26-10-22 – Nasal Cavity, Paranasal Air Sinuses, and Nasopharynx Flashcards
Learning outcomes
- List the functions of the respiratory system
- Define upper and lower divisions of the respiratory tract
- Identify the main skeletal elements forming the roof, lateral wall and septum of the nasal cavity
- Describe the para-nasal air sinuses and their sites of drainage into the nasal cavity
- Briefly describe the neurovascular supply of the nasal cavity and sinuses
- Describe the Waldeyer’s ring
- Describe the relationships of the nasal cavity, nasopharynx and paranasal air sinuses to each other and to adjacent structures
- Describe the functions of the nasal cavity, nasopharynx, tonsils and paranasal air sinuses
- Discuss clinical conditions that affect the nasal cavity, nasopharynx, tonsils and sinuses
- Identify paranasal sinuses on standard sinus radiographs
What are the 3 stages of respiration?
- 3 stages of respiration:
1) Ventilation (breathing)
2) Gas exchange
* Between the air and blood in the lungs
* Between the blood and other tissues of the body
3) Oxygen utilisation
* By the tissues in energy-liberating reactions
What are the 8 functions of the respiratory system?
- 8 functions of the respiratory system:
1) Warm, humidify and filter inhaled air
2) Olfaction (smell)
3) Help produce sound
4) Provide O2 and remove CO2
5) Acid-base balance – aids the kidneys in this. Can have metabolic or respiratory acidosis depending on what fails
6) Protective and reflexive non-breathing air movements (coughing and sneezing)
7) Assist circulation of blood and lymph towards the heart
8) Help the abdominal muscles during defecation, parturition, lifting a heavy object to function effectively
What are 7 requirements of the RS?
- 7 requirements of the RS:
1) Surface for gas exchange
* Located deep within the body to warm, moisten, and cleanse the incoming air
2) Thin-walled membrane
* To facilitate diffusion
3) Selectively permeable membrane
* To facilitate diffusion
4) Moist membrane
* O2 and CO2 can be dissolved in water to facilitate diffusion
5) Extensive capillary network
6) Effective ventilation mechanism
* To constantly replenish the air
7) The system must function autonomically
* Effective monitoring and feedback mechanisms
* Be able to function voluntarily for desired increased or decreased rates
What are the 2 components of the upper respiratory tract?
What are the 6 components of the lower respiratory tract?
- Upper respiratory tract
1) Nose (nasal cavity)
2) Nasopharynx - Lower respiratory tract
1) Larynx
2) Trachea
3) Bronchial tree (go into terminal bronchioles)
4) Alveolar ducts
5) Alveolar sac
6) Pulmonary alveoli
What are the 5 components of the conducting division of the RS?
What are the 3 components of the Respiratory division of the RS?
- 5 components of the Conducting division of RS:
1) Nose (nasal cavity)
2) Nasopharynx
3) Larynx
4) Trachea
5) Bronchial tree (go into terminal bronchioles) - 3 components of the Respiratory division of the RS:
1) Alveolar ducts
2) Alveolar sac
3) Pulmonary alveoli
What holds the nasal cavity open?
Why is bone needed?
What are the anterior openings supported by?
- The nasal cavity is held open by a box made of bone and cartilage (osteocartilaginous)
- Bone is needed because the decreasing intrathoracic pressure on inhalation would result in the nasal cavity closing if it was held open by cartilage
- The anterior opening (aka nostrils/nares) are supported by cartilages
What are the 3 muscles around the nostrils?
What are 2 functions of the muscles around the nostrils?
Where do nostrils lead to?
What is this lined by? What does this act as?
- 3 muscles around the nostrils:
1) Levator Labii Superioris Alaeque Nasi
2) Procerus
3) Nasalis - 2 functions of the muscles around the nostrils:
1) Act as sphincters or dilators
2) Control the diameter of the nares and adjust air flow - The nostrils lead immediately to the nasal vestibule
- The nasal vestibule is lined by skin that has hair follicles – the hair (vibrissae)
- Vibrissae are the first air filters in the RS
What is the nasal septum?
What is its structure like?
How can its positioning differ?
- The nasal septum acts as the medial wall in the nasal cavity, dividing it into the right and left nasal fossa
- The nasal septum consists of bone (vomer and ethmoid) posteriorly and cartilage anteriorly
- The septum’s position may deviate from the midline
What are the 4 bones of the roof of the nasal cavity?
