Title

The Fifth muscle of the Amphibian Larynx

Poster Number

23

Lead Author Major

Biological Sciences

Format

Poster Presentation

Faculty Mentor Name

Marcos Gridi-Papp

Faculty Mentor Department

Biological Sciences

Abstract/Artist Statement

Frogs protect their airways with a pair of arytenoid cartilages. Four pairs of laryngeal muscles lay on top of these cartilages: one dilator and three constrictors (anterior posterior and external). The dilator separates the arytenoid cartilages for breathing, while the constrictors close them. Panamanian tungara frogs (Engystomops pustulosus) might exhibit a fifth laryngeal muscle. As in other frogs, the dilator muscles of tungaras extend from a narrow attachment of the posteromedial process of the hyoid cartilage to a broad attachment along the center of the arytenoid cartilage's medial edge. The new muscle lies deep to the dilator muscle and it has a broader attachment to the medial edges of the arytenoid cartilages. Its fibers converge to pass through a slit between the arytenoid and cricoid cartilages and attach to the large fibrous mass. This renders the new muscle less well positioned than the dilators to open the arytenoids, and its contraction is more likely to produce a lateral displacement of the fibrous masses. Tungara frogs have a large larynx with a pair of greatly enlarged fibrous masses. Their vibration allows males to facultatively add notes with distinctive acoustic structure to their calls, enhancing their attractiveness. We are currently analyzing the innervations of the two muscles through histology, dissection, and stimulation in isolated larynges to elucidate the function of the new muscle and determine whether it is a derived feature of tungara frogs or an ancestral feature that may be less evident in species studied previously.

Location

DeRosa University Center, Ballroom

Start Date

26-4-2014 2:00 PM

End Date

26-4-2014 4:00 PM

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Apr 26th, 2:00 PM Apr 26th, 4:00 PM

The Fifth muscle of the Amphibian Larynx

DeRosa University Center, Ballroom

Frogs protect their airways with a pair of arytenoid cartilages. Four pairs of laryngeal muscles lay on top of these cartilages: one dilator and three constrictors (anterior posterior and external). The dilator separates the arytenoid cartilages for breathing, while the constrictors close them. Panamanian tungara frogs (Engystomops pustulosus) might exhibit a fifth laryngeal muscle. As in other frogs, the dilator muscles of tungaras extend from a narrow attachment of the posteromedial process of the hyoid cartilage to a broad attachment along the center of the arytenoid cartilage's medial edge. The new muscle lies deep to the dilator muscle and it has a broader attachment to the medial edges of the arytenoid cartilages. Its fibers converge to pass through a slit between the arytenoid and cricoid cartilages and attach to the large fibrous mass. This renders the new muscle less well positioned than the dilators to open the arytenoids, and its contraction is more likely to produce a lateral displacement of the fibrous masses. Tungara frogs have a large larynx with a pair of greatly enlarged fibrous masses. Their vibration allows males to facultatively add notes with distinctive acoustic structure to their calls, enhancing their attractiveness. We are currently analyzing the innervations of the two muscles through histology, dissection, and stimulation in isolated larynges to elucidate the function of the new muscle and determine whether it is a derived feature of tungara frogs or an ancestral feature that may be less evident in species studied previously.