Anatomy - Upper GI Tract Flashcards
At which joints does jaw opening and closing occur?
temporomandibular joints
Which muscles open your jaw?
Lateral pterygoid
Which muscles close your jaw?
Masseter
Temporalis
Medial pterygoid
Which nerve innervates the muscles responsible for mastication?
Mandibular division of the trigeminal nerve (CN V3)
What prevents anterior dislocation of the temporomandibular joint?
articular tubercle
Describe the course of the mandibular division of the trigeminal nerve (CN V3)
Pons --> foramen ovale --> muscles of mastication and inferior half or oral cavity
What kind of nerve fibres does CN V3 have
sensory and motor
what is the oral vestibule?
gap between the lips and teeth
What is the oral cavity?
from teeth –> oropharynx
Is the hard palate anterior or posterior?
Hard palate (palatine bone) is anterior
Soft palate is posterior
How many teeth is a full set in adults?
32
Name the 4 quadrants of the dental arches
How many teeth per quadrant?
Right upper dental arch
Left upper dental arch
Right lower dental arch
Left lower dental arch
8 teeth (max.) per quadrant
Match each teeth number to its tooth type
1-2 = incisors 3 = canine 4-5 = premolars 6-8 = molars
Which teeth are wisdom teeth?
tooth 8 in each quadrant
i.e. the furthest back tooth
Define the gingivae
the gums
Describe the arches of the soft palate
What sits between them?
There is a posterior and anterior arch
Between them (laterally) are the palatine tonsils
Name the 3 major pairs of salivary glands
Where are they located
Parotid = cheeks
Submandibular = under jaw
sublingual = under tongue
How is the saliva transported from gland to oral cavity?
Where is the saliva from each gland released?
Transported via salivary ducts
Parotid –> cheeks
Submandibular –> under tongue (medially)
sublingual –> under tongue (spread out)
Describe the general sensory innervation of the oral cavity and gingivae
Superior half:
- Superior gingiva, palate, etc.
- by CN V2
Inferior half:
- Superior gingiva, tongue, oral cavity floor
- by CN V3
Describe the course of CN V3
pons --> foramen rotundum --> superior half of the oral cavity, and other nearby places
What kind of fibres does CN V2 have?
sensory only
Describe the gag reflex
What nerves?
Physical reaction?
Protective reflex that constricts the pharynx
Sensory = CN IX Motor = CN IX and X
Describe the sensory innervation of the tongue
Anterior 2/3rds (horizontal):
- general sensory = CN V3
- special sensory = CN VII
Posterior 1/3rd (vertical):
- general sensory = CN IX
- special sensory = CN IX
Describe the course of CN VII
pontomedullary junction --> internal acoustic meatus --> stylomastoid foramen --> anterior 2/3rds of tongue muscles of facial expression submandibular gland
What kinds of fibres does CN VII have?
special sensory (for tongue)
general sensory
motor
parasympathetic (for submandibular gland)
Describe the chorda typani
branch of CN VII which connects to the lingual branch of CN V3
It carries:
- Special sensory neurons for the anterior 2/3rds of the tongue
- Parasympathetic neurons for the salivary glands
Describe the course of CN IX
Medulla --> jugular foramen --> posterior wall of oropharynx (sensory)
parotid gland (secretomotor)
posterior 1/3rd Tongue (Sensation and Taste)
Describe the sensory innervation of the posterior wall of the oropharynx?
CN IX
List the extrinsic muscles of the tongue
4 pairs:
palatoglossus
styloglossus
hyoglossus
genioglossus
What are the functions of the extrinsic tongue muscles?
Tongue position
mastication, swallowing, speech
What are the functions of the extrinsic tongue muscles?
Tongue shape
What nerve innervates the tongue muscles?
CN XII (hypoglossal)
except the palatoglossus
Describe the course of CN XII
Medulla --> hypoglossal canal --> extrinsic and intrinsic tongue muscles (except the palatoglossus)
Describe the pharyngeal constrictor muscles
Form the external layer of muscle
3 slightly overlapping circular sheets:
- Superior
- Middle
- Inferior
Innervated by CN X (vagus)
All insert into the midline raphe (at the posterior midline)
Describe the contraction of the pharyngeal constrictor muscles
The contract voluntarily
Always contract sequentially
e.g. if the superior starts to contract the others WILL contract (this part is involuntary)
Describe the longitudinal pharyngeal muscles
form the inner layer of pharyngeal muscle
(i.e. are deep to the pharyngeal constrictors)
Raise the larynx to close over the laryngeal inlet (prevents aspiration)
Innervated by CN X and IX
Describe the cricopharyngeus (upper esophageal/cricopharyngeal sphincter)
Circular muscle sphincter at the top of the oesophagus
At the level of C6
Divides the pharynx and oesophagus
Usually contracted to prevent reflux
List the steps of swallowing
1) Lips close to stop drooling
2) Tongue pushes the bolus posteriorly towards the oropharynx. (CN XII)
3) Pharyngeal constrictor muscles contract sequentially (CN X) to push the bolus inferiorly towards the oesophagus
4) at the same time the inner longitudinal pharyngeal muscles (CN IX & X) contract to raising the larynx, shortening the pharynx and closing off the laryngeal inlet, preventing aspiration
5) Bolus passes through the relaxed cricopharyngeus and reaches the oesophagus
Name the 2 sphincters of the oesophagus
Anatomical:
cricopharyngeal (upper esophageal) sphincter
Physiological:
lower esophageal sphincter
Describe the esophageal plexus
Runs on oesophageal surface
Supples smooth muscle within its walls (distally)
Contains parasympathetic nerve fibres (vagal trunks) and sympathetic nerve fibres
These fibres influence the enteric nervous system to speed up (P) or slow down(S) peristalsis
Terminates by entering the cardia of the stomach
At what level does the oesophagus pass the diaphragm?
T 10
Describe the lower oesophageal sphincter
Is physiological, not anatomical
Is immediately superior to the gastroesophageal junction (Z line)
Reduces reflux
Factors for the sphincter:
- Contraction of diaphragm
- Intra-abdominal pressure slightly higher than intragastric pressure
- Oblique angle at which oesophagus enters the cardia of stomach
Name the sections of the stomach
Fundus - most superior
Cardia - esophageal entrance
Body
Pyloric antrum
Describe the gastric rugae
Ridges produced by folding of the inner wall of the stomach
Describe the pyloric sphincter (pylorus)
sphincter at aboral end of stomach
stomach --> pylorus --> duodenum
