L11 - The nasal cavity and paranasal sinsues

Question 1

The nose: what is it, what does it contain, what does it consist of, and what functions does it have?

Answer 1

Part of the respiratory tract

Contains the peripheral organ of smell

Consists of:
– External nose
– Nasal cavity

Functions
* Olfaction
* Respiration
* Warms, humidifies and filters air
* Deals with the secretions of the nasal mucosa, paranasal sinuses and nasolacrimal ducts

Question 2

External nose: what parts are there to it and where do they lie?

Answer 2

Root - lies between the orbits
Dorsum - extends from root to apex
Apex - tip of the nose
Septum - midline partition
Ala - forms wing of nose
Naris - nostril/anterior nasal aperture

Question 3

Nasal cavity: what is it divided into, where is it located, what does it extend to, and what are its parts?

Answer 3

Right and left halves by the nasal septum, subdivided by the nasal conchae

• Medial to orbits & maxillary sinuses
• Superior to oral cavity & palate
• Inferior to the anterior cranial fossa

Extends from nares to choanae

– Vestibular part
– Respiratory part
– Olfactory part

Question 4

Vestibular part of the nasal cavity: what is it, what does it do, what is it composed of, what epithelia is it lined with, and why?

Answer 4

Area just inside the nostril

Filters out particulate matter

epithelium (skin stuff)
– Sweat glands
– Sebaceous glands (secrete sebum)
– Vibrissae (stiff hairs)
– Keratinised stratified squamous epithelium

Frontal part connected to the skin

Question 5

Respiratory part of the nasal cavity: where is it located, what epithelia is it lined with, what does it do, what does its lamina propria contain, and what part is it?

Answer 5

Between vestibular and olfactory parts

Pseudostratified columnar ciliated epithelium with goblet cells

Warms, filters and humidifies the air

• mucous cells which trap particles
• serous cells which humidify the air and some produce lysozyme
• Immune cells - form a defence against
  invading organisms
• Many blood vessels which warm the air

Innermost part

Question 6

Olfactory part of the nasal cavity: where is it located, what epithelia is it covered with, and what part is it?

Answer 6

Located above the superior nasal concha on
lateral wall, adjacent parts of the roof and nasal septum

Covered with pseudostratified columnar ciliated
epithelium containing receptors for smell

Central part

Question 7

Nasal skeleton

Answer 7

Anterior part – cartilaginous
* Posterior part – bony
* Mucosa is firmly bounded to
underlying perichondrium
(cartilaginous) or periosteum
(bony)

Question 8

Cartilaginous skeleton

Answer 8

Consists of
* 5 principle cartilages
– Septal cartilage x 1 (septal)
– Lateral nasal cartilage x 2 (upper cartilage)
– Greater alar cartilage x 2 (left/roght loopy cartilage)
* Minor (unnamed) cartilages
* Fatty fibrous tissue that fills the
gaps between the cartilages and
the bony skeleton

Question 9

NAsal septum

Answer 9

Divides the nasal cavity into
two compartments

Perpendicular plate of ethmoid bone
Vomer
D

Question 10

Roof of the nasal cavity

Answer 10

Nasal bone
Frontal bone
Cribriform plate of the ethmoid
Body of sphenoid and sinus

Question 11

Floor of nasal cavity

Answer 11

Palatine process of the maxilla
Horizontal process of palatine bone

Question 12

Lateral wall

Answer 12

Maxilla
Lacrimal
* vertical plate of palatine bone
* medial pterygoid plate of sphenoid
* superior & middle nasal conchae of ethmoid
* Inferior nasal concha

Under the cover of each choncha lies the corresponding meatus
superior meatus
middle meatus
inferior meatus
The sphenoethmoidal recess lies superoposterior to the superior
choncha

Irregular due to nasal conchae projection

Superior, middle, and inferior nasal conchae

Swell bodies are located in the lamina propria of the mucosa covering the
conchae. consider their function (slow down air? allow blood vessels to warm up wair)

Irregular due to the nasal conchae projecting from it

Question 13

Middle meatus

Answer 13

• Ethmoid bulla
  – A rounded elevation
  formed by the middle
  ethmoid sinuses
• Hiatus semilunaris – a
  semicircular groove
  inferior to the bulla

Question 14

Inferior meatus

Answer 14

The inferior meatus presents
* The opening of the
nasolacrimal duct

Question 15

Ethmoid bone

Answer 15

Cristal galli
Perpendicular plate
Labyrinth (containing air cells)

Question 16

Nasal cavity blood supply

Answer 16

Ophthalmic artery
Maxillary artery
Facial artery

Question 17

Kisselbach’s area

Answer 17

Anastamoses here, easy area to cause bleeding

Question 18

Venous plexus

Answer 18

Sphenopalatine facial and ophthalmic veins

Question 19

Nasal cavity innervation

Answer 19

General sensations - Maxcillary and opthalmic divisions of the trigeminal nerve

Posteroinferion portion

Anterosuperior portion

Olfaction - olfactory nerve

Question 20

Paranasal sinuses

Answer 20

Modified air spaces

• Possible functions; lighten skull, resonance of voice
• Lined by pseudostratified columnar ciliated epithelium with goblet cells
• Drain into nasal cavity

Question 21

Frontal sinus

Answer 21

Located in the frontal bone

Drains via the infundibulum
into the middle meatus at
the anterior end of the
hiatus semilunaris
frontal sinus

Innervated by supraorbital branch of ophthalmic division of trigeminal nerve

Question 22

Sphenoid sinus

Answer 22

Located in the sphenoid bone
inferior to the sella turcica

Drains via an opening in the
anterior wall of sphenoidal
body into sphenoethmoidal
recess

Innervated by pharyngeal branch of maxillary division of
trigeminal nerve

clinical significance - pit gland just above it, can put a needle through the sinus to interact with the pit gland

Answer 23

Antrum

Located in the body of the
maxilla

Drains via an opening on the
posterior end of the hiatus
semilunaris in the middle
meatus.

Innervated by superior alveolar
nerves from maxillary division of
trigeminal nerve

Most frequently
congested – drains upwards, can only drain when lying down

Question 24

Ethmoid air cells

Answer 24

Consists of three groups of air cells;
anterior, middle & posterior
Drainage
anterior → middle meatus, on floor of
hiatus semilunaris
middle → middle meatus, onto ethmoid
bulla
posterior → superior meatus
Innervation by maxillary division of
trigeminal nerve
Anterior & middle – anterior ethmoidal
Posterior – posterior ethmoidal