Nose and Nasal Cavity

The external nose is supported by the frontal bone, nasal bones, and maxillae, supplemented by a cartilaginous framework including septal nasal cartilage, lateral nasal cartilage, and alar cartilage. This hyaline cartilage composition provides the external nose with flexibility. The nostrils, or external nares, serve as the entrance to the nasal vestibules.

The superior, middle, and inferior conchae divide the nasal cavity into grooves called meatuses, which increase the internal nose's surface area. As inhaled air circulates around these structures, it is warmed and moistened by mucus secreted by goblet cells. This expanded surface area prevents dehydration and allows dust particles to be trapped in mucus.

The nasal vestibules are lined with skin containing coarse hairs that filter larger dust particles from inhaled air before it enters the nasal cavity. This initial filtration stage protects deeper respiratory structures. Smaller particles are subsequently trapped in mucus within the nasal cavity and moved toward the pharynx by ciliary action.

The paranasal sinuses are hollow, mucous membrane-lined spaces located in the frontal, sphenoid, ethmoid, and maxillary bones surrounding the nasal cavity. These sinuses release mucus into the nasal cavities, contributing to air conditioning and particle filtration. They also modify vibrations of speech, enhancing communication by creating resonating chambers.

The nasal cavity is divided into right and left sections by the nasal septum. Located below the nasal bone and above the oral cavity, it connects posteriorly to the pharynx through paired internal nares. The nasal cavity's lateral walls are formed by the ethmoid, maxillae, lacrimal, palatine, and inferior nasal conchae bones.

The nasal cavity is divided into a larger inferior respiratory region and smaller superior olfactory region. The respiratory region is lined with respiratory epithelium containing goblet cells that secrete mucus for air conditioning. The olfactory epithelium contains olfactory receptor cells, supporting cells, and basal cells with cilia but lacks goblet cells, enabling smell detection.

The nose serves as the primary passageway for air entering the respiratory system, conditioning incoming air through warming and moistening. It filters dust particles and enables smell detection through olfactory receptors. Additionally, the nose modifies speech vibrations through its resonating chambers, contributing to communication while preparing air for deeper respiratory structures.