Nose is delicate sensory organ which provides you with some of the greatest pleasures. Most importantly it is designed to warn and protect the body against dangers. The inside of the nose (also termed internal nose) is splitted into left and right nasal cavities by a nasal septum.
Every nasal cavity interacts with the outside via nostril (or naris) and together with the nasopharynx via the posterior nasal aperture (or the choana) every nasal cavity is splitted into 2 portions: (a) a small anteroinferior part lined by skin-the vestibule and (b) a large posterosuperior part lined by mucosa-the nasal cavity appropriate.
Vestibule of NoseIt’s the anteroinferior part of nasal cavity, lined by skin. The skin includes sebaceous glands, hair follicles and the stiff interlacing hair termed vibrissae. Its upper limit on the lateral wall of nasal cavity is marked by limen nasi. Its medial wall is composed by a mobile columella.
Nasal Cavity Proper
BordersThe nasal cavity appropriate presents the following bounds:
- Medial wall (septum).
- Lateral wall.
RoofThe roof is extremely narrow in front and widens to about 1 cm near the choanae. It’s horizontal in the middle third, where it’s created by the cribriform plate of the ethmoid. Via this olfactory nerves goes into the cranial cavity from the nasal cavity. The anterior third of roof inclines downwards and forwards. It’s created by the nasal spine of the frontal, the nasal bone and the junction of the septal and lateral cartilages. The posterior third of the roof also slopes downwards and backwards. It’s created by the anterior surfaces of the body of the sphenoid.
FloorThe floor is virtually horizontal. It’s created by the upper surface of the hard palate, i.e., anterior 3-fourth is composed by palatine process of maxilla and posterior 1 fourth is composed by the horizontal plate of the palatine bone.
Medial WallIt is composed by nasal septum the nasal septum is a median osseocartilaginous partition between the 2 nasal cavities it’s rarely just in the median plane but bulges to 1 or the different side, more often to the right the bony part is composed by:
- Perpendicular plate of ethmoid, which creates the posterosuperior part of the septum and
- Vomer, which creates the posteroinferior part of the septum.
- septal cartilage, which creates the major anterior part of the septum and fits in the angle between the vomer and perpendicular plate of ethmoid and
- septal processes of both major alar cartilages
Clinical SignificanceDeviated nasal septum (DNS): The deviated nasal septum isn’t unusual and is an essential cause of nasal obstruction. The males are affected more than females. It takes place because of numerous variables like trauma, developmental blunder, etc. If DNS is acute and causing mechanical obstruction, resulting in trouble in breathing sinusitis, headache, excessive snoring, etc., it’s corrected by submucous resection (SMR) or septoplasty. The septal cartilage not only creates partition between the left and right nasal cavities but also gives support to the dorsum of the anterior two-third of the nose. For that reason, its destruction as a result of disease or excessive removal in submucous resection leads to supratip depression of the external nose.
Lateral WallThe lateral wall of the nose is complicated. It’s created by a number of bones and cartilages. The bones creating the lateral wall are:
- frontal process of maxilla,
- conchae and maze of ethmoid,
- inferior nasal concha,
- perpendicular plate of palatine and
- medial pterygoid plate of sphenoid.
- lateral nasal cartilage (upper nasal cartilage),
- major alar cartilage (lower nasal cartilage) and
- 3 to 4 miniature cartilages of the alae (small alar cartilages).
- Anterior part presents a small depressed area, the vestibule. It’s lined by the skin including vibrissae (short, stiff curved hair).
- Middle part is called atrium of the middle meatus. Itis restricted above by a faint ridge of mucous membrane, the agger nasi. The curved mucocutaneous junction between the atrium and vestibule is called limen nasi.
- Posterior part presents 3 scroll-like projections, the conchae or turbinates. The spaces dividing the conchae are referred to as meatuses.
- Superior and middle nasal conchae are the projections from the medial surface of the ethmoidal labyrinth.
- Inferior concha is a separate bone.
- The superior concha is smallest and inferior concha is largest in size.
- Meatuses are the passages (recesses) below the overhanging conchae. They’re visualized once conchae are removed.
- Inferior meatus is the largest and is located underneath the inferior nasal concha.
- Ethmoidal bulla (bulla ethmoidalis), a round elevation generated by the underlying middle ethmoidal sinuses.
- Hiatus semilunaris, a deep semicircular sulcus below the bulla ethmoidalis.
- Infundibulum, a short passage in the anterior end of middle meatus.
- Superior meatus is the smallest and is located below the superior concha.
- A triangular depression, above and behind the superior concha is called the sphenoethmoidal recess.
Lining of Nasal CavityThe lining of the different regions of nasal cavity are as follows:
- Vestibule: It’s lined by the skin comprising a large number of sebaceous glands and interlacing rough hair-the vibrissae. As the air goes through the nostrils the large particles of dust in the air are trapped by the vibrissae.
- Olfactory region: The upper third of the nasal cavity bounded above by cribriform plate of ethmoid, laterally by superior nasal concha and medially by upper one-third of the nasal septum creates the olfactory region. It’s lined by the olfactory epithelium, which includes receptor cells for scent. Here mucous mem-brane is lighter in color.
