Lecture 9 - Alimentary 1 Flashcards
What does the oral cavity consist of?
Vestibule and oral cavity proper
What does the vestibule consist of?
Space between lips/cheek and teeth/alveolar arches
What are the three divisions of the pharynx (be able to spell)
nasopharynx
oropharynx
laryngopharynx
Where does the nasopharynx extend?
choana (posterior opening of nose) to soft palate
Where does the oropharynx extend?
soft palate to epliglottis
Where does the laryngopharynx extend?
epiglottis to the top of the trachea
What does the wall of the pharynx consist of (2)?
mucosa and three vertically overlapping constrictor muscles
How are the regions of the gut divided?
By basis of arterial supply
What does the foregut consist of (4)?
Oesophagus, stomach, duodenum to just below greater duodenal papilla and organs which develop in mesentaries of the foregut
Which organs developed in the mesentaries of the foregut (4)
Liver, pancreas, gall bladder and ducts, spleen
What does the midgut comprise of (7)
duodenum from just below the greater duodenal papilla, jujunem, ileum, caecum, appendix, ascending colon, right two thirds of transverse colon
What does the hindgut consist of (5)
left one third of the transverse colon, descending colon, sigmoid colon, rectum and most of the anal canal
What four layers comprise the microstructure of the alimentary tract proper?
Mucosa, submucosa, external muscle, adventitia
What does the mucosa comprise of? (4)
Epithelium, glands, lamina propria, muscularis mucosa
What does the submucosa comprise of?
Connective tissue
What are the two types of muscle in the external muscle?
Inner circular and outer longitudinal
What is the adventitia connected to?
Either the surrounding fascia or the serosa (peritoneum)
Which direction is proximal vs distal?
Mouth vs anus
What is the oesophagus?
A muscular tube passing through the neck, thorax, and abdomen
What does the oesophagus connect?
The pharynx to the stomach
Trace the anatomical path of the oesophagus
C6 through superior and posterior mediastinum, through diaphragm about 2-3cm from midline at T10 (posterior to the central tendon of the diaphragm) and through the right crus to enter cardia of the stomach at T11
What is the relationship of the oesophagus to the aorta?
Lateral and anterior to the aorta
What is the oesophagus posterior to in relationship to the mediastinum ( 4)
Trachea, bronchi, pericardium and left atrium
What is the oesophagus anterior to in relationship to the mediastinum?
The vertebral column
What is the oesophagus medial to from T5-6 down?
thoracic duct, azygos and descending aorta
What is the lining epithelium made of in humans?
Non-keratinised stratified squamous
What is visible in prosections when the surrounding fascia of the mediastinum has been removed?
The outer longitudinal layer of external muscle
What gives the oeseophagus its characteristic appearance of longitudinal streaks?
The outer longitudinal layers of external muscle
What forms a plexus on the oesophagus?
The left and right vagus nerves
What does the plexus on the oesophagus go on to form?
Left and right vagal TRUNKS in the lower abdomen which pass through the diaphragm with the oesophagus
What is the posterior attachment of the abdominal oesophagus to the diaphragm
Gastrophrenic ligament
Where does the abdominal part of the oesophagus (1cm) run?
In a groove on the posterior surface of the liver to the cardia of the stomach
What is provides the contrast in the x-rays?
Barium swallow
Where are the four constrictions in the lumen?
- Commencement - upper oeseophageal sphincter or the cricopharyngeus
- Level of arch of the aorta
- level of left main bronchus
- Oesophageal hiatus - lower spincter
What does the lower oesophageal sphincter comprise of?
Specialised CIRCULAR muscle in the wall of oeseophagus at the level of the diaphragm and around the abdominal oesophagus
What maintains the tone of the lower oesophageal sphincter?
Myenteric plexus
When does the lower oesophageal sphincter relax?
During swallowing and vomiting
What does the muscle of the right crus form?
External sphincter of the oesophagus
What is the function of the external sphincter of the oesophagus?
Tightens during inspiration or when intraabdominal pressure is increased to prevent gastrooesophageal reflux
In early development, what is attached to the posterior body wall by the dorsal mesentery?
