Interval 14: Larynx Flashcards
Vestibule of the larynx begins at the _____________ and extends to the ___________.
- larynx behind the epiglottis
- vestibular folds
What is the ventricle?
-narrow ellipse-shaped space situated between the vestibular folds and vocal folds
What is the name of the space inferior to the vocal folds? What is the rima glottis and the glottis?
- infraglottic space
- rima glottidis is the opening between the vocal folds
- glottis consists of the rima glottidis and vocal folds
Name the cartilages of the larynx and what is created at their articulation.
- cricoid
- thyroid
- pair of arytenoid cartilages
- synovial joints
Where can one find the arytenoid cartilages and contain what 2 kinds of processes?
- posterosuperior aspect of the cricoid cartilage
- muscular and vocal processes
Where do the vocal ligaments extend from and to? What is it covered by?
- extend anteriorly from the vocal processes of the arytenoids and attach to the posterior aspect of the thyroid cartilage
- covered by thyroarytenoid muscle, which is then covered by mucosa
- *these 3 structures form the vocal cord/fold
What is the only cartilage of the larynx that completely encircles the airway?
-cricoid cartilage
Full adduction of the vocal ligaments causes the vocal folds to meet in the midline, closing the glottis during what 3 activities?
- swallowing
- defecation
- urination
Functions and mechanisms of the thyroarytenoid and cricothyroid muscles
- thyroidarytenoid: relax vocal ligaments by pulling the arytenoid cartilages closer to the thyroid cartilage
- cricothyroid muscles tense the vocal ligaments by rocking the superior aspect of the thyroid anteriorly at its articulation with the cricoid, increasing the distance between these 2 cartilages
Where is the vocalis muscle and what does it do?
-forms the medial aspect of the thyroarytenoid and adjusts the tension in small segments of the vocal ligament
All of the muscles of the larynx are innervated by what nerve? Any exceptions?
- inferior laryngeal nerve (branch of recurrent laryngeal nerve of the vagus)
- except for cricothyroid muscle which is innervated by external branch of the superior laryngeal nerve
Describe the innervation of mucosa above and below the vocal folds
- internal branch of superior laryngeal nerve innervates above the folds
- inferior laryngeal nerve innervates mucosa below the vocal folds
Describe what happens in the superior laryngeal nerve lesions.
-Superior: largely asymptomatic because its fibers are mainly sensory. If the motor fibers of the external branch leading to the cricothyroid are affected, patient may experience mild hoarseness and a slight decrease in vocal strength, with tendency to produce monotonous speech
How can recurrent laryngeal nerves be lesioned? Which one is more commonly lesioned? What is the result of a lesion?
- both susceptible to injury in surgical procedures involving the thyroid gland
- left is injured more commonly because of its course through the mediastinum (aortic aneurysm)
- results in fixed vocal cord and transient hoarseness
The nasal cavity begins at the ___________ and communicated posteriorly with what?
- external nares
- nasopharynx through the choanae
The nasal septum divides the nasal cavity in the midline and the lateral wall of the nasal cavity contains 3 scroll-like bones which form what?
- superior
- middle
- inferior conchae
Where does the posterior ethmoidal cells drain?
-superior meatus
What drains into the middle meatus?
-anterior and middle ethmoid air cells, frontal sinus, maxillary sinus
What drains into the inferior meatus?
-opening of the nasolacrimal duct which drains tears from the lacrimal sac in the medial part of the orbit
Where does the sphenoid sinus drain?
-sphenoethmoidal recess
What is the largest paranasal sinus and where can it be found?
- maxillary
- between the orbit and the alveolar process of the maxilla, which contains the maxillary teeth
Why is the maxillary sinus a common site of sinusitis?
-it have poor gravitational drainage because the ostium of the sinus is situated on the superior part of the medial wall of the sinus
What innervates the mucosa of the nasal cavity?
- olfactory nerve (CN I)
- V1 ophthalmic division
- V2 maxillary division
What may happen in an olfactory nerve lesion? How can this occur and what else is a potential comorbitity of this injury?
- may alter (hyposmia) or distort (dysosmia) the sense of smell or result is complete loss (anosmia)
- may be due to fracture of the cribiform plate, which damages the primary olfactory neurons
- fracture of cribiform plate may also tear the meninges of the olfactory bulb and result in CSF rhinorrhea, a discharge of CSF from nostrils
Olfactory nerves supply sense of smell to the mucosa of the nasal cavity, but what do the V1 and V2 divisions of the trigeminal nerve do?
- V1 innervates small part of the lateral nasal wall
- V2 supply most of the lateral nasal wall and septum
What innervates the mucous glands of the nasal cavity?
