Session 4: The Pharynx and Larynx Flashcards
(42 cards)
What is the pharynx?
A muscular tube which lies in the neck.
- it forms part of the respiratory and gastrointestinal systems.
What occurs during swallowing?
- food in the oral cavity is pushed into the oropharynx by the tongue
- The soft palate rises and closes off the nasopharynx from the oropharynx.
- Food enters the laryngopharynx and the muscles of the pharyngeal wall constrict it to move the food into the oesophagus.
- The epiglottis closes off the laryngeal inlet and prevents food or liquids from entering the larynx.
What is the pharynx composed of?
The pharynx is composed of three parts:
the nasopharynx, the oropharynx, and the laryngopharynx.
- The nasopharynx is posterior to the nasal cavity.
- The oropharynx is posterior to the oral cavity.
- The laryngopharynx is posterior to the larynx (sometimes called the hypopharynx).
What are tonsils?
The tonsils are collections of lymphoid tissue in the upper parts of the pharynx.
What nerves innervate the pharynx?
The pharynx is innervated by sensory fibres from the glossopharyngeal nerve and motor fibres from the vagus nerve.
What is the gag reflex mediated by?
It is mediated by the glossopharyngeal and vagus nerves.
The gag reflex protects the airway.
What happens after a stroke to swallowing ?
swallowing difficulties.
If these swallowing pathways are interrupted, swallowing is dysfunctional, and loss of sensation impairs the cough reflex.
What is the larynx composed of?
The larynx is composed of nine cartilages. Three are unpaired, and three are paired.
Membranes and very small joints connect the cartilages to each other.
What forms the hyoid bones?
- the superior and inferior horns.
- The superior horns attach to the hyoid bone.
- The inferior horns articulate with the cricoid cartilage below.
What is the internal larynx like?
- modified for phonation
- Intrinsic muscles of the larynx move the laryngeal cartilages which in turn move the vocal cords that lie inside the larynx.
Injury to the nerves that innervate the intrinsic laryngeal muscles therefore affect speech.
What are the vocal fold and cords like?
- vestibular folds (false vocal cords) superiorly
- vocal folds (true vocal cords) inferiorly
- A narrow space separates the vestibular and vocal folds.
What are the extrinsic muscles of the ?
Extrinsic muscles - the suprahyoid and infrahyoid muscles.
They do not move the individual cartilages, but rather move the larynx as one with speech and swallowing.
Which muscles affect the vocal cords a?
They include the:
- left and right cricothyroid muscles
- left and right posterior cricoarytenoids
- transverse arytenoid
Which nerves help vocal cords?
Two nerves – both are branches of the vagus nerve:
- The superior laryngeal nerve innervates the cricothyroid muscle and is sensory to the larynx above the vocal folds.
- The recurrent laryngeal nerve innervates all the intrinsic muscles except for the cricothyroid and is sensory to the larynx below the vocal folds.
What is vocal cord palsy?
The recurrent laryngeal nerve lies close to the inferior thyroid artery, which is ligated during thyroidectomy.
The nerve innervates all but one of the intrinsic muscles of the larynx.
If it is injured, the intrinsic muscles of the ipsilateral side do not function and subsequently the vocal cords on the affected side cannot move. When the vocal cords on one side are unable to adduct, hoarseness of the voice results.
What is laryngeal cancer?
Malignancy of the larynx typically presents with a change in the quality of the voice, such as hoarseness.
Visualisation of the larynx - laryngoscopy – is used to examine the larynx and vocal cords
What is endotracheal intubation?
Endotracheal intubation is the passage of a semi-rigid tube into the trachea for ventilation. It is commonly performed when patients have a general anaesthetic for surgery, or when patients are sedated in intensive care.
A laryngoscope is used to lift the tongue and epiglottis so that the vocal cords can be directly seen, and the tube is passed between them into the trachea.
How do we make an emergency airway?
If the airway is obstructed above the level of the cricoid cartilage an emergency airway that bypasses the upper airway can be created by piercing the cricothyroid membrane.
This is a lifesaving but temporary measure, and a more secure airway is established as soon as possible
What nerves lie close to the pharynx?
- Several nerves lie close to the posterior pharyngeal wall.
- The cervical part of the sympathetic trunk and superior cervical ganglion.
- Superior laryngeal nerve.
- Hypoglossal nerve - lies close to the vagus nerve.
- Glossopharyngeal nerve.
What is the pharynx composed of?
The walls of the pharynx are composed of:
- an outer layer of circular muscle
- an inner layer of longitudinal muscle
What is the external circular muscle layer of the pharynx composed of?
Three constrictor muscles:
the superior, middle, and inferior constrictors - that overlap each other.
- contract superior to inferior, so that swallowed food moves down the pharynx towards the oesophagus.
Where are the tonsils?
- The pharyngeal and tubal tonsils are found in the nasopharynx.
- The pharyngeal tonsil (adenoid) lies in the roof of the nasopharynx.
- The tubal tonsil surrounds the opening of the auditory tube (which connects the nasopharynx to the middle ear).
- The palatine tonsil lies next to the pharyngeal wall in the oropharynx.
- The lingual tonsil is a collection of lymphoid tissue on the posterior aspect of the tongue.
The tonsils may become inflamed and infected
How does the gag reflex work?
When the back of the mouth, posterior wall of the pharynx or the tonsils are stimulated, this sensation is carried to the CNS via the glossopharyngeal nerve. In response, the muscles of the soft palate and pharynx immediately contract (via motor fibres in the vagus nerve).
What is aspiration?
Following a stroke that affects swallowing:
Patients are at risk of ‘aspiration’ – swallowed liquid or food may pass into the lungs and cause infection.
