1 Larynx Model Team: Karen Chen, Chou Mai, Rexxi Prasasya, Jason Tham Client: Sherri Zelazny Advisor: Professor Murphy2 Table of Content Abstract……………………………………………………………………….………………………………..……….……..3 Background………………………………………………………………….…………………………………..……………3 Motivation……………………………………………………..…………………………………..……..………3 Larynx Anatomy and Physiology…………………….……………………………………..……...……3 Competition………………………………………………….………………..………………..………………..5 Problem Statement…………………………………………….……………….................................5 Design Requirement…………………………………………………………………..……..……………...5 Design Proposal………………………………………………………………...…...…………………….……………..6 Rotational Spring……………………………………………………………..……...……………………….………....6 Ball and Socket………………………………………………………………...….…………………………….……….…6 Spring and Track………………………………………………………………………………………………….………..7 Design Selection……………………………………………………………….……………………………………..…….7 Final Design…………………………………………………………………………………………………………………..8 Testing and Result.……………………………………………………………………………………………….……...10 Future Work…………………………………………..……………………………………………………………...….…13 References……………………………………………………………………………...……………………………...…..14 Appendix A: 3D Larynx with Moving Parts Quiz…………………………………………….………………15 Appendix B: Product Design Specifications……………………………………………………………………163 Abstract The goal of the project is to continue the development of a three-dimensional larynx model with moving cartilage and muscles. This device is intended to use as a patient educational tool for improved understanding of the laryngeal mechanics by exaggerating its subtle movements. We would like to demonstrate the relation between muscle and cartilage motions, and also apply automated cartilages to the model. The final design of the device consists of three motors that control the motions of the cartilage, and the muscle tissue associated with each motion. To test the efficacy of the model, a population of students was given a laryngeal anatomy presentation either with the aid of a static model or the prototyped dynamic model. The group presented with our dynamic prototype scored higher in our questionnaire compared to the control group presented with the static model. In the subsequent semester, we would like to introduce several laryngeal disorders into the model. Background Motivation Speech pathologists see about 500 patients with laryngeal disorders per month, each of whom need to be educated about the larynx and their particular laryngeal disorder. Patients frequently face difficulty in comprehending laryngeal muscle and cartilage movements, even with the presence of a visual aid. Currently, the tool that our client uses to explain normal laryngeal function is a two-time life-size static larynx model. However, this model has a limited capability in illustrating laryngeal anatomy and essentially no ability to demonstrate the subtle and complex laryngeal muscle movements. Due to the aforementioned limitations, our client proposed a three-time life-size laryngeal model with electronically controlled movable muscles and cartilages. The model is intended to accurately simulate intricate muscle and cartilage movement of the larynx so that the patients can have visual representation as well as auditory explanation of how the larynx works. Additionally, the model will also be used to demonstrate therapeutic measures on a dysfunctional larynx. Larynx Anatomy and Physiology The larynx is an organ located in the airway, lying immediately below the pharynx and above the trachea. The larynx houses the vocal cords that are essential during phonation or sound production. Six sets of laryngeal muscles control three different sets of cartilage that anchor the vocal cords. These muscles control the speed of vocal cord vibration as well as the pitch of the sound being produced. Three cartilages to which the vocal cords are attached to are thyroid cartilage, arytenoid cartilages, and cricoid cartilage, and are illustrated in Figure 1 below.4 Figure 1. Cartilages of the larynx (facstaff.gpc.edu) The six sets of muscles of the larynx are named after cartilages of which they are attached to and their functions are listed below. - Thyroarytenoid muscle – Attaches to the two arytenoids cartilages and the inner side of the thyroid cartilage, the thyroarytenoid muscle’s contraction pulls the arytenoid cartilages toward the thyroid cartilage, causing shortening of the vocal cords. - Posterior cricoarytenoid muscles – Attaches to the posterior of the cricoids cartilage and to the arytenoid cartilages, this pair of muscles is the main abductor muscle of the arytenoid cartilage. They are responsible for the rocking motion of the arytenoid cartilages which caused the abduction of the vocal cords. - Interarytenoid muscle – Attaches to the right and left arytenoid cartilages, this muscle is responsible for the adduction of the arytenoid cartilages, and thus the vocal cords. - Lateral cricoarytenoid muscles – Attaches to the lateral side of the cricoid cartilage and the arytenoid cartilages, this pair of muscles works with the interarytenoid muscle to rotate the arytenoid cartilages inward and thus adducting the vocal cords. - Arytenoid