Nasal Septum
Median osseocartilaginous partition dividing internal nose into right + left nasal cavities. Seldom exactly median — usually deviates to one side, more commonly right.
Components
Bony part:
| Bone | Position |
|---|---|
| Perpendicular plate of ethmoid | Posterosuperior |
| Vomer | Posteroinferior |
Minor contributions: nasal spine of frontal, crest of nasal bones, sphenoidal crest, nasal crest (palatine processes of maxillae + horizontal plates of palatine bones)
Cartilaginous part:
| Cartilage | Position |
|---|---|
| Septal cartilage (quadrangular) | Major anterior part; fits in angle between vomer + perpendicular plate of ethmoid |
| Medial crura of major alar cartilages | Anteroinferior (columella) |
Membranous part — between columella + caudal border of septal cartilage; double layer of skin, no bony/cartilaginous support; freely mobile side-to-side (membranous septum)
Columella = medial crura of both major alar cartilages united by fibrous tissue
Arterial Supply (5 arteries from 3 sources)
| Artery | Parent | Territory |
|---|---|---|
| Anterior ethmoidal (septal branch) | Ophthalmic (ICA) | Anterosuperior septum |
| Posterior ethmoidal (septal branch) | Ophthalmic (ICA) | Posterosuperior septum |
| Sphenopalatine (septal branch) | Maxillary (ECA) | Posterosuperior + posterior septum |
| Greater palatine (septal branch) | Maxillary (ECA) | Posterior + inferior septum |
| Superior labial (septal branch) | Facial (ECA) | Anteroinferior septum |
Little’s Area (Kiesselbach’s Plexus)
- Anteroinferior septum, just above vestibule
- All 5 septal arteries anastomose here
- Most vascular area of septum
- Commonest site of epistaxis (especially children/young adults — fingernail trauma)
Nerve Supply
| Nerve | Origin | Territory |
|---|---|---|
| Olfactory nerves (CN I) | — | Upper 1/3 (just below cribriform plate) |
| Internal nasal branch of anterior ethmoidal | Nasociliary → V1 | Anterosuperior |
| Medial posterior superior nasal branches of pterygopalatine ganglion | V2 | Posterosuperior |
| Nasopalatine nerve (pterygopalatine ganglion) | V2 | Posteroinferior |
| Nasal branch of greater palatine nerve | V2 | Posterior |
| Anterior superior alveolar nerve | Infraorbital → V2 | Anteroinferior |
Venous Drainage
- Submucous plexus → facial vein, pterygoid venous plexus, pharyngeal venous plexus
- Most marked at Little’s area; retrocolumellar vein = common site of venous bleeding in young
Lymphatic Drainage
- Anterior half → submandibular nodes
- Posterior half → retropharyngeal nodes
Applied Anatomy
Deviated Nasal Septum (DNS)
- Common; more in males; causes: trauma, developmental error
- Symptoms: nasal obstruction, sinusitis, headache, excessive snoring
- Rx: Submucous Resection (SMR) or Septoplasty
Excessive SMR → removes septal cartilage → loss of dorsal nose support → supratip depression
Epistaxis
- Commonest site: Little’s area / Kiesselbach’s plexus (anteroinferior septum) — children/young adults
- Posterior epistaxis (less common, more severe): sphenopalatine artery — elderly hypertensives
Rhinitis and Vidian nerve — allergic/vasomotor rhinitis → sectioning Vidian nerve (nerve of pterygoid canal) disrupts parasympathetic supply to nasal glands → controls excessive rhinorrhoea
Definition
The nasal septum is a median osseocartilaginous partition dividing the internal nose into right and left nasal cavities. It is seldom exactly in the median plane — it usually deviates to one side, more commonly the right.
