First Aid, Chapter 5, Anatomy, Physiology, and Pathology, Upper Airway (Nose, Sinuses, and Middle Ear)

Question 1

What are conchae? What covers conchae?

Answer 1

• The lateral walls of nose are rigid bony structures with bony conchae that protrude into the nasal cavity (Figures 5-4A and 5-4B, respectively).
• Conchae are covered by an erectile mucosa with a rich blood supply, forming turbinates.

Question 2

What are concha bullosa?

Answer 2

The concha bullosa is the pneumatization of the concha and is one of the most common variations of the sinonasal anatomy (Figure 5-5).

Question 3

What are the components of the nasal septum? What can cause deviation? What can cause facial pain syndromes if its present on the nasal septum?

Answer 3

The nasal septum has bony and cartilaginous components. Trauma or other factors can cause septal deviation, leading to blockage and sometimes formation of nasal spurs that can cause facial pain syndromes.

Question 4

What is the narrowest part of the whole airway? Where is it located?

Answer 4

The nasal valve, or internal ostium, is the narrowest point of the whole airway. It is located at the junction between the nasal vestibule and the main nasal cavity, just anterior to the tip of the inferior turbinate.

Question 5

What role does airflow play in the nose? What causes turbulance?

Answer 5

The turbinates increase the surface area of the nasal cavity, thereby providing turbulence to the airflow. Airflow is essential for the humidification and thermal regulation of all inspired air, not just the portion in contact with nasal mucosa.

Question 6

What controls nasal airway resistance?

Answer 6

Nasal airway resistance is regulated at the level of the nasal valve, which is controlled by the swelling of the inferior turbinate. Dilator naris muscles voluntarily increase patency of the nasal vestibule.

Question 7

What kind of epithelium is found in the nasal vestibule? Nasopharynx? Trachea? Respiratory area of the nasal cavity? Olfactory area?

Answer 7

The nasal epithelium is the stratified squamous membranous tissue in the nasal vestibule and nasopharynx.

• Pseudostratified ciliated columnar epithelia are found in the lines of the trachea and the respiratory area of the nasal cavity.
• Specialized olfactory epithelium is found in the olfactory area.

Question 8

What is found in the submucosa of respiratory epithelium?

Answer 8

Submucosa contains serous and mucous glands, fibroblasts, inflammatory cells, nerves, and blood vessels. Smooth muscle is not present in the submucosa.

Question 9

How much mucus does the nose make every day?

Answer 9

a quart of thin mucus

Question 10

What does nasal fluid contain?

Answer 10

Nasal fluid contains immunoglobulins (IgA) and other serum proteins, enzymes, antioxidants (glutathione, uric acid and vitamin C), and cellular mediators.

Question 11

Where is the innervation located in nasal epithelium? What kind of innervation?

Answer 11

Seromucous glands in nasal epithelium have parasympathetic cholinergic innervations, causing watery nasal secretion; hence, an anticholinergic is used to decrease rhinorrhea.

Question 12

How can mucociliary clearance be tested?

Answer 12

Mucociliary clearance can be tested by placing saccharin on the anterior end of an inferior turbinate and timing the onset of sweet taste in the mouth. (The normal range is 7–11 minutes.)

Question 13

Describe primary ciliary dyskinesia?

Answer 13

Primary ciliary dyskinesia (PCD) is a disease that results in decreased mucociliary clearance. PCD is a rare autosomal recessive genetic disorder that causes a defect in the function of cilia lining in the respiratory tract, fallopian tubes, and flagella of sperm. This causes reduced/absent mucous clearing from the lungs, leading to chronic recurrent respiratory infections (sinusitis, bronchitis, pneumonia, otits media), bronchiectasis, infertility, and in some cases hearing loss.

Question 14

What syndrome is characterized by ciliary dyskinesia, situs inversus, bronchiectasis, and chronic sinusitis?

Answer 14

Kartagener’s syndrome—50% of individuals with PCD have Kartagener’s syndrome

Question 15

Describe resistance vessels, capacitance vessels, and subepithelial capillaries.

Answer 15

• Resistance vessels (i.e., small arteries and arterioles) control nasal blood flow via local mediators and sympathetic stimulation, which causes vasoconstriction.
• Capacitance vessels, or venous erectile tissue located primarily over inferior and middle turbinates and nasal septum, have sympathetic adrenergic innervation, which controls nasal airway resistance.
• Subepithelial capillaries and veins are fenestrated, leading to the high permeability-increased absorption of intranasal drugs.

Question 16

What is the nasal cycle and why does it occur?

