Structure of the nasal septum
The nasal cavity (cavitas nasi) is divided into two symmetrical halves by the nasal septum — septum nasi. Its anatomical structure comprises three main parts:
- membranous part — pars membranacea
- cartilaginous part — pars cartilaginea
- bony part — pars ossea
The basis of the cartilaginous part is the septal nasal cartilage (cartilago septi nasi), which has an irregular quadrilateral shape. Its posterosuperior margin is firmly fixed, fitting into the angle between the perpendicular plate of the ethmoid bone and the vomer.
The base of the septum separates the nostrils and forms the mobile part of the nasal septum — pars mobilis septi nasi. The entire cavity is broadly divided into the nasal vestibule (vestibulum nasi), which is lined with skin continuous with that of the external nose through the nostrils, and the nasal cavity proper (cavitas nasi), covered with a mucous membrane.
Nasal meatuses and conchae
Paired nasal meatuses are formed within the nasal cavity, the boundaries of which are determined by the nasal conchae:
- Superior nasal meatus (meatus nasi superior) — bounded by the superior and middle nasal conchae.
- Middle nasal meatus (meatus nasi medius) — located between the middle and inferior nasal conchae.
- Inferior nasal meatus (meatus nasi inferior) — lies between the inferior concha and the floor of the nasal cavity.
A space remains between the medial surfaces of all nasal conchae and the nasal septum, forming the common nasal meatus (meatus nasi communis). An important topographical feature is that the nasolacrimal duct — ductus nasolacrimalis — opens specifically into the inferior nasal meatus.
Mucous membrane of the nasal cavity
The mucous membrane of the nasal cavity proper is heterogeneous and subdivided into two functional zones:
- Respiratory region (pars respiratoria) — occupies the greater part of the nasal cavity.
- Olfactory region (pars olfactoria) — localized in the upper part of the nasal septum and contains the endings of the olfactory nerves (nn. olfactorii).
The mucous membrane is very rich in mucous glands (glandulae nasales), especially within the respiratory region. A dense network of blood and lymphatic vessels lies in the submucosa. In the region of the inferior and middle nasal conchae, these vessels form massive cavernous plexuses — plexus cavernosi concharum.
Blood supply, venous drainage, and innervation
The blood supply to the nasal cavity is provided by branches of several major arteries:
- Sphenopalatine artery (a. sphenopalatina)
- Maxillary artery (a. maxillaris)
- Anterior and posterior ethmoidal arteries (aa. ethmoidales anterior et posterior)
Venous blood from the walls of the nasal cavity drains into the pterygoid plexus — plexus pterygoideus. Lymphatic vessels pass to the submandibular and submental lymph nodes (nodi lymphoidei submandibulares et submentales).
The innervation of the nasal cavity has a clear zonal division:
- Anterior parts are innervated by the anterior ethmoidal nerve (n. ethmoidalis anterior) — a branch of the nasociliary nerve (n. nasociliaris), which arises from the ophthalmic nerve (n. ophthalmicus).
- Posterior parts receive innervation from the posterior nasal nerves (nn. nasales posteriores) — branches of the maxillary nerve (n. maxillaris) passing through the pterygopalatine ganglion (ganglion pterygopalatinum).
Briefly: answers to topical questions
Which bones form the bony part of the nasal septum?
The bony part of the nasal septum is formed by:
- Perpendicular plate of the ethmoid bone (lamina perpendicularis)
- Vomer (vomer)
- Nasal spine of the frontal bone
- Sphenoidal crest of the body of the sphenoid bone
Which paranasal sinuses open into the middle nasal meatus?
The frontal and maxillary sinuses, as well as some of the ethmoidal cells, open into the middle nasal meatus. These include:
- Frontal sinus (sinus frontalis) — opens into the anterosuperior part of the semilunar hiatus.
- Maxillary sinus (sinus maxillaris) — opens into the posteroinferior part of the semilunar hiatus.
- Anterior and middle ethmoidal cells (cellulae ethmoidales anteriores et mediae).
Where exactly is the olfactory region of the nasal mucosa located?
The olfactory region of the nasal mucosa is located in the upper parts of the nasal cavity. It occupies the following anatomical structures:
- Roof of the nasal cavity (superior wall)
- Superior nasal concha (concha nasalis superior)
- Middle nasal concha (concha nasalis media) — partially
- Upper third of the nasal septum
- Superior nasal meatus
Which arteries supply blood to the nasal cavity?
Blood supply to the nasal cavity is provided by branches of the maxillary and ophthalmic arteries. The vascularization involves:
- Sphenopalatine artery (a. sphenopalatina) — a branch of the maxillary artery (a. maxillaris).
- Anterior and posterior ethmoidal arteries (aa. ethmoidales anterior et posterior) — branches of the ophthalmic artery.
Where does lymph drainage from the nasal cavity occur?
Lymph drainage from the mucous membrane of the nasal cavity occurs into the regional lymph nodes of the head and neck. A dense network of lymphatic capillaries is located in the submucosa, from where collecting vessels pass to:
- Submandibular lymph nodes (nodi lymphoidei submandibulares)
- Submental lymph nodes (nodi lymphoidei submentales)
What opens into the superior nasal meatus?
The air-filled cavities of the sphenoid and ethmoid bones open into the superior nasal meatus. These include:
- Sphenoidal sinus (sinus sphenoidalis)
- Posterior ethmoidal cells (cellulae ethmoidales posteriores)
In addition, at the level of the superior nasal meatus posteriorly lies the sphenopalatine foramen (foramen sphenopalatinum), which in the natural state is covered by the mucous membrane.
To remember where tears drain, recall that they "flow downward"—the nasolacrimal duct opens specifically into the inferior nasal meatus.
Class and exam questions
What parts is the nasal septum anatomically divided into?
The nasal septum is divided into three parts: membranous, cartilaginous (including the septal nasal cartilage), and bony.
Where does the nasolacrimal duct open?
The nasolacrimal duct (ductus nasolacrimalis) opens into the inferior nasal meatus, located between the inferior nasal concha and the floor of the nasal cavity.
Where is the olfactory region of the mucous membrane located?
The olfactory region (pars olfactoria) is located in the superior part of the nasal septum.
Which nerves innervate the anterior parts of the nasal cavity?
The anterior sections are innervated by the anterior ethmoidal nerve (n. ethmoidalis anterior), which is a branch of the ophthalmic nerve.
What else to study on this topic
- Formation of the bony part of the nasal septum (vomer and perpendicular plate)
- Topography of the pterygoid plexus (plexus pterygoideus) and venous outflow pathways
- Connection of the olfactory nerves with the bulbs and pathways
- Histological structure of the cavernous plexuses of the conchae
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