Glands inside human vocal folds

Glands in human vocal folds
- Pointed presentation of the finding and the ways and wrong turns to its
determination -
E. W. Grundmann
At the end of the 19th century there was a debate as to whether the vocal folds had
glands or not. The database was weak. No one had made complete series of sections
through a sufficient number of vocal folds. There was no clear definition – in the
literal sense of the word – what the “vocal fold” actually was. With "vocal cord",
"vocal string", "vocal chord / chorda vocalis" some meant the entire vocal fold, the
plica vocalis of today's nomenclature, others the lig. vocale or the "edge", the "free
edge" of the vocal fold.
It was noticed that compound mucous glands (later identified as tubulo-alveolar) are
abundant throughout the respiratory epithelium (stratified ciliated epithelium with
interspersed goblet cells), but few or none depending on which sections one
happened to be looking at the edge of the vocal fold with its non-keratinizing
stratified squamous epithelium, which also has no goblet cells.
The dispute led to a certain precision and calming of minds when it was agreed:
there would be no glands on the narrow strip on the "free edge" / "edge" of the vocal
fold, on the other hand right next to it on the upper side of the vocal fold towards the
ventriculus laryngis and down towards the conus elasticus and trachea in the ciliated
epithelium there they would very well exist.
A teleological and utilitarian theory was immediately at hand: Because the edge of
the vocal folds was considered to be free of glands, it must be sprinkled from above,
from the ventriculus laryngis or from the ventricular folds. At that time, the transport
routes of the cilia stream from the bottom up in the trachea were just as unknown as
the glands in the edge of the vocal folds.
The glandless strip has been referred to as "free margin", "ridge-bearing", "papillarybearing",
"crest-bearing", and "squamous epithelium bearing free margin of the vocal
fold". In the term "bearing papillae" (which are in fact fibrous crests) as well as in the
assertion that there are no glands, there is the oldest sin of science, namely to assert
more than is known. It had been seen on transverse sections through the plica vocalis
that the ligamentum vocale had a humped surface at the edge, while contiguously

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higher up and on the lower slope it was smooth-bordered. Without further ado, the
humps were declared to be papillae. It was only when someone made the effort of
looking at a couple of cuts side by side in series that it turned out that the supposed
humps were small elongated relief stripes, which from then on were called ridges or
crests. One can assume that they better anchor the mucous membrane to its substrate
through interlocking in an area of high mechanical stress caused by vibrations
during voice production. In the meanwhile theses structures disappeared out of the
English literature – you’ll find them in the anatomy textbook of v. LANZ and
WACHSMUTH.
With the culture shock of World War II, the hard-won concession of glands in the
vocal folds, albeit with the exception of their "free rim," was lost again. The old
theory of drizzled glandless "vocal cords" was out of the bottle again and on the rise.
In science, a thesis is valid until it is falsified. The chance of falsification through
cysts on the vocal folds was wasted because these uncomfortable structures were
summarily declared to be mysterious spreads of germs, since they were not simply
allowed to be retentions of glands that had been denied.
The data situation changed when Hermann Voss found a glandular body in the vocal
ligament in 1965, however, their perception in the professional world did not. The
dissertation he supervised (1967) on the subject revealed:
The bodies of tubulo-alveolar mucous glands as well as their excretory ducts and
orifices can be found in the free edge of the vocal folds, in the area of the fibrous
crests of the vocal ligament and the squamous epithelium. Exceptionally, a glandular
body is deeply embedded in the vocal ligament. The glands and their duct orifices lie
in the upper and lower part of the strip of squamous epithelium and right at its free
marginal edge. The excretory ducts are directed towards the edge of the vocal fold.
Their frequency is lower towards the middle of the vocal folds (longitudinal section)
and towards the edge (cross-section). 10 human right-sided vocal folds were
examined and an average of 29 glandular openings were found within the edge strip.
In the anatomical nomenclature there is a consensus today: The vocal fold (Plica
vocalis) has a triangular shape in cross section. It consists of the M. vocalis, the
overlying Lig. vocale (vocal cord in the narrower sense), which merges downwards
into the Conus elasticus and has ridges or crests on its edge. Above this there is
mucous membrane consisting of non-keratinizing, multi-layered squamous

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epithelium with the special sub-epithelial REINKE space. The term "vocal cord" for
the whole structure is popular speech and should be avoided by doctors.
Figure 1 Distribution of orifices of glandular ducts in the squamous
epithelium area of vocal fold
References
Figure 2 Vocal fold, frontal (cross)
section: Gland and duct in the squamous
epithelium area
VOSS, H.: Beobachtungen über das Vorkommen von Drüsen im Ligamentum vocale
des Menschen. – Anat. Anz. 117 (1965) 247-250.
GRUNDMANN, E. W.: Untersuchung über das Vorkommen von Drüsen sowie Zahl
und Verteilung ihrer Mündungen an der menschlichen Plica vocalis.
Inauguraldissertation, Greifswald, 1967
GRUNDMANN, E. W.: Retentionszysten der Stimmlippen. - HNO , Springer,
Heidelberg, 27, 156-158 (1979)
v. LANZ, T., WACHSMUTH, W.: Praktische Anatomie, I/2 Hals. - Berlin, Springer
1955, S. 311-312.