W--The Whale: How the Intrinsic Muscles and Cartilages of the Bowhead Whale Larynx May Influence the "Politics" of Mysticete Vocalization Theory
IAAAM 2005
Jeff Schumacher; D.J. Hillmann; W.G. Henk; W.R. Wilhite
Louisiana State University, School of Veterinary Medicine
Baton Rouge, LA, USA


One, complete, fresh larynx from a bowhead whale was dissected with study focused on the origin, insertion and action of the intrinsic muscles and their functional relation with the cartilages of the laryngeal apparatus. This project represents an analysis of the only complete (i.e., not transversely sectioned during extirpation) adult bowhead whale larynx available for study. The larynx was fixed in Jore's solution for preservation and pliability, sagitally sectioned, and the left half used to conduct a layer by layer removal of musculature and cartilage. Additionally, magnetic resonance imaging (MRI) was conducted on the cervical region of a bowhead fetus. The cartilages are equivalent to those of domestic species and include the epiglottis, paired arytenoids, thyroid, and cricoid. Their structural form and positional relationships are unique and adapted specifically for inspiration and expiration in an aquatic environment. It is hypothesized that these cartilages and their associated intrinsic muscles also facilitate phonation. The intrinsic muscles of the laryngeal apparatus consists of the cricothyroid, cricothyroarytenoid, transverse arytenoid, and cricoarytenothyroid muscles. Of these muscles, the cricothyroid, cricothyroarytenoid, and transverse arytenoid muscles are instrumental in inspiration and expiration. The cricoarytenothyroid muscle that encloses a mucosal diverticulum is situated between the cricoid and thyroid cartilages and is most commonly referred to in the literature as the ventral laryngeal sac. We have chosen cricoarytenothyroid rather than ventral laryngeal sac because extensive study has revealed its origins encompass more than the mucosal diverticulum of the laryngeal sac. Function of the cricoarytenothyroid muscle remains partially unclear. However, we believe it is antagonistic to the cricothyroarytenoid muscle and it is an essential component involved in vocalization.

Note: This will also be presented as a poster.

Speaker Information
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Jeff Schumacher

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