Upper Gastrointestinal Tract Flashcards
What structure is the oral cavity continuous with?
Pharynx
What is the oral cavity divided into?
Oral vestibule- behind the lips, continuous with oral cavity proper
Oral cavity proper- median to teeth
What circular muscle surrounds orifice of mouth?
Orbicularis oris - helps out lips
What muscle is lateral to the orbicularis oris?
Buccinator muscle - helps blow out cheeks
Where is saliva produced/
Parotid gland
Why is buccinator muscle an important landmark?
Parotid duct transports saliva over masseter muscle to enter into oral cavity by travelling through buccinator muscle
What does the floor of the oral cavity consist of?
Mylohyoid muscle (superficial) runs from mandible to hyoid bone (floating bone)
Geniohyoid muscle (superior to mylohyoid)
What forms the roof of the oral cavity?
Hard palate (bone- roof of mouth) Soft palate (posterior)
What is the horizontal plane extending from maxilla?
Palatine process of maxillary bone
Has a suture- horizontal plate of palatine bone
What structure is a part of the soft palate and what does it consist of?
Uvula
Made of muscle -> Musculus uvulae
Red mucus membrane around it- covering whole of oral cavity and pharynx
What structure is exposed on protraction of the tongue?
Palatoglossal fold- under it is palatoglossal muscle
What structure is posterior to the palatoglossal fold?
Palatopharyngeal fold
Under it is palatopharyngeas muscle
What structure is between the palatoglossal and palatopharyngeas folds?
Palatine tonsil
Tensor veli palatini muscle and levator veli palatini muscle
Tensor- tenses soft palate
Levator- elevates soft palate
What innervates the muscles of the soft palate? Are there any exceptions?
Vagus nerve EXCEPT tensor veli palatini (supplied by mandibular division of trigeminal nerve)
Identify vagus nerve
First identify nearby common carotid artery
Lateral to it is internal jugular vein
In between them is vagus nerve
What structure is this
Root of tongue
attached to hyoid bone and mandible
What structure is this
Dorsum of tongue
What two parts is the tongue divided into?
Anterior 2/3 (oral)
Posterior 1/3 (pharyngeal)
What structure is this
Thyroid cartilage
What structure is this
Thyroid glands
What is the V shaped structure on the dorsal surface of the tongue?
Terminal sulcus
defines boundary between oral and pharyngeal parts of tongue
Foramen cecum
Thyroid gland started embryological development at this point, then descends
a shallow depression in the posterior dorsal midline of the tongue that is the remnant of the more cranial part of the embryonic duct from which the thyroid gland developed.
What connects foramen cecum to thyroid gland in embryos?
Thyroid glossal duct- atrophies after birth but can remain open as a thyroid glossal cyst in children
Identify this nerve
Lingual branch of mandibular division of trigeminal nerve
What sits here?
Trigeminal ganglion
What nerve gives sensation to oral part of tongue
Lingual branch of mandibular division of trigeminal nerve
What nerve travels with lingual nerve to send sensations of taste to brain?
Chorda tympani- branch of facial nerve
What nerve supplies sensation of taste and general sensation to pharyngeal part of tongue
Glossopharyngeal nerve (cranial nerve 9)
What structure is this
Parotid gland
Posterior to masseter muscle
What two vessels run through surface of parotid gland?
External carotid and retromandibular vein
What is this vessel and what structure is it going into?
Parotid duct going into buccinator muscle
Once in the oral cavity what is opposite the parotid duct?
2nd molar tooth upper jaw
What structure is this
Submandibular gland
What structure opens up in the mouth lateral to the frenulum?
Submandibular duct
Identify the structure
Frenulum
Identify the structure
Sublingual salivary glands
What are the 3 salivary glands?
Parotid glands
Submandibular glands
Sublingual glands
Pharynx
Fibromuscular tube that runs behind and is continuous with the nasal cavity, oral cavity and larynx
Identify the structures- what 3 parts is the pharynx divided into?
What is this structure?
Choanae- opening of nasal cavity (posterior nasal aperture)
Where does nasopharynx run from and to?
From just below sphenoid sinus to tip of uvula
Where does oropharynx run from and to?
From tip of uvula to epiglottis
What is epiglottis attached to?
Thyroid cartilage
What tube is the pointer in?
Trachea and top of larynx- anterior to oesophagus
What small depressions are anterior to epiglottis?
Valleculae where saliva will pool and food passes through to stimulate epiglottis and close larynx
What is this structure?
Larynx (voicebox) just under epiglottis
What is this area?
Piriform recess
a small cavity or pocket between the lateral walls of the pharynx on each side and the upper part of the larynx.
What can get stuck in the piriform recess?
Food, eg fish bones
Vocal cords aka larynx
What are the 3 circular pharyngeal muscles and what do they do?
Superior constrictor
Middle constrictor
Inferior constrictor - 2 parts (superior component fibres attach to thyroid cartilage and inferior component fibres attach to cricoid cartilage)
The circular muscles contract sequentially from superior to inferior to constrict the lumen and propel the bolus of food inferiorly into the oesophagus.
Where does oesophagus run from and to?
From pharyngoesophageal junction at C6 to stomach
What is this space
Oropharynx (just before laryngopharynx)
Where is the main point that the oesophagus becomes constricted?
Cricoid cartilage
can also get constricted at the point where aorta arches and bronchus
What are these structures?
Anterior vagal plexus- branches of vagus nerve supplying oesophagus
Thoracic duct
Lymphatic duct that drains all lymph back into veinous system
At what point does oesophagus go through diaphragm?
T10
Through oesophageal hiatus
What is the point where the stomach is closest to the oesophagus?
