HNS Anatomy 5 -Upper Airway

Question 1

What is the principal function of the larynx?

Answer 1

• To prevent food entering the airway (valve)

- Sound producer

Question 2

What are the nasal cavities?

Answer 2

• Upper part of the respiratory tract
• Anterior and posterior regions
• Contain conchae
• Warm and humidify air, help to trap pathogens. Important drainage route for the sinuses
• Meatuses inbetween the conchae

Question 3

List the bones that make up the nasal cavity

Answer 3

• Major and minor alar cartilage
• Nasal bone
• Maxilla
• Lacrimal bone
• Superior and middle nasal concha
• Uncinate process of ethmoid
• Inferior concha
• Meal pterygoid plate of sphenoid bone
• Palatine bone

Question 4

Describe the innervation of the nasal cavity

Answer 4

• Main sensory nerve is trigeminal nerve (opthalmic anterior region, and maxillary posterior region)
• Olfactory nerve innervates olfaction
• Facial nerve supplies glands
• Sympathetic nerves supply the vascular smooth muscle

Question 5

Where does the blood supply of the nasal cavity come from?

Answer 5

• Internal carotid and external carotid artery
• Venous drainage - the superior veins drain into the cavernous sinus in the cranial cavity, while there is also drainage to the facial vein and pterygoid plexus

Question 6

What is the function of the paranasal sinuses?

Answer 6

• Provides a crumple zone to protect head
• Help produce resonant sounds and project the voice
• Makes the skull lighter

Question 7

What supplies the paranasal sinuses?

Answer 7

• All supplied by the trigeminal nerve
• Frontal sinus opthalmic
• Ethmoid air cells opthalmic and maxillary
• Sphenoid sinuses opthalmic and maxillary
• Maxillary sinus maxillary

Question 8

Describe the sinus drainage

Answer 8

• Middle ethmoidal cells drain into ethmoidal bulla
• Posterior ethmoidal cells into the lateral wall of the superior meatus
• Sphenoidal sinus drains into spheno-ethmoidal recess
• Semilunar hiatus has opening of maxillary sinus and infundibulum opening of frontonasal duct

Question 9

What is the larynx composed of?

Answer 9

• Cartilages
• Membrane
• Muscles

Question 10

What do the arytenoid cartilages do?

Answer 10

They swivel to open and close the airways

Question 11

What is the effect of the thyroid cartilage moving?

Answer 11

It increases and decreases tension on the vocal cords

Question 12

What are the vocal folds?

Answer 12

• Mucosal tissue draped over the larynx, which forms laryngeal vesicles
• Open during speech, and close while eating to prevent food entering the trachea
• Made of a false and true vocal fold

Question 13

What is the opening between the vocal cords?

Answer 13

Rima glottis

Question 14

List the intrinsic muscles of the larynx

Answer 14

• Cricothyroid muscle (when these muscles shorten, the thyroid cartilage drops forwards)
  Essential to adduct and abduct the arytenoid
• Transverse arytenoid
• Vocalis put pressure on the vocal folds, antagonist to the cricothyroid muscle
• Oblique artytenoid, posterior cricoarytenoid, and transverse arytenoid open the vocal folds
• Lateral cricoarytenoid (will spin the arytenoid cartilage around)

Question 15

What is the function of the intrinsic muscles of the larynx?

Answer 15

Opening and closing the airway, and adjusting tension on the vocal folds for phonation to occur

Question 16

Which nerves supply the larynx?

Answer 16

• Superior laryngeal nerve, which splits to form the internal (more important) and external laryngeal nerve
• Recurrent laryngeal nerve

Question 17

What are the results of a lesion in the vagus nerve on the larynx?

Answer 17

Complete paralysis

Question 18

What is the result of a lesion in the internal branch of the superior laryngeal nerve?

Answer 18

Loss of sensation above the vocal folds (damages cough reflex)

Question 19

What is the result of a lesion in the external branch of the superior laryngeal nerve?

Answer 19

Paralysis of the cricothyroid

Question 20

What is the result of a lesion in the recurrent laryngeal nerve?

Answer 20

Paralysis of all muscles of the larynx except the cricothyroid muscle, and loss of sensation below the vocal folds

Question 21

Compare the pathway of the superior laryngeal nerve to that of the recurrent laryngeal nerve

Answer 21

• Superior laryngeal nerve (both the internal and external) travel with the superior thyroid artery
• Recurrent laryngeal nerve travels with the inferior thyroid artery

Question 22

List the protective mechanisms for the airway

Answer 22

• Swallowing
• Gag reflex
• Sneezing
• Coughing

Question 23

Describe the difference between coughing and sneezign

Answer 23

• When the soft palate is raised, there will be coughing, when the soft palate is depressed against the tongue this will cause sneezing
• Coughing uses vagus afferents
• Sneezing uses maxillary afferents
• Soft palate depression uses vagus nerve (palatopharyngeus and palatoglossus)
• Soft palate raising uses levator veli palatini (vagus), tensor veli palatini (mandibular) superior constrictor (vagus))

Question 24

How do you intubate a patient?

Answer 24

• Chin lift/jaw thrust
• Oropharyngeal or nasaoharyngeal airway
• Endotracheal intubtion
• Cricothyroidotomy
• Tracheostomy

Question 25

What is the facial nerve motor to?

Answer 25

- Muscles of facial expression - Stapedius - Digastric (posterior belly) - Stylohyoid

Question 26

What is the facial nerve sensory to?

Answer 26

- Anterior 2/3 of the tongue taste - Parasympathetic to lacrimal glands, mucous glands of nasal cavity, hard and soft palats, sublinguial and submandibular glands - General sensation from external acoustic meatus and deeper parts of the auricle

Question 27

Where does the facial nerve emerge?

Answer 27

Stylomastoid foramen and then through the internal acoustic meatus

Question 28

Compare the effect of contraction of the posterior cricoarytenoid muscle to contraction of the lateral cricoarytenoid muscle.

Answer 28

- The posterior cricoarytenoid muscle rotates the arytenoid cartilage, and abducts the vocal processes to open the rima glottidis - The lateral cricoarytenoid muscle also rotates the arytenoid muscle, but this time it is to adduct the vocal processes and close the rima glottidis

Question 29

What does the superior laryngeal nerve supply?

Answer 29

- Internal branch is sensory to the larynx and hypopharynx | - External branch is motor to the cricothyroid muscle

Question 30

What does the recurrent laryngeal nerve supply?

Answer 30

- All laryngeal muscles except the cricothyroid muscle (posterior cricoarytenoid, lateral cricoarytenoid, thyroarytenoid) - Sensation below the vocal cords - Oesophagus

Question 31

Describe the pathway of the recurrent laryngeal nerves

Answer 31

- Right recurrent laryngeal nerve hooks around the right subclavian artery - Left recurrent laryngeal nerve hooks around the aortic arch (ligamentum arteriosum)

Question 32

What is the auditory tube? What is its importance?

Answer 32

- Links the nasopharynx to the middle ear | - Makes the pressure within the middle ear equal with the air pressure outside the body

Question 33

What is the relevance of the relationship between the roots of some teeth and the maxillary sinus?

Answer 33

- Roots of some upper teeth can project into the maxillary sinus - This can result in infection of the upper molars and premolars spreading to the maxillary sinus (causing sinusitis)

Question 34

Compare a cricothyroidotomy to a tracheotomy

Answer 34

- Cricothyroidotomy is used in emergency situations, it involves piercing the median cricothyroid ligament to access the airways - Tracheotomy is insertion of a tube into the trachea between the 3rd and 4th ring of cartilage, used more permanently