Session 5: The Pharynx, Larynx and Trachea Flashcards
Where does the pharynx arise from and extend to?
It extends from the base of the skull to the lower border of cricoid cartilage.
What are the three parts of the pharynx and where do they lie?
Nasopharynx - posterior to nasal cavity
Oropharynx - posterior to oral cavity
Laryngopharynx - posterior to larynx
Which muscles comprise the outer layer of the pharynx?
Three circularly disposed muscles:
- Superior constrictor
- Middle constrictor
- Inferior constrictor.
Where does the superior constrictor arise from?
Pterygomandibular raphe (between the pterygoid hamulus and the mandible).
Where does the middle constrictor arise from?
Stylohyoid ligament, and the greater and lesser horns of the hyoid bone.
Where does the inferior constrictor arise from?
The hyoid and cricoid cartilages.
At what point do the constrictor muscles interdigitate?
Posteriorly at the midline pharyngeal raphe.
What is the name given to the cricoid fibres of the inferior constrictor and what function do they have?
Cricopharyngeus, they are sphincteric.
Which muscles comprise the inner layer of the pharynx? (3)
Stylopharyngeus
Palatopharyngeus
Salpingopharyngeus
(three small longitudinally oriented muscles)
Where does stylopharyngeus arise from?
Styloid process
Where does palatopharyngeus arise from?
Palatine aponeurosis
Where does salpingopharyngeus arise from?
Medial end of the cartilagenous auditory tube
What is the action of the muscles of the inner layer of the pharynx?
They pull the larynx and pharynx upwards in swallowing
What are the pharyngeal muscles supplied by?
Pharyngeal plexus (pharyngeal branch of vagus nerve + accessory nerve cranial root + sympathetics)
Which of the pharyngeal muscles receives extra nerve supply and what is this extra nerve supply?
Inferior constrictor receives some additional nerve fibres from the external laryngeal and recurrent laryngeal branches of the vagus.
What supplies sensation to the pharynx?
Branches of the glossopharyngeal nerve (CN IX)
What conveys parasympathetic preganglionic fibres for the pharyngeal glands?
Branches of the glossopharyngeal nerve (CN IX)
What does the glossopharyngeal nerve do in the pharynx?
Sensation + parasympathetic preganglionic fibres
What does Waldeyer’s ring consist of?
4 groups of specialised lymphatic tissue at the entrance of the digestive and respiratory tracts:
- pharyngeal tonsil
- tubal tonsils
- palatine tonsils
- lingual tonsil
Where do the tubal tonsils lie?
At the medial end of the Eustachian/auditory tube
Where do the palatine tonsils lie?
Between the palatoglossal and palatopharyngeal folds
Where does the lingual tonsil lie?
On the posterior surface of the tongue.
What lies between the palatoglossal and palatopharyngeal folds?
The palatine tonsils.
What is the larynx made up of?
- cartilages
- ligaments
- muscles
- mucous membrane lining
What is the function of the larynx?
It guards the entrance to the lower respiratory tract and houses the vocal cords.
What are the cartilages of the larynx? (4)
1) the epiglottis
2) the arytenoid cartilages
3) the cricoid cartilage
4) the thyroid cartilage
Describe the shape and position of the epiglottis.
It is a leaf shaped cartilage lying deep to the body of the hyoid.
The stem of the ‘leaf’ is directed inferiorly, and the tip rises approximately 1cm above the body of the hyoid at the back of the tongue.
What kind of cartilage is the epiglottis made of?
Yellow elastic cartilage which never calcifies.
What are the three longitudinal reflections of mucous membrane between the anterior surface of the epiglottis and and back of the tongue called?
The glosso-epiglottic folds.
What are the depressions on either side of the median glosso-epiglottic fold called?
Valleculae.
What are the depressions inferior to each lateral glosso-epiglottic fold called?
The piriform fossae.
Describe the arytenoid cartilages.
Each arytenoid cartilage resembles a three sided pyramid, with the base inferior and the apex superior.
Where does the vocal ligament attach?