What are the 2 bones of the floor of the nasal cavity?
Where are soft and hard palates located?
How is the hard palate oriented?
Why is this important?
- 4 bones of the roof of the nasal cavity:
1) Nasal bone
2) Frontal bone
3) Ethmoid bone
4) Sphenoid bone - 2 bones of the floor of the nasal cavity:
1) Palatine bones
2) Maxilla bone - The hard and soft palates make up the roof of the mouth
- The soft palate sits at the back of the mouth, behind the hard palate, which holds the teeth and gums.
- The hard palate is horizontal and quite flat, not curved
- This means when we insert a Nasogastric tube, we will push it backwards, not upwards
What are nasal conchae?
How many are there?
What do they form?
Where does each pair of conchae originate from?
What are conchae with a mucous membrane called?
- Nasal conchae are pairs of bones that project from the lateral wall of the nasal cavity like shelves
- There are 3 conchae: superior, middle, and inferior
- Conchae produce passages between the inferior surface of the concha and the lateral wall called meatuses
- The superior and middle conchae are part of the ethmoid bone
- The inferior conchae are their own separate bone
- Concha with a mucous membrane are known as turbinates
What are the 2 purposes of conchae?
What drains into the meatuses?
- 2 purposes of conchae:
1) Increase surface area for humidifying or cooling air
2) Form air channels (the meatuses) - Paranasal sinuses and nasolacrimal duct open into the meatuses of the nasal cavity
What are 5 gateways in the nasal cavity?
- 5 gateways in the nasal cavity
1) Foramen caecum
2) Cribriform plate
3) Sphenopalatine foramen
4) Small foramina in the lateral wall
5) Incisive canal
Where is the foramen caecum found?
What is the function of the foramen caecum?
What does the superior sagittal sinus act as?
What can the foramen coecum allow to spread?
- The foramen caecum is found on the ethmoid bone
- The foramen caecum acts as a connection between nasal veins in the nasal cavity and superior sagittal sinus in the cranial cavity
- The superior sagittal sinus acts as a vein and drains the superior cerebral veins, but it is not called a vein because of the structure of its wall
- The foramen caecum can allow infection to spread from the nasal cavity to the cranial cavity
Where is the cribriform plate found?
What do axons from olfactory receptor cells project?
Where do these axons pass through?
- The Cribriform plate is found on the ethmoid bone
- Axons from the olfactory receptor cells in the nasal cavity send projections into the olfactory bulb, which bundles into cranial nerve I (Olfactory nerve).
- These axons pass through tiny holes in the cribriform plate called foramina and enter into the cranial cavity
Where is the sphenopalatine foramen located?
What 3 structures pass through the spehnopalatine foramen?
- The sphenopalatine foramen is located bewteen the sphenoid and palatine bones
- 3 structures that pass through the spehnopalatine foramen:
1) Sphenopalatine artery (of the maxillary artery)
2) Nasopalatine nerve (of the maxillary nerve)
3) Superior nasal branches of the maxillary nerve
What structure passes through the small foramina in the lateral wall of the nasal cavity?
Where is the incisive canal found?
What does the incisive canal connect?
What 2 structures pass through the incisive canal?
- Inferior nasal branches from the greater palatine nerve (of the maxillary nerve) passes through the small foramina in the lateral wall of the nasal cavity
- The incisive canal is found just behind the incisors (teeth)
- The incisive canal connects the nasal cavity and oral cavity
- 2 structures that pass through the incisive canal:
1) Nasopalatine nerve (enters the oral cavity)
2) Terminal end of the greater palatine artery (enters the nasal cavity)
How are paranasal sinuses formed?
What are the 2 roles of the paranasal sinuses?
Where does the nasal mucous membrane extend to?
What covers the mucous membranes?
What does cilia help to do?
What can happen if they are disrupted?
Where do sinuses drain to?
What nerves innervate the paranasal sinuses?
When in life are paranasal sinuses formed?
