Anatomy and physiology of the nose and paranasal sinuses

Anatomy and physiology of the nose and paranasal sinuses

Dr.Ali Abed Mohammed

EXTERNAL NOSE

Bony constituents
Cartilaginous constituents

ANATOMY OF THE NASAL CAVITY

medial wall is the Nasal Septum
Floor
Roof
Lateral wall

Paranasal sinuses

Maxillary sinus
Ethmoid Sinus
Frontal Sinus
Sphenoid Sinus

PHYSIOLOGY AND MICROSCOPIC ANATOMY

Air Flow
The nasal airway serves important physiologic functions, including filtration, humidification, and olfaction; these functions are dependent upon unrestricted airflow through the nasal cavity.Air which passes from the nares to the lungs encounters its greatest resistance at the internal nasal valve

Warming and Humidification

The total increase in air temperature, as air leaves the nasopharynx, is approximately 8°C. Inspired air is also dramatically humidified by the nose, with an increase in ambient humidity from 40 to 98% between the nasal vestibule and the glottis

Olfaction

The olfactory neuroepithelium is distributed in 3 major areas:-
-The superior septum; the superior aspect of the
-Superior turbinate; and to a slightly lesser degree
-The superior aspect of the middle turbinate. These structures define the olfactory cleft.

Microscopic Anatomy

The ciliated cells have 50 to 200 cilia per cell, and each cilium has a 9 plus 2 microtubular structure with dynein arms. Experimental data indicate a typical ciliary beat frequency of 700 to 800 times a minute, with mucociliary transport occurring at a rate of 1cm/minute

Microscopic Anatomy

Goblet cells produce glycoproteins which are responsible for the viscosity and elasticity of mucus and respond to parasympathetic and sympathetic neural inputs. Between 20 and 40 mL of mucus are secreted from the normal nose daily from 160 cm2 of nasal mucosa. The cilia beat within the lubricating periciliary layer fluid, termed the sol layer. The outer, more viscous mucus layer, is termed the gel layer.


Function of Paranasal Sinuses
1-Humidifying and warming inspired air
2-Regulation of intranasal pressure
3-Increasing surface area for olfaction
4-Lightening the skull
5-Resonance
6-Absorbing shock
7-Contribute to facial growth

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