Endoscopic views of the ostia and ostia-like structures in the lateral nasal wall.

Any surgeon who performs endoscopic sinus surgery must recognize the anatomy of the many ostia and ostia-like structures located in the lateral nasal wall. During surgery, it is important to visualize these ostia, ensure their patency, and alleviate obstructions when indicated.

Most of the ostia represent drainage sites of the paranasal sinuses and related cells. The two most inferior ostia represent the openings of the nasolacrimal duct and the eustachian tube. In the accompanying videographic montage, all nine of the ostia of the lateral nasal wall are displayed as they appeared during actual endoscopic sinus surgery (figure):

[FIGURE OMITTED]

Nasolacrimal duct ostium. The ostium of the nasolacrimal duct is usually located in the anterosuperior portion of the lateral wall of the inferior meatus. (1,2) The shape of the opening varies considerably, from round to slit-like. The ostium is usually protected by a fold of mucous membrane called Hasner's valve. The easiest way to identify the opening of the nasolacrimal duct is to put light digital pressure on the lacrimal sac at the medial canthus while simultaneously observing the inferior meatus with the endoscope. This pressure usually expresses a few tears from the opening of the nasolacrimal duct. (3)

Accessory maxillary sinus ostium, This ostium is present in approximately 30% of the population. (1) It is located in the lateral wall of the middle meatus, usually in the anterior or posterior fontanelle where the medial wall of the maxillary sinus is membranous. The size and shape of the accessory ostia vary considerably; most are round or oval. The accessory ostium may be responsible for the recirculation phenomenon in which maxillary sinus secretions pass via ciliary transport through the natural maxillary ostium and immediately back into the sinus via the accessory ostium. Surgical correction involves connecting these ostia. (2,3)

Frontal recess. The frontal recess is located in the middle meatus in the most superomedial portion of the anterior ethmoid complex that leads to and communicates with the frontal sinus. (2,3) Excessive manipulation of this area should be avoided if possible to prevent scar formation and resultant obstruction.

Natural maxillary sinus ostium. This ostium is located within the ethmoid infundibulum; it is hidden by the uncinate process in the middle meatus. To find this ostium, the uncinate process must be removed with a back-biting forceps and a microdebrider. This will expose the entire ethmoid infundibulum. (4) The natural ostium can be visualized in the ethmoid infundibulum with a 0[degree] telescope. A 30[degree] telescope will clearly show the entire natural ostium. Most of these ostia are round or oval. (2,3)

Ethmoid bulla ostium. The location of the ethmoid bulla ostium varies. The telescopic view reproduced in the figure shows the inside lumen of the right ethmoid bulla following the removal of its anterior wall. in this case, the ostium was located in the posterosuperior portion of the medial wall of the ethmoid bulla. (5,6) Note that a Lusk ball probe was passed from the hiatus semilunaris superiorly into the ethmoid bulla through its patent ostium.

Concha bullosa ostium. The concha bullosa of the middle turbinate sometimes drains through the opening of the superior portion of the lateral wall of the concha bullosa. (7) In other cases, the concha bullosa drains directly into the ethmoid sinus.

Sphenoid sinus ostium. The sphenoid sinus ostium is usually located in the sphenoethmoid recess between the superior turbinate and the nasal septum. The ostium may be round, oval, or slit-like. (1-3) The sphenoid sinus ostium opens in the superior portion of the anterior wall of the sphenoid sinus approximately 15 mm from the floor of the sinus. (1-3,8) Accordingly, when performing a sphenoidotomy, the surgeon should enlarge the sphenoid sinus inferiorly from the ostium. Great caution must be exercised when working superiorly or laterally to the ostium because the neurovascular structures are situated superolaterally.

Posterior ethmoid sinus ostium. The posterior ethmoid sinus ostium is usually situated in the narrow space of the superior meatus between the superior and middle turbinates. (1) If a supreme turbinate is present, the ostium may be found in the supreme meatus. Its shape may be round, oval, or slit-like.

Eustachian tube orifice. The eustachian tube orifice is situated just posterior to the posteriormost portion of the inferior meatus of the nose. It opens during phonation "k" and becomes triangular. This orifice may be obstructed by adenoidal hypertrophy, choanal polyps, or neoplasms; such an obstruction can result in serous otitis media.

From the Southern New England Ear, Nose, Throat, and Facial Plastic Surgery Group, New Haven, Conn., the Section of Otolaryngology, Hospital of St. Raphael, New Haven, and the Section of Otolaryngology, Yale University School of Medicine, New Haven (Dr. E. Yanagisawa and Dr. K. Yanagisawa); the Department of Otolaryngology, University of South Florida College of Medicine, Tampa, and the Halifax Medical Center, Daytona Beach, Fla. (Dr. Christmas); and WENT Studio, Woodbridge, Conn. (Mr. R. Yanagisawa).

References

(1.) Hollinshead WH. Anatomy for Surgeons, 2nd ed. Vol. 1. The Head and Neck. New York: Harper and Row, 1968.

(2.) Yanagisawa E. Atlas of Rhinoscopy: Endoscopic Sinonasal Anatomy and Pathology. San Diego: Singular Thomson Learning, 2000.

(3.) Stammberger HR. Functional Endoscopic Sinus Surgery: The Messerklinger Technique. Philadelphia: B.C. Decker, 1991.

(4.) Christmas DA, Yanagisawa E, Joe JK. Transnasal endoscopic identification of the natural ostium of the maxillary sinus: A retrograde approach. Ear Nose Throat J 1998;77:454-5.

(5.) Yanagisawa E, Joe JK, Christmas DA. Where is the ostium of the ethmoid bulla? Ear Nose Throat J 1999;78:886-7.

(6.) Hechl PS, Setliff RC III, Tschabitscher M. Endoscopic Anatomy of the Paranasal Sinuses. New York: Springer Verlag, 1997.

(7.) Yanagisawa E, Mirante JP, Christmas DA. An unusual lateral ostium of a concha bullosa of the middle turbinate. Ear Nose Throat J 2003;82:159-60.

(8.) Yanagisawa E, Yanagisawa K, Christmas DA. Endoscopic localization of the sphenoid sinus ostium. Ear Nose Throat J 1998;77: 88-9.