Turbinated

Generality

The turbinates, or nasal horns, are small lateral bony protrusions of the nasal septum, covered by erectile-cavernous vascular tissue (more internally) and by ciliated respiratory mucosa (more externally).
Arranged horizontally and one above the other, the turbinates are generally three for each nostril: the turbinate that lies higher than all is the superior turbinate; the turbinate located in the middle is called the middle turbinate; finally, the turbinate that resides lowest of all is the inferior turbinate.
The particular anatomy of the turbinates creates, inside the nasal nostrils, an extended contact surface between the inhaled air and the respiratory mucosa of the turbinates themselves.

The turbinates play a very important role in the breathing process. In fact, they contribute to the heating, purification and humidification of the air inspired by the nose and directed to the lungs.
Furthermore, turbinates also have an immunological function, as one of its coatings hosts cells of the immune system.
The most important pathology involving the turbinates is the so-called hypertrophy of the turbinates.

What are the turbinates?

The turbinates, or nasal horns, are lateral bony protrusions of the nasal septum, located inside the two nasal cavities and lined with vascular tissue and respiratory mucosa.

Anatomy

The turbinates protrude from the bony structure that makes up the nasal septum. The nasal septum is the vertical osteo-cartilage lamina, which separates the two nasal cavities and whose linearity guarantees the correct flow of air inside both nostrils.
For each nasal cavity, there are 3 turbinates, arranged horizontally, one above the other: the turbinate that lies higher than all is the superior turbinate; the turbinate located in the middle is called the middle turbinate; finally, the turbinate that resides lowest of all is the inferior turbinate.

• Superior turbinate: it is an offshoot of the skull bone called the ethmoid (or ethmoid bone). Due to its particular position, it guarantees protection to the olfactory bulb.
• Middle turbinate: like the superior turbinate, it is an offshoot of the ethmoid. However, compared to the superior turbinate, it has larger dimensions.
  In terms of length, it is comparable to a little finger on a human's hand.
  A large part of the inspired air passes between the middle turbinate and the inferior turbinate.
• Inferior turbinate: unlike the other two turbinates, it is a bone in its own right, which articulates with the maxillary bone.
  Typically, it is as long as the index finger of a human's hand.
  From a functional point of view, it probably represents the most important turbinate.

The particular anatomy of the turbinates means that the contact surface between the inspired air and the turbinates themselves is considerable.

The considerable contact surface between inspired air and turbinates plays a fundamental physiological role (see the chapter dedicated to functions).

HISTOLOGY OF TURBINATES

The turbinates have a double covering: an external covering, in direct contact with the inhaled air in the nose, and an internal covering, underneath the previous one.

• The outer lining of the turbinates is a ciliated respiratory epithelium, having the ability to secrete mucus. In other words, it is a mucous membrane provided with cilia.
  Similar in fact to the mucosa that covers the outermost layers of the airways to the lungs, the ciliated respiratory epithelium of the turbinates has a thickness varying between 2 millimeters (upper turbinates) and 5 millimeters (lower turbinates).
• The inner lining of the turbinates, underlying the respiratory mucosa, is a highly vascularized (hypervascularized) erectile-cavernous tissue (similar to that of the penis).
  Like all blood vessels in the human body, the blood vessels of the erectile-cavernous tissue of the turbinates can, as a result of specific stimuli, dilate (swelling the turbinates) or narrow (deflating the turbinates).

CHANGES

In some individuals, a fourth pair of turbinates is present above the upper pair of turbinates: the so-called supreme turbinates. Generally, the supreme turbinates are small bony ridges with unclear functions.

Function

The turbinates play an important role in the breathing process, contributing in a decisive way to the heating, purification and humidification of the air inspired and directed to the lungs.

• Warm up: the heating action of the air belongs to the complex and wide network of blood vessels, which distinguishes the erectile-cavernous tissue forming the internal lining of the turbinates.
• Purification and humidification: the purification and humidification actions of the air belong, respectively, to the cilia and the respiratory mucosa, constituting the external lining of the turbinates. In fact, the cilia block impurities, while the respiratory mucosa produces mucus.

The efficiency in the actions of heating, purification and humidification is due to the large contact surface that the turbinates make available to the inhaled air. In fact, a large contact surface prolongs the permanence of the air in the cavities that house the turbinates, thus ensuring sufficient time for a correct heating, purification and humidification action.

IMMUNOLOGICAL ROLE OF TURBINATES

The turbinates also have an immunological role.
In fact, several medical studies have shown that the respiratory epithelium of the turbinates is home to cells of the immune system.
The presence of immune cells on the respiratory epithelium guarantees an effective defense against possible bacteria, viruses and other pathogens, which could populate the inhaled air with the nose.

Associated pathologies

The turbinates are the protagonists of a well-known condition, which doctors call turbinate hypertrophy.

WHAT IS THE HYPERTROPHY OF THE TURBINATES AND WHAT SYMPTOMS DOES IT CAUSE?

Turbinate hypertrophy is the result of chronic and permanent swelling of the ciliated respiratory mucosa of the turbinates. This swelling leads to a reduction in the space available for normal nasal breathing, so those suffering from turbinate hypertrophy develop symptoms such as:

• Stuffy nose, which causes you to breathe through your mouth;
• Dry mouth
• Leakage of serous material from the nose (runny nose)
• Decreased sense of smell (hyposmia);
• Nasal itching;
• Tendency to snoring and sleep apnea.

• Feeling of bad breathing
• Pain in the root of the nose
• Sneezing
• Nosebleeds (epistaxis)
• Halitosis
• Nasal or metallic voice (rhinolalia)
• Headache (headache)
• Reduced hearing (hypoacusis)
• Muffling of the ear
• Dry and irritating cough

CAUSES OF THE HYPERTROPHY OF THE TURBINATES

The mucosa of the turbinates reacts to certain stimuli - such as changes in humidity or temperature, irritants, viral or bacterial infections, etc. - with dilation.
In the presence of healthy turbinates, the mucosa deflates and returns to its normal appearance as soon as the stimulus ends.
On the other hand, in the presence of an "anomaly affecting the turbinates and the mechanism that regulates their dilation, the mucosa remains permanently swollen, despite the fact that the stimulus ceases.
To alter the behavior of the turbinates, in response to certain stimuli, can be conditions such as allergic rhinitis, vasomotor rhinitis, deviation of the nasal septum (deviated nasal septum) and chronic exposure to irritants (eg: cigarette smoke, etc.).