- flare ups of both diseases can be serious and may lead to life-threatening complications
- if medications fail to control symptoms, the affected part of the gut may be removed
231
Crohn's disease
- inflammation of gut mucosa
- can affect any part of GI tract but typically affects small intestine
- symptoms: abdominal pain, diarrhoea, bloody stools, weight loss, tiredness
232
Ulcerative Colitis
- affects colon and rectum
- mucosa becomes inflammed and ilcerated
- abdominal pain, bloody diarrhoea, weight loss, tiredness
233
Colon cancer
- common
- main symptoms: change in bowel habit, blood in stools and abdominal pain/bloating
- colonoscopy allows visulaisation of colon and biopsies can be taken if a mass is seen
234
Volvulus
- twisting of gut
- affects part of gut that are mobile (parts that have a mesentery)
- most common in sigmoid colon
- twisting obstructs the passage of faces and may cause ischaemia and infarction of the affected part of the gut
235
Location of the liver
- right upper quadrant and epigastrium of the abdomen
236
What is the liver protected by?
- the ribs
237
How does the liver move with inspiration?
inferiorly
238
Where may the lowermost part of the liver be palpable?
- below the right costal margin in inspiration
239
What are the two surfaces of the liver?
- diaphragmatic surface lies anterosuperior and is related to the inferior surface of the diaphragm
- visceral surface lies posteroinferior and is related to other organs
240
What regions of the liver are not covered by visceral peritoneum?
- bare area of the liver (a region on the posterior surface that lies in contact with the diaphragm
- the rgeion where the gallbladder lies in contact with the liver
- region of the porta hepatic (where hepatic blood vessels and ducts of the biliary system enter and exit the liver)
241
Describe the two anatomical lobes of the liver
- large right lobe
- small left lobes
- separated by the falciform ligament
- these lobes do not represent the internal, functional organisation of the liver
242
What is the falciform ligament?
connects the anterior surface of the liver to the internal aspect of the anterior abdominal wall
243
What are the two accessory lobes of the liver and where are they located?
- caudate and quadrate lobes
- located on the posteroinferior surface
- these lobes do not represent the internal, functional organisation of the liver
244
Internal organistion of the liver
- eight functional segments
- each segment is served by its own branch of the hepatic artery and portal veins and by its own hepatic duct
245
Arterial Blood vessels of the liver
*see the diagram*
246
Venous blood vessle of the liver
- two or three large hepatic veins that lie within the liver
- they are not visible external to the liver
- they unite with the inferior vena cava as it passes posterior to the liver
247
What is the hepatic plexus?
- innervation of the liver
- formed of parasympathetic fibres from the vagus nerve and sympathetic fibres
- fibres follow the paths of the hepatic vessels and ducts of the biliary tree
248
Why is pain arising from the liver referred to the epigastric region?
because the liver is a foregut derivative
249
What three structures is the liver connected to?
1. diaphragm by the coronary and triangular ligaments
2. anterior abdominal wall by the falciform ligament
3. stomach and duodenum by the lesser omentum
250
What are the three stuctures in the portal triad?
- hepatic artery
- hepatic portal vein
- bile duct
(in the free edge of the lesser omonetum)
251
What do the portal triad combined with the free edge of the lesser omentum form?
the anterior boundary of the epiploic foramen (the entrance into the lesser sac - which lies posterior to the stomach)
252
What are the two recesses related to the liver?
1. hepatorenal recess
2. left and right subphrenic recesses
253
Hepatorenal recess
- lies between the right kidney and the posterior (visceral) surface of the right side of the liver
- fluid flows in to this space in the supine position
254
Left and Right Subphrenic recesses
- lie either side of the falciform ligament
- between the anterosuperior surface of the liver and the diaphragm
255
True or false? The liver develops embryologicaly from the foregut
true - it grows from a tissue bud that develops in the ventral mesentery (a peritoneal fold in the upper abdomen that connects the stomach to the anterior abdominal wall)
256
What happens to the liver as it grows?
