Скачать или смотреть Human Nose—Anatomy, Physiology & Clinical Insights Part-22

Human Nose
The nose is the main organ of the respiratory system and the primary sensory organ for the sense of smell (olfaction). It also plays a major role in speech resonance, air filtration, humidification, and immune defense.

2. Structure of the Nose

The nose has two major parts:

A. External Nose (Outside part)

Root: Top part between the eyes

Bridge (Dorsum nasi): Middle bony part

Apex/Tip: Lower pointed part

Nostrils (Nares): Two external openings

Columella: Tissue between the nostrils

Alae: Soft sidewalls of the nostrils

Supporting framework

Bones: Nasal bone, maxilla, frontal bone

Cartilages: Septal cartilage, lateral nasal cartilage, alar cartilage (gives shape and flexibility)

B. Internal Nose (Nasal Cavity)

A hollow chamber divided into two halves by the nasal septum.

Nasal Septum

Made of bone and cartilage

Bones: Vomer, perpendicular plate of ethmoid

Cartilage: Septal cartilage

Function: Separates left and right nasal passages

Nasal Cavity Walls

The sidewalls contain 3 curved bony shelves called nasal conchae (turbinates):

Superior concha

Middle concha

Inferior concha

Functions of conchae:

Increase surface area

Warm and humidify inhaled air

Create airflow turbulence for better filtration

Meatuses

Spaces under each concha:

Superior meatus

Middle meatus

Inferior meatus

3. Nasal Mucosa (Inner lining)

The nasal cavity is lined with mucous membrane of 2 types:

A. Respiratory Mucosa

Contains ciliated epithelial cells

Has mucus-secreting goblet cells

Rich blood supply
Functions:

Traps dust, microbes, allergens

Cilia move mucus toward throat to be swallowed or expelled

B. Olfactory Mucosa

Present in roof of nasal cavity near superior concha

Contains olfactory receptor cells

These receptors connect to the olfactory nerve (Cranial nerve I)

4. Blood and Nerve Supply
Blood supply

Major arteries:

Sphenopalatine artery

Anterior & posterior ethmoidal artery

Superior labial artery

Important area:

Kiesselbach’s plexus (Little’s area) → a network of blood vessels where nosebleeds (epistaxis) commonly occur.

Nerve supply

Olfactory nerve (I) → smell

Trigeminal nerve (V) → sensation (pain, touch, temperature)

Autonomic nerves control blood flow and mucus secretion

5. Paranasal Sinuses

Air-filled cavities connected to the nose:

Frontal sinus

Maxillary sinus

Ethmoidal sinus

Sphenoidal sinus

Functions:

Lighten skull weight

Add resonance to voice

Produce mucus for nasal cavity

6. Functions of the Nose
Function Role
Breathing Passage for air entry
Air filtration Mucus traps dust and microbes
Humidification & Warming Blood vessels and conchae warm air
Smell (Olfaction) Detects odors via olfactory receptors
Immune defense Enzymes like lysozyme kill microbes
Speech resonance Enhances voice quality
Taste enhancement Smell contributes to flavor perception
7. Sense of Smell Mechanism

Steps:

Odor molecules enter nasal cavity

Dissolve in mucus layer

Stimulate olfactory receptor cells

Signal travels through olfactory nerve

Reaches olfactory bulb → brain for interpretation

8. Common Nose-Related Conditions
Epistaxis (Nosebleed)

Often from Kiesselbach’s area

Causes: injury, dry air, infections, high BP

Sinusitis

Inflammation of sinuses

Symptoms: blocked nose, headache, facial pain

Rhinitis

Inflammation of nasal mucosa

Types: allergic, infectious, vasomotor

Deviated Nasal Septum

Septum not straight

May cause breathing difficulty or frequent sinus infections

Nasal Polyps

Soft non-cancerous tissue growth

Causes obstruction

9. Protection & Maintenance

Hairs in nostrils block large particles

Mucus traps microbes

Cilia clear mucus

Blood vessels help regulate temperature

Tears from eyes drain into nose via nasolacrimal duct