Anatomy and physiology of the nose and sinuses Flashcards
What are functions of the nose?
- Primary function is respiration
- Warming of inspired air
- Humidification
- Filtration of large particulate matter by hairs (vibrisae)
- Mucus production, trapping and clearance of small particulate matter
- Immune protection
- Olfaction
- Drainage/aeration of the middle ear via Eustachian tube
- Drainage of paranasal sinuses and nasolacrimal duct
- Voice modification
- Pheromone detection
Describe the epithelium of the nose
Ciliated columnar epithelium with goblet cells
What are the coarse hairs in the nasal vestibule called?
vibrisae
What in the nose is responsible for pheromone detection?
Pheromone detection via the vomero-nasal organ of Jacobsen
What are the functions of the sinuses?
- Help with vocal resonance
- Decrease the weight of skull and facial bones
- Act as buffer for trauma
What makes up the internal nose?
Midline partition - nasal septum
Lateral walls
– Turbinates
Roof
– Cribiform plate of the ethmoid bone
Floor
– Hard palate
Associated structures
– Paranasal sinuses
– Nasopharynx
What makes up the septum of the nose?
Made up of the:
- perpendicular plate of the ethmoid bone
- vomer bone
- septal nasal cartilage
- crest of the maxillary bone
- crest of the palatine bone
What is a serious complication often associated with a deviation or perforation of the septum?
Septal haematoma
What can result from the delayed treatment of a septal haematoma?
Saddle nose deformity - collapsed nose due to necrosis of tissue due to compression of blood supply by a haematoma
What is the clinical significance of the nasal turbinates?
Clinical relevance – usually inferior turbinate only
Can cause nasal blockage due to
• Infection
• Inflammation e.g allergic rhinitis
Usually managed medically with topical steroid sprays
Can be managed surgically with turbinate reduction surgery
Can also become inflamed and cause nasal congestion, so are surgically removed
List the paranasal sinuses
• Frontal • Maxillary x 2 • Ethmoid – Anterior and posterior • Sphenoid
Describe the drainage pathways of the three meatuses of the nose
Inferior meatus
– Nasolacrimal duct
Middle meatus
– Frontal sinus
– Maxillary sinus
– Anterior ethmoid sinus
Superior meatus
– Posterior ethmoid sinus
– Sphenoid sinus
Describe both acute and chronic rhinosinusitis
Rhinosinusitis – reflects a concurrent inflammatory and infective process that affects the nasal passageway and contiguous para-nasal sinuses
Acute (bacterial): lasts <12 weeks
Chronic: lasts >12 weeks • Allergic • Non allergic – With gelatinous polyps – Without polyps
Describe some important anatomical relations of the sinuses
Frontal and ethmoid sinus
– Anterior cranial fossa
Maxillary sinus
– Orbits
Sphenoid sinus
– Optic nerve
– Internal carotid artery
– Cavernous sinus
What is the importance of the neighbouring anatomical relations to the sinuses?
Spread of infections
– Meningitis
– Intracranial abscess’
– Orbital sepsis
Risks of surgery
– CSF leak
– Orbital complications - blindness
Describe the nasopharynx
The nasopharynx is the upper part of the throat (pharynx) that lies behind the nose. It is a box-like chamber about 1½ inches on each edge. It lies just above the soft part of the roof of the mouth (soft palate) and just in back of the nasal passages
Describe the blood supply of the nasopharynx
Anterior
– Derived from branches of internal carotid artery
• Ophthalmic artery, which branches into the anterior and posterior ethmoid arteries
Posterior
– Derived from branches of external carotid artery
• Sphenopalantine artery
What is Little’s area?
Kiesselbach’s plexus, which lies in Kiesselbach’s area, Kiesselbach’s triangle, or Little’s area, is a region in the anteroinferior part of the nasal septum where four arteries anastomose to form a vascular plexus.
What is the other name for Little’s area?
Kiesselbach’s plexus
What is the clinical relevance of Little’s area?
Epistaxis: nose bleeds
– Most commonly occurs from Little’s area
Common causes • Trauma aka nose picking • Anticoagulants • Iatrogenic – surgery • Idiopathic • Hypertension
What neural structure of the vertebrate forebrain is involved in olfaction?
The olfactory bulb (bulbus olfactorius) is a neural structure of the vertebrate forebrain involved in olfaction, the sense of smell.
What nerve provides sensory innervation to the skin of the lower half of the nose and the septum?
The external nasal nerve (or external nasal branches) are terminal branches of the anterior ethmoidal nerves (from the ophthalmic division of the trigeminal nerve), and provide sensory innervation to the skin of the lower half of the nose and of the septum mobile nasi.
