Nares, commonly known as the nostrils, are the two external openings of the nose that function as the primary entrance for air into the respiratory system. They are the first point of contact for inhaled air, allowing for the continuous flow necessary for breathing. The nares also initiate the process that enables the sense of smell.
Location and Structure
The nares are situated on the underside of the nasal apex, the rounded tip of the nose. They are paired openings that lead directly into the nasal vestibule, the anterior-most part of the nasal cavity. A flexible wall of tissue, called the nasal septum, separates the two nares, creating two distinct air passages.
The shape and stability of the nares are maintained by surrounding cartilage, specifically the major alar cartilages. This flexible tissue allows the nostrils to open and close slightly, which is noticeable during strenuous breathing.
Essential Roles in Breathing and Sensation
The nares initiate the process of air conditioning before the air reaches the lungs. As air enters, it passes over the internal nasal hairs, or vibrissae, which provide the first line of defense by trapping large particulate matter like dust and pollen. Beyond filtration, the nares facilitate the warming and humidification of the inhaled air. The rich blood supply and mucous membranes lining the passages quickly raise the air temperature and moisture content. This conditioning process protects the delicate lung tissue from being damaged by cold, dry air.
The airflow passing through the nares is also essential for the sense of smell, or olfaction. Air carries odor molecules to the upper regions of the nasal cavity where specialized olfactory receptor neurons are located.
Health Issues and Medical Procedures
Temporary blockages of the nares, often called congestion, are common symptoms of conditions like the common cold or allergies. This temporary narrowing is caused by swelling of the internal mucous membranes. Structural abnormalities can also affect airflow, such as a deviated septum, where the dividing wall is crooked and restricts one passage more than the other.
Narrowed nares or nasal valve collapse can sometimes be corrected surgically to improve breathing function. Procedures like septoplasty and rhinoplasty adjust the internal structure and supporting cartilage to maximize air intake. Furthermore, the nares are frequently used as access points for medical purposes, such as administering nasal spray medications or collecting samples for diagnostic tests like nasal swabbing.