Functional anatomy of larynx and pharynx Flashcards
What are the three parts of the pharynx and their corresponding vertebral levels?
Nasopharynx – Behind the nose, from the roof to the soft palate (C1).
Oropharynx – Behind the mouth, from the soft palate to the epiglottis (C2–C3).
Laryngopharynx – Behind the larynx, from the epiglottis to the cricoid cartilage (C3–C6).
What are the functions of the pharynx?
Respiratory: Air passage.
Deglutition (swallowing): Transports food to the esophagus.
Protective: Prevents food from entering the nasal cavity (via soft palate elevation) and larynx (via epiglottis).
Which nerves provide sensory innervation to the pharynx?
Nasopharynx: Maxillary nerve (V2).
Oropharynx: Glossopharyngeal nerve (IX).
Laryngopharynx: Vagus nerve (X).
What is Waldeyer’s ring?
A ring of mucosa-associated lymphoid tissue (MALT) surrounding the openings of the digestive and respiratory tracts, including:
Pharyngeal tonsil (adenoids).
Palatine tonsils.
Lingual tonsil.
Tubal tonsils.
What are the unpaired and paired cartilages of the larynx?
Unpaired: Epiglottis, thyroid, cricoid.
Paired: Arytenoid, corniculate, cuneiform.
What is the function of the intrinsic laryngeal muscles?
To control vocal fold movement:
Posterior cricoarytenoid: Abducts (opens) vocal folds.
Lateral cricoarytenoid: Adducts (closes) vocal folds.
Cricothyroid: Tenses vocal folds (elevates pitch).
Thyroarytenoid (vocalis): Relaxes vocal folds.
What is the name of the only muscle that abducts the vocal cords?
Posterior cricoarytenoid
Which nerves innervate the laryngeal muscles?
All intrinsic muscles (except cricothyroid): Recurrent laryngeal nerve (branch of vagus/X).
Cricothyroid: External laryngeal nerve (branch of superior laryngeal nerve/X).
What is the clinical significance of the piriform fossa?
Location where foreign bodies (e.g., fish bones) may lodge.
Internal laryngeal nerve runs beneath its mucosa; damage can cause loss of cough reflex and aspiration risk
What are the blood supply and lymphatic drainage of the larynx?
Arteries:
Superior laryngeal artery (from superior thyroid artery).
Inferior laryngeal artery (from inferior thyroid artery).
Lymphatics:
Above vocal cords: Deep cervical nodes (via superior thyroid artery).
Below vocal cords: Deep cervical nodes (via inferior thyroid artery).
What is the gag reflex, and which nerves are involved?
Definition: Reflex contraction of the pharynx to prevent choking.
Afferent (sensory): Glossopharyngeal nerve (IX).
Efferent (motor): Vagus nerve (X).
What is the difference between tracheostomy and tracheotomy?
Tracheotomy: Temporary opening into the trachea.
Tracheostomy: Permanent stoma created in the trachea.
What is the pharyngobasilar fascia, and what is its function?
A submucosal fibrous thickening in the nasopharynx.
Function: Holds the nasopharynx permanently open for breathing.
Why is the recurrent laryngeal nerve more prone to injury on the left side?
Because it loops under the aortic arch (vs. subclavian artery on the right), making it longer and more susceptible to damage (e.g., during thoracic surgery).
Why are adenoidectomies common in preschool children?
The pharyngeal tonsil (adenoid) grows rapidly until age 5, then atrophies by 8–10 years.
Enlarged adenoids can obstruct nasal breathing, leading to recurrent infections/sleep apnea.
What structures form the boundaries of the nasopharynx?
Roof: Sphenoid bone + pharyngeal tonsil.
Floor: Soft palate (mobile).
Anterior: Choanae (openings to nasal cavity).
Lateral: Pharyngotympanic tube openings + torus tubarius.
What is the clinical significance of the vallecula?
Depression between the median and lateral glossoepiglottic folds.
During intubation: The epiglottis is lifted via pressure on the vallecula to visualize the laryngeal inlet.
Which muscles elevate the larynx during swallowing?(LIst them)
Suprahyoid muscles:
Digastric
Stylohyoid
Mylohyoid
Geniohyoid
Thyropharyngeus (part of inferior constrictor).
What is the conus elasticus, and what does it form?
The lower part of the fibroelastic membrane of the larynx.
Forms: The vocal ligaments (upper free edge) and the cricothyroid ligament.
Why is the cricoid cartilage unique?
It is the only complete ring-shaped cartilage in the larynx.
Clinical relevance: Site for emergency cricothyrotomy in airway obstruction.
What happens in unilateral vs. bilateral recurrent laryngeal nerve damage?
Unilateral: Hoarse voice (vocal fold paralysis in paramedian position).
Bilateral: Airway obstruction (folds may close completely).
What is the “tubarial gland,” and where is it located?
A recently discovered salivary gland located near the torus tubarius in the nasopharynx.
Significance: May be spared during radiotherapy to reduce xerostomia (dry mouth).
What is the role of the quadrangular membrane?
Connects the arytenoid cartilages to the epiglottis.
Forms: The vestibular folds (false vocal cords) and the aryepiglottic folds.
How does the larynx prevent aspiration during swallowing?
Epiglottis diverts food laterally into piriform fossae.
Vocal folds close (adduct).
Aryepiglottic muscles constrict the laryngeal inlet.
What is the rima glottidis, and how does it change during breathing vs. phonation?
Breathing: Widens (abducted by posterior cricoarytenoid).
Phonation: Narrowed (adducted by lateral cricoarytenoid + interarytenoids).
Why is the external laryngeal nerve at risk during thyroid surgery?
It runs close to the superior thyroid artery.
Damage: Weakens voice (paralyzes cricothyroid muscle, reducing pitch control).
What is laryngitis, and how does it affect the voice?
Inflammation of the vocal folds.
Effect: Swollen folds vibrate more slowly → deeper/hoarse voice.
What are the boundaries of the piriform fossa?
Medial: Aryepiglottic fold.
Lateral: Thyroid cartilage + thyrohyoid membrane.
Posterior: Inferior pharyngeal constrictor.
What is subglottic stenosis, and what causes it?
Narrowing below the vocal folds.
Causes: Congenital malformation or scarring from prolonged intubation (e.g., in neonates).
Which muscles are supplied by the glossopharyngeal nerve (CN IX)?
Stylopharyngeus (only pharyngeal muscle it innervates).
Sensory: Oropharynx, palatine tonsils, and gag reflex afferents.
