Upper respiratory tract Flashcards
What is the anatomy of the nasal cavities?
- Located between two bony orbits which contain eyes
- both have :
- Anterior/ posterior opening
- Floor/ roof - floor forned by maxillary bone and palatine bone, which form the hard palate
- Medianal and lateral walls
3 regions: - Nasal vestibules
- Olfactory regions
- Respiratory regions
- anterior openings (nares) formed by nostrils
- posterior openings - choanae- open into nasopharynx
What is the roof of the oral cavity made of ?
- frontal and nasal bones of the skull
- Cribriform plate contains small perforations for the olfactory nerves
What are the lateral walls of the nasal cavity formed of?
3 nasal conchae( shelves) of bone aka turbinates:
superior concha
middle concha
inferior conca
create 4 air channels/meatuses - contained within respiratory regions of the nasal cavity
What is the function of the conchae/ turbinates?
Conchae and meatuses = increase SA of contact between tissues of the lateral wall of the nasal cavity and the respired air
- Improves filtration, heating, humidification of inspired air
- Foreign material caught by nasal hairs in the vestibyle and mucus = usually swallowed
- pushes inspired air and odorants to the olfactory area due to turbulent airflow
Explain the histology of the conchae and nasal cavities
- Covered with thick, vascular, glandular mucosal layer with pseudostratified ciliated columnar resp epithelium
- Contains erectile tissue with venous sinusoids which will intermittently fill with blood
What are nasal polyps?
Caused by swelling and inflammation of the respiratory epithelium due to recurrent attacks of rhinitis .
What can deviated septums cause?
Sinus infections, snoring, difficulty breathing and sleep apnoea
What are paranasal air sinuses?
Air-filled spaces which lie within the bones of the skull of the same name
lined with ciliated, mucous secreting resp epithelium
Mucus from the sinuses drain into the nasal cavities via aperatrures within the lateral wall and roof
- close anatomical relations to the orbit (meninges lining of the brain, make the spread of infection possible
What is the blood supply of the nasal cavities and the air sinuses?
-Come from branches of the :
- facial: supply lip and anterior nasal cavity
- maxillary : Supply the nasal mucosa and supplies maxillary and sphenoidal sinuses
- opthalmic arteries : supply ethmodial and frontal sinuses
- internal and external carotid arteries
What is epistaxis?
- Nosebleeds caused by an anastomic plexus of arteries which lies on the anterior cartilaginous septum
What is the sensory nerve supply to the paranasal sinuses?
Trigmenal nerve:
Opthalmic division - provides sensory supply to the upper part of the face, maxillary divisom and mandibular division to the lower part of the face
1. Frontal sinuses supplied by the opthalmic V1 division
2. Ethmoidal and sphenoidal sinuses and nasal cavity are supplied by both the opthalmic and maxillary divisions
3. Maxillary sinuses are supplied solely by the maxillary V2 division
What is anosmia?
Loss of sense of smell and some loss of taste caused by an affect on the olfactory nerve cells ( fractures and COVID-19)
What are the mucous producing cells of the nasal mucosa supplied by?
- Parasympathetic neurons
What are the smooth muscle walls of blood vessels in the resp epithelium supplied by?
Sympathetic neurons which are both carried in the maxillary division of the trigeminal nerves
```
~~~
What is the nerve supply for general sensation in the nasal cavities?
Touch, pain and temperature from the nasal mucosa is carried by branches of the opthalmic CNV1 and maxillary (CN V2) divisions if the trigeminal nerve
What is sinusistis + symptoms?
- inflammation of the lining of the nasal cavity & sinuses caused by a viral/bacterial infection of a sinus
Symptoms: - Nasal blockage, congestion, obstruction - essential for diagnosis
- Nasal discharge (anterior rhinorrhoea/ post-nasal drip)
- Reduced sense of smell (hyposmia)
What are the pain patterns associated with sinusitis?
- Irritation of sensory nerves by inflammatory mediators, pressure changes and blocked non-draining sinuses may present with pain felt away from site of pathology
- Headache = may result from frontal sinusitis due to compression/irritaton of branches from the opthalmic division of the trigeminal nerve
- Toothache may occur with acute maxillary sinusitis due to compression/irritation of branches from the maxillary (CNV2) of the trigeninal berve (CNV)
What are apertures in the nasal cavity walls?
sinuses drain into the nasal cavity assisted by gravity except maxillary sinuses - more prone to infections
- Infections result in swollen mucosa, blocked drainage holes and subsequent pressure of the nearby structures
- Cribriform plate fibres of the olfactory nerve and branches from the opthalmic vessels pass through here
- Sphenoid sinus drains into the spehnoethmoidal reccess above the superior concha
- Maxillary, ethmoidal and frontal sinuses mainlu drain into the middle meatus
- Nasolacrimal duct drains teats into the inferior meatus
What is the pharynx?
