Logo

    Nasal Cavity

    Reviewed by our medical team

    Warms, moistens, and filters inhaled air.

    1. Overview

    The nasal cavity is a large, air-filled space located behind the external nose that serves as the primary entry point for inhaled air. It is the beginning of the respiratory tract, where air is filtered, humidified, and warmed before reaching the lungs. In addition to its respiratory functions, the nasal cavity plays a major role in olfaction (smell), immune defense, and voice resonance.

    2. Location

    The nasal cavity lies within the midline of the face, extending from the external nares (nostrils) anteriorly to the choanae posteriorly, where it communicates with the nasopharynx. It is bordered:

    • Superiorly: By the cribriform plate of the ethmoid bone and sphenoid sinus

    • Inferiorly: By the hard and soft palates (roof of the oral cavity)

    • Laterally: By the maxillary and ethmoid bones (lateral nasal walls)

    • Medially: By the nasal septum, which divides the cavity into left and right halves

    3. Structure

    The nasal cavity is anatomically divided into distinct regions:

    Vestibule

    • The anterior-most part just inside the nostrils

    • Contains hair (vibrissae) and sebaceous glands

    • Lined with skin, not respiratory epithelium

    Respiratory Region

    • Main posterior portion of the nasal cavity

    • Lined with pseudostratified ciliated columnar epithelium and goblet cells

    • Contains nasal conchae (turbinates) and meatuses

    Olfactory Region

    • Superior aspect near the cribriform plate

    • Contains olfactory epithelium with sensory receptors for smell

    Septum

    • Medial wall formed by the vomer, perpendicular plate of the ethmoid, and septal cartilage

    Lateral Wall

    • Features the superior, middle, and inferior nasal conchae, under which lie the superior, middle, and inferior meatuses

    • Openings for paranasal sinuses and nasolacrimal duct drain into the meatuses

    Blood Supply

    • Richly supplied by branches of:

      • Ophthalmic artery (from internal carotid)

      • Maxillary and facial arteries (from external carotid)

    • Site of anastomosis in Kiesselbach's plexus—a common source of epistaxis

    Innervation

    • Sensory: Trigeminal nerve (CN V1 and V2)

    • Olfactory: Olfactory nerve (CN I) in the olfactory region

    4. Function

    The nasal cavity performs multiple critical functions:

    • Air filtration: Traps dust, pollen, and microbes via mucus and vibrissae

    • Air humidification: Moistens inspired air through mucous secretions

    • Air warming: Blood-rich mucosa warms air to near body temperature

    • Olfaction: Detects odors via the olfactory epithelium

    • Resonance: Enhances voice by acting as a resonating chamber

    5. Physiological Role(s)

    Beyond ventilation, the nasal cavity supports respiratory physiology through:

    • Mucociliary clearance: Ciliated epithelial cells transport mucus and debris toward the pharynx for swallowing

    • Immune defense: Mucosa contains immunoglobulins, antimicrobial peptides, and lymphoid tissues

    • Smell perception: Airflow to the olfactory region allows detection of chemical stimuli

    • Airflow direction: Conchae and meatuses create turbulence for optimal air contact with mucosa

    6. Clinical Significance

    Rhinitis

    Inflammation of the nasal mucosa due to:

    • Allergies (allergic rhinitis)

    • Infections (viral, bacterial)

    Leads to congestion, sneezing, and increased mucus production.

    Nasal Septum Deviation

    Common congenital or traumatic condition where the septum deviates from the midline, causing:

    • Unilateral obstruction

    • Recurrent sinusitis or epistaxis

    May require surgical correction (septoplasty).

    Epistaxis (Nosebleeds)

    Commonly originates from Kiesselbach’s plexus on the anterior nasal septum. Triggered by trauma, dry air, or hypertension.

    Sinus Drainage Disorders

    Obstruction of meatuses can impair drainage from sinuses, leading to sinusitis, especially in the middle meatus (osteomeatal complex).

    Anosmia

    Loss of smell due to damage to the olfactory mucosa or nerve—can result from infections (e.g., COVID-19), trauma, or neurodegenerative diseases.

    Nasal Polyps

    Benign mucosal overgrowths associated with chronic inflammation. May obstruct airflow or sinus drainage and require medical or surgical management.

    Nasal Tumors

    Rare, but malignancies may arise from the nasal epithelium. Symptoms include:

    • Persistent nasal obstruction

    • Epistaxis

    • Facial pain or swelling

    Did you know? The lungs are the only organs in the human body that can float in water.