Nasal cavity, paranasal sinuses and pharynx Flashcards
What does septum do?
Divide nasal cavity
What are the three conchae
Superior, middle, inferior
Function of external nose
- Airway provision
- Warming and humidification of inspired air
- Filtering of large particulate matter
- Mucous production, trapping, ciliary clearance
- Olfaction
- Alar made of alar cartilage
- Drainage of paranasal sinuses
Roof of nasal cavity
Cribriform plate
Floor of nasal cavity
Palate
Medial wall of nasal cavity
- Nasal septum
- Smooth surface
- Bone (frontal, ethmoid, sphenoid, maxilla, vomer, nasal bone)
- Vomer sits on maxilla
- Septal cartilage
- Cartilage blood supply from perichondrium
Septal haematoma
Haematoma causes perichondrium to pull way from cartilage, starving it of blood supply - septal cartilage necrosis
What are the four air channels?
Inferior, middle, superior meatus and sphenoid-ethmoidal
What do meatus do?
Increases SA in contact with air
When you have a blocked nose, why does the feeling switch between sides?
Intermittent switching of conchae to warm air
Blood supply to nasal cavity
Facial, ophthalmic and maxillary
Where does epistaxis mainly occur?
Little’s area - lots of blood vessels join and end here
venous drainage of nasal cavity
- Venous drainage follows arteries
- Drain backwards into cavernous sinus
- Can result in cavernous sinus thrombosis - blood clot puts pressure on CNs and blocks venous drainage = swelling and oedema, diplopia, abnormal eye movements
Special sensation nerves to nasal cavity
Smell, olfactory nerves
General sensation nerves to nasal cavity
Nasopalatine nerve, nasociliary nerve
External skin sensation to nose nerves
Trigeminal
What are paranasal sinus?
Paired air-filled spaces
lined with pseudostratidied ciliated epithelium with goblet cells
Nasolacrimal ducts
Lacrimal gland produces lacrimal fluid to protect. and lubricate eye. This drains into nasal cavity (at inferior meatus) via nasolacrimal duct, a groove formed by lacrimal bone and frontal process of maxilla
What is the pharynx?
- Muscular tube that connects nasal and oral cavities with larynx and oesophagus
- Begins at base of skull and ends at cricoid cartilage (C6)
- Divided into naso/oro/laryngo pharynx
Muscles in pharynx
- All innervated by vagus nerve apart from stylopharyngeus which is innervated by glossopharyngeal nerve
- Rich blood supply from lingual, facial and ascending pharyngeal branches of external carotid artery
- Venous drainage via pharyngeal venous plexus, which drains into internal jugular vein
What causes mouth breathing?
Adenoid hypertrophy blocking nasopharynx
What do Eustachian tube do?
Equalise pressure in middle ear by connecting middle ear to nasopharynx
What does oropharynx contain?
Posterior 1/3 of tongue, lingual tonsils, palatine tonsils
What is quinsy?
Peritonsilar abcess, complication of bacterial tonsilitis, signs (dysphagia, trismus, hot potato voice), can obstruct airway, needs drainage
What is laryngopharynx?
Superior border of epiglottis to inferior border of cricoid cartilage]Continuous with oesophagus
Piriform fossa is deep recess anterolateral to larynx on each side - fish bones get lodged here
Sensory innervation by vagus nerve via internal branch of superior laryngeal nerve
What is the pharyngeal pouch?
Potential gap between upper and oblique fibres (thyropharyngeus) and lower transverse fibres (cricopharyngeus) of inferior constrictor
Submucosa and mucosa of pharynx may herniate into space, forming pouch - halitosis, dysphagia and cachexia
Stages of swallowing
3 phases: 1) voluntary chewing and pushing food into oropharynx
2) Involuntary soft palate seals off nasopharynx, larynx elevated and pulled forward, widens pharynx
3) involuntary - sequential contraction of pharyngeal constrictors causes peristalsis into oesophagus for semi-solid or solid material - liquids may shoot down oesophagus passively