- Paranasal sinuses are formed when some of the bones surrounding the nasal cavity (maxilla, ethmoid, frontal and sphenoid) are excavated by air sinuses
- 2 roles of the paranasal sinuses:
1) Lighten the skull
2) Resonant chamber – can change tone of voice - The nasal mucous membrane extends into the sinuses
- The mucous membranes are covered by cilia and mucus secreting respiratory mucosa
- Cilia pushes fluid to the opening of the sinuses (especially important in maxillary sinus, where the opening is superior to the sinus)
- If they are disrupted, this can lead to the accumulation of fluid and growth of microbes
- Each sinus has a drainage for mucus, which opens in into the nasal cavity through meatuses or sphenoethmoidal recesses
- The paranasal sinuses are innervated by branches of the trigeminal nerve
- Paranasal sinuses are formed in early childhood to adolescence
Where do paranasal sinuses drain into?
Where does the frontal sinus drain to?
Where does the maxillary sinus drain to?
Where does the middle and anterior ethmoid sinuses drain to?
Where does the posterior ethmoid sinus drain to?
Where does the sphenoid sinus drain to?
Where does the nasolacrimal duct drain to?
What is the nasolacrimal duct a passage between?
How do we get a runny nose when we cry?
- Each paranasal sinus has a drainage for mucus, which opens in into the nasal cavity through meatuses or sphenoethmoidal recesses
- Paranasal sinus drainage:
1) Frontal sinus
* Drains into frontonasal duct, then ethmoidal infundibulum (middle meatus)
2) Maxillary sinus
* Drains into middle meatus
3) Middle and anterior ethmoid sinuses
* Drains into Bulla ethmoidalis and ethmoidal infundibulum, then middle meatus
4) Posterior ethmoid sinus
* Drains into superior meatus
5) Sphenoid sinus
* Drains into spheno-ethmoidal recess, then superior meatus
6) Nasolacrimal duct
* Drains into the inferior meatus
* Only structure that drains here
* The nasolacrimal duct is a passage between the lacrimal sack and nasal cavity
* The lacrimal sack contains lacrima (tear drops)
* Excess of tears pass into nasal cavity
* This is why we get a runny nose when we cry, it is actually made from tears
What is the wall between the ethmoid sinuses and the orbit called?
What is its structure like?
What can an infection in the ethmoid sinuses cause?
What can occur in the floor between the maxillary sinus and oral cavity?
- The wall between the ethmoid sinuses and the orbits is called the lamina papyracea
- It is very thin
- An infection in the ethmoid sinuses that isn’t treated well can easily erode this wall, meaning it can enter the orbit
- The floor between the maxillary sinus and the oral cavity can be so thin that when teeth are extracted, it can break this wall and can create a continuous foul-smelling drainage from the maxillary sinus to the oral cavity
What is the vascular supply in the nasal cavity like?
What 2 artery branches does the external carotid artery supply?
What do they supply?
What artery branches does the Internal carotid artery supply?
What do they supply?
Do the external and internal carotid arteries anastomose?
- The nasal cavity is highly vascular
- Artery supply in the nasal cavity:
1) External carotid artery
* Gives off terminal branches of the maxillary and facial arteries
* Supplies things in the face and nasal cavity
2) Internal carotid artery
* Gives off ethmoidal branches of the ophthalmic artery
* Primarily supplies intracranial structures
- There is an anastomosis between internal and external carotid arteries
What are the 5 arteries that supply the nasal septum?
What 3 arteries meet at Little’s/Kiesselbach’s area on the nasal septum?
What is this point the site of?
- 5 arteries that supply the nasal septum:
1) Sphenopalatine artery (of the maxillary artery of the external carotid)
* Passes through the sphenopalatine foramen
2) Anterior ethmoidal artery (of ophthalmic artery of the internal carotid)
3) Posterior ethmoidal artery (of ophthalmic artery of the internal carotid)
4) Branches from the greater palatine artery
5) Superior labial artery
* Goes through the nares into the nasal cavity
- 3 arteries meet at Little’s/Kiesselbach’s area on the nasal septum:
1) Sphenopalatine artery
2) Anterior ethmoidal artery
3) Superior labial artery - Little’s/Kiesselbach’s area is the point of anastomosis between these arteries, and is a common area for epistaxis (nosebleed)
What 2 arteries supply the frontal sinus?
What 3 arteries supply the ethmoid sinuses?
What artery supplies the sphenoid sinus?
What 4 arteries supply the maxillary sinus?
