Human Anatomy and Physiology - N. I. Fedyukovich 2003

Internal Organs
Respiratory System
Nasal Cavity

The Nasal cavity (cavitas nasi) is the initial section of the respiratory tract and, at the same time, the Organ of Smell. As air passes through the nasal cavity, it is either cooled or warmed, humidified, and filtered. The nasal cavity is formed by the External Nose and the BONES OF THE facial Skeleton, and is divided by a septum into two symmetrical halves. Anteriorly, the nostrils serve as the entrance to the nasal cavity, while posteriorly, it connects to the nasopharynx via the choanae. The nasal septum consists of membranous, cartilaginous, and bony parts. Within each half of the nose, a nasal vestibule is distinguished. Internally, it is lined with Skin continuous with that of the external nose, containing Sweat Glands, Sebaceous Glands, and coarse hairs (vibrissae) that trap dust particles. Projecting from the lateral wall into the lumen of each half of the nose are three curved bony plates: the superior, middle, and inferior nasal conchae. They divide the nasal cavity into narrow, interconnected passages called nasal meatuses.

A distinction is made between the superior, middle, and inferior nasal meatuses, which are located beneath the corresponding nasal conchae. The Paranasal Sinuses and cranial canals open into each nasal meatus: the openings of the Ethmoid bone, the sphenoid, maxillary (Highmore's), and frontal sinuses, and the nasolacrimal duct. The nasal mucosa is continuous with the mucous membrane of the paranasal sinuses, the lacrimal sac, the nasopharynx, and the soft palate. It is tightly fused with the periosteum and perichondrium of the nasal cavity walls and is lined with epithelium containing numerous goblet Cells, mucous glands, Blood Vessels, and nerve endings.

The olfactory neurosensory (sensory) cells are located in the superior nasal concha, partially in the middle concha, and in the upper section of the septum. From the nasal cavity, air enters the nasopharynx and then passes into the oral and laryngeal PARTS OF THE Pharynx (oropharynx and laryngopharynx), where the opening of the Larynx is located. The digestive and respiratory tracts cross in the pharynx; air can also enter this region through the Mouth.