The Pharynx and Larynx Flashcards
Describe the muscles of the pharynx
External layer of circular muscle (superior, middle inferior)
Inner layer of longitudinal muscle
Describe the external layer of muscle in the pharynx
Composed of 3 constrictor muscles that overlap each other
Superior, middle, inferior constrictors
Contract superior to inferior to swallow down
What happens during swallowing?
Tongue pushes food from oral cavity into oropharynx
Soft palate rises and closes off nasopharynx
Food enters laryngopharynx
Constriction of muscles of pharyngeal wall move food into oesophagus
What does the epiglottis do during swallowing?
It is a cartilage of the pharynx
It closes off the laryngeal inlet
Prevents food or liquids entering larynx
What are the 3 parts of the pharynx?
Nasopharynx - posterior to nasal cavity
Oropharynx - posterior to oral cavity
Laryngopharynx - posterior to larynx
What are tonsils?
How many tonsils?
Collections of lymphoid tissue
4
Pharyngeal
Tubal
Palatine
Lingual
Tonsils in the nasopharynx?
Pharyngeal tonsil (adenoid) is at the roof of the nasopharynx
Tubal tonsil surrounds opening of auditory tube.
Tonsils in the oropharynx?
Palatine tonsil - next to the pharyngeal wall in the oropharynx
Where is the lingual tonsil?
On the posterior aspect of the tongue
What is the pharynx innervated by?
Sensory fibres from the glossopharyngeal nerve
Motor fibres from the vagus nerve
What nerves lie close to the posterior pharyngeal wall?
Sympathetic trunk (+cervical ganglion)
Superior laryngeal nerve (branch of vagus nerve) descends over posterior aspect of the internal carotid artery, passes between inferior and middle constrictors
Hypoglossal nerve(XII) close to vagus nerve
Glossopharyngeal nerve(IX) deep to internal carotid artery
Pharynx and gag reflex
Gag reflex protects airway
Mediated by vagus and glossopharyngeal
IX carries sensory input to CNS
Motor fibres in X stimulates muscles of the soft palate and pharynx to contract
How can there be swallowing difficulties if a stroke affects regions of the brain involved in swallowing?
In normal swallowing, vagus causes contraction of pharyngeal muscles and soft palate also conveys sensation from larynx.
Glossopharyngeal conveys sensory info from larynx
Interruptions of these pathways cause dysfunctional swallowing.
Loss of sensation impairs cough reflex.
Risk of aspiration - swallowed food passing into lungs, causing infection
Describe the laryngeal skeleton
9 cartilages
3 unpaired
3 pairs
Connected by membranes and very small joints
Name the three unpaired cartilages in the larynx
Epiglottis
Thyroid
Cricoid
Larger than paired cartilages
Name the three paired cartilages in the larynx
The arytenoids
The cuneiforms
The corniculate
Much smaller than unpaired cartilages, latter 2 are very small
Describe the thyroid cartilage
Composed of laminae - 2 flat cartilages that meet in the anterior midline to form laryngeal prominence (adams apple)
Posteriorly the laminae form extensions projecting superiorly and inferiorly
The superior and inferior horns
Superior horns attach to hyoid bone
Inferior horns articulate with the cricoid cartilage below
What is the cricothyroid membrane?
Connects inferior border of thyroid and superior border of cricoid. It can be pierced to create an emergency airway.
Describe the epiglottis cartilage
Attached to superior aspect of thyroid cartilage where the thyroid laminae meet
Covers laryngeal inlet during swallowing
Describe the arytenoids
Sit on superior cartilage of cricoid cartilage
Articulate with it at small joints
Vital for phonation, as the vocal chords attach to them
Movement of arytenoids moves vocal chords
What is the internal aspect of the larynx modified for?
Modified for phonation
Intrinsic muscles of larynx move laryngeal cartilages, moving the vocal chords
What are the two pairs of folds projecting into the cavity of the larynx?
Vestibular folds (false vocal chords) superiorly
Vocal folds (true vocal chords) inferiorly
Both are folds of mucous membrane
Describe the true vocal chords in the larynx
Vocal folds (folds of mucous membrane) cover and protect the vocal ligaments.
Vocal ligaments attach anteriorly to the internal aspect of laryngeal prominence and posteriorly to arytenoid cartilages
Describe action of vocal chords and rima glottidis during phonation
Phonation - adduction of vocal chords and closure of rima glottidis
Abduction opens the rima glottidis…
- a small degree in whispering
- partially in normal breathing
- fully in forced breathing
What is the space between the vocal chords called?
Rima glottidis
Closed when vocal chords adduct
Opened when vocal chords abduct
What muscles act upon the larynx?
Extrinsic and intrinsic
Describe extrinsic muscles in the larynx
Suprahyoid and infrahyoid muscles
Move the larynx as a whole during speech and swallowing instead of individual cartilages
Describe the intrinsic muscles in the larynx
Move the laryngeal cartilages, so also vocal chords
Include the…
- l/r cricothyroid muscles anteriorly, places tension on vocal chords
- l/r posterior cricoarytenoids on posterior surface of cricoid, abduct vocal chords to open rima glottidis
- transvere arytenoid - unpaired on posterior aspect of larynx, connects two arytenoids, adduct vocal chords to close rima glottidis
Describe innervation of the larynx
2 nerves - both branches of vagus
Superior laryngeal nerve - innervates cricothyroid, sensory to the larynx above the vocal chords
Recurrent laryngeal - innervates all the intrinsic muscles, sans cricothyroid, sensory to larynx below the vocal chords
What structures in the neck are palpable upon examination?[7]
(bone, cartilage,membrane, gland, pulse)
Hyoid bone inferior to mandible
Thyroid cartilage
Cricoid cartilage, inferior to thyroid cartilage
First tracheal cartilage inferior to cricoid
Cricothyroid membrane (emergency airway)
Lobes of thyroid gland either side of upper trachea and inferior larynx
Carotid pulse - best just anterior to sternocleidomastoid at level of thyroid cartilage