- it migrates to the right side of the abdomen
- its peritoneal attachments are pulled with it
- the remains of the ventral mesentery form the lesser omentum and the falciform ligament
- ther peritoneal attachments of the liver anchor it to the surrounding structures includign the diphragm superior to it
257
What does the free edge of the falciform ligament contain?
the round ligament of the liver (the ligamentum teres)
258
What is the ligamentum teres?
- the remnant of the umbilical vein which carries oxygenated blood from the placenta to the foetus
259
What is the ligamentum venosum?
- also another embryological remnant
- lies on the posterior surface of the liver in the groove between the cuadate lobe and left lobe of the liver
- it is the remains of the ductus venosus
260
What is the ductus venosus?
- in foetal life, it diverts blood from the umbilical vein to the IVC
- thus shunting oxygen-rich blood to the heart and bypassing the liver
261
What does the gallbladder store and concentrate?
bile
262
Where is the gallbaladder?
- lies on posteroinferior (visceral) surface of the liver and lies close to the duodenum
263
What are the three parts of the gallbladder?
1. fundus
2. the body
3. the neck
- Body forms the main part of gallbladder which sits in the gallbaldder fossa on the visceral surface of the liver. - It tapers towards the neck, which communicates with the cystic duct
- the fundus is the rounded end of the gallbladder whic htypically extends to the inferior border of the liver
264
Where is the surface marking of the fundus of the gallbladder?
- at the tip of the 9th costal cartilage
- at the point where the right midclavicular line intersects the right costal margin
265
Which cells continuously produce bile?
hepatocytes
266
Where is bile first excreted into?
small channels called bile canaliculi
(the canaliculi drain into bile ducts of increasing calibre which ultimately converge to form the right and left hepatic ducts that exit the liver at the porta hepatis)
267
The bile duct positioning
- runs in the free edge of the lesser omentum
- lies posterior to the superior part of the duodenum and posterior to the head of the pancreas
268
What happens to bile leaving the liver if it is not needed for digestion?
- it enters the gallbladder via the cystic duct
269
What is the spiral fold?
- the spiral valve
- lies at the junction between the gallbladder neck, and the cystic duct
270
Blood vessels of the gallbladder
- blood supply via the cystic artery (typically arises from the right hepatic artery)
- drained by cystic veins that pass directly into the liver or join the hepatic portal vein
271
Innervation of the gallbladder
- innervated by parasympathetic and sympathetic fibres
- visceral afferent from the gallbladder return to the CNS with the sympathetic fibres
- visceral pain from the gallbladder enters the spinal cord level T5-T9 and is therefore referred to in the epigastrium
272
Where may gallbladder pain be felt?
- epigastrium
- right shoulder (if gallbladder pathology irritates the diaphragm)
- right hypochondrium (if gallbladder irritates the parietal peritoneum, which is innervated by somatic nerves)
273
Why may gallbladder pain be felt in right shoulder if diaphragm is also inflammed?
- diaphragm is innervated by the phrenic nerve (C3-5)
- spinal cord segments C3-5 also recieve somatic sensory information from the skin over the shoulder
- therefore gallbladder pathology involving the diaphragm may be felt in the right shoulder
274
Hepatomegaly
- enlargement of the liver
- caused by: hapatitis, malignancy and heart failure
- when the liver is enlarged, its inferior border becomes palpable inferior to the right costal margin
275
Hepatitis
inflammation of the liver from various causes
276
Liver Metastases
- most liver metastases are cancer from elsewhere in the body
- because venous blood from the gut passes through the liver, bowel cancers often metastasize to the liver
277
Cirrhosis of the liver
- Cirrhosis is sometimes referred to as 'scarring' of the liver
- caused by chronic excess alcohol consumption, chronic infection with hepatitis B/C or a build-up of fat in the liver
- Hepatocytes are destroyed and replaced with fibrous tissue
- the liver becomes shrunken, hard and nodular
- loss of hepatocytes impairs the function of the liver and liver failiure may ultimately result
278
Portal hypertension and portosystemic anastomosis
- portal hypertension is high blood pressure in the portal venous system
- results when blood flow through liver and portal vein is obstructed
- portosystemic anastomoses are communications between veins draining to the systemic circulation and veins draining to the portal circulation
- e.g. distal oesophagus - venous blood drains into both the systemic veins (via azygous) and into the portal system (via gastric veins)
- if flow in portal system obstructed: pressure in portal system increases and blood is diverted from portal veins into the systemic veins
- systemic veins become distended and varicose and prone to rupture whcih can cause catastrophic bleeding
279
What are varicose veins in the oesophagus called?
