Nasal Anatomy, Physiology and embryology

Question 1

Describe the muscles of the nose

Answer 1

Elevators (shorten nose, dilate nares)

• Levator labii superioris alaquae nasi
• procerus

Depressors (lengthen nose, dilate nares)

• depressor septi nasi
• alar nasalis

Compressors (lengthen nose, compress nares)

• trasnverse nasalis

Question 2

What forms the nasal septum

Answer 2

Bone

• vomer
• perpendicular ethmoid plate
• palatine bones
• maxillary crest

Cartilage

• quadrangular cartilage

Question 3

Describe the sensory innervation to the nose

Answer 3

• V1 - dorsum, tip
• V2 - sidewall, ala
  *

Question 4

Define the nasal subunits

Answer 4

9 subunits

• dorsum
• tip
• columella
• paired nasal side wall
• paired soft triangle
• paired ala

Question 5

Describe the vascular supply of the nose

Answer 5

ECA

• columella branches
• lateral nasal branch
• sphenopalatine

ICA

• External nasal
• Dorsal nasal
• ethmoid artery
• supra/infraorbital

Question 6

What is the external nasal valve?

Answer 6

formed by the septum/columella and LLC/alae

Question 7

What is the internal nasal valve

Answer 7

Site of maximal resistance in caucasians

junction between septum, caudal end of ULC, anterior end of inferior turbinate and pyriform aperture

Question 8

What is the nasal cycle

Answer 8

Every 30mins to 4hrs, there is a alternation of nasal resistance due to ANS control of congestion and decongestion of turbinates

Question 9

What drains from each of the three meatuses

Answer 9

1. Superior meatus=> posterior ethmoid sinuses
2. Middle meastus=> NF duct for frontal sinus
3. Inferior meatus=> Nasolacrimal duct

Question 10

Describe nasal embryologic development

Answer 10

SUMMARY

MNP forms tip, columella, medial crus of LLC, par of septum

FNP forms cephalad septum

LNP forms external nose, nasal bones (from IOM), ULC, Lateral crus of LLC

Nose development 3-10wks GA

1. Nasal placodes: ectodermla thickenings form in FNP (wk4 GA)
2. Nasomedial process and Nasolateral process (NMP, NLP) (wk5 GA) develop from mesenchymal proliferation on placodes
3. Nasal pits form and deepen to become oronasal membrane which will break down posteriorly to form nasal choanae
4. NMPs fuse across midline and with maxillary crest to meet primary palate and to form Nasal Tip, crest, part of septum
5. Nasal septum partially grows from FNP down to meet secondary palate
6. Nares recanalize (4mths GA)
7. Septum fuses w palate and ingrowth separates ULC LLC (6mth GA)