anatomy Anatomy () is the branch of biology concerned with the study of the structure of organisms and their parts. Anatomy is a branch of natural science that deals with the structural organization of living things. It is an old science, having its ...

, the term nasal meatus can refer to any of the three meatuses (passages) through the

skull The skull is a bone protective cavity for the brain. The skull is composed of four types of bone i.e., cranial bones, facial bones, ear ossicles and hyoid bone. However two parts are more prominent: the cranium and the mandible. In humans, t ...

nasal cavity The nasal cavity is a large, air-filled space above and behind the nose in the middle of the face. The nasal septum divides the cavity into two cavities, also known as fossae. Each cavity is the continuation of one of the two nostrils. The nasal ...

: the superior meatus (''meatus nasi superior''), middle meatus (''meatus nasi medius''), and inferior meatus (''meatus nasi inferior''). The nasal meatuses are located beneath each of the corresponding nasal conchae. In the case where a fourth,

supreme nasal concha The supreme nasal concha or highest nasal concha is a nasal concha (turbinate) that occurs in some cases. It is shaped like a seashell and found on the posterosuperior part of the lateral nasal wall.Supreme nasal concha. (n.d.) ''Medical Dictionary ...

is present, there is a fourth supreme nasal meatus.

Structure

The superior meatus is the smallest of the three. It is a narrow cavity located obliquely below the

superior concha The superior nasal concha is a small, curved plate of bone representing a medial bony process of the labyrinth of the ethmoid bone. The superior nasal concha forms the roof of the superior nasal meatus. Anatomy Anatomical relations The superi ...

. This meatus is short, lies above and extends from the middle part of the

middle concha The medial surface of the labyrinth of ethmoid consists of a thin lamella, which descends from the under surface of the cribriform plate, and ends below in a free, convoluted margin, the middle nasal concha (middle nasal turbinate). It is rough, ...

below. From behind, the sphenopalatine foramen opens into the cavity of the superior meatus and the meatus communicates with the posterior ethmoidal cells. Above and at the back of the

is the

sphenoethmoidal recess The sphenoethmoidal recess is a small space in the nasal cavity into which the sphenoidal sinus and posterior ethmoid sinus open. It lies posterior and superior to the superior concha The superior nasal concha is a small, curved plate of bone r ...

which the sphenoidal sinus opens into. The superior meatus occupies the middle third of the nasal cavity’s lateral wall. The middle meatus is the middle-sized and located nasal opening, lying underneath the middle concha and above the inferior concha where the meatus extends along its length. On it is a curved fissure, the hiatus semilunaris, limited below by the edge of the uncinate process of the ethmoid and above by an elevation named the bulla ethmoidalis; the middle ethmoidal cells are contained within this bulla and open on or near to it. Through the hiatus semilunaris the meatus communicates with a curved passage termed the infundibulum, which communicates in front with the anterior ethmoidal cells and in rather more than fifty percent of skulls is continued upward as the frontonasal duct into the frontal air-sinus; when this continuity fails, the frontonasal duct opens directly into the anterior part of the meatus. Below the bulla ethmoidalis and hidden by the uncinate process of the ethmoid is the opening of the

maxillary sinus The pyramid-shaped maxillary sinus (or antrum of Nathaniel Highmore (surgeon), Highmore) is the largest of the paranasal sinuses, and drains into the middle meatus of the nose through the osteomeatal complex.Human Anatomy, Jacobs, Elsevier, 2008, ...

(ostium maxillare); an accessory opening is frequently present above the posterior part of the inferior nasal concha. The inferior meatus is the largest of the three. It lies below the inferior concha and above the nasal cavity. It extends most of the length of the nasal cavity’s lateral wall. It is broader in the front than at the back, and presents anteriorly the lower orifice of the nasolacrimal canal.

References

External links

* * — Coronal section {{Authority control Nose