Head/Neck--Nose,Paranasal Sinuses, Palate Flashcards
Nose
- the nose is an olfactory and respiratory organ
- it is divided into external and internal parts
External part of the nose (be able to label)
Composed of:
1) tip/apex
2) nostril/nares
3) root
4) dorsum (innervated by CN V1)
5) alar/winged lateral part
Which bones make up the nasal skeleton (be able to label)
- nasal
- frontal
- maxilla
The nasal skeleton (external) is made up of:
- bones
- cartilage (multiple, small, septal)
- dens fibrous CT (most lateral aspect of the nose)
Describe the functions of the nasal cavity
1) warms and humidifies the inspired air
2) removes and traps pathogens and particulate matter from inspired air
3) it is responsible for sense of smell
4) it drains and clears the paranasal sinuses and lacrimal duct
Internal part of the nose (be able to label)
- also referred to as the nasal cavity
- it is the most superior part of the respiratory tract
- it extends from the vestibule to the nasopharynx
- or from the nares (anterior nasal opening) to the choanae (posterior nasal opening)
Nasal vestibule
- it is the most anterior part of the nasal cavity
- it is initially lined by skin (keritanized) but as you go inward it transitions to typical respiratory epithelium before entering the nasal cavity
- small hairs called vibrissae that function to filter dust and other microscopic matter
What are the regions of the nasal cavity
- vestibule
- olfactory
- respiratory
Describe the olfactory region of the nasal cavity
It is located at the apex of the nasal cavity. It is lined by olfactory cells with olfactory receptors
Describe the respiratory region of the the nasal cavity
- it is the largest region and it is lined by ciliated pseudostratified epithelium
- within the epithelium are interspersed mucus-secreting goblet cells
Nasal septum
The medial wall of the nasal cavity
Which bones make up the nasal septum (be able to label them)
1) perpendicular plate of ethmoid (olfactory region)
2) vomer (posterior portion of nasal cavity)
3) maxilla (small contribution)
4) palatine (small contribution)
The anterior portion of the nasal septum is made of
-it is the septal cartilage made up of cartilage
Deviated septum
- occurs in 80% of all nasal septums
- common symptom from baldly deviated septum is difficulty breathing through the nose
- symptoms worse on one-side, can interfere with drainage of paranasal sinuses, resulting in repeated sinus infections
Lateral wall of the nasal cavity
- it is irregularly shaped compared to the smooth medial wall
- has 3 curved shelves of bones called conchae (turbinates)
1) inferior (largest/most anterior)
2) middle
3) superior (smallest/most posterior)
What are the functions of nasal conchae (turbinates)
- increase surface area of the nasal cavity to increase the amount of inspired air that can come into contact with the cavity walls
- disrupt fast laminar flow or air making it turbulent
- turbulent air spends longer time in nasal cavity so that it can be warmed and humidified
Nasal meatuses
- the air pathways created by concha projections
1) inferior meatus
2) middle meatus
3) superior meatus
Paranasal sinuses and superior/middle meatuses
-the paranasal sinuses drain into the nasal cavity using the superior and middle meatus
Nasolacrimal duct
- the nasolacrimal duct acts to drain tears from the eye
- it opens into the inferior meatus
- **hypertrophy of the inferior turbinate causes blockage of the inferior meatus and causes congestion
Blood supply to the nasal cavity
- the nasal cavity is highly vascular with good collateral circulation (anastomosis)
- supplied by branches from the orbit, palate, and face
- **Kiesselbach (Little’s) area has very high collateral circulation thus prone to bleeding
Epistaxis
- nosebleeds
- anterior nosebleeds make up 90% or more of all nosebleeds (little’s area)
- posterior nosebleeds are less common and occur mostly in the elderly
- more common in children 2-10 y/o and adults 50-80 y/o
Why do nosebleeds occur more frequently during winter months and in dry, cold climates?
