L42. Nasal Cavity and Nasopharynx Flashcards
What are the main boney parts of the external nose?
- Frontal bone
- Frontal proxess of the maxilla
- 2 nasal bones
These all articulate together to form the bridge of the nose
What is most of the external nose composed of?
Cartilage
Describe the cartilaginous components of the external nose
- Made up of lateral cartilages making up the bulk of the external nose
- Septal cartilage runs in the midline of the lateral cartilages and articulates with the back of the nasal cavity bones (creates two nasal cavities)
- The Alar cartilages create the shape of the nostrils
(Alar fibrofatty tissue makes up the rest of the nostrils on the lateral side)s
What are the skeletal boundaries on the lateral wall of the nasal cavity?
(there are 6 bones involved - draw them)
- The sphenoid bone (its body and the descending pterygoid plates) forms the posterior nasal cavity
- The ethmoid bone forms the roof of the nasal cavity
- The frontal bone and nasal cartilages corm the anterior part
- The maxilla forms a majority of the wall
- The Palatine bone forms the rest of the roof and closes in the posterior part
- The inferior concha is boney projection (its own bone)
What are the skeletal boundaries making up the medial wall of the nasal cavity?
(there are 5 major aspects - draw this)
- The ethmoid bone and its cribiform plate make up the roof
- The septal cartilage of the external nose makes up the anterior
- The floor is still made up of the maxilla and palatine bones
- The posterior wall is still body sphenoid bone (note the pterygoid only forms the lateral wall)
- The vomer is a separate boney process that closes off the entire nasal septum (separating it entirely into two)
There is a space between the septal processes and the lateral wall of the nasal cavities.
What is it called and what is the function?
The posterior nare
It is the opening where air goes in and out
(there is an anterior nare which is the external opening of the nose)
What is in very close relation to the nasal cavity at the level of the ethmoid bone?
Describe how this is significant in Bad breaks of the nose
The ethmoid bone is very intimately related to the CNS especially the meninges
Bad breaks of the nose that involve the ethmoid bone may lead to infection (meningitis), bleeds of the CNS or rhinorrea
What is Rhinorrea?
Damage to the meninges by an ethmoid bone fracture (or something similar) that causes leakage of the CSF into the nasal cavity
What is the nasal cavity lined with?
What is the exception?
Lined by a highly vascular mucous membrane except for the very front vestible which is lined by skin and hair.
What is a common pathological implication of this highly vascular mucous membrane?
Rupture of these vessels (most commonly by having penetrating objects) is the most common cause of epistaxis (nose bleeds)
Why is this vasculature network so important to the nasal cavity?
Because the warmth from these anastomosing network is used to warm up and humifity the air (cold air can cause spasm of smooth muscles in the respiratory tract)
Describe the two major sections of the vascular mucous membrane lining the nasal cavites
- The superior third of the mucous membrane is the olfactory area
- The rest of the membrane is respiratory epithelium
Describe the olfactory epithelium of the superior third of the mucous membrane
The olfactory epithelium contains filaments for sensory nerves up through the cribiform plate where they synapse in the olfactory bulb with the secondary order neurons (olfactory nerves; CN I)
Describe the respiratory epithelium of the nasal cavity, what is its major function?
It is lined by pseudostratified, columnar, ciliated epithelium and is continuous with the remainder of the airways
These cilia beat actively in the direction towards the anterior part of the nasal cavity to move mucuos towards the nose to be removed
What are the turbinate bones of the lateral wall?
They are three bones/projections that are also lined by mucosa that protrude into the nasal cavity.
- Superior concha
- Middle concha
- Inferior Conca
What bones do the turbinates/choncae stem from?
The superior and the middle conchae are projections off the ethmoid bone
The inferior conchae is its own bone