The image on the right is animated. If you wait it will walk you through the openings of
the air sinuses. You can rerun it by clicking 'reload'.The nose is divided in the
midline by the nasal septum. The lateral wall of the nose is formed
into three curved projections, the conchae or turbinate bones. The cavity is lined by a mucous
membrane typical of the conducting airway of the respiratory system. In the upper part of the
chamber the epithelium is olfactory. The conchae increase the surface area of mucosa which aids
cleaning, moistening and warming of the inspired air. Below each concha is a meatus into which
drain the air sinuses and the lacrimal duct. The inferior concha is a separate bone. Into the
inferior meatus drains the nasolacrimal duct, bringing fluid from the medial corner of the eye into
the nose. Below the middle concha, a projection of the ethmoid, the frontal and maxillary sinuses
open into a groove, the hiatus semilunaris, and the anterior and middle ethmoidal sinuses open
onto a bump, the bulla ethmoidalis. Below the superior concha the posterior ethmoidal air sinuses
open into the superior meatus. Above the superior concha is the spheno-ethmoidal recess. The
sphenoidal sinus opens into this recess.
The frontal, sphenoidal, ethmoidal and
maxillary air sinuses lie in these
bones in the skull. They can be seen in a plain film of the skull,
although the sphenoid since it lies behind the others is most easily seen
in a lateral view.
The maxillary sinus
The maxillary sinus is a large chamber in the maxillary bone. The signs and symptoms of
maxillary sinusitis are due to the peculiar drainage of this sinus and its relationship to neighboring
structures. The roof of the sinus forms the floor of the orbit, and is therefore related to the
intraorbital vessels and nerves. The floor of the sinus has projections from the roots of the second
premolar and first two molar teeth. Medially the sinus is separated by a thin wall from the inferior
meatus, and drains through an opening high up into the middle meatus. The sinus drains through
ciliary action. Inhibition of the ciliary mechanism or obstruction of drainage lead to sinusitis.
Most cases of acute sinusitis are due to common cold, flu, measles, whooping cough,
dental problems, abscess or extraction.
Symptoms are pain over the sinus, often referred to the supraorbital region, aggravated by
bending coughing or walking.
Drainage of the maxillary sinus can be improved by physically clearing and widening the ostium..
If this is not successful and chronic sinusitis is present, an opening can be made into the sinus
through the thin wall of the inferior meatus. Through this opening the sinus can be drained and
washed out.
The frontal sinus
The frontal sinus lies in the frontal bone close to the midline. It is usual for the two sinuses to be
of different shapes and sizes. The sinus drains into the middle meatus. Infection of the sinus
mucosa results in pain mainly in the supraorbital area. The upper eyelid may be swollen. There is
tenderness over the sinus. In severe cases where there is increasing edema and redness of the
eyelid the sinus may be drained by passing a trephine into the chamber below the medial one third
of the eyebrow. Sinusitis in the frontal sinus has significance due to its anatomical relationships.
The posterior wall of the sinus forms the anterior wall of the anterior cranial fossa. Extension of
the infection through this wall may result in meningitis, extradural and subdural abscesses, or
cerebral abscess. Frontal sinusitis is usually an accompaniment of maxillary and ethmoidal
sinusitis.
The nasopharynx
At the back of the nasopharynx lies the opening of the eustachian tube. Infection of the nasopharynx is closely related to middle ear infection. Otitis media, acute inflammation of the middle-ear cavity is common in children. Since both middle ear chambers connect to the nasopharynx, it is usually bilateral. Infection most commonly follows an acute upper respiratory tract infection. The symptoms of otitis media are earache which may be throbbing and severe and deafness. The signs include tenderness to pressure on the mastoid process and changes in the tympanic membrane. The tympanic membrane may be bulging with loss of landmarks, or may even be perforated. The chamber of the middle ear is continuous through the eustachian tube with the nasopharynx, but also with the mastoid antrum and mastoid air cells. Infection of the mucosa lining the middle ear will extend to the mastoid air cells. Within the middle ear are the small bones, the ear ossicles, which transmit movement of the tympanic membrane to the cochlear apparatus. Infection in the middle ear can result in limitation of movement of the malleus, stapes and uncus resulting in some level of deafness. Movement of these bones is controlled normally to some extent by two muscles. The tensor tympani attaches to the malleus and the stapedius inserts on the stapes. The middle ear is usually at atmospheric pressure since the eustachian tube is open to the nasopharynx. In respiratory infection the mucosa swells and the tube becomes obstructed. If antibiotics do not control the infection and inflammation then the pressure in the middle ear can be relieved by puncturing the tympanic membrane. A myringotomy is performed by making a crescent shaped cut over the cone of light.
The adenoid mass of lymphoid tissue is situated on the posterior wall of the nasopharynx and
bulges into the cavity in children. As a result of upper respiratory infection the adenoids become
hypertrophied and obstruct the nasopharynx. Obstruction leads to mouth breathing and dry
mouth. This lymphoid tissue forms part of a ring of such tissue around the pharynx.
Adenoidectomy is carried out under general anesthesia with endotracheal intubation.
The soft palate usually closes off the nasopharynx from the oropharynx during swallowing and
speech. Removal of part of the posterior pharyngeal wall might leave a gap allowing fluid to pass
up into the nose, and speech to be altered.
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Neck Anatomy