Head an Neck: The pharynx Flashcards
What are the boundaries of the nasopharynx?
Behind the nasal cavity:
Base of skull to upper border of the soft palate. Posterior is C1 and C2
What does the nasopharynx contain?
The pharyngeal tonsil (when enlarged they are called adenoids)
What is the problem with adenoids?
They are next to the opening of the eustachian tubes so can harbour chronic infection eg otitis media and sinusitis.
They can also block nasal air flow and cause mouth breathing and snoring
At what age do adenoids commonly present?
They are largest between 5 and 7 so present at this age. After 7 they begin to regress
Why does blockage of the eustachian tube cause an otitis media with effusion?
Cells in the middle ear constantly absorb gasses such as oxygen and nitrogen
The pressure cant equilise so this causes a negative pressure which pulls transudate from the mucosa.
This stasis of fluid then allows proliferation of bacteria
What are the complications of otitis media?
- hearing loss (temporary)
- mastoiditis and necrosis of mastoid
- this can spread to cause meningitis and brain abscess
- cholesteatoma which is a growth that invades surrounding tissues (not cancerous though)
What are the boundaries of the oropharynx?
Behind the oral cavity:
Soft palate to the epiglottis
Posterior is C2 and C3
What does the oropharynx contain?
The palatine tonsils
What are the boundaries of the laryngopharynx?
Located behind the larynx:
Extends from epiglottis to cricoid cartilage
Posterior is C4 5 6
What does the laryngopharynx contain?
The piriform fossa
How is the orientation of smooth muscle in the pharynx different to the rest of the alimentary tract ?
The pharynx has an inner longitudinal smooth muscle layer and outer circular whereas the GI tract has inner circular and outer longitudinal
What is the piriform fossa?
A recess than runs either side of the epiglottis
Acts as a channel for food and liquids to pass, reducing the chance of entrance into the larynx
Which muscles elevate the pharynx and larynx during swallowing?
What is their innervation?
3 longitudinal muscles:
Stylopharyngeus - glossopharyngeal nerve
Palatopharyngeus - vagus nerve
Salpingopharyngeus - vagus nerve
Which muscles constrict the pharynx?
What is their innervation
3 circular muscles:
Superior, middle and inferior pharyngeal constrictor muscles - all vagus
NB. The inferior pharyngeal constrictor has a thyropharyngeal part and a cricopharyngeal part. There is a point of weakness between them called Killian’s dehiscence
What is a pharyngeal pouch?
How is it caused?
A posterolateral diverticulum (not directly posterior due to the strong raphe)
Caused by failure of the upper oesophageal sphincter to relax, abnoraml timing of swallowing causing high pressure in the laryngopharynx.
The out-poaching goes through killians dehiscence. This causes dysphagia, halitosis due to food getting trapped, gurgling and coughing.
