This section is from the book "Applied Anatomy: The Construction Of The Human Body", by Gwilym G. Davis. Also available from Amazon: Applied anatomy: The construction of the human body.
The pharynx is the common air and food tract that lies behind the nose, mouth, and larynx. It extends from the base of the skull above to the oesophagus below. Its lower end is at the cricoid cartilage, which is opposite the sixth cervical vertebra. In passing an instrument directly backward through the nose, one strikes the base of the skull or interval between the basilar process and the atlas. In looking into the throat through the mouth, one is level with the body of the second vertebra. If, by means of a hook, the soft palate is raised or pushed aside and the head tilted slightly backward one sees the anterior tubercle of the atlas. The rounded projection can readily be felt. The pharynx has seven openings into it, viz.: the two posterior nares, the two Eustachian tubes, the mouth, the larynx, and the oesophagus.
These can readily be seen by means of the rhino-scopic mirror. They are separated by the posterior edge of the bony septum, the vomer bone. They are 2.5 cm. (1 in.) long and 1.25 cm. wide, hence are of sufficient size to allow a well lubricated little finger to pass into them from the anterior nares. The tip of an index finger can be inserted through the mouth below, hence the entire length of the lower meatus of the nose and upper surface of the soft palate can be palpated.
Projecting from each lateral wall toward the septum are the rounded posterior ends of the middle and inferior turbinated bones. Sometimes, high up, the posterior end of the superior turbinate can be seen. The posterior end of the inferior turbinate is frequently enlarged by a swelling of its membrane, forming a posterior turbinate hypertrophy. Not only does the mucous membrane of the inferior turbinate bones become enlarged, but that on the septum likewise. This constitutes hypertrophy or thickening of the septum. A polypus may project from the nasal cavities backward into the throat. I removed a very large one by pushing it with the finger into the pharynx and then dragging it out of the mouth.
Fig. 147. - Lateral view of pharynx and larynx.
The posterior nares are quite a distance anterior to the edge of the soft palate, hence it is extremely difficult to make applications by way of the mouth. A much easier way is to make them through a tube introduced into the nose, or even, as when the electrocautery is used, without a protecting tube.
On each side, at a point about opposite the inferior turbi-nals, are the orifices of the Eustachian tubes with the fossa of Rosenmiiller above. The Eustachian tube runs from the upper portion of the pharynx to the middle ear, opening just behind the tympanic membrane, on the anterior wall. It is about
4 cm. long, 2.5 cm. being cartilaginous (pharyngeal portion) and 1.5 cm. being bony. At the junction of the bony and cartilaginous portions the lumen is slightly diminished, forming the isthmus. The tube runs upward, backward, and outward.
The mucous membrane of the throat is continuous with that lining the tube and tympanum, therefore inflammation of the pharynx travels up the tube and affects the middle ear. This is the manner in which earache or inflammation and suppuration of the middle ear is produced. This also explains why impairment of hearing so often accompanies or follows sore throat. When the tube is in a healthy condition, the air finds free access to the ear, in swallowing, sneezing, etc. This is readily demonstrated by closing the nostrils and swallowing, when the pressure of air outside the ear drum will be distinctly felt. When inflammation affects the lining membrane it swells and blocks up the tube and prevents the tree access or air to the ear. If the swelling is not too great, air can be forced from the throat to the ear by three different means. The distention of the middle ear by air is called inflating it. The method of Valsalva consists in holding the nostrils and mouth shut and blowing. If the air enters the middle ear, the tympanic membranes will be felt to bulge outward. The method of Politzer is to have the patient hold a small quantity of water in the mouth. The nozzle of a rubber bag is introduced into one nostril, closing both nostrils with the fingers and thumb of the unengaged hand. On telling the patient to swallow, the bag is compressed and the air enters the Eustachian tube. As the patient swallows, the tensor palati muscle opens the mouth of the tube and as the bag is compressed the air rushes up the tube. Sometimes the vapors of ether, chloroform, etc., are used. The third method is by the Eustachian catheter.
Fig. 148 - Rhinoscopic mirror in position. A view can be obtained of the vault of the pharynx and posterior nares.
Fig. 149. - Palpation of the posterior nares and pharyngeal tonsil.
Fig. 150. - View of posterior nares in the pharyngeal mirror.
The Eustachian catheter is a small, hard rubber or silver tube, slightly bent at the extremity and long enough to reach from the anterior nares in front to the posterior wall of the pharynx. The end of the catheter having been inserted into the mouth of the Eustachian tube, air is blown in with the Politzer air-bag. By means of a rubber tube going from the patient's ear to the surgeon's ear, the air can be heard entering the middle ear.
Fig. 151. - Anteroposterior frozen section, showing a lateral view of the pharynx and the relation of the various neighboring structures.