From the vocal processes of the arytenoid cartilages.
What attaches to the muscular process of the arytenoid cartilages?
The posterior and lateral cricoarytenoid muscles.
What attaches to the vocal processes of the arytenoid cartilages?
The vocal ligament (the superior edge of the cricothyroid membrane)
What do the arytenoid cartilages articulate with?
The cricoid cartilage (upper border of cricoid lamina)
What kind of joint is the cricoarytenoid joint?
Synovial
What movements does the cricoaryteniod joint allow?
Rotatory and gliding movements
Describe the cricoid cartilage.
Shaped like a signet ring. Only complete cartilaginous ring in the entire respiratory tract.
What does the cricoid cartilage articulate with?
Inferior horns of the thyroid cartilage
Arytenoid cartilages
Describe the thyroid cartilage.
It lies below the hyoid bone and consists of 2 flat pentagonal plates known as the LAMINAE which are fused anteriorly.
What do the posterior borders of the laminae project upwards and downwards to form?
The superior and inferior horns (cornua).
What is the anatomical name for the ‘Adam’s apple’?
The laryngeal prominence
What is the laryngeal prominence formed by?
The point of junction of the 2 laminae anteriorly.
What does the thyrohyoid membrane lie between?
The superior border of the thyroid cartilage and the superior border of the posterior surface of the hyoid bone.
What are the 3 main membranes of the larynx?
1) Thyrohyoid membrane
2) Quadrangular membrane
3) Cricothyroid membrane
What is the midline thickening of the thyrohyoid membrane known as?
The median thyrohyoid ligament
What are the posterior edges of the thyrohyoid ligament known as?
The lateral thyrohyoid ligaments
Where do the lateral thyrohyoid ligaments extend between?
The superior horn of the thyroid cartilage to the tip of the greater horn of the hyoid bone
Which structures pierce the thyrohyoid ligament?
The superior laryngeal vessels and the internal branch of the superior laryngeal nerve (branch of X)
Where does the quadrangular membrane extend between?
The epiglottis and arytenoid cartilages
What kind of membrane is the quadrangular membrane?
A broad FIBROELASTIC membrane
What is the upper margin of the quadrangular membrane known as?
The aryepiglottic fold
What is the lower margin of the quadrangular membrane known as?
The vestibular fold/false cord.
What are other names for the cricothyroid membrane?
The conus elasticus or cricovocal membrane
What does the cricothyroid membrane lie between?
The superior rim of the cricoid arch and the vocal processes of the arytenoids to the inner surface of the thyroid angle.
What is the thickening of the most anterior fibres of the cricothyroid membrane known as?
The median cricothyroid ligament
What are the vocal folds comprised of?
The vocal ligaments and their overlying epithelium
What is the laryngeal inlet?
The communication of the larynx with the pharynx
What are the boundaries of the laryngeal inlet?
Epiglottis anteriorly
Arytenoid cartilages posteriorly
Aryepiglottic folds laterally
What is the part of the interior of the larynx that lies between the vocal folds known as?
The rima glottidis
What do the vocal folds form?
The glottis
What does the supraglottic part of the laryngeal cavity consist of?
The vestibule
What does the vestibule extend between?
The laryngeal opening –> vestibular folds.
What is the saccule of the larynx?
A small herniation of mucous membrane anteriorly within the ventricle between the vestibular and vocal folds.
It contains mucous glands for lubrication of the vocal folds.
Describe the infraglottic part of the interior of the larynx.
It is narrow at the vocal folds, and widens towards the cricoid cartilage. It is continuous inferiorly with the trachea.
What type of epithelium line the vocal cords and epiglottis.
Non-keratinising stratified squamous epithelium (thickened on the cords because of greater wear and tear)
What type of epthelium are the parts of the larynx which aren’t the vocal folds and epiglottis lined by?
Respiratory (pseudostratified ciliated columnar) epithelium.
