Nose & Sinus - Anatomy and Physiology Flashcards
What is the primary nasal function?
To function as an airway in respiration.
Describe the sinonasal mucosa.
Respiratory ciliated columnar epithelium with goblet cells.
Why is nasal function so important in neonates?
Neonates are obligate nasal breathers.
What changes does the nasal passage carry out to the air coming in?
- Warms the air
- Humidification
What are some of the basic protective functions of the nasal passage?
- Filtration of large particulate matter by coarse hairs (vibrisae) in the nasal vestibule.
- Mucus production, trapping and ciliary clearance of particulate matter.
- Immune protection
Smell is one of the other important functions of the nose. What is the medical terms?
Olfaction.
The nasal passage is also responsible for the drainage of what?
- Drainage/aeration of the middle ear via Eustachian tube
- Drainage of paranasal sinuses and nasolacrimal duct
What are the function of the sinuses?
Debated, but some thoughts are..
- Help with vocal resonance
- Decrease the weight of skull and facial bones
- Act as buffer for trauma
How much of the external nose is bone vs cartilage?
• 1/3rd bony, 2/3rd cartilage
What are the structures which make up the external nose?
.
What is the name of the midline partition in the internal nose?
Nasal septum.
What form the lateral walls of the internal nose?
Turbinates
What froms the “roof” of the internal nose?
Cribiform plate
What is the name of the “floor” of the internal nose?
Hard palate
What are the associated structures of the internal nose?
Paranasal sinuses
Nasopharynx
What are the structures which make up the nasal septum?
- Perpendicular plate of ethmoid bone.
- Vomer bone
- Septal Cartilage
(mainly)
What is the clinical relevance of the septum?
Deviation may occur. (this can be congenital or aquired)
Septal perforation and haematoma may occur.
What are turbinates?
- Bony scroll-like projections from lateral wall of nose.
How many and what are the names of the turbinates? (also known as conchae)
3
- Superior
- Middle
- Inferior
What are the names of the air pathyways created by these bony projections?
These pathways are called meatuses.
What is the clnincal relevance of the turbinates?
- Usually the only clinical relevance is the inferior turbinate.
- This can cause blockages due to inflammation or infection.
- Usually this can be managed through the use of topical steroid sprays.
- If the issue requires so there can be surgical management with turbinate reduction surgery.
What are the paranasal sinuses?
Air cavities in the bones of the face.
What are the names of the paranasal sinuses?
- Frontal
- Maxillary (x2)
- Ethmoid (anterior and posterior)
- Sphenoid
What is the function of the Nasolacrimal duct and where does it drain?
The nasolacrimal duct acts to drain tears from the eye – it opens into the inferior meatus.
Which sinuses drain into the middle meatus?
The frontal, maxillary and anterior ethmoidal sinuses open into the middle meatus.
What sinuses drain into the superior meatus?
The posterior ethmoid and sphenoid sinuses drain into the superior meatus.
What is the clinical relevance of knowing the associations between a sinus and where it drains?
Relevant in Rhinosinusitis, which reflects a concurrent inflammatory an dinfective process that affects the nasal passageway and contiguous para nasal sinuses.
What are the 2 subtypes of rhinosinusitis?
- Acute (bacteial) (less than 12 weeks)
- Chronic (more than 12 weeks) - Allergic and Non Allergic, there may also be polyp formation.
What is the importnat anatomical relation for the frontal and ethmoid sinuses?
Anterior cranial fossa
What are the important anatomical relations of the maxillary sinus?
Orbits
What are the important anatomical relations of the sphenoid sinus?
Optic nerve
Internal carotid artery
Cavernous sinus
Why is it important to understand the the anatomical relations of the various sinuses in the head?
Spread of infections
- Meningitis
- Intracranial abscess
- Orbital sepsis
Risks of Surgery
- CSF leak
- Oribital complications (worst case scenario - blindness)
How is the blood supply of the nasal passage roughly divided?
Broadly divided into an anterior and posterior supply
Outline the anterior blood supply in the nasal passage.
Derived from branches of internal carotid artery
- Ophthalmic > Anterior/posterior ethmoid arteries
Outline the posterior blood supply in the nasal passage.
Derived from branches of external carotid artery
- Sphenopalantine
What is Little’s Area?
Area in the anterior nose where there are lots of anastomoses between the supplying arteries.
What is Epistaxis? What are the common causes?
Nose bleed
(occurs mostly from Little’s Area)
- Trauma aka nose picking
- Anticoagulants
- Iatrogenic – surgery
- Idiopathic
- Hypertension
What is the venous drainage of the nose?
The veins of the nose tend to follow the arteries. They drain into the pterygoid plexus, facial vein or cavernous sinus.
Outline the innervation of the nose in terms of the “special innervation”.
- Special sensory innervation refers to the ability of the nose to smell.
- This is carried out by the olfactory nerves. The olfactory bulb, part of the brain, lies on the superior surface of the cribriform plate, above the nasal cavity.
- Branches of the olfactory nerve run through the cribriform plate to provide special sensory innervation to the nose.
Oultine the nerves involved in the general innervation of the nasal cavity.
- General sensory innervation to the septum and lateral walls is delivered by the nasopalatine nerve (branch of maxillary nerve) and the nasociliary nerve (branch of the ophthalmic nerve).
- Innervation to the external skin of the nose is supplied by the trigeminal nerve.
