Henry Gray (18251861). Anatomy of the Human Body. 1918.
With the laryngoscope many other structures can be seen. In the nasal part of the pharynx (Fig. 1203), the choanæ, the nasal septum, the nasal conchæ, and the pharyngeal ostia of the auditory tubes can all be examined. Further down, the base of the tongue, the anterior surface of the epiglottis with the glossoepiglottic and pharyngoepiglottic folds bounding the valleculæ, and the piriform sinuses, are readily distinguished. Beyond these is the entrance to the larynx, bounded on either side by the aryepiglottic folds, in each of which are two rounded eminences corresponding to the corniculate and cuneiform cartilages.
Within the larynx (Fig. 1204) on either side are the ventricular and vocal folds (false and true vocal cords) with the ventricle between them. Still deeper are seen the cricoid cartilage and the anterior parts of some of the cartilaginous rings of the trachea, and sometimes, during deep inspiration, the bifurcation of the trachea.
The Eye.The palpebral fissure is elliptical in shape, and varies in form in different individuals and in different races of mankind; normally it is oblique, in a direction upward and lateralward, so that the lateral commissure is on a slightly higher level than the medial. When the eyes are directed forward as in ordinary vision the upper part of the cornea is covered by the upper eyelid and its lower margin corresponds to the level of the free margin of the lower eyelid, so that usually the lower three-fourths are exposed.
At the medial commissure (Fig. 1205) are the caruncula lacrimalis and the plica semilunaris. When the lids are everted, the tarsal glands appear as a series of nearly straight parallel rows of light yellow granules. On the margins of the lids about 5 mm. from the medial commissure are two small openingsthe lacrimal puncta; in the natural condition they are in contact with the conjunctiva of the bulb of the eye, so that it is necessary to evert the eyelids to expose them. The position of the lacrimal sac is indicated by a little tubercle which can be plainly felt on the lower margin of the orbit; the sac lies immediately above and medial to the tubercle. If the eyelids be drawn lateralward so as to tighten the skin at the medial commissure a prominent core can be felt beneath the tightened skin; this is the medial palpebral ligament, which lies over the junction of the upper with the lower two-thirds of the sac, thus forming a useful guide to its situation. The direction of the nasolacrimal duct is indicated by a line from the lacrimal sac to the first molar tooth of the maxilla; the length of the duct is about 12 or 13 mm.
FIG. 1205 Front of left eye with eyelids separated to show medial canthus. (See enlarged image)
On looking into the eye, the iris with its opening, the pupil, and the front of the lens can be examined, but for investigation of the retina an ophthalmoscope is necessary. With this the lens, the vessels of the retina, the optic disk, and the macula lutea can all be inspected (Fig. 1206).
On the lateral surface of the nasal part of the frontal bone the pulley of the Obliquus superior can be easily reached by pushing the finger backward along the roof of the orbit; the tendon of the muscle can be traced for a short distance backward and lateralward from the pulley.