oesophageal varices
280
Gallstones, biliary colic and cholecystitis
- common
- mostly composed of cholesterol
- often asymptomatic but cause symptoms when they migrate into the biliary tree and lodge there
- when it lodges in the cystic duct, contraction of the gallbladder, the pain eases
- if not, stone becomes stuck and blocks the flow of bile into the cystic duct
- gallbladder becomes inflamed
- cholecystectomy
281
Cholecystitis
inflammation of the gallbladder
282
Cholecystectomy
removal of gallbladder (usually performed laparoscopically)
283
What is the duodenum?
- first and shortest part of the intestine
- continuous promixally with the pylorus of the stomach and distally with the jejunum
- most of it is retroperitoneal
284
What is the pyloric sphincter?
- it regulates gastric emptying into the duodenum
285
What shape is the duodenum?
- forms a C-shape that cups the head of the pancreas
286
What are the four parts of the duodenum?
1. superior
2. descending
3. inferior
4. ascending
287
What three structures lie posterior to the first part of the duodenum?
- bile duct
- gastroduodenal artery
- hepatic portal vein
288
Which structure lies anterior to the third part of the duodenum?
superior mesenteric artery
289
What is the name of the point where the fourth part of the duodenum meet the jejunum?
- duodenojejunal flexure
290
Major duodenal papilla
- approximately halfway along the internal wall of the duodenum
- small elevation
- marks the point whcih bile and digestive pancreatic secretion (pancreatic juice) enter the duodenum
291
Where is the first half of the duodenum derived from?
the foregut
292
Blood supply of the first half of the duodenum
- branches of the coeliac trunk (which is the artery of the foregut)
293
Where is the second half of the duodenum derived from?
the midgut
294
Blood supply of the second half of the duodenum?
- branches of the superior mesenteric artery(the artyer of the midgut)
295
Arterial branches that supply the duodenum are derived from the...
- gastroduodenal artery (from common hepatic artery and hence the coeliac trunk)
- inferior pancreaticoduodenal arteries (from superior mesenteric artery)
296
Veins in duodenum
- follow arteries and are tributaries of the hepatic portal vein
297
Where is the pancreas?
- lies horizontally on posterior abdominal wall at level of L1
- retroperitoneal
- does not have a capsule (so appears bumpy in cadaver rather than smooth)
298
True or false? The pancreas forms the dorsal and ventral pancreatic buds which fuse during development
TRUE
299
What are the four parts of the pancreas?
1. head - cupped by the C--shaped duodenum
2. neck
3. body
4. tail - extends to the hilum of the spleen
300
What is the ucinate process on the pancreas?
- a hook-like projection of the head of the pancreas
301
What does the posterior wall of the pancreas form?
the lesser sac
302
Which artery running towards the spleen is embedded in the upper border of the pancreas?
- the splenic artery (the splenic vein lies posterior to the pancreas)
303
Where do the main pancreatic duct and the accessory pancreatic duct run within?
the substance of the pancreas
304
What are the two functions of the pancreas?
1. endocrine
2. exocrine
305
Describe the endocrine function of the pancreas
synthesizes and secretes insulin and glucagon
306
Describe the exocrine function of the pancreas
produces pancreatic juice that contains digestive enzymes
307
How is pancreatic juice transported from the pancreas to the duodenum?
