3-D Larynx Model with Moving Parts Advisor: Professor William Murphy Client: Sherri Zelazny Rexxi Prasasya – Team Leader Chou Mai – Communicator Karen Chen – BSAC Jason Tham - BWIG

Larynx Anatomy Transverse arytenoid muscle contracts Arytenoid cartilages pulled Vocal fold closed Parts of larynx involved in vocalization Arytenoid cartilages rotate around the vertical axis Lateral cricoarytenoid muscles adduct Vocal fold closed Adduction (AD) Abduction (AB) Anterior-posterior sliding (AP) Medial-lateral sliding (ML) (Wesley, 1999)

Thyroarytenoid muscle pulls the arytenoid cartilages Vocal fold loosen High-pitch sound produced Posterior cricoarytenoid muscle rotates arytenoid cartilages laterally Vocal cords separate Cricothyroid muscle rotates the thyroid cartilage Vocal fold stretched (Wesley, 1999)

Larynx Movement

Problem Statement 3-D, automated, functional larynx model Show anatomical structure of larynx Animate dynamics of the larynx in sound production Educational model Improve understanding of larynx Assist in planning laryngeal treatments and therapy

Available Products Static functional larynx model Movable arytenoid cartilage and pliable plastic vocal cords No automation Visual-aid software program (Sargent- Welch, 2008)

Design Requirements Anatomical Representation Dynamic Representation Cartilages and muscles present and labeled Scaling of 3X actual size Dynamic Representation Abduction/Adduction of arytenoid cartilage Flexion/Extension of thyroid cartilage All muscles associated with cartilage motion

Past Achievement Integrated precision motor system Three reversible electric motors – three cartilage movements Flexible wires connect cartilages to motors Increase comprehension of laryngeal function by 36% The prototype dysfunctional Plaster cartilages Silicone muscles Spring 2008 prototype

New Model 3x functional larynx Anatomically accurate movement Muscles included Plastic – simple modification Focus on dynamic automation Epiglttis, vocal cords, and arythenoid cartilage http://www.einsteins-emporium.com

Arytenoid Cartilage Motion Designs Rotational string Ball and socket Spring and track (Wesley, 1999)

Rotational Spring Use spring to attach arytenoid cartilage to cricoid cartilage Attach strings to each cartilage Strings mimic contraction and motion Strings attach to motor Sketch of rotational spring design

Ball and Socket Socket implemented on cricoid cartilage Ball attached to each arytenoid cartilage Allows “gliding” and “rocking” motions Sketch of ball and socket design

Spring and Track Springs attached to arytenoid cartilages Track attached to cricoid cartilage Allows arytenoid cartilages to slide and rock Sketch of spring and track design

Design Matrix 2 1 3 7 9 8 Rotational spring Ball and Socket Cost (2) Teaching effectiveness (3) Motion accuracy (3) Compatibility / feasibility (2) Total Rotational spring 2 1 3 7 Ball and Socket 9 Spring & Track 8

Future Work Automate cartilage movement Implement LED indication of muscle contraction Create demonstration coordinating motion and sound Test effectiveness as educational tool

References http://www.einsteins-emporium.com Meyer, J., Roggow, K., Hanson, K., Ladwig, N. Larynx model: final report. 2008 Sargent-Welch Company. 2008 Wesley, N. “The Anatomy Lesson.” Georgetown University. 1999.