Cardia
Pylorus
Valve that opens and closes during digestion. This allows partly digested food and other stomach contents to pass from the stomach to the small intestine.
Controls gastric emptying into duodenum
Where is the cardiac notch?
What is the spaghetti string structure hanging from the greater curvature of the stomach?
Greater omentum
Function of greater omentum
If infection in abdomen, in bowl area, greater omentum can slowly migrate and enclose it to stop spread of infection
What is this structure
Transverse colon
Attached to posterior surface of greater omentum
What structure is attached to lesser curvature of stomach?
Lesser omentum (goes to liver)
What are these in the stomach?
Rugae
Cranial cavities
Oral cavity is continuous with nasal cavity via the pharynx.
Pharynx is continuous and posterior to the nasal cavity, oral cavity and larynx.
Pharynx is continuous inferiorly with the oesophagus (food pipe)
Larynx (voice box) is continuous inferiorly with the trachea (wind pipe)
Buccal region
(cheeks)
Movable lateral walls
Buccinator muscle
Continuous with lips (orbicularis oris)
Buccal fat pad assists in suckling
Remember that the buccinator muscle is a muscle of facial expression, not a muscle of mastication!
Saliva function
Keeps mucous membrane moist
Lubricate oral cavity
Initiate digestion of starch
Prevent teeth decay
Three salivary glands
Empty via ducts into oral cavity
- Parotid gland
- Submandibular gland
- Sublingual gland
Innervation to salivary glands
Parasympathetic to submandibular and sublingual glands supplied by presynaptic parasympathetic fibres -> conveyed from the lingual nerve (branch of mandibular (CVN3) by the chorda tympani nerve (branch of facial nerve) to the submandibular ganglion.
Here they synapse with post synaptic parasympathetic fibres and run to the glands.
The parotid gland Parasympathetic supply
Presynaptic parasympathetic from glossopharyngeal nerve to otic ganglion. Post synaptic parasympathetic travel in auricular temporal nerve (branch of mandibular nerve) to parotid gland.
What is root of tongue attached to?
Mandible and hyoid bone
Note nerve supply Maxillary Nerve (CNV2)
Eustachian tube
NERVE SUPPLY: glossopharyngeal nerve (CN IX)
note tonsil and valleculae location
NERVE SUPPLY: Vagus nerve (CN X)
Epiglottis location
Pharyngeal blood supply:
Upper pharynx
Lower pharynx
Palatine tonsil
What lymphatic node drains palatine tonsils?
Jugulodigastric lymph node
Oesophagus
Muscular tube: 25 cm
Extends from pharyngo-oesophageal junction (C6) to cardiac orifice of stomach (T11)
Functions to transport food from pharynx to stomach
Pierces diaphragm at oesophageal hiatus (T10)
Two sphincters
- Upper oesophageal sphincter (UES)
- Inferior constrictor muscle - Lower oesophageal sphincter (LES)
- GORD
Constrictions of oesophagus
A.B.C.D.
A: Arch of aorta
B. Bronchus (left)
C. Cricoid cartilage (junction between oesophagus and pharynx)
D. Diaphragmatic hiatus
Oesophageal layers
Arterial supply of oesophagus
Upper third: Inferior thyroid artery
Middle third: Thoracic aorta
Lower third: Left gastric artery
Innervation of oesophagus
Oesophageal plexus arise from:
- Vagus nerve (CN X):
- Parasympathetic fibres
- General sensation fibres - Nerves from cervical and thoracic sympathetic trunk
- Sympathetic fibres
- Pain fibres
Oesophageal lymphatics
Very complex
Important in oesophageal cancer
BIDIRECTIONAL:
- Upwards to deep cervical lymph nodes
- Downwards to juxta-oesophageal nodes
Function of stomach
Storage of ingested food.
Regulate rate of emptying into small intestines.
Mechanical and chemical breakdown of food.
Histological layers of stomach
Stomach openings
3 layers of stomach muscular structure
- Inner oblique layer: mechanical break down food.
- Middle circular layer: thickest at pylorus forming pyloric sphincter.
- Outer Longitudinal layer: moving bolus towards pylorus through muscular shortening
What are the features of the stomach’s inner mucosa?
Gastric canal
Gastric Rugae/folds
Peptic ulcer
Open lesion in mucosa lining.
Location:
Oesophageal
Gastric
Duodenal
Causes:
H. pylori
NSAID (nonsteroidal anti-inflammatory drugs)
Stress
Development of GI tract
Blood supply of:
Foregut
Midgut
Hindgut
Foregut- COELIAC TRUNK
Midgut- SUPERIOR MESENTERIC ARTERY
Hindgut- INFERIOR MESENTERIC ARTERY
3 main branches from coeliac trunk
Common hepatic artery
Left splenic artery
Splenic artery
Arteries of stomach
Parasympathetic innervation of stomach
Vagus Nerve (CN X) increases rate of digestion when stimulated
- > Secretomotor to gastric glands
- > Motor to smooth muscular walls of GIT (peristalsis)
Right vagus -> posterior vagal trunk (posterior aspect of stomach supplied)
Left vagus -> anterior vagal trunk (anterior surface of stomach supplied)
due to stomach rotation
Sympathetic innervation of stomach
Greater splanchnic nerve (T5 – T9) cause pyloric sphincter to contract reducing rate of gastric emptying
Motor to pyloric sphincter
Referred pain:
Pain fibres hitchhike with splanchnic nerve
Pain from foregut referred to epigastric region
Convergent nerve roots result in the concept of referred pain.
Foregut innervation - greater splanchnic nerve
Lymphatics of stomach
Follow blood vessels
All lymph eventually passes into coeliac nodes
Important for cancer spread: gastrectomy