The nasal nares, commonly known as nostrils, are the two external openings of the human nose. They serve as the initial point of entry and exit for air into and out of the respiratory system, leading to the complex internal structures of the nasal cavity.
Anatomy of the Nares
The nasal nares are situated at the bottom, rounded tip of the nose, known as the nasal apex. These openings are separated by the lower part of the nasal septum, a structure of bone and cartilage that divides the nasal cavity into two halves. Flexible alar cartilages provide the primary structure and support to the nostrils, allowing them to dilate and constrict.
The external nose has a bony bridge and a cartilaginous lower part. The major alar cartilage forms the nasal apex, while minor alar cartilages support the ala nasi, or the wings of the nostrils. These structures connect the external openings to the nasal vestibule, the most anterior part of the nasal cavity, which is lined with tissue containing short, coarse hairs.
Primary Functions
The nasal nares serve as the entry point for air into the respiratory system. As air passes through the nostrils and into the nasal cavity, it undergoes warming, moistening, and filtering before reaching the lungs. This preparation helps protect the delicate tissues of the respiratory tract.
Tiny hairs, or cilia, and mucous membranes lining these passages trap dust, pollen, and other airborne particles, preventing them from entering the lower respiratory system. This filtering action is an important defense against irritants and pathogens. The nasal nares also play a role in the sense of smell, or olfaction, as odor molecules enter through these openings to reach specialized nerve cells within the nasal cavity.
Common Issues and Variations
The shape and size of nasal nares vary among individuals, but these variations generally do not affect their function. Temporary blockages are common, often caused by increased mucus production due to allergies, colds, or mild irritants.
Allergic reactions can lead to inflammation and swelling of nasal tissues, resulting in a stuffy or runny nose, sneezing, and congestion. During physical exertion, such as exercise, the nostrils may flare to allow for increased airflow. While most issues are temporary and resolve on their own, persistent congestion may indicate an underlying condition requiring attention.