1. the main pancreatic duct
2. the accessory pancreatic duct
308
True or false? The main and accessory pancreatic ducts usually communicate with each other
true
309
What substances does the duodenum recieve from other organs?
1. bile from liver and gallbladder via bile duct
2. pancreatic juice from the pancreas via the main and accessory pancreatic ducts
310
Where do the bile duct and main pancreatic duct merge?
- at the hepatopancreatic ampulla
- it opens into the second part of the duodenum at the major duodenal papilla
311
Where is the major duodenal papilla located?
the internal wall of the duodenum about halfway along its length
312
What is surrounded by the hepatoapncreatic ampulla?
smooth muscle - the sphincter of oddi (the contraction of the sphincter prevents reflex of duodenal contents into the bile and main pancreatic ducts
313
The accessory pancreatic duct empties pancreatic juice into the duodenum at the minor duodenal papilla, which lies just proximal to...
the major duodenal papilla
314
Arterial Blood supply of the pancreas
- splenic artery (runs along the upper border of the pancreas and gives rise to pancreatic arteries)
- gastroduodenal artery (gives rise to superior pancreaticoduodenal arteries)
- superior mesenteric artery (gives rise to inferior pancreaticoduodenal arteries)
315
True or false? The pancreas is supplied by blood vessels derived from the coeliac trunk and superior mesenteric artery
true
316
Veins of the pancreas
- veins follow arteries
- splenic artery drains the pancreas and unites with the superior mesenteric vein to form the hepatic portal vein posterior to the neck of the pancreas
317
What is the spleen?
- haematopoietic and lymphoid organ
318
Where is the spleen located?
left upper quadrant (protected by ribs 9-11)
319
What is the spleen covered with?
visceral peritoneum
320
Functions of the spleen
- breakdown of old RBC
- storage of RBC and platelets
- various immune responses (including production of IgG)
321
What are the two surfaces of the spleen?
1. diaphragmatic surface (lies adjacent to the diaphragm)
2. visceral surface (lies in contact with the stomach, left kidney and colon)
322
Where do the splenic vessels enter and exit the spleen?
at the hilum on the visceral surface
323
Describe the four border of the spleen?
- anterior and superior borders are typically notched
- posterior and inferior borders are smooth
324
True or false? A normal sized spleen is not palpable below the costal margin
true (if it is palpable then it is enlarged by at least three times its normal size)
325
Arterial blood supply of the spleen
- supplied by the splenic artery
- it is a branch of the coeliac trunk
- runs along the superior border of the pancreas, embedded within it
- divides into approximately five branches at the hilum
326
Venous drainage of the spleen
- via splenic vein
- runs posterior to the pancreas
- unites with the superior mesenteric vein to form hepatic portal vein
327
Duodenal ulcer
- duodenal (peptic) ulcers are most common in the first part of the duodenum
- a duodenal ulcer here may erode the duodenal wall and the gastroduodenal artery (which lies posterior to the first part of the duodenum, resulting in severe intrinsic-abdominal bleeding)
328
Pancreatitis
- inflammation of the pancreas ay be chronic or acute
- acute pancreatitis is a life-threatening condition
- there are many causes but in the UK, it is the most commonly due to excess alcohol intake or impaction of a gallstone at the hepatopancreatic ampulla
- in gallstone pancreatitis, impaction of the gallstone prevents pancreatic uice from leaving the pancreas and it starts to break down the pancreas (autolysis)
- it is extremely painful
329
Pancreatic cancer
- can affect any part of the pancreas and typically causes pain that radiates to the back
- when it affects the head of the pancreas, it can obstruct flow of bile in the bile duct
- this leads to an accumulation of bile pigments in the blood and results in jaundice (yellowing of the skin)
330
Diabetes Mellitus
- results when the insulin-producing cells of the pancreas no longer produce insulin (or produce inadequate amounts)
- this leads to sustained high blood glucose levels which are detrimental to many tissues of the body and are ultimately fatal if not controlled
- some patients diabetes secondary to pancreatitis
331
Splenomegaly
- enlargement of the spleen is splenomegaly
- causes include infection (e.g. infectious, mononucelosis, malaria), haematological malignancy (e.g. leukaemia) and portal hypertension
- when the spleen enlarges it does so towards the midline, in the direction of the right ilias fossa because the phrenicocolic ligament prevents its direct descent towards the left iliac fossa
332
Splenic rupture
- spleen is soft and highly vascular and is therefore vulnerable to blunt abdominal trauma or rib fractures that may puncture the spleen
- splenic haemorrhage is life-threatening and is managed by removing the spleen (splenectomy)
- the spleen is not essential for life, although patients are more prone to some bacterial infections after splenectomy
333
What two things form the first part of the respiratory tract?
