The Pharynx Flashcards
What is the pharynx?
A muscular tube
Connects the larynx and oesophagus to the nasal cavities
What can pass down the pharynx?
Air and food
Where, precisely, does the pharynx begin and end?
Begins at the base of the skull
Ends inferior to the cricoid cartilage (C6)
Name the three parts of the pharynx
Nasopharynx
Oropharynx
Laryngopharynx
What are the muscles of the pharynx innervated by?
The vagus nerve (CN X)
Except for the stylopharyngeus, innervated by the glossopharyngeal nerve (CN IX)
What is the function of the circular muscles of the pharynx?
Contract sequentially from superior to inferior to constrict the lumen and propel bolus of food inferiorly into the oesophagus.
Structure of the circular muscles of the pharynx?
Stacked like glasses
Form an incomplete muscular circle
Name the circular muscles of the pharynx and the parts in which they are found.
Superior pharyngeal constrictor - oropharynx
Middle pharyngeal constrictor - laryngopharynx
Inferior pharyngeal constrictor - laryngopharynx
What are the two components of the inferior pharyngeal constrictor
Superior (thyropharyngeus) - has oblique fibres that attach to the thyroid cartilage
Inferior (cricopharyngeus) - horizontal fibres attaching to the cricoid cartilage
Generally, what is the structure of the wall of the pharynx?
Pharyngeal mucosa
Incomplete ring of lymphoid tissue
Longitudinal muscular layer
Circular muscular layer
Buccopharyngeal fascia
Function of the longitudinal muscles of the pharynx?
Shorten and widen the pharynx
Elevate it during swallowing
Attachements of the longitudinal muscles of the pharynx?
Stylopharyngeus - styloid process of temporal bone to the pharynx
Palatopharyngeus - hard palate of oral cavity to the pharynx
Salpingopharyngeus - Eustachian tube to pharynx
What extra function does the salpingopharyngeus perform?
Opens the Eustachian tube to equalise pressure in the middle ear with the atmosphere.
Sensory innervation of the pharynx?
Nasopharynx - maxillary
Oropharynx - glossopharyngeal
Laryngopharynx - vagus
Sympathetic innervation to the pharynx?
From the superior cervical ganglion
Arterial supply to the pharynx?
Branches of the external carotid
- ascending pharyngeal
- lingual
- facial
- maxillary
Venous drainage of the pharynx?
Pharyngeal venous plexus, drains into the internal jugular
Where does the nasopharynx run between?
Base of the skull to the soft palate
Function of the nasopharynx?
Extension of the nasal cavity
Conditions inspired air and propogates it into the larynx
Epithelium of the nasopharynx?
Ciliated pseudostratified columnar with goblet cells
Where are the adenoid tonsils found?
In the posterio-supeior nasppharynx
What can cause enlargement of the adenoid tonsils?
Viral infections of the upper respiratory tract
What can happen if the adenoids keep becoming infected and enlarged?
Obstruct the opening of the Eustachian tube
Prevents equalising of pressure in the middle ear and normal drainage of fluids for excretion
Glue ear
Where does the oropharynx run from and to?
Soft palate and supeior border of the epiglottis
What does the oropharynx contain?
Posterior third of the tongue
Lingual tonsils
Palatine tonsils
Superior constrictor muscle
What is the function of the oropharynx?
Voluntary and involuntary phases of swallowing
Where are the palatine tonsils found?
In the tonsilar fossa between the palatoglossal and palatopharyngeal arches of the oral cavity
Where are the lingual tonsils found?
Inferiorly to the tongue
What is inflammation of the palatine tonsils (tonsilitis) accompanied by?
Enlarged jugulo-digastric lymph nodes
What can bleed during a tonsillectomy?
External palatine vein
Tonsilar branch of the facial artery
What can be damaged during a tonsillectomy?
Glossopharyngeal nerve
Internal carotid artery
If an infection spreads from the palatine tonsils to the peritonsilar tissue, what is this known as and what happens?
Why is it an emergency?
Cause an abscess
Can get deviation of the uvula (quinsy)
Potential obstruction to the pharynx
How is quinsy treated?
Drain the abscess
Antibiotics
Where does the laryngopharynx run between?
Superior border of the epiglottis
Inferior border of the cricroid cartilage (C6)
Becomes continuous with the oesophagus
Where is the laryngopharynx found in relation to the larynx?
Posterior to the larynx
What does the laryngopharynx contain?
Middle and inferior pharyngeal constrictors
Where can foreign objects become lodged in the pharynx?
Valleculae in the nasopharynx
Piriform fossae in the laryngopharynx
How are objects in the piriform fossae visualised and removed?
With a pharyngoscope
What can be affected when something is lodged in the piriform fossa?
Can compress the internal laryngeal nerve and the recurrent laryngeal nerve
What happens during swallowing normally with the inferior pharyngeal constrictor?
The superior part - thyropharyngeus - contracts
The cricopharyngeus relaxes
This allows the bolus to be propelled into the oesophagus and prevent intrapharyngeal pressure from rising
What can happen if there is not the relaxation of the cricopharyngeus during swallowing?
Intrapharyngeal pressure rises
Pharyngeal mucosa forms a midline diverticulum between the thyropharyngeus and cricopharyngeus
Food can accumulate here, leading to dysphagia
Where are the widest and narrowest parts of the pharynx?
Widest (5cm) opposite the hyoid
Narrowest (1.5cm) at the inferior end
What is between the muscle layer and the mucosa of the pharynx?
The pharyngobasilar fascia
What are the phases of swallowing?
Voluntary phase
Pharyngeal phase
Oesophageal phase
What happens in the voluntary phase of swallowing?
Tongue moves bolus to the back of the pharynx
What happens in the pharyngeal phase of swallowing?
Afferent info from pressure receptors in the palate and anterior pharynx reaches the swallowing centre in the brain stem
Triggers movements:
- Inhibition of breathing
- Raising of larynx
- Closure of the glottis
- Opening of the upper oesophageal sphincter
What happens in the oesophaeal phase of swallowing?
- Wave of peristalsis sweeps down the oesophagus, propelling the bolus into the stomach in about 9 seconds
- Coordinated by extrinsic nerves from the swallowing centre of the brain
- Lower oesophageal sphincter opens
What triggers the gag reflex and what is the pathway?
Touching the back of the oropharynx
Afferent pathway - glossopharyngeal
Efferent pathway - vagus nerve
Clinical features of enlarged adenoids?
- Nasal obstruction
- Mouth breathing and nasal speech
- Feeding difficulty especially in infants
- Snoring/obstructive sleep apnoea
- Block opening of Eustachian tube