- Arterial supply to the sinuses:
1) Frontal sinus
* Supra-orbital artery
* Anterior ethmoidal artery
2) Ethmoid sinuses
* Anterior ethmoidal artery
* Posterior ethmoidal artery
* Sphenopalatine artery
3) Sphenoid sinus
* Posterior ethmoidal artery
4) Maxillary sinus
* Infraorbital branches of maxillary artery
* Superior alveolar branches of maxillary artery
* Greater palatine artery
* Facial artery
How is nasal venous drainage related to artery supply?
What is the cavernous sinus?
What 4 veins drain into the cavernous sinus?
What 3 other veins do we have in the nasal cavity?
What might emissary veins allow?
- Nasal venous drainage mirrors arteries – arteries supplied are from internal and external carotid, veins are from internal and external jugular
- The cavernous sinus is not a vein but contains venous blood in the cranial cavity (similar to superior sagittal sinus)
- 4 veins drain into the cavernous sinus:
1) Anterior ethmoidal vein
2) Middle ethmoidal vein
3) Posterior ethmoidal vein
4) Superior ophthalmic vein - 3 other veins do we have in the nasal cavity:
1) Pterygoid plexus of veins in the infratemporal fossa
2) Facial vein
3) Emissary vein in the foramen caecum – may allow the spread of infection to the cranial cavity
What is the lymph drainage systems for anterior and posterior nasal cavity?
Which lymph node is palpable if inflamed?
- Anteriorly, the nasal cavity drains to the submandibular nodes
- Posteriorly, it drains via the retropharyngeal nodes to the upper deep cervical nodes
- Jugulodigastric node is palpable if inflamed
What 2 nerve divisions supply the lateral wall of the nasal cavity?
What are the 3 divisions of V1 that supply the nasal cavity?
What is the division of V2 that supplies the nasal cavity?
What are olfactory nerves capable of?
- 2 divisions of the Trigeminal nerve (cranial nerve 5) supply the lateral wall of the nasal cavity:
1) Ophthalmic division of trigeminal nerve (V1)
2) Maxillary division of trigeminal nerve (V2) - 3 Divisions of V1 that supply nasal cavity:
1) Nasociliary nerve
2) Mainly ethmoidal nerve
3) Nasal branches - Division of V2 that supplies nasal cavity
1) Nasal branches – mainly great palatine nerve - Olfactory nerves are capable of regeneration
What does the trigeminal get sensation from?
What 2 nerve divisions Is the nasal septum supplied by?
What are the 2 divisions of V1 that supply the nasal septum?
What is the division of V2 that supplies the nasal septum?
- The trigeminal nerve (cranial nerve 5) takes all general sensation from the chin to the vertex at the top of the head, except for the angle of mandible
- 2 divisions of the Trigeminal nerve supply the nasal septum:
1) Ophthalmic division of trigeminal nerve (V1)
2) Maxillary division of trigeminal nerve (V2) - 2 Divisions of V1 that supply nasal septum:
1) Anterior ethmoidal nerve
2) Septal branches - Division of V2 that supplies nasal septum:
1) Mainly nasopalatine nerve
Where does the pharynx extend from?
What will it be adjacent to throughout this?
What does the nasopharynx serve as?
Where does the nasopharynx extend from?
- The pharynx extends from the base of the skull to the oesophagus
- The pharynx will be adjacent to the nasal cavity (nasopharynx), the oral cavity (oropharynx), and the larynx (laryngopharynx), so it is divided into 3
- The nasopharynx serves only as a posterior air passageway between nasal cavity and oropharynx.
- The nasopharynx extends from the choanae to the level of the soft palate
What are choanae?
Where do choanae extend from?
What is the role of choanae?
What is the structure of the choanae like?
What are the 3 structures that make up choanae?
- Choanae are oval-shaped openings between the nasal cavities and the nasopharynx
- Choanae extend from the soft palate to the sphenoid
- Choanae serve as the connection between the nasal cavity and the nasopharynx
- The structure of the choanae is rigid, and is formed by bones covering mucous membranes
- 3 structures that make up choanae:
1) Horizontal plate of the palatine bone
2) Medial plate of the pterygoid process
3) Vomer – bone that forms part of the nasal septum
What is the pharyngotympanic tube?
What can it also be known as?
Where can its opening be found?
How many tubes do we have?
How is the pharyngotympanic tube linked to air travel?