-cold, dry air dries out mucousal membranes…
Nasal polyps
- small soft growths in the nose that occur in 30 % of American adults
- usually asymptomatic unless the are large and block nasal airways
- they are more common in patients with allergies and/or asthma
What er the most common symptoms from nasal polyps
1) decreased or absent sense of smell
2) difficulty breathing through the nose
3) nasal airflow blockage
Innervation to the nasal cavity
- the olfactory mucous membrane is innervated by the olfactory nerve (CN I)
- the upper part of the respiratory mucous membrane is innervated by the ophthalmic trigeminal nerve (CN V1)
-the lower part of the respiratory mucous membrane is innervated by the maxillary trigeminal nerve (CN V2)
Olfactory innervation
- receptors in the mucous membrane of the superior part of the nasal cavity sense “dissolved smell”
- the central processes transmit action potential through the cribriform plate and into the cranial cavity
- axons enter the olfactory bulb of the brain
Describe the paranasal sinuses
- group of air-filled spaces that surround the nasal cavity
- lined with mucous membrane continuous with that of the nasal cavity
- directly communicates with het nasal cavity
What are the proposed functions of the paranasal sinuses
1) decreasing the relative weight of the skull (most important)
2) increasing resonance of the voice (think cold)
3) providing a buffer against facial trauma
4) aiding in humidifying and heating of inhaled air
5) regulations of intranasal pressures
What are the names of the paranasal sinuses
1) maxillary
2) frontal
3) sphenoid
4) ethmoid
Describe the maxillary paranasal sinus
It is the largest of the sinuses and is located under the eyes, in the maxilla
Describe the frontal sinus
It is superior to the eyes and in the frontal bone (forehead)
Describe the sphenoid sinus
- It is contained within the body of thee the sphenoid bone
- it has a “well” that is the pituitary fossa which houses the pituitary glandular
Describe the ethmoid sinus
- it is made up of several discrete air cells within the ethmoid bone
- it located between the nasal cavity and the eyes
Paranasal sinuses drainage
- all sinuses drain into the nasal cavity
- most of our sinuses do not drain by gravity but by mucoescaltory cells
- only frontal sinuses drains by gravity
- **irritation of mucous membrane of the paranasal sinuses is the most likely cause of sinusitis
What is sinusits
- inflammation or swelling of the mucous membrane lining the sinuses
- the sinuses become blocked and filled with fluid
What are the most common causes of sinusitis
- common cold
- allergies
- nasal polyps
- deviated septum
What are the main signs/symptoms associated with sinusitis
- facial pain/pressure (felt through innervation of respective trigeminal nerve
- stuffed-up or runny nose
- loss of smell
- cough or congestion
Frontal/ethmoid sinus pain/pressure
Ophthalmic trigeminal nerve (CN V1)
Maxillary sinus pain/pressure
Maxillary trigeminal nerve (CN V2)
What is the clinical significance between maxillary teeth and the maxillary sinus
- the close proximity to the maxillary sinus floor increases the risk of communication between the two
- sinusitis resulting in maxillary sinus pain could cause toothache
Describe the palate
- it is the floor of the nasal cavity and the arched roof of the oral cavity
- its superior side is covered with respiratory mucous membrane (ciliated pseudostratified)
- its inferior side is covered with oral mucous membrane (stratified squamous)
- has 2 parts (hard and soft)
Describe the hard palate
- it is the bony palate and is anterior
- its mucous membrane is ascribed “mucoperiosteum”
- this means the periosteum of bone and mucous membrane are stuck together
- this forms palatine rugae (helps tongue with bolus formation)
Describe the composition of the hard palate
1) the anterior aspect is maxilla (majority of hard palate)
2) the posterior aspect is the palatine bone
3) the hard palate is Innervated by the maxillary trigeminal nerve (CN V2)
Describe the soft palate
- it is muscular rather than bony and is posterior
- has a conical projection (uvula) and is covered in mucous membrane
- it functions as a “swing gate” to wall off the nasopharynx during swallowing (prevent spaghetti out of a kids nose)
Which muscles elevate the soft palate and close off the nasopharynx
1) tensor veli palatini (anterior; CN V3)
2) levator veli palatini (posterior; CN X)
Which muscles depress the soft palate and open the passageway to the oropharynx
1) palatoglossus (anterior)
2) palatopharyngeus (posterior)
***both Innervated by the vagus nerve (CN X)
Cleft palate
- cleft palate is the result of incomplete fusion of the palate during development
- can involve hard and/or soft palate
- occur in 1/700 births and usually occurs with cleft lip (but doesn’t have to)
Describe snoring
- snoring occurs when air flows past relaxed tissues (tongue, soft palate, and pharynx) as you breathe
- sagging tissues narrow the airway causing them to vibrate
