Larynx Model Team Karen Chen Chou Mai Rexxi Prasasya Jason Tham Client Sherri Zelazny Advisor Professor Murphy 1 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 16 2 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 3 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 muscles oblique and transverse Attaches to posterior surface of one arytenoid cartilage and lateral border of the opposite cartilage this set of muscles work with the interarytenoid and lateral cricoarytenoid muscles to adduct the arytenoid cartilages Cricothyroid muscle Attaches to the cricoids and the thyroid cartilages the contraction of this muscle causes the tilting forward of the thyroid cartilage In turn the forward tilting of the thyroid cartilage lengthens as well as abducts the vocal cord Thus sound with higher pitch is created Bielamowixz Merati 2006 4 Competition Currently a static model is commonly used by speech pathologists to help educate their patients on larynx anatomy and physiology The static model although anatomically accurate has limited capability in presenting larynx cartilages and muscle movements This function is an integral component of patients understanding of laryngeal function A second option is the widely available functional larynx model Based on our research currently available functional model only includes the rocking motion of the arytenoid cartilages Additionally these functional models lack muscle representation that responsible for movement of the cartilage For this reason patients are not able to observe the specific muscles responsible for cartilage movement Lastly computer software and video recording have also been used as laryngeal functions teaching aids It is difficult to understand the anatomy and physiology of the larynx through in vivo video clips of a human larynx since the view is obstructed by enveloping connective tissue that enclose muscles and cartilages of the larynx Problem Statement The goal of this project is to continue the development of a physical three dimensional laryngeal model incorporating moving laryngeal cartilage bones membranes and muscles We would like to demonstrate laryngeal musculature and interaction in the larynx for voice production The model is to be used as a patient educational tool for improved understanding of the laryngeal mechanism It will also be used to plan treatment based on diagnosis of voice airway and or swallowing disorders This semester we