Answer 16

The nasal airflow is usually asymmetrical due to the “nasal cycle” of alternating congestion and decongestion of nasal venous sinuses. About 80% of the population exhibits a nasal cycle, with reciprocal changes in airflow over time as controlled by the sympathetic nervous system.

Question 17

What nerve allows for sense of smell?

Answer 17

Olfactory nerve

Question 18

What nerves are responsible for sensory innervation of the nose?

Answer 18

Ophthalmic and maxillary branches of the trigeminal nerve are responsible for sensory innervation.

Question 19

What parts of the nasal tissue layers do parasympathetic and sympthatic nerves provide innervation to?

Answer 19

• Parasympathetic innervation to nasal glands controls glandular secretion and is mediated primarily by acetylcholine.
• Sympathetic innervation of arterial vessels controls nasal blood flow (i.e., nasal patency), and venous erectile tissue controls airflow resistance.

Question 20

What causes normal nasal airflow asymmetry?

Answer 20

With nasal airflow there is normal asymmetry of nasal mucosal swelling, in which one side of the nose is swollen as a result of dilatation of venous sinuses in the inferior turbinate and the other side is open.

Question 21

How does symphathetic activity affect nasal airflow and what is the mechanism?

Answer 21

Mechanims: Vasoconstriction

Effect on airflow: Increased flow

Question 22

How does posture (sitting to supine) affect nasal airflow and what is the mechanism?

Answer 22

Mechanism: increased venous filling

Effect on airflow: decreased flow

Question 23

How does the lateral recumbent position affect nasal airflow and via what mechanim?

Answer 23

Mechanism: reflex vasomotor activity

Effect on airflow: Increased flow in upper nostril Decreased flow in lower nostril

Question 24

How does mild to moderate exercise affect nasal airflow and via what mechansim?

Answer 24

Mechanism: Increased sympathetic activity

Effect on airflow: Increased flow

Question 25

How does an increase in blood carbon dioxide levels affect nasal airflow and via what mechanism?

Answer 25

Mechanism: Sympathetic supply to blood vessels

Effect on airflow: Increased flow

Question 26

How does epinephrine affect nasal airflow and via what mechanism?

Answer 26

Mechanism: vasoconstriction

Effect on airflow: Increased flow

Question 27

How does puberty, menstruation, and pregnancy affect nasal airflow and via what mechanism?

Answer 27

Mechanism: vasodilation and glandular hypersecretion

Effect on airflow: decreased flow

Question 28

What is the mnemonic for where sinuses drain?

Answer 28

Sinuses listen to the following radio channels: FM AM PS SS Frontal sinus, Maxillary sinus, and Anterior ethmoids all drain into Middle meatus. Posterior ethmoids and Sphenoid sinus drain into Sphenoethmoidal recess above Superior turbinate.

Question 29

How do sinuses develop in the embryo? When do they become well developed? What are they lined by?

Answer 29

Paranasal sinuses develop in the embryo as an excavation of bone by air-filled sacs (pneumatic diverticula) from the nasal cavity. They are rudimentary at birth and slowly grow to be well developed by about 8 years of age. They are lined with ciliated pseudostratified columnar epithelia with goblet cells, which secrete mucus.

Question 30

How large are ostia of sinuses?

Answer 30

Ostia are 2–6 mm wide sinus openings into the nose.

Question 31

What are the functions of sinuses?

Answer 31

The function of the sinuses is debatable. The following have been proposed:

• Decreasing the relative weight of the front of the skull
• Increasing resonance of the voice
• Insulating intracranial structures
• Humidifying and heating of inhaled air
• Source of nitric oxide.

Question 32

Which paranasal sinus cavity is absent at birth?

Answer 32

Frontal sinus. It is generally well developed by 7–8 years of age and reaches full size after puberty.

Question 33

Describe what drains into the inferior meatus, middle meatus, and superior turbinates?

Answer 33

• Inferior meatus: Opening of nasolacrimal duct
• Middle meatus: Frontal, maxillary and anterior ethmoids open into hiatus semilunaris
• Superior turbinate: Has sphenoethmoidal recess above it where postethmoids and sphenoid sinuses drain

Question 34

Where is the tympanic cavity or middle ear located?

Answer 34

The tympanic cavity, or middle ear, is an irregular space in the petrous part of the temporal bone. It is lined by mucous membrane and filled with air that reaches it from the nasopharynx via the eustachian tube (ET), which is also known as either the auditory or pharyngotympanic tube.

Question 35

What is the tympanic membrane innervated by? What does it perceive?

Answer 35

The tympanic membrane is innervated by the auriculotemporal nerve, which can perceive only pain.

Question 36

What lies posterior to the middle ear?

Answer 36

Posterior to the middle ear are the mastoid antrum and mastoid air cells.