the left and right nasal cavities
334
What does mucosa in the upper part of the nasal cavity contain?
olfactory receptors (the axons of these receptors form the olfactory nerves (CN I)
335
What are the left and right nasal cavities separated from?
- each other by a thin midline septum formed of cartilage and bone (when the head is bisected the septum is seen on one half only)
- the oral cavity inferiorly by the hard palate
- the brain superiorly by bone
336
What does the nasal cavity communicate with?
- nasopharynx (it does it posteriorly)
- parasinal sinuses (which are cavities within the skull and bones)
337
Describe the midline nasal septum
- formed of cartilage anteriorly
- two thin plates of bone posteriorly
- the perpendicular plate of ethmoid bone forms the superior part of the posterior septum
- and the vomer forms the inferior part of the septum
338
What does the lateral wall of the nasal cavity bear?
- three projections of bone:
1. the superior conchae
2. middle conchae
3. inferior conchae (turbinates)
339
What are the space inferior to the conchae called?
meatuses
340
Describe the three meatuses
1. superior meatus lies inferior to the superior concha
2. middle meatus lies inferior to middle concha
3. inferior meatus lies inferior to the inferior concha
As inspired air travels through the meastuses it is warmed, humidified and filtered
341
What is the nasal cavity separated from the cranium and the brain by?
the cribriform plate
342
Describe the cribriform plate
- a delicate section of bone
- perforated with tiny holes (like a sieve)
- axons of olfactory neurons pass through these perforations to form olfactory nerves which travel to the brain
343
Where are olfactory receptors located?
- in the sphenoid-ethmoidal recess in the upper nasal cavity
- between superior concha and cribriform plate
344
What are parasinal sinuses?
- cavities within the skull bones
- are named accordign to the bones within which they are located
345
What are the four parasinal sinuses?
1. frontal sinuses
2. ethmoid air cells
3. sphenoid sinuses
4. maxillary sinuses
346
Frontal sinus
- lie within the anterior part of the frontal bone
347
Ethmoid air cells
- lie within the ethmoid bone
- superior to the nasal cavity and medial to the orbits
348
Sphenoid sinus
- lie within the sphenoid bone
349
Maxillary sinus
- lie within the maxillae of the facial skeleton
- lateral to the lateral walls of the nasal cavity
350
Which two sinuses are usually clearly seen in the bisected head?
1. frontal
2. sphenoid
351
Describe how the parasinal sinuses communicate with the nasal cavity
- via small ducts/channels:
1. frontal sinus drains into the middle meatus
2. sphenoid sinus drains into the spheno-ethmiodal recess
3. the ethmoid air cells drain into the superior and middel meatuses
4. maxillary sinus drains into the middle meatus
352
Where is the opening of the maxillary sinus into the middle meatus?
superomedially (therefore it cannot drain freely when the head is upright)
353
True or false? The nasal cavity also receives the nasolacrimal duct
true
- it drains the fluid ('tears) that lubricates the anterior surface of the eye
- the duct opens into the inferior meatus
354
Why do we get a runny nose when we cry?