- Respiratory region: The remainder of the nasal cavity (lower two-third) is lined by the respiratory epithelium, i.e., pseudostratified ciliated columnar epithelium with goblet cells. The respiratory mucosa is extremely vascular and includes a large number of cavernous spaces and sinusoids to warm the air. Moreover, it includes a large number of serous and mucous glands. The secretion of the serous glands makes the air damp while the secretion of the mucous glands traps the dust and other particles. Farther, the cilia on the top layer of the mucous membrane sweep the mucous posteriorly into the pharynx where it’s consumed and removed by the GIT.
Arterial Supply of Nasal CavityThe nasal cavity has abundant arterial supply.
Arterial Supply of Nasal SeptumThe nasal septum is supplied by these arteries:
- Septal branch of the anterior ethmoidal artery (a branch of ophthalmic artery).
- Septal branch of the posterior ethmoidal artery (a branch of ophthalmic artery).
- Septal branch of the sphenopalatine artery (a branch of maxillary artery).
- Septal branch of the greater palatine artery (a branch of maxillary artery).
- Septal branch of the superior labial artery (a branch of facial artery).
Little’s AreaIt’s an area in the anteroinferior part of the nasal septum just above the vestibule. It’s highly vascular. Here the septal branches of the anterior ethmoidal sphenopalatine, greater palatine and superior labial arteries anastomose to create a vascular plexus referred to as Kiesselbach’s plexus. This area of nasal septum is the commonest site of epistaxis (nose bleeding) in kids and young adults generally because of finger nail trauma following deciding of the nose.
Arterial Supply of Lateral WallThe arterial supply of the different parts of the lateral wall is as follows:
- Anterosuperior quadrant, by the anterior ethmoidal artery, a branch of ophthalmic artery.
- Anteroinferior quadrant, by branches of facial and greater palatine arteries.
- Posterosuperior quadrant, by sphenopalatine artery, a branch of maxillary artery.
- Posteroinferior quadrant, by branches of greater palatine artery, which pierces the perpendicular plate of palatine.
Venous Drainage of Nasal CavityThe veins draining the nasal cavity create plexus below the mucosa and in general follow the arteries. The veins of nasal cavity drain into facial vein, pterygoid venous plexus and pharyngeal venous plexus. The submucous venous plexus is more marked in the region of little’s area. The retrocolumellar vein runs vertically downwards, crosses the floor of nasal cavity to join the venous plexus on the lateral wall. This is the common site of venous bleeding in young people.
Lymphatic Drainage of Nasal CavityLymph from anterior half of nasal cavity (both medial and lateral walls) is emptied into submandibular lymph nodes and from posterior half into retropharyngeal lymph nodes.
Nerve Supply of Nasal CavityThe nasal cavity is supplied by the following nerves:
- Olfactory nerves: They carry sense of smell from olfactory region of nasal cavity.
- Nerves of general sense: These are:
- anterior ethmoidal nerve,
- branches of sphenopalatine ganglion and
- branches of infraorbital nerve
RhinitisIt’s the inflammation of mucus membrane lining the nasal cavity. The hypertrophy of mucosa over inferior concha is a familiar characteristic of allergic rhinitis. Medically it presents as: nasal blockage, sneezing and water discharge from nose (rhinorrhea). The excessive rhinorrhea on account of vasomotor and allergic rhinitis can be restrained by sectioning the Vidian nerve.
Nerve Supply of Nasal SeptumThe nasal septum gets supply from the following nerves:
- Olfactory nerves-supply the upper part (one-third) just below the cribriform plate.
- Internal nasal branch of the anterior ethmoidal nerve, a branch from nasociliary-supplies the anterosuperior part.
- Nasopalatine nerve, a branch of pterygopalatine ganglion-supplies the posteroinferior part.
- Medial posterior superior nasal branches of pterygopalatine ganglion-supply the posterosuperior part.
- Nasal branch of greater palatine nerve-supplies the posterior part.
- Anterior superior alveolar nerve, a branch of maxillary nerve-supplies the anteroinferior part.
Nerve Supply of Lateral WallThe following nerves supply the different partsof the lateral wall:
- Olfactory nerves-supply the upper part (one-third) just below the cribriform plate of ethmoid up to the superior concha.
- Anterior ethmoidal nerve (from ophthalmic)-supplies the anterosuperior quadrant.
- Anterior superior alveolar nerve, a branch of infraorbital nerve (from maxillary)-supplies the anteroinferior quadrant.
- Posterior superior lateral branches, of pterygopalatine ganglion-supply posterosuperior quadrant.
- Nasal branches of greater palatine nerve, (from pterygopalatine ganglion)-supply posteroinferior quadrant.
Evaluation of the Nasal Cavity (Rhinoscopy)The nasal cavity can be analyzed in the living individual either via the nostril (anterior rhinoscopy) or via the pharynx (posterior rhinoscopy). Anterior rhinoscopy: It’s performed by fitting a nasal speculum via a nostril. These features are visualized by this approach:
- Middle and inferior conchae.
- Superior middle and inferior meatuses.
- Nasal septum.
- Floor of the nasal cavity.
- Posterior border of the nasal septum.