Nose

The nose is the facial feature located at the center of the face and is the primary gateway for air entering the body. It has two nostrils (passages) through which air flows, and an internal cavity called the nasal cavity. The nose performs two main functions: breathing and smell (olfaction).

Structurally, the nose comprises bone in its upper portion and cartilage—a firm, inflexible tissue—in its lower portion and sides. This is why the upper part fractures easily when struck, while the lower part flexes.

Anatomy

The nasal cavity is divided by a central septum made of bone and cartilage. Inside are scroll-like structures called turbinates, which increase the internal surface area to allow air to be filtered. The inner surface is lined with sensitive mucous membrane (mucosa) that secretes mucus.

The nose connects to air-filled cavities within the facial and skull bones, known as sinuses. These passages allow air to move through the nose and affect voice production. When sinuses become infected, a condition called sinusitis develops.

The function of breathing

When air is breathed through the nose, three processes occur: air is filtered, it is warmed, and particles and microorganisms are removed. Tiny hairs (cilia) and mucus trap these particles, then move them toward the throat where they are swallowed or expelled. Mouth breathing bypasses this filtering, allowing cold, unfiltered air to reach the lungs.

The sense of smell

In the upper part of the nasal cavity lies a small area of sensory tissue called the olfactory epithelium. When odor molecules contact this tissue, they stimulate its cells, and the signal travels through the olfactory nerve directly to the brain. Smell plays a significant role in taste—when the nose is blocked, the taste of food diminishes.

Common conditions

Nasal disorders include: cold and flu causing congestion, allergic rhinitis, nosebleeds (epistaxis), deviated septum, and nasal polyps that obstruct airflow. Nasal fracture is one of the most common facial bone injuries.