Anatomy - Week 4 - Pharynx, Larynx, Trachea

Define the pharynx.

A muscular tube that connects the oral and nasal cavity to the larynx and esophagus.

Where does the pharynx begin?

At the base of the skull.

Where does the pharynx end?

At the inferior border of the cricoid cartilage (C6).

List the three subdivisions of the pharynx.

Nasopharynx, Oropharynx, Laryngopharynx.

Where is the nasopharynx located?

Between the base of the skull and the soft palate.

What is the main function of the nasopharynx?

Respiratory function — conditioning inspired air and propagating it into the larynx.

What type of epithelium lines the nasopharynx?

Respiratory epithelium: ciliated pseudostratified columnar epithelium with goblet cells.

Which tonsil is located in the posterosuperior nasopharynx?

Adenoid tonsil (pharyngeal tonsil).

What clinical issue is caused by enlarged adenoid tonsils?

Obstruction of the Eustachian tube opening → prevents equalization of pressure in the middle ear → chronic otitis media with effusion (“glue ear”).

What ear condition is associated with enlarged adenoid tonsils?

Otitis media with effusion.

List otoscopic signs of otitis media with effusion.

Retracted tympanic membrane, dull/opaque TM, loss of light reflex, shortened handle of malleus, air bubble or fluid level.

Where is the oropharynx located?

Between the soft palate and superior border of the epiglottis.

What are the functions of the oropharynx?

Breathing, swallowing, directing food and air to proper pathways.

What structures are found in the oropharynx?

Lingual tonsils, palatine tonsils, superior constrictor muscle.

Where are lingual tonsils located?

At the base of the tongue.

Where are palatine tonsils located?

In the tonsillar fossa, between palatoglossal and palatopharyngeal arches.

What is Waldeyer’s ring?

A ring of lymphoid tissue in the naso- and oropharynx.

What is the function of Waldeyer’s ring?

Defense against inhaled and ingested pathogens.

Why is Waldeyer’s ring located at the junction of respiratory and digestive systems?

It is a prime location for antigen screening and filtering.

Which tonsils form Waldeyer’s ring?

Paired palatine tonsils, adenoid tonsil, lingual tonsils.

Where is the laryngopharynx located?

Between superior border of epiglottis and inferior border of cricoid cartilage (C6).

What is posterior to the laryngopharynx?

The larynx.

How does the laryngopharynx communicate with the larynx?

Via the laryngeal inlet.

What is located lateral to the laryngeal inlet?

Piriform fossae.

What muscles are found in the laryngopharynx?

Middle and inferior pharyngeal constrictors.

What are piriform fossae?

Small recesses on either side of the laryngeal inlet.

What bounds piriform fossae medially?

Aryepiglottic fold.

What bounds piriform fossae laterally?

Thyroid cartilage and thyrohyoid membrane.

Into what two groups are pharyngeal muscles divided?

Circular muscles and Longitudinal muscles.

What is the function of circular pharyngeal muscles?

Serially constrict the pharynx to move bolus downward.

What is the function of longitudinal pharyngeal muscles?

Shorten and widen the pharynx; elevate larynx during swallowing.

What nerve innervates most pharyngeal muscles?

Vagus nerve (CN X).

Which pharyngeal muscle is the exception to vagus innervation?

Stylopharyngeus (innervated by glossopharyngeal nerve CN IX).

List the three circular (constrictor) pharyngeal muscles.

Superior constrictor, Middle constrictor, Inferior constrictor.

What is the common insertion of pharyngeal constrictors?

Pharyngeal raphe.

What is the origin of the superior pharyngeal constrictor?

Pterygomandibular raphe.

What is the insertion of the superior pharyngeal constrictor?

Pharyngeal tubercle of occiput and pharyngeal raphe.

What is the origin of the middle pharyngeal constrictor?

Hyoid bone.

What is the insertion of the middle pharyngeal constrictor?

Pharyngeal raphe.

What are the two parts of the inferior pharyngeal constrictor?

Thyropharyngeus and Cricopharyngeus.

What is the origin of thyropharyngeus?

Thyroid cartilage.

What is the origin of cricopharyngeus?

Cricoid cartilage.

What is the insertion of the inferior pharyngeal constrictor?

Pharyngeal raphe.

List the three longitudinal pharyngeal muscles.

Stylopharyngeus, Palatopharyngeus, Salpingopharyngeus.

What is the origin and innervation of stylopharyngeus?

Origin: styloid process; Innervation: CN IX glossopharyngeal.

What is the origin and innervation of palatopharyngeus?

Origin: hard palate; Innervation: CN X vagus.

What is the origin and innervation of salpingopharyngeus?

Origin: Eustachian tube; Innervation: CN X vagus.

What additional function does salpingopharyngeus serve?

Opens Eustachian tube to equalize middle ear pressure.

During swallowing, what happens to thyropharyngeus and cricopharyngeus?

Thyropharyngeus contracts, cricopharyngeus relaxes.

What clinical condition occurs if thyropharyngeus and cricopharyngeus fail to coordinate?

Zenker’s diverticulum — a midline pharyngeal pouch where food accumulates.

What symptoms does Zenker’s diverticulum cause?