The entire abdominal part of the gut tube
In early development, what is attached to the anterior body wall by the ventral mesentery
The stomach and the foregut
Which organs/systems form in the ventral mesentery during early development (3)
The liver, biliary system and ventral pancreas
What does the ventral mesentery anterior to the liver form during early development
falciform ligament (supporting structure of the liver)
During early development what forms the lesser omentum
The part of the ventral mesentery which is between the liver anteriorly and the stomach posteriorly
What does the dorsal mesentery form during early development? (4)
Mesentery, mesoappendix, transverse mesocolon, sigmoid mesocolon
What organs form within the dorsal mesentery during early development (2)
Dorsal pancreas and spleen
What is fixation of the intestines?
Where regions destined to be retroperitoneal, the dorsal mesentery fuses with the posterior wall and is subsequently obliterated
The dorsal and ventral pancreas fuse during development true or false?
True
Why are the post natal positions of the organs very different to early development?
Due to complex rotation and rearrangement
What is the greater omentum?
A double fold of peritoneum
What is the greater omentum attached to
The greater curvature of the stomach and the first part of the duodenum
What is the greater omentum continuous with?
Gastrosplenic or gastrolienal ligament - The ligament that attaches the stomach to the spleen
What is the greater omentum also attached to?
The transverse mesocolon
The greater omentum adheres to the organs under normal circumstances true or false?
False
What does the greater omentum hang down to cover?
The anterior surface of most of the abdominal organs
Fully formed omentum has mesothelium on the posterior surface only, true or false?
False, it has mesothelium on both surfaces
What is the defining characteristic of fully formed greater omentum?
It is shiny (mesothelium) with fatty regions separated by translucent fat free regions, grainy appearance
How does the appearance of the greater omentum differ to the mesentery
Mesentery has a more even distribution of fat (but also has mesothelium on both posterior and anteriorsurfaces)
What can you also recognised in unembalmed greater omentum?
Macrophages which appear as whitish, opaque ‘milk spots’
Give the development of the greater omentum in a fetus (4)
Initially a bag-like structure
Inner layers fuse
Then disappear to give a single structure
Transverse mesocolon becomes attached to posterior surface of the greater omentum
What is the function of the greater omentum (2)?
Protective via macrophages and other immune cells, also adheres to areas of peritoneal damage and inflammation
Where does the lesser omentum extend?
From the lesser curvature of the stomach and the first part of the duodenum to the posterior surface of the liver
What does the lesser omentum terminate as and on what side?
A free edge on the right
Where does the free edge extend?
From the duodenum to the posterior liver
What runs through the lesser omentum just to the left of the free edge? (5)
Hepatic artery, portal vein, bile duct, lymph vessels and nerves
What is the lesser sac or omental bursa
The space posterior to the stomach and lesser omentum
What does the omental bursa allow for?
Movement and expansion of the stomach
What is the greater sac?
The rest of the peritoneal cavity that is not the omental bursa/lesser sac
What is the epiploic or omental foramen
The opening behind the free edge of the lesser omentum
What connects the greater and lesser sacs?
The omental or epiploic foramen
What is at the posterior wall of the omental bursa?
The stomach bed
What does the stomach bed include (5)
Upper pole of left kidney and left suprarenal, diaphragm, part of spleen, pancreas, part of transverse mesocolon
Stomach bed includes retroperitoneal structures true or false?
True
The stomach is highly distensable true or false,?
True
What is the function of the stomach (2)
Food storage and digestion
What doe the stomach consist of (4)
Cardia, fundus, body and pyloric part
What does the pyloric part of the stomach consist of (3)?
Antrum, canal and sphincter
What are some other non-main features of the stomach (4)
Cardiac notch, angular incisure, lesser curvature and greater curvature
The cardia and fundus are fairly mobile, true or false?
False
What are the temporary, internal longitudinal folds of the stomach called?
Rugae
What are the anterior relationships of the stomach? (2)
Liver, diaphragm
What are the posterior relationships of the stomach (2)?
Omental bursa and the structures of the stomach bed
Where is the cardiac orifice of the stomach anatomically?
The 7th costal cartilage which attaches at the xiphosternal joint and is 3cm left of the midline
Where is the pyloric sphincter surface anatomy wise
Roughly at the level of the transpyloric plane (halfway between the suprasternal notch and pubic symphysis)
What is the function of stomach mucosa?
To produce mucus in the cardia and pyloric part
Which parts of the stomach (2) produce digestive enzymes and HCl
fundus and body