because the excess fluid runs down the nasolacrimal duct
355
Describe the middle ear
- a small cavity within the temporal bone that is modified for hearing
- it contains three tiny bones that transmit sound waves to the inner ear
356
Describe how the nasal cavity also communicates with the middle ear
- the auditory tube connects the middle ear to the nasopharynx
- the opening of the auditory tube can be seen on the lateral wall of the nasopharynx surrounded by a slight bulge (which is formed by tonsillar tissue)
- the auditory tube allows air to pass into the middle ear so that the pressure on either side of the tympanic membrane (eardrum) which lies between the middle and external ear is equal
- this is important for optimal conduction of sound waves
357
Auditory tube
Eustachian tube
358
Tympanic membrane
eardrum
359
Arterial blood supply of the nasal cavity
- branches of maxillary artery (terminal branch of external carotid artery)
- anastomotic network formed supplies the nasal septum and is often the site of bleeding in a nosebleed
360
Nosebleed
epistaxis
361
Sensory innervation of the nose
branches of the trigeminal nerve CN V
362
What does the palate separate?
the nasal cavities from the oral cavity
363
What is the palate made of?
- composed anteriorly of bone (the hard palate)
- posteriorly of muscle (soft palate)
- the palate forms the roof of the oral cavity
364
Describe the hard palate
- composed of two bones:
1. palatine bone of maxilla
2. horizontal plate of the palatine bone
365
Why is the hard palate functionally important?
- prevents food or fluid entering the nasal cavity
- we push our tongue up against the hard palate during the first phase of swallowing, whcih forces food and fluid backwards into the oropharynx
- we push our tongue up against the hard aplate to articulate certain sounds
366
Cleft palate
- hard palate does not form properly during embryological development
- casues difficulty with eating, swallowing and speech if not repaired
367
Where is the soft palate?
lies posterior to the hard palate
368
Uvula
- a midline conical projection
- 'hangs' from the posterior border of the soft palate
- can be seen at the back of the mouth
369
What happens when the muscles of the soft palate contract during swallowing?
- elevates the soft palate
370
Why is nasopharynx closed off from the oral cavity in swallowing?
preventing reflux of food and fluid into the nasal cavity
371
What are the muscles of the soft palate innervated by?
the vagus nerve (X)
372
How is the oral cavity bounded?
- superiorly: by the hard and soft palate (the roof of the mouth)
- inferiorly: by soft tissues and muscles (the floor of the mouth)
- laterally: by the cheeks (whcih contain the buccinator muscle)
373
True or false? The oral cavity is continuous posteriorly with the oropharynx
true - it contains the tongue, teeth and gums and the openings of the salivary ducts
374
Could a dental abcess cause sepsis or spread to the deep tissues of the face?
yes - patients sometimes present to AandE with acute dental problem such as severe toothache or mouth pain and swelling caused by a dental abscess
- treatment: provide analgesia and ensure that the patient is not systemically unwell (e.g. rule out sepsis)
- if the patient is not unwell, efforts are made to try and arrange an urgent dental appointment for them
- antiobiotics may be prescribed if appropriate
375
Basics of teeth
- adults: 32 teeth (16 embedded in the maxilla (upper jaw) and 16 embedded in the mandible
- in the upper and lower jaws there are four in premolars and six molars
- the teeth are composed of:
- an inner pulp which contains blood vessels and nerves
- dentin which surrounds the pulp
- an outer, hard coating of enamel
376
What can enamel and dentin can be eroded by?
- bacteria or foodstuffs (this can lead to decay, inflammation and infection of the pulp which is painful)
- infection may spread to the bone, leadio abcess formation
377
What is the tongue essential for?
- normal chewing, swallowing and speech
378
What is the function of the papillae on the surface of the tongue?
some detect test
379
Positioning of the tongue
- anterior part: oral cavity
- posterior (root) part: extends into the oropharynx
380
What is the space between the posterior tongue and the anterior aspect of the epiglottis?
