[MUSIC] Welcome to Module 1. In this first module, we're going to talk about the basic anatomy and physiology of the speaking and singing voice. Remember, anatomy is a process of memorization. For those of you taking this course without prior courses in anatomy, you may need to repeat the video a few times to keep all of these concepts straight within your head. The specific educational objectives of this course are to describe the anatomy of the larynx and pharynx, important for speaking and singing production. We'll describe the vocal fold histology, the cellular structure, and the layered structure of the laryngeal mucosa, or skin surface. And we're here to provide an understanding of laryngeal vibration and physiology for voice production. These are concepts that I have developed over my 25 years of practice. Most vocal fold lesions are created to inefficient voice use patterns. The initiation of efficient flow and resonant voice use production techniques in speaking and singing often eliminates the need for surgery because speaking is a behavioral activity. I believe that optimal care is provided through a multidisciplinary or interdisciplinary approach between a speech language pathologist and a physician. The approach should be based on a sound understanding of a laryngeal anatomy, physiology and pathophysiology. Pathophysiology is a fancy name for disease state. I think it's important that the health care professional understand the individuals local requirements. Let me present to you some of my dogma. Surgery should never be the initial treatment option for patients with voice disorders. Early surgery often results in irreversible scar tissue that causes permanent voice change. I think that surgery is recommended only when there is persistent troublesome difficulty speaking, after completing work with a speech language pathologist, who has additional training in voice therapy methods. It's important for healthcare professionals to know that speech language pathology is a broad field. Speech language pathologists deal with difficulty in word finding, difficulty in articulation, difficulty in sentence or grammar structure, difficulty in swallowing and many other areas. For this reason, not all speech language pathologists receive significant training in voice production techniques. It's incumbent on the healthcare professional, caring for patients with voice disorders to identify speech language pathologists who have this additional interest and training. Finally, dysphonia is really just defined as the inability to meet vocal demands. Technically dysphonia is a symptom of a change in voice quality. This change can be one of quality, or just one of effort required to produce voice. So let's talk about how voice is produced. This first from an anatomical standpoint, the form of the larynx or voice box. And second from the physiology or the function of the larynx or voice box. In the human voice, the power supply is the lungs. The lungs exhale air and the air is driven through the trachea past the vocal fold, this air then stimulates the vocal folds into vibration. And this faint vibratory source is resonated through the resonating chamber or the superglottic vocal tract. Essentially, the area above the vocal folds between the patient's vocal folds and lip. We're going to discuss the Laryngeal Anatomy in terms of the the laryngeal framework or structure. Then the muscles that attach inside the larynx, also known as the intrinsic laryngeal muscles. And the muscles that attach outside the larynx, also know as the extrinsic laryngeal musculature. Very simply, the laryngeal framework consists of a series of bones and cartilage. The first bone is the hyoid bone. It can be felt in our neck just below our tongue base. Below that is the thyroid lamina. We often feel the thyroid prominence or Adam's apple in men, and just to either side of that is the thyroid lamina. This is actually a cartilage structure that becomes calcified in all patients as we age. Below the thyroid lamina is the cricoid ring, and below that is the trachea. The voice box itself is actually defined as the cricoid ring plus the thyroid lamina plus the hyoid bone. Within the thyroid lamina, there are additional cartilages. The arytenoid complex of cartilages includes the arytenoid, the main body. The corniculate cartilage, or a small crown-like cartilage sitting on top of the arytenoid body. And then the cuneiform cartilage. This cartilage hangs within the fold of tissue separating the voice box, or the vocal folds from the swallowing tube, the pyriform sinuses. Lastly, within the thyroid lamina is something called the epiglottis. The epiglottis is a type of cartilage that's attached to the voice box with various ligaments. The purpose of the epiglottis is to help to steer food around the vocal folds during the act of swallowing. Here is a clinical picture of the inside of the larynx taken with a little mirror or a Hopkins rod-lens telescope. At the very bottom of this screen, we see the tongue base and the space between the tongue base and the epiglottis. Down within the larynx itself, we see these white structures that form a V. The V stands for voice, and these white structures are the vocal folds. Above the vocal folds, we see the false vocal fold, and between the false vocal fold and the true vocal fold, we see a structure called the ventricle. Just above or outside of the false vocal fold, we have the structure called the aryepiglottic fold that attaches to the arytenoid complex of cartilages. We can see the bump or the prominence of the cuneiform cartilage and then we can see the whole arytenoid body underneath of the skin of the structure here. Down in the distance, we have the trachea. When we swallow, food comes in over the tongue base down at the bottom of the screen and then is steered into vallecula and in through the pyriform sinuses into the esophageal inlet. The aryepiglottic fold helps to contain the food and steer it into the esophageal inlet rather than letting it spill over into the voice box, causing aspiration and coughing. The Larynx has three basic functions. It controls respiration, protects the airway during swallowing and creates the sound source for voice production. By slightly opening and closing the vocal folds during respiration, we can control how fast the air comes in and out of the larynx. It helps us during physical activity, it helps us during lifting. We can hold our breath and grunt so we can get a stronger lift. During swallowing, our laryngeal structures close down so that the food is steered toward the outside of the larynx and through the pyriform sinuses and then into the esophagus. The third function of the larynx is for voice production. This involves vocal fold vibration. The larynx has different groups of muscles. First, we have the extrