Nose and Larynx Development Flashcards
What are the structures of the external nose?
- nasal aperture (maxilla and nasal bones)
- cartilages (lateral, alar and septal), ala nasi
What do the maxilla and palatine bones form?
nasal cavity walls and hard plate
What does the ethmoid bone form?
the roof and part of the septum
What are ethmoid sinuses?
air pockets in the ethmoid bone
Perpendicular plate
part of the septum
cribriform plate
holes for the passage of olfactory nerves
crista galli
attachment for dura
What makes up the nasal septum?
perpendicular plate of ethmoid and vomer bones with a septal cartilage
- vomer spans the sphenoid and hard palate
What problems occur with a deviated septum?
obstruction to nasal passage, difficulty breathing, snoring, sleep apnea, sinus infections, headaches, nosebleeds
When can a perforated septum occur?
Long term usage of cocaine nasal sprays, chronic epistaxis, aggressive nose picking, chromium toxicity
What are the conchae?
curved bones covered with mucus that increase the surface area to heat and filter the air inhaled through the nose
–> turbulence is caused to maximize mucosal contact with inspired air
What are the three types of conchae?
Inferior: largest, separate bone
Middle: projection of the maxilla
Superior: variable concha extending from maxilla anterior to the sphenoid
What is the meatus?
The space between a concha and the lateral wall
superior, middle and inferior meatuses
What are the paranasal sinuses?
- sphenoid
- frontal
- maxillary
- ethmoid
Sphenoid sinus
cavity in the sphenoid, opens out near superior concha
frontal sinus
cavity in the frontal bone deep to the glabella and superior orbital ridge, opens into middle meatus
maxillary sinus
cavity in maxilla that opens from upper sinus into middle meatus
–> proximity to teeth allows intercommunication of infection
ethmoid sinus
cluster of air cells in ethmoid bone that open into middle meatus
Where does mucus mostly drain to?
mostly the middle meatus but also nasal cavity
What is the inferior meatus the site of?
the opening of the nasolacrimal duct, which drains tears from the eyes
What is the lamina propria?
loose CT deep to the epithelium of mucus membranes, containing blood vessels, lymphatics, nerves, and usual loose CT cells
what is the venous plexus of the conchae?
- erectile tissues; the increased blood flow within these tissues can cause nasal congestion
What is the mucosal reflex?
Temperature, humidity, air flow and irritants can stimulate sensory neurons of the trigeminal nerve (CN V), eliciting secretion of mucus or dilation of venous plexus by parasympathetic nerves from the pterygopalatine ganglion.
What is the Kiesselbach’s plexus?
in the anteroinferior part of the nasal septum is the anastomoses of the terminal branches of the sphenopalanite, ethmoidal, and superior labial arteries
- 90% of nosebleeds happen here
What is the significance of the trigeminal nerve? (CN V)
- sensory nerve to the face
- divides into three parts: ophthalmic V1, maxillary V2, and mandibular V3
Where do the ophthalmic branches of CN V go?
descend from orbital cavity to innervate anterior nasal cavity, frontal sinus, and anterior ethmoidal sinuses
Where do the maxillary branches of the CN V go?
enter nasal cavity through sphenopalatine foramen and innervate conchae, septum, and inferior surface of the hard palate.
Explain “hay fever ganglion”
pterygopalatine ganglion receives preganglionic neurons from CN VII
The postganglionic neurons project along V1 and V2 (concha, sinuses, septum innervation)
–>produces venodilation and secretion of mucus from nasal and palantine glands, as well as tears from the lacrimal duct
What are olfactory receptors?
- bipolar neurons within olfactory epithelium
- life span of 2-4 months (replaced by basal cells)
What have receptors for specific odorants?
sensory process cilia that project into the mucus layer
What do Bowman’s glands do?
secrete mucus lipids that assist in transporting odorant molecules to the cilia
What is the larynx?
Modified tracheal cartilages controlling air intake and sound production
What is the thyroid cartilage?
Lamina with thyroid notch; superior and inferior horns; laryngeal prominence (Adam’s Apple)
What is the cricoid cartilage?
A full ring with a tall posterior arch
Arytenoid cartilages?
the swivels atop cricoid posterior arch
Epiglottis?
attaches to the inner surface of the thyroid cartilage
Thyroid membrane?
suspends larynx from hyoid bone
Conus elasticus?
CT sheet from arytenoid and cricoid cartilage to the thyroid cartilage
Glottis?
(rima glottidis) the space between vocal cords
What makes the vocal cords?
the upper free edges of the conus elasticus
Epiglottis?
the cartilage hinged on the interior of the thyroid cartilage, that opens and closes the laryngeal inlet
Quadrangular membrane?
CT sheet from arytenoid cartilage to epiglottis
vestibular fold?
lower free edge of the quadrangular membrane
ventricle of the larynx
cavity between vestibular and vocal folds
What happens to the epiglottis during swallowing?
epiglottis is pulled down by muscles in the quadrangular membrane (areypiglottic, thyropiglottic, oblique arytenoid) and closes the laryngeal inlet
What happens to the epiglottis during breathing or speaking?
epiglottis is pulled up by intrinsic elasticity and opens the inlet
How do vocal cords open and close?
by intrinsic muscles that separate or converge with the arytenoid cartilages
- open during inhalation
- closed during speaking or singing
What muscles open the vocal cords?
Posterior criocarytenoid
- opens vocal cords
- abduct and laterally rotate arytenoids
What muscles close the vocal cords?
Lateral criocarytenoid, transverse and oblique arytenoid
- close vocal cords
- adduct and medially rotate arytenoids
How is sound created?
What is a mucosal wave?
- bursts of air passing between nearly closed vocal folds
- vocal folds separating and then closing to create sound
How is pitch altered?
by changing the tension of the vocal folds
How is vocal fold tension increased?
- cricothyroid muscle tilts the thyroid cartilage (tightens and lengthens the folds)
- Thyroarytenoid and vocalis muscles on external of conus elasticus contract conus elasticus to shorten the folds
What is sexual dimorphism?
When testosterone increases the length of the thyroid cartilages and vocal cords, giving off a deeper tone of voice
What innervates the larynx?
the vagus nerve splits into:
- superior laryngeal nerve (motor to cricothyroid and sensory to mucosa)
- recurrent laryngeal nerve (motor to all intrinsic larynx, sensory to mucosa)
