Nose, Sinuses and Smell

04 May 2024
Nose, Sinuses and Smell

Smell is often considered the least important of all the senses, but it may be one of the oldest, and probably acts on the subconscious more than the other senses.

Most of the nose is concerned with filtering and providing a passage for air on its way to the lungs. The walls of the nasal cavity enable both these functions. In particular, the nasal conchae are filled with mucosal respiratory membranes coated in cilia-tiny hair-like cells that act to move waves of mucus toward the throat. These protections trap inhaled bacteria, dirt, viruses, and chemical particles in the mucus. The cilia and swallowing action then serve to sweep the allergens and infectious agents into the back of and down the throat for destruction (digestion) in the stomach.

A limited portion of the nose and nasal cavity is further dedicated to the sense of smell, through its olfactory organs. These olfactory sense organs are located beneath the bridge of the nose atop the nasal cavity. These organs, the olfactory membranes, are to be found in two clefts there and can be identified as a small grey or yellow patch of tissue.

Of course, we always smell something, and most airflow passes through the nose during normal breathing. This allows a limited fraction of the inhaled air to reach the olfactory clefts, yet is sufficient to trigger an olfactory response. Even more effective is when a person forcefully sniffs at an odor, quickly drawing air into the nose. The increased speed alters the direction of airflow, drawing more of the scent toward the sensors of the olfactory clefts.

The sinuses of the face, sometimes called the paranasal sinuses, are air pockets within the bones of the skull located behind and beside the nose, cheeks, and eye sockets. The roles played by the sinuses within the head are debated. However, there is little doubt about the role of scents in human behavior. The human nose can remember 50,000 different smells, and the body is provided with glands to produce specific odors, many of which appear to be associated with sexual attraction and excitement, and others that have considerable significance as well. The bond between a baby and its mother is thought to be tightened by a form of scent imprinting.

Maxillary Sinus

The maxillary sinus, also known as the antrum of Highmore, is the largest of the sinuses--air-filled spaces that extend from the floor of the orbits to the roots of the upper teeth.

Opening of Maxillary Sinus

The opening of the maxillary sinus enters into these largest of the sinuses, air-filled spaces that extend from the floor of the orbits to the roots of the upper teeth.

Ethmoid Sinus

The ethmoid sinus is actually a pair of paranasal sinuses. They help filter the air that goes into the nasal cavity. These are located inside the ethmoid bone, which consists of ethmoidal air cells. There are three groups of the ethmoidal air cells: posterior, middle, and anterior. The cells are made up of a lot of cavities that have thin walls that reside in the ethmoidal labyrinth and are finished by the maxilla, frontal, lacrimal, palatine, and sphenoidal bones. They rest amid the top portion of the orbits and the nasal cavities, and thin and bony laminae keep them apart from the cavities.

Frontal Sinus

The frontal sinus is located in the frontal bone above each eye. They are air spaces lined with mucous membranes and located above each orbit.