-preganglionic parasympathetics in the facial nerve and by postganglionic parasympathetic axons from the pterygopalatine ganglion
What is the blood supply of the nasal cavity? What do branches of these 3 vessel contribute to?
- maxillary, ophthalmic, and facial arteries
- Kiesselbach’s plexus on anterior part of nasal septum which helps regulate thermal environment of inspired air
What is epistaxis and what usually causes it?
-bleeding from the nose, which usually results from laceration of the arteries of Kiesselbach’s plexus
What muscle closes the anterior opening of the vestibule?
-obicularis oris
The cheeks form the lateral walls of the vestibule and contain the buccinator muscles which act to do what?
-compress the cheek against the molar teeth to keep food between the teeth during chewing
What line separates the anterior 2/3 of the tongue from the posterior 1/3 of the tongue? What is the apex called?
- sulcus terminalis
- foramen cecum
What muscle and arch demarcate the posterolateral boundary between the oral cavity and oropharynx?
-palatoglossal arches and palatoglossus muscles
Describe the sensory innervation of the anterior 2/3 of your tongue and the posterior 1/3 of the tongue. Also describe the innervation at the root of the tongue (in front of the epiglottis)
- dual sensory innervation for anterior 2/3
- general sensations are carried by lingual nerve of CN V3 and taste is carried by the chorda tympani of the facial nerve (CN VII)
- both taste and general sensation from the posterior 1/3 of the tongue are carried by the lingual branch of the glossopharyngeal nerve (CN IX)
- root: internal laryngeal branch of the vagus nerve (CN X)
The inferior surface of the tongue contains the openings of the ducts of which glands? What is the innervation of these glands?
- sublingual and submandibular
- innervated by preganglionic parasympathetic axons of CN VII and by postganglionic parasympathetic axons from the submandibular ganglion
The tongue consists of intrinsic muscles and extrinsic muscles. Describe the functions of these muscles and name the extrinsic muscles. Also give the innervation.
- intrinsic: alter the tongue’s shape
- 4 pairs of extrinsic muscles: genioglossus, styloglossus, hyoglossus, and palatoglossus; act to move the tongue
- all of the muscles of the tongue except the palatoglossus are innervated by the hypoglossal nerve (CN XII) while the palatoglossus is innervated by the vagus nerve (CN X)
What type of axon fibers does the hypoglossal nerve contain? Where does it exit the cranial cavity? How does it enter the floor of the mouth (between what 2 muscles?)
- skeletal motor axons
- hypoglossal canal
- hyoglossus and mylohyoid muscles
What do patients present with if they have a hypoglossal nerve lesion?
- deviation of the tongue towards the side of the injured nerve on protrusion
- may experience dysarthria and difficulty moving a bolus of food from the oral cavity into the oropharynx
What innervates the mucosa of the hard and soft palate? What nerve does taste from the soft palate enter the CNS?
- palatine branches of maxillary nerve (CN V2)
- facial nerve (CN VII)
Which gland can be found to partially cover the trachea?
-thyroid gland
What is the foramen cecum a remnant of?
-remnant of site where thyroglossal duct descended
The hard palate is anterior and contains what foramina? What traverses these foramina?
- incisive foramina, greater and lesser palatine foramina
- transmit branches of maxillary division of CN V and branches of maxillary artery that supply the oral cavity
What does the incisive foramine transmit? How about the greater and lesser palatine foramen?
- nasopalatine nerve and artery
- greater: greater palatine nerve and artery
- lesser: lesser palatine nerve and artery
The core of the soft palate is formed by a ____________. Name the 4 pairs of skeletal muscles that attach to this and act on the soft palate. Also give the innervation of these muscles.
- membranous palatine aponeurosis
- Palatopharyngeus, palatoglottus, levator veli palatini, tensor veli palatini
- All except for tensor veli palatini are innervated by pharyngeal branches of the vagus nerve (CN X). Tensory is by CN V3
The palate is covered by mucosa containing glands and taste receptors. What innervates the mucosa, glands, and taste fibers?
- Hard palate mucosa: nasopalatine and greater palatine nerves of maxillary division V2
- Soft palate: less palatine nerves of V2
- Glands: postganglionic parasympathetic axons from cell bodies in the pterygopalatine ganglion
- Taste fibers: course with less palatine nerves of V2, pass through pterygopalatine fossa and follow nerve of the pterygoid canal and greater petrosal nerve of CN VII back to cell bodies in geniculate ganglion
Foreign bodies entering the pharynx may become lodged where?
- piriform recess
- small, pear-shaped depression of the laryngopharyngeal cavity on each side of the inlet of the larynx
What innervates the mucous membrane of the piriform recess? What membrane does this nerve pierce through?
- internal laryngeal nerve, a branch of the superior laryngeal nerve from vagus
- pierces through thyrohyoid membrane