Musculo-membranous tube extending from choanae to the oesophagus , which starts at the cricoid cartilage (C6 lecel)
conducts air into the larynx, trachea and lungs
- directs food to the oesophagus
What are the divisions of the pharynx?
- Nasopharynx- nasal cavities open here. Can be closed by lifting the soft palate
- Oropharynx- start of oral cavity. Can be closed by depression of the soft palate.
– Laryngopharynx inlet opens into here
Nasopharynx to Oropharynx at the pharyngeal isthmus, which closes during swallowing
What are the muscles of the pharynx?
Voluntary skeletal muscles:
* Superior, Middle and Inferior constrictors x3
* 3 logitudinal elevators, salpingopharyngeus, Palatopharyngeus, Levator veli palatini (all vagus nerve), Stylopharyngeus (supplied by glossopharyngeal nerve) elevators
* Tensor veli palatini (Mandibular division of trigeminal nerve)
What can resylt in airway occlusion?
Collections within the retropharyngeal space
What is the nerve supply to the Pharynx?
Nasopharynx- maxillary (CV2) of trigeminal nerve
Oropharynx + sylopharyngeus muscle- supllied by glossorpharyngeal nerve
Laryngopharynx + tatse - supplied by vagus nerve
Motor supply to the pharynx = mostly by vagus nevre, each region has a diff sensory innervation
What do dysphagia and strije result in ?
-diminished gag reflex
- poor swallowing reflex - because of pharygeal and laryngeal muscle paralysis due to vagus nerve loss
- Dyspaghia (discomfort/ difficulty in swallowing), affects the vast majority of acute stroke patients
- aspiration pneumonia- inhalation of food or liquids into the lowe airways that leads to lung injury and resultant bacterial infection of the lungs
What is the larynx?
- Air passage , sphincyer, organ of phonation and raises intra-abdominal prssure
- extends from the tongue (C3) to trachea (C6 level)
- hollow tube formed by as eries of nine cartilages interconnected by the ligaments and fibrous membranes
- moves up and down during swallowing due to extrinsic muscles
- Intrinsic muscles move vocal cords and modify the larngeal inlet
What is the laryx suspended fro?
The hyoid bone
What are the 9 layrngeal cartilages?
- Thyroid, cricoid, epglotis = unpaired
- arytenoid, corniculate and cuneiform = paired
What are the membranes of the larynx?
- Thyrohyoid membrane- broad,firboealstic membrane attached to thyroid c and hyoid bone
- Cricothyroid membrane - attaches to thyroid and cricoid cartilage to vocal processes of arytenoid cartilage
What is a cricothyrotomy?
cricothyroid ligament can be accessed in the midline to establish an airway
What are true vocal folds?
- Vocal ligaments covered with a non-keratinised stratified squamous epithelial mucosa
- This protects the tissue from effects of mechanical stresses that act on the surfaces of the vocal folds
- True vocal folds are formed by the mucosal coverigng and underlying vocal ligaments
- Vocal folds can be abducted and adducted by intrinsci muscles of the larynx
- moving vocal folds opens and closse the rima glottidis- open to produce sound and protect the airway
What are the primary muscles that open the glottis?
- the posteripr cricoarytenoids
- if paralysed - asphyxiation can result as the airway will be unable to open
W
What is the motor supply to the intrinsic muscles of the larynx?
-Supplied by the bagus nerve but by different branches:
Cricothyroid- superior laryngeal branch
- all muscles except cricothyroiud are supplied by recurrent laryngeal branch of the vagus nerve
- Arch ot the aorta - CNX gives off recurrent laryngeal branch which then ascends back up the left side of the nexk to innervate the intrinsic muscles of the larynx
What is the pathology of bilateral lesions of Recurrent Laryngeal Nerves?
Causes:
- Thyroid, cervical spinal surgery
- Viral infections
Signs and symptoms:
- patient may have a near normal voice because vocal cords will lie close to the midline
- voice will be minimally affected
- Airway will be very compromised becasue abduction of the vocal cords will not be possinle on either side
- Patients can present with resp distress resulting in hypoxia, resp arrest and death
- may require urget tracheotomy
