The following chapter summarises the anatomy and terminology (including common synonyms) of the human glottis. It is offered as a supplement to the description of the porcine glottis in chapter 2.2 (The unique structure of the porcine glottis). In this respect, it is supposed to help to distinguish between differences in terminology of these two species which may be caused by inappropriate assumption of homology, or by inconsistent use of anatomical terms.
In human anatomy, the term glottis generally refers to the phonatory part of the larynx, namely to the vocal folds (FENEIS 1998). It is not to be confused with the rima glottidis, which refers to the cleft between the vocal folds (FENEIS 1998).
The human vocal fold (FEDERATIVE COMMITTEE ON ANATOMICAL TERMINOLOGY 2011) is also called plica vocalis (FEDERATIVE COMMITTEE ON ANATOMICAL TERMINOLOGY 2011), vocal cord (STANDRING 2005), true vocal cord (STANDRING 2005), Stimmfalte* (SOBOTTA and WELSCH 2009) or Stimmlippe* (DRUNCKER and KUMMER 2008). All terms consistently refer to the structure consisting of three distinct anatomical components, i.e. vocal ligament, vocal muscle, and mucosa. Put topographically, the vocal fold is made up of all tissues protruding into the laryngeal cavity at the level of the glottis (DRUNCKER and KUMMER 2008).
The vocal ligament of humans (FEDERATIVE COMMITTEE ON ANATOMICAL TERMINOLOGY 2011) is referred to as ligamentum vocale (FEDERATIVE COMMITTEE ON ANATOMICAL TERMINOLOGY 2011) or Stimmband*
(DRUNCKER and KUMMER 2008). It extends from the thyroid cartilage to the vocal
* Term commonly used in German language
process of the arytenoid cartilage (FENEIS 1998). The vocal ligament consists of the free upper edge of the conus elasticus, also known as cricovocal membrane (STANDRING 2005). This elastic structure represents the inferior part of a fibroelastic membrane, which is located between the mucosa and the cartilaginous skeleton of the larynx (STANDRING 2005).
A frequent misapprehension appears to be related to the confusion of the two terms vocal cord and vocal ligament. Even though the term ‘cord’ implies the shape of a string, or a band, it is mostly used to refer to the entire vocal fold (see e.g. McCOY and HALSTEAD 2004; STANDRING 2005), instead of – as readers may expect – to the vocal ligament alone.
Another structure requiring particular attention is located superior to the vocal fold:
The so-called vestibular fold (FEDERATIVE COMMITTEE ON ANATOMICAL TERMINOLOGY 2011), plica vestibularis (FEDERATIVE COMMITTEE ON ANATOMICAL TERMINOLOGY 2011), false vocal fold (STANDRING 2005), ventricular fold (STANDRING 2005), Taschenfalte* (SOBOTTA and WELSCH 2009) or Vorhoffalte* (LIPPERT 1990) in humans. It consists of two components, i.e.
vestibular ligament and mucosa (STANDRING 2005).
The human vestibular ligament (FEDERATIVE COMMITTEE ON ANATOMICAL TERMINOLOGY 2011) is also called ligamentum vestibulare (FEDERATIVE COMMITTEE ON ANATOMICAL TERMINOLOGY 2011), Taschenband*
(DRUNCKER and KUMMER 2008) or falsches Stimmband* (DRUNCKER and KUMMER 2008). It is described as the thickened lower (inferior) body of the quadrangular membrane, which is the superior part of the fibroelastic membrane (STANDRING 2005).
Between the vocal fold and the vestibular fold of humans lies the opening into the laryngeal ventricle (FEDERATIVE COMMITTEE ON ANATOMICAL TERMINOLOGY
* Term commonly used in German language
2011), also called ventriculus laryngis (FEDERATIVE COMMITTEE ON ANATOMICAL TERMINOLOGY 2011), ventricle of Galen (REUTER and REUTER 1996), Morgagni’s ventricle (REUTER and REUTER 1996) or sinus of Morgagni (REUTER and REUTER 1996). It is consistently described as a recess extending upwards into the laryngeal wall, lateral to the vestibular fold (STANDRING 2005;
DRUNCKER and KUMMER 2008).
The thyroarytenoid muscle (REUTER and REUTER 1996), also called musculus thyroarytenoideus (FEDERATIVE COMMITTEE ON ANATOMICAL TERMINOLOGY 2011) or just thyro-arytenoid (FEDERATIVE COMMITTEE ON ANATOMICAL TERMINOLOGY 2011) is the main muscle in the glottal region of humans. It extends between the anterior surface of the thyroid cartilage and the arytenoid cartilage; the thyroarytenoid muscle is a broad, thin muscle lying lateral to vocal fold, cricovocal membrane, and laryngeal ventricle (STANDRING 2005).
The medial portion of the thyroarytenoid muscle forms the vocal muscle (REUTER and REUTER 1996), musculus vocalis (FEDERATIVE COMMITTEE ON ANATOMICAL TERMINOLOGY 2011) or just vocalis (FEDERATIVE COMMITTEE ON ANATOMICAL TERMINOLOGY 2011). It lies lateral to the vocal ligament and comprises the major tissue mass of the vocal fold (STANDRING 2005; SOBOTTA and WELSCH 2009).
Although the term musculus ventricularis – referring to a thin strand of muscle inside the vestibular fold – can occasionally be found in literature on humans (SOBOTTA and WELSCH 2009), it is neither an isolated structure nor an official anatomical term*, but probably a part of the thyroarytenoid muscle.
*The term ‘musculus ventricularis’ is not listed in Terminologia Anatomica (FEDERATIVE COMMITTEE ON ANATOMICAL TERMINOLOGY 2011).
A comparative survey on synonyms and definitions of terms related to the human and porcine glottis is given in table 1 (see chapter 2.2: The unique structure of the porcine glottis).
Acknowledgements
I would like to express my great appreciation to Prof Dr Hagen Gasse for providing me with the topic of this thesis. His patient guidance, enthusiastic encouragement and useful critiques on this research work have been much appreciated.
Advice and assistance provided by Dr Rüdiger Koch have been a great help to me.
His expert opinion has always been held in high esteem.
I wish to sincerely thank Ms Gudrun Wirth for the laborious preparation of all histological specimens, as well as for her assistance with the scoring of fibre diameters.
Dr Karl Rohn provided me with valuable critical comments and technical assistance regarding the statistical analyses and the handling of the SAS program.
I would like to offer my special thanks to Ms Sherwood-Brock for her valuable advice on my English writing skills and for revising the English manuscripts.
Assistance provided by Mr Oliver Stünkel, Mr Peter Stahlhut and Mr Thorben Meyer in technical aspects such as the retrieval of samples was greatly appreciated.
My special thanks are extended to my colleagues at the Institute of Anatomy, who largely contributed to making the past three years a very enjoyable experience.
Finally, I wish to thank my family for their ever-present support and encouragement.