Components — Formation
The nasal septum is formed by three components:
Bony Part
| Bone | Position in Septum |
|---|---|
| Perpendicular plate of ethmoid | Posterosuperior part |
| Vomer | Posteroinferior part |
Minor bony contributions:
- Nasal spine of frontal bone
- Crest of nasal bones
- Sphenoidal crest (rostrum of sphenoid)
- Nasal crest formed by fusion of palatine processes of maxillae and horizontal plates of palatine bones
Cartilaginous Part
| Cartilage | Position in Septum |
|---|---|
| Septal cartilage (quadrangular cartilage) | Major anterior part; fits in the angle between vomer and perpendicular plate of ethmoid |
| Septal processes (medial crura) of major alar cartilages | Anteroinferior (columella) |
Membranous Part
A small portion between the columella and the caudal border of the septal cartilage — formed by a double layer of skin with no bony or cartilaginous support. This part is called the membranous septum. Freely mobile side-to-side.
Columella = medial crura of both major alar cartilages united by fibrous tissue in the midline; also called columellar septum.
Arterial Supply
Five arteries supply the nasal septum — from three main sources:
| Artery | Parent Artery | Territory |
|---|---|---|
| Anterior ethmoidal artery (septal branch) | Ophthalmic artery (ICA) | Anterosuperior septum |
| Posterior ethmoidal artery (septal branch) | Ophthalmic artery (ICA) | Posterosuperior septum |
| Sphenopalatine artery (septal branch) | Maxillary artery (ECA) | Posterosuperior and posterior septum |
| Greater palatine artery (septal branch) | Maxillary artery (ECA) | Posterior and inferior septum |
| Superior labial artery (septal branch) | Facial artery (ECA) | Anteroinferior septum |
Little’s Area (Kiesselbach’s Plexus)
- Located at the anteroinferior part of the nasal septum, just above the vestibule
- All five septal arteries anastomose here to form Kiesselbach’s plexus
- Most vascular area of the septum
- Commonest site of epistaxis (nosebleed) — especially in children and young adults due to fingernail trauma
Nerve Supply
| Nerve | Origin | Territory |
|---|---|---|
| Olfactory nerves (CN I) | — | Upper one-third (just below cribriform plate) |
| Internal nasal branch of anterior ethmoidal nerve | Nasociliary → Ophthalmic (V1) | Anterosuperior part |
| Medial posterior superior nasal branches of pterygopalatine ganglion | Maxillary (V2) | Posterosuperior part |
| Nasopalatine nerve (branch of pterygopalatine ganglion) | Maxillary (V2) | Posteroinferior part |
| Nasal branch of greater palatine nerve | Maxillary (V2) | Posterior part |
| Anterior superior alveolar nerve | Infraorbital → Maxillary (V2) | Anteroinferior part |
Mnemonic for nerve supply quadrants: Upper = olfactory; Anterosuperior = ethmoidal; Posterosuperior = pterygopalatine ganglion (medial posterior superior); Posteroinferior = nasopalatine; Anteroinferior = anterior superior alveolar
Venous Drainage
Veins form a submucous plexus. Drain into:
- Facial vein
- Pterygoid venous plexus
- Pharyngeal venous plexus
Submucous venous plexus is most marked at Little’s area. The retrocolumellar vein runs vertically downwards and crosses the floor of the nasal cavity — a common site of venous bleeding in the young.
Lymphatic Drainage
| Region | Drains to |
|---|---|
| Anterior half (both medial and lateral walls) | Submandibular lymph nodes |
| Posterior half | Retropharyngeal lymph nodes |
Clinical Correlations
Deviated Nasal Septum (DNS)
- Very common; more in males
- Causes: trauma, developmental error
- Symptoms: nasal obstruction, sinusitis, headache, excessive snoring
- Treatment: Submucous Resection (SMR) or Septoplasty
Removal of the septal cartilage destroys its role in supporting the dorsum of the external nose → supratip depression of the nose after excessive SMR.
Epistaxis (Nosebleed)
- Commonest site: Little’s area / Kiesselbach’s plexus (anteroinferior septum)
- Commonly in children and young adults (finger nail trauma)
- Posterior epistaxis (less common, more severe): from sphenopalatine artery — seen in elderly hypertensives
Rhinitis and Vidian Nerve
- Allergic/vasomotor rhinitis → hypertrophied inferior concha, excessive rhinorrhea
- Controlled by sectioning the Vidian nerve (nerve of pterygoid canal) — this disrupts parasympathetic supply to nasal glands
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