Nasal anatomy Flashcards
What is this?
Columella
The nostril openings are separated by the columella.
What is this?
Philtrum
The concave area from the columella down to the lip is the philtrum
What is this?
Vermillion notch.
The piece of upper lip at the lower end of the philtrum is the vermillion notch.
Describe the spatial orientation of the nasal cavity
The nasal cavity stretches backwards from the vestibule as two channels, divided by the nasal septum. The cavity is directed horizontally backwards, at a right angle to the plane of the face. This means that anything inserted into the nose should be directed straight back– not ‘up’ the nose
Describe the structure of the nasal cavity
(lateral walls, medial wall, inferior and posterior borders, and lining)
The nasal cavity is formed by:
* Lateral walls: three turbinate bones which arise from the lateral wall of the nasal space. Inferior turbinate (largest), middle turbinate, superior turbinate (smallest)
* Medial: nasal septum in the midline, which divides the cavity from the vesibule back to the posterior nasal space (where the nasal space unites). USUALLY DEVIATED - rarely straight
* Inferiorly: hard and soft palates
* Posteriorly: Posterior nasal space (floor = soft palate, eustacian opening laterally) and bony posterior wall (formed by the anterior wall of the sphenoid sinus, the clivus bone of the base of the skull, and the cranio-cervical junction).
The inner lining consists of respiratory and olfactory epithelium
Describe the bony posterior wall of the nasal cavity (structures, lining)
Formed by the anterior wall of the sphenoid sinus, the clivus bone of the base of the skull and the cranio-cervical junction. These structures are only covered by mucosa and connective tissue
What is this
Posterior nasal space, showing the septum on the left and the eustachian opening on the right. The soft palate forms the floor of the space.
The septum ends here, and the nasal space unites.
Describe the relative sizes and clinical relevance of the three turbinate bones
The three turbinate bones arise from the lateral walls of the nasal space
* Inferior: the largest.
* Middle: useful landmark in endoscopy. If the middle turbinate can be seen, then the route being taken through the nasal cavity is excessively high.
* Superior turbinate: the smallest. Supports the olfactory epithelium (responsible for sense of smell)
The turbinate bones are very easily traumatized as they occupy the majority of the space in the cavity
Which nasal structure supports the olfactory epithelium
Superior turbinate, the smallest of the three turbinate bones
Describe 5 major complications of instrumentation of the nose
- **Perforation of the mucosa by tracheal tubes -> medastinitis and infection of the deep cervical tissues. **
The axis of the airway changes by almost 90 degrees in the posterior nasal space (from horizontal to vertical). A semi-rigid pointed device such as a tracheal tube could easily perforate this. Therefore nasotracheal tubes should be inserted over a flexible introducer, such as a suction catheter or endoscope to avoid perforation of the mucosa. - Accidental insertion of nasogastric and nasotracheal tubes into the cranial cavity in patients with base of skull fractures
-
Turbinate fracture
The turbinates occupy most of the space within the nasal cavity. They are particularly vulnerable to injury. Commonly fractured by nasotracheal intubation; -> bleeding. Entire turbinates have been amputated during intubation. -
Epistaxis and bleeding
The nasal mucosa is highly vascular (aids its function as an ‘air-conditioner’ for the respiratory tract.) Deaths from epistaxis occur, usually from Little’s area (a carotid system anastomosis at the antero-inferior region of the septum.) -
Damage to the paranasal sinuses
Obstruction of drainage from the paranasal sinues -> sinusitis. Rarely: shrinkage of the sinus due to obstruction of drainage by a nasotracheal tube -> ipsilateral eye appears lower due to collapse of the underlying sinus.
What complication is shown here
This skull radiograph depicts an nasotracheal tube piercing the base of skull and entering the cranium
Nasogastric and nasotracheal tubes have been inserted into the cranial cavity in patients with base of skull fractures.
What is Little’s area
A carotid system anastomosis at the antero-inferior region of the septum.
Deaths from epistaxis usually originate from here
Name two topical vasoconstrictors to reduce bleeding during nasal instrumentation, and potential complications
Xylometazoline
Cocaine
Cocaine can be toxic, causing dysrhythmias and coronary vasoconstriction.
Describe the blood supply to the nose
- Sphenopalantine artery: supplies most of nasal mucosa
- Anterior and posterior ethnoidal arteries (most superior) - nasal mucosa
- Continuation of facial artery - nasal mucosa
- Greater and lesser palatine artery (most inferior)- nasal septum
Note: The nose is a highly vascular structure. This attribute facilitates its function of warming and humidifying air, but also makes it vulnerable to trauma and epistaxis.
Describe the nerve supply to the nose (sensory innervation, smell, secreto-motor)
The nose contains the olfactory epithelium (sense of smell) and nerves providing general sensation and secreto-motor function
* Sensory innervation: opthalmic and maxillary divisions of the trigeminal nerve (CN V)
* Smell: oldactory nerve fibres supply a variable amount of the epithelium on the superior aspect of the nasal cavity (CN I)
* Secreto-motor fibres: distributes via the pterygopalatine ganglion
Describe the anatomy and function of the paranasal sinuses (4)
There are 4 paranasal sinuses:
* Maxillary
* Frontal
* Ethmoid
* Sphenoid
These drain through the ostia into the nasal cavity.
Function of the sinuses is unknown, but theories include:
* Reduce skull weight
* Aid vocal resonance
* Provide ‘crumple zone’ to protect the brain from trauma
What complication is shown here
Sinus injury due to nasal intubation – ‘imploding antrum’
Rarely, the nasotracheal tube blocks sinus drainage, resulting in shrinkage of the sinus. The ipsilateral eye appears lower due to collapse of the underlying sinus
Name these areas of the nasal cavity
- Frontal sinus
- Superior turbinate
- Pituitary fossa
- Sphenoid sinus
- Eustacian tube orifice
- Inferior turbinate
- Middle turbinate
Name the areas shown (nasal endoscopy)
What area is shown (nasal endoscopy)
Nasopharynx
What is shown here?
Junction of oro and nasopharynx with a laryngeal mask in situ