Vallecula
381
True or false? The tongue is composed of intrinsic and extrinsic muscles
true
- intrinsic: all in the tongue, paired bilaterally and fuse in the midline
- extrinsic: attached to the tongue but originate from outside it (from mandible and hyoid bone)
382
Function of intrinsic muscles in the tongue
change the shape of the tongue
383
Function of the extrinsic muscles in the tongue
move the tongue
384
What are the muscles of the tongue innervated by?
hypoglossal nerve (CN XII)
385
How many nerves provide sensory innervation of the tongue?
three cranial nerves
386
What are the three cranial nerves that provide sensory innervation?
- CN VII: taste in anterior two thirds
- CN V: general sensation (touch, pain, temp.) in anterior two thirds
- CN IX: taste and general sensation in posterior third
387
Which arteries supply the oral cavity?
- lingual
- maxillary
- facial arteries
(these are all branches of the external carotid artery)
388
Innervation of the oral cavity
- muscles of soft palate: CN X
- tongue: (CN V, VII, IX and XII)
389
Where is tonsillar tissue found?
several locations in nasal and oral cavities
390
Where is pharyngeal tonsil tissue found?
- lies in the roof and posterior wall of nasopharynx
- 'adenoid'
391
Where is the tubal tonsil tissue?
surrounds the opening of the auditory tube on the lateral wall of the nasopharynx
392
Where is the palatine tonsil found?
- lies on the lateral wall of the oropharynx
- usually referred to as the 'tonsils'
- they are visible on either side of the oropharynx when the mouth is open
393
Where is the lingual tonsil?
- a collection of lymphoid tissue in the posterior tongue
394
Epistaxis (nosebleed)
- common: trauma, but can occur spontaneously
- can usually be stopped by applying pressure, but soemtimes bleeding can be profuse (especially if patient taking anticoagulants
- if bleeding cannot be stemmed by pressure, the bleeding vessels can be cauterised
- nasal tampon can also be inserted into the nostril which compresses the blood vessels inside the nose
395
Fracture of the nose
- nasal bones or septum may be broken by blunt trauma
- nose may be deviated to one side as a result
- traumatic blows to the nose may fracture the cribriformplate and this must be considered in patients with nasal trauma
396
Sinusitis
- this is inflammation or infection of the mucosa lining the paranasal sinuses
- it is painful
- sinusitis affecting the maxillary sinuses is problematic as they do not drain freely, unless lying down on one side
- inflammation of the maxillary sinus may cause pain in the cheek, as the sensory nerve that supplies the cheek runs in teh roof of the maxillary sinus
397
Cleft palate
- development of the palate is complex
- if the bones of the hard palate do not develop properly or do not fuse in the midline, a celft remains that allows communication between the nasal and oral cavities
- a cleft palate is surgically repaired
398
Hypoglossal nerve palsy
- injury to the left or right hypoglossal nerve results in atrophy (wasting) and weakness or paralysis of the ipsilateral tongue muscles
- because the muscles on the unaffected side continue to function, the tongue deviates to the affected (injured) side when the patient protrudes their tongue
399
Nasal and oral cancer
- cancer of the nasal cavity or sinuses is rare
- cancer can develop in structures associated with the mouth, including the oral mucosa, tonsils, tingue and salivary glands
- mouth cancers may present as ulcers, lumps or patches of discolouration on the oral mucosa
400
Tonsilitis and tonsillectomy
- tonsilitis is inflammation of the tonsils
- the palatine tonsils are commonly affected
- cause may be viral or bacterial infection
- the tonsils become elarged, red and may be covered in pus which appears as white spots on the surface of the tonsils
- swallowing is painful
- inflammation and enlargement of the pharyngeal tonsil (adenoid) is common in children
- enlargemeny may obstruct the nearby opening of the auditory tube
- recurrent infection of the tonsils may be managed by tonsillectomy - surgical removal of the tonsils