Dysphagia (difficulty swallowing).

What plexus provides motor and sensory innervation to most of the pharynx?

Pharyngeal plexus.

Which nerves contribute to the pharyngeal plexus?

Glossopharyngeal nerve (CN IX), vagus nerve (CN X), external laryngeal nerve, sympathetic fibers from superior cervical ganglion.

What nerve provides sensory innervation to anterior/superior nasopharynx?

Maxillary nerve (CN V2).

What nerve provides sensory innervation to inferior laryngopharynx?

Internal branch of vagus nerve (CN X).

What is the general rule for motor innervation of pharyngeal muscles?

All by vagus (CN X) except stylopharyngeus (CN IX).

Which arteries supply the pharynx?

Ascending pharyngeal artery, branches of facial artery, branches of lingual artery, branches of maxillary artery.

From which main artery do pharyngeal arteries branch?

External carotid artery.

Into what vein does the pharyngeal venous plexus drain?

Internal jugular vein.

Front

Back

What is the larynx also called?

Voice box.

List the three primary functions of the larynx.

Phonation (voice production), cough reflex, protection of the lower respiratory tract.

What is the structural composition of the larynx?

Primarily cartilaginous, with muscles, ligaments, and membranes.

Where is the larynx located in the neck?

Anterior compartment of the neck, suspended from the hyoid bone, spanning C3–C6 vertebral levels.

What is inferior to the larynx?

Trachea.

What is superior to the larynx?

Laryngeal part of the pharynx.

What lies anterior to the larynx?

Infrahyoid muscles and upper part of the epiglottis.

What lies laterally to the larynx?

Lobes of thyroid gland and aryepiglottic folds.

What lies posterior to the larynx?

Oesophagus.

What is the clinical importance of the cricoid cartilage during intubation?

Cricoid pressure (Sellick’s manoeuvre) can be applied to occlude oesophagus and prevent regurgitation of gastric contents.

What type of epithelium lines the interior surface of the larynx?

Pseudostratified ciliated columnar epithelium (respiratory epithelium).

What type of epithelium lines the vocal cords?

Stratified squamous epithelium.

Name the three regions of the larynx.

Supraglottis, Glottis, Subglottis.

What anatomical boundaries define the supraglottis?

From interior surface of epiglottis to vestibular folds (false vocal cords).

What anatomical boundaries define the glottis?

Vocal cords and rima glottidis (the space between vocal cords).

What is the rima glottidis?

Opening between the vocal cords; its size is altered by muscles of phonation.

What anatomical boundaries define the subglottis?

From inferior border of glottis to inferior border of cricoid cartilage.

What are the two groups of laryngeal muscles?

Intrinsic muscles and Extrinsic muscles.

What is the general function of intrinsic laryngeal muscles?

Control vocal cords, voice production, airway protection.

What is the general function of extrinsic laryngeal muscles?

Move the larynx as a whole; assist in swallowing and speech.

What nerve innervates intrinsic laryngeal muscles (general rule)?

Inferior laryngeal nerve (branch of recurrent laryngeal nerve).

Which intrinsic muscle is the exception to the above rule?

Cricothyroid, innervated by external branch of superior laryngeal nerve.

Name the intrinsic muscle that tenses vocal cords.

Cricothyroid.

What is the function of the cricothyroid muscle?

Stretches and tenses vocal ligaments, increases pitch, important in forceful speech (“singer’s muscle”).

What is the origin and insertion of the cricothyroid muscle?

Origin: cricoid cartilage; Insertion: thyroid cartilage.

Name the intrinsic muscle that relaxes vocal cords.

Thyroarytenoid.

What is the function of the thyroarytenoid muscle?

Relaxes vocal ligaments, decreases pitch, produces softer voice.

What is the origin and insertion of thyroarytenoid?

Origin: thyroid cartilage; Insertion: arytenoid cartilage.

What is the innervation of thyroarytenoid?

Inferior laryngeal nerve (branch of recurrent laryngeal nerve).

Name the only muscle that abducts the vocal cords.

Posterior cricoarytenoid.

What is the function of the posterior cricoarytenoid?

Sole abductors of vocal folds, widen rima glottidis, allow breathing.

What is the origin and insertion of posterior cricoarytenoid?

Origin: cricoid cartilage; Insertion: arytenoid cartilage.

What is the innervation of posterior cricoarytenoid?

Inferior laryngeal nerve (branch of recurrent laryngeal nerve).

Name the muscles that adduct the vocal cords.

Lateral cricoarytenoid, Transverse arytenoid, Oblique arytenoid.

What is the function of lateral cricoarytenoid?

Adducts vocal cords, narrows rima glottidis, modulates tone and volume of speech.

What is the origin and insertion of lateral cricoarytenoid?

Origin: cricoid cartilage; Insertion: arytenoid cartilage.

What is the innervation of lateral cricoarytenoid?

Inferior laryngeal nerve.

What is the function of transverse and oblique arytenoids?

Adduct arytenoid cartilages, close posterior rima glottidis, narrow laryngeal inlet.

What is the innervation of arytenoid muscles?

Inferior laryngeal nerve.

What is the function of the vocalis muscle?

Fine-tunes vocal cords, modulates vocal quality.