Name all the intrinsic muscles of the larynx. (9)
Aryepiglotticus Thyroepiglotticus Oblique arytenoids Posterior cricoarytenoid Lateral arytenoids Interarytenoids Cricothyroid Thyroarytenoid (+vocalis)
Which muscle closes the inlet of the larynx?
Aryepiglotticus
Which muscle opens the inlet of the larynx?
Thyroepiglotticus
Where does the aryepiglotticus muscle run?
In the aryepiglottic folds (it is an extension of the oblique arytenoids)
At which joints are adduction and abduction of the vocal folds produced.
Cricoarytenoid joints
What are the origin of the posterior cricoarytenoid muscles?
The posterior surfaces of the cricoid lamina.
What is the insertion of the posterior cricoarytenoid muscle?
The muscular process of the ipsilateral arytenoid
What is the action of the posterior cricoarytenoid muscle?
It is the sole abductor of the vocal cords
It rotates the muscular processes posterolaterally so that the vocal processes are separated. It also slides the arytenoids downwards, causing them to move apart.
What is the action of the lateral arytenoids and the interarytenoids?
Adduction of the vocal cords
What is the action of the cricothyroid muscle?
Tightens the vocal cords by lengthening them. This raises the pitch.
Causes cricoid cartilage to tilt upwards and backwards around a transverse axis, with rotation at the cricothyroid joints.
What is the action of the thyroarytenoid muscle?
Adducts and reduces tension in the vocal folds
What is the medial part of the thyroarytenoid known as?
Vocalis
What is the action of vocalis?
Reduces the length and alters the thickness of the vocal cords
Where does vocalis lie?
Within the vocal folds
Describe the position of the vocal cords in breathing, speaking, phonation and coughing
Held open for breathing
Closed intermittently for speaking
Change of length for phonation
Tightly opposed in coughing
What is sensation to the mucous membrane above the vocal folds and to the vocal folds themselves mediated by?
The internal branch of the superior laryngeal nerve (CN X)
What is sensation below the vocal folds mediated by?
Recurrent laryngeal nerve (CN X)
What are the intrinsic muscles of the larynx supplied by? What is the exception?
They are all supplied by the recurrent laryngeal nerve (CN X) except cricothyroid which is supplied by the external branch of the superior laryngeal nerve (CN X)
Describe the trachea.
A midline structure extending from the cricoid cartilage into the thorax, where it divides into right and left main bronchi.
Describe the tracheal rings.
C-shaped cartilages embedded in the the connective tissue wall of the trachea, that are deficient posteriorly.
What muscles are the openings of the tracheal rings spanned by?
Trachealis muscle
What type of muscle is the trachealis muscle?
Smooth muscle
What is the action of the trachealis muscle?
Reducing the diameter of the trachea, thereby diminishing the dead space during quiet respiration.
Where does the oesophagus lie in relation to the trachea?
Posteriorly
Describe the interaction between the oesophagus and trachea during swallowing
The oesophagus can bulge into the soft trachealis during swallowing
Describe the course of the recurrent laryngeal nerves in relation to the oesophagus and trachea.
They ascend on each side between the oesophagus and trachea.
What is the relation of the inferior thyroid veins to the trachea?
The inferior thyroid veins cross the trachea anteriorly as they descend to drain into the left brachiocephalic vein
What is the lining of the trachea?
Ciliated, pseudostratified columnar epithelium of the upper respiratory tract
What is the keel of cartilage formed at the bifurcation of the trachea known as?
The carina
What is special about the carina?
The mucosa is especially sensitive to irritation
What is the blood supply of the trachea?
Branches of the inferior thyroid and bronchial arteries.
What is the lymphatic drainage of the trachea?
Tracheobronchial nodes from its lower part
Paratracheal and deep cervical nodes from its upper part.
What is the nerve supply of the trachea?
Sensory and secretomotor from the recurrent laryngeal nerves (CN X)
Sympathetic supply from the thoracic sympathetic chain.
What is the origin of cricothyroid?
The arch of the cricoid.
What is the insertion of cricothyroid?
The lower lamina and inferior horn of the thyroid cartilage.