- The pharyngotympanic tube is a tube between the middle ear cavity and the nasopharynx
- The pharyngotympanic tube is also known as the auditory or Eustachian tube
- The opening of the pharyngotympanic tube can be found on the inferior lateral wall of the nasopharynx
- We have a left and right pharyngotympanic tube on either side of our head
- During air travel, swallowing, eating, or squeezing our nose increases intrathoracic pressure
- By doing this, we are opening the opening of the pharyngotympanic tube, allowing air to go into the middle ear cavity and equalise the pressure between the internal and external environment of the ear drum
- This causes relief
What is the structure of the pharyngotympanic tube like?
What is the torus tubarius?
What is it often covered with?
What 2 muscles are found in this area?
What do they form?
Where do they attach? What are folds?
- The structure of the pharyngotympanic tube is musculocartilaginous, with muscle laterally and cartilage medially
- The torus tubarius is an upside-down u-shaped cartilage of the pharyngotympanic tube that protrudes into the nasal cavity
- It is often covered with mucous membrane, making it very visible
- Salpingopharyngeus and Salpingopalatine muscles run between torus tubarius and pharynx and palate, respectively, forming Salpingopharyngeal and Salpingopalatine folds
- The Salpingopharyngeus and Salpingopalatine muscles attach to the legs of the torus tubarius cartilage
- Fold means a structure covered with something else, e.g mucous membrane on bone/cartilage or peritoneum on vessel
What 2 muscles open the pharyngeal opening of the pharyngotympanic tube?
What happens when either of these muscles contract?
- 2 muscles open the pharyngeal opening of the pharyngotympanic tube:
1) Salphingopharyngeus
2) Tensor Veli Palatini - When either of these muscles contract, this produces a sufficient positive pressure in the oral cavity, so the air will open this opening and flow into the middle ear cavity
What are tubal tonsils?
Where are they found?
What are pharyngeal tonsils/adenoids?
Where are they located?
How can they cause problems in small children?
What procedure is used to remove them?
- Tubal tonsils are masses of lymphoid tissue found around the opening of the left and right pharyngotympanic tubes
- Pharyngeal tonsils or adenoids are lymphoid (tonsillar) tissues on the roof of the nasopharynx in the midline
- Pharyngeal tonsils can overgrow in small children and block the nasal cavity, which can hinder airflow
- They need to be removed via an adenoidectomy
What is the pharyngeal recess (fossa of rosenmuller)?
What is it the most common site for?
How can catheter insertion cause problems in this region?
What develops from the pharyngeal recess?
- The pharyngeal recess is is the recess behind the pharyngotympanic tube
- The pharyngeal recess is the most common site for craniopharyngioma (rare type of noncancerous (benign) brain tumour)
- A catheter intended for the auditory tube (pharyngotympanic tube) may miss & enter the pharyngeal recess − If the pharynx is pierced, the catheter could enter the internal carotid artery
- Adenohypophysis (anterior lobe of the pituitary gland) develops from this region (Rathke’s pouch)
What are all tonsils made from?
What are the 2 types of tonsils in the nasal cavity?
What are the 2 types of tonsils in the oral cavity?
What do tonsils collectively form?
- All tonsils are made form lymphoid tissue
- 2 types of tonsils in the nasal cavity:
1) Pharyngeal tonsils
2) Tubal tonsils - 2 types of tonsils in the oral cavity:
1) Palatine tonsils
2) Lingual tonsils - Tonsils collectively form a lymphatic ring (Waldeyer’s Ring) around the openings of the respiratory and gastro-intestinal tracts to try and prevent infection from moving distally
What can cause mouth breathing?
What can mouth breathing lead to the formation of?
What can cause middle ear infections?
- Inflammation and swelling of the pharyngeal tonsil may obstruct the airway and lead to mouth breathing
- Mouth breathing can lead to adenoid face/adenoid facies
- Adenoid facies refers to the atypical appearance of facial features, and can result from persistent adenoid hypertrophy
- Enlargement of the tubal tonsil may obstruct the pharyngotympanic tube and cause middle-ear infections
Label these structures in a Water’s view x-ray. What can this view be used for?
- Water’s view x-ray can be used to check if there is fluid build-up/air in paranasal sinuses and structures where there shouldn’t be
Where is the maxillary sinus opening?
What is clearance of mucus dependent on?
What can happen if this is compromised?
- The maxillary sinus opening is high in its medial wall
- Clearance of mucus is dependent upon ciliary action, which may be compromised by infection, possibly leading to sinusitis.
Label these sinuses
