Anatomy 7 Flashcards
What is the pharynx?
A muscular tube which lies in the neck.
It forms part of the respiratory and gastrointestinal systems.
What are the 3 parts the pharynx is composed of?
● 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 the walls of the pharynx composed of?
Composed of an outer layer of circular muscle and an
inner layer of longitudinal muscle
What is the external circular muscle layer in the pharynx composed of?
Composed of three constrictor muscles
- the superior, middle, and inferior constrictors -
that overlap each other.
They contract superior to inferior, so that swallowed food moves down the pharynx towards the oesophagus
What happens when food is swallowed?
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 constriction of the muscles of the pharyngeal wall move the food into the oesophagus.
The epiglottis - one of the cartilages of the larynx - closes off the laryngeal inlet and prevents food or liquids from entering the larynx.
What is the pharynx innervated by?
The pharynx is innervated by sensory fibres from the glossopharyngeal nerve and motor fibres from the vagus nerve.
What nerves are found in the posterior pharyngeal wall?
● The cervical part of the sympathetic trunk and superior cervical ganglion.
● Superior laryngeal nerve. This branch of the vagus nerve descends over the posterior aspect of the internal carotid artery. It passes between the inferior and middle constrictors of the pharynx to the larynx.
● Hypoglossal nerve. This lies close to the vagus nerve
● Glossopharyngeal nerve. From the posterior aspect, it lies deep to the internal carotid artery.
What is the larynx made up of?
Composed of several cartilages, membranes, and small muscles.
What does the larynx do?
Protects the airway and contributes to phonation/speech.
How many cartilages is the larynx composed of?
Composed of nine cartilages.
Three are unpaired, and three are paired.
What are the cartilages in the larynx connected by?
Membranes and small joints
What are the 3 unpaired cartilages in the larynx?
Epiglottis, thyroid cartilage, and the cricoid cartilage
What are the 3 paired cartilages in the larynx?
Arytenoids, the cuneiforms and the corniculate cartilages.
What is the thyroid cartilage composed of?
Composed of two flat cartilages (laminae) that meet in
the anterior midline to form the laryngeal prominence, or ‘Adam’s apple’, which is usually visible in males.
What does the laminae form?
Forms extensions that project superiorly and inferiorly -
the superior and inferior horns.
What the the superior horn attach to?
Hyoid Bone
What does the inferior horn articulate with?
Cricoid Cartilage
What does the cricothyroid membrane do?
Connects the inferior border of the thyroid and superior border of the cricoid.
This membrane is pierced to create an emergency airway.
What is the epiglottis and what does it do?
Attached to the superior aspect of the thyroid cartilage, where the two thyroid laminae meet.
During swallowing, the epiglottis covers the entrance to the larynx (the laryngeal inlet) and protects the airway from the
entry of liquid or food.
What is the arytenoids?
Sit on the superior surface of the cricoid cartilage.
They articulate with the cricoid cartilage at small joints
What do the arytenoids do?
Vital for phonation, as the vocal cords attach to them
Movements of the arytenoids move the vocal cords.
What are the two groups of muscles that act on the larynx?
● Extrinsic muscles - the suprahyoid and infrahyoid muscles. They do not move the individual cartilages, but rather move the larynx as one
● Intrinsic muscles - these small muscles move the individual cartilages of the larynx relative to each other.
By moving the cartilages, they move the vocal cords, and this in turn alters the quality of speech.
Where is the hyoid bone located?
Inferior to the mandible
Where is the thyroid cartilage located?
In the midline of the neck (Adam’s Apple)
Where is the cricoid cartilage located?
In the midline, inferior to the thyroid cartilage
Where is the first tracheal cartilage located?
Inferior to the cricoid cartilage
Where is the cricothyroid membrane located?
Between the thyroid cartilage and cricoid cartilage
Why is the cricothyroid membrane important?
Can be punctured to create an emergency airway
Where are the lobes of the thyroid gland located?
Either side of the upper trachea and inferior larynx
Where can the carotid pulse be found?
Best palpated just anterior to sternocleidomastoid at the level of the thyroid cartilage
What is the purpose of a gag reflex?
Protects the airway.
It is mediated by the glossopharyngeal and vagus nerves.
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).
This reflex does not occur in normal swallowing but does occur at any other time the posterior mouth or pharynx are touched (e.g. swabbing the tonsils).
Why may you have swallowing difficulties after a stroke?
If a stroke affects the regions of the brain involved in the control of swallowing, then patients may have swallowing difficulties.
In normal swallowing, the vagus nerve coordinates contraction of the pharyngeal muscles and soft palate and conveys sensation from the larynx.
The glossopharyngeal nerve provides sensory innervation to the pharynx.
If these pathways are interrupted, swallowing is
dysfunctional, and loss of sensation impairs the cough reflex. Patients are at risk of ‘aspiration’ – swallowed liquid or food may pass into the lungs and cause infection.
What is the emergency airway?
If the airway is obstructed above the level of the cricoid cartilage (e.g. a foreign body is stuck at the vocal cords, or the vocal cords have become suddenly grossly swollen)
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.
