Nasal Cavity and Smell Flashcards
alar cartilage
- this along with the lateral cartilage is the most anterior portion of the nose
nasal septum
- this is made up of the perpendicular plate of the ethmoid bone and the vomer
- the septum separates the left and right aspects of the nasal cavity
nasal conchae
- there is a superior, medial, and inferior
- these form the the lateral wall for each cavity and are very important for the warming, moistening and conditioning of the air
- they cause the air to swirl and come in contact with the mucus for a longer amount of time
nasal cavity
- the inferior boarder is formed by the maxilla and the palatine bone (the bones of the roof of the mouth)
- the superior boarder is formed by the cribriform plate of the ethmoid bone
cribiform plate foramina
this is where the olfactory nerve travels through to get to the olfactory bulb
what does the mucus layer do in the nasal cavity
this is what is conditioning the air, it moistens it and warms it before entering the lungs to protect the gas exchange surfaces of the lungs
paranasal sinuses
- these are air filled spaces in the skull around the nasal cavity
- have a mucus lining
functions:
- lighten the skull
- humidify/warm air
- can trap things in the mucus lining
- they are resonance chambers in sound production
- frontal sinus
- ethmoid air cells
- sphenoidal sinus
- maxillary sinus
what does it mean that the sinuses aid in sound production
- if someone has a sinus infection of a bad cold and the sinuses get clogged up then the can affect how people sounds when they speak
frontal sinus
this is within the frontal bone
ethmoid air cells
these are within the ethmoid bone and they are smaller openings within the bone
sphenoidal sinus
- this is in the sphenoid bone
maxillary sinus
- this is in the maxillary bone
olfactory epithelium
specialized region of tissue lining
- this is at the superior aspect of the nasal cavity
- this contains a mucus layer that traps particles
- contains olfactory receptor cells
- contains olfactory hairs
what happens at the mucus layer
this is what captures the molecules of the substance that is causing the odor and the breakdown of these molecules allows for the stimulation of the olfactory hairs
olfactory receptor cells
- these are bipolar neurons
- their axons form CN I (olfactory nerve)
olfactory hairs
- these are free nerve endings (cilia) projectioning into the mucous layer
- they contain receptors for the airborne molecules
- they are able to rapidly adapt and that is why we get used to smells (good or bad)
describe what happens when the olfactory hairs come in contact with smell molecules
- the mucus layer traps and breaks them down, allowing the hairs to come in contact
- the hairs sense the smell and send information through the bipolar cells (olfactory receptor cells)
- the axons of these form the olfactory nerve and travel through the foramina of the cribriform plate to the olfactory bulb
how long is CN I
the olfactory nerve is very short and only travels from the olfactory epithelium to the olfactory bulb and synapses there
olfactory bulb
receive information about smells from the nose and send it to the brain by way of the olfactory tracts
olfactory tract
a bundle of nerve fibers that connect the olfactory bulb with olfactory nuclei and the olfactory cortex
- this travels to the primary olfactory cortex of the brain
- this is not part of CN I
- the axons travel posteriorly away from the olfactory bulb
primary olfactory cortex
- this provides conscious awareness of smell
- this is highly connected to the hippocampus and the limbic systems allowing for smell to be tied to different memories and emotions and smells can trigger memories
primary smells
there are up to 50 of these
- these are things like mint, fishy, or sweat
secondary smells
- these are produced by a combination of chemicals
- flower blossoms can have ~100 different compounds
- what we smell is ultimately the CNS’s interpretation of the activity of the different receptors on the olfactory hairs
olfactory discrimination
neurons have different sensitivities to different molecules of odor
how does aging relate to smells
- olfactory neurons are continually replaced throughout life
- this is unique because as we have learned neurons typically do not divide
- this makes sense evolutionarily because many animals rely on smell for survival so it makes sense to have a replenishment of them
- the total number of neurons declines with age and the sensitivity becomes less
does the nose grow with age
- the nose is not technically growing
- the nose is getting more cross sectioning and scaring of collagen fibers and unlike other collagen in the body, the collagen here does not degrade, so it may appear to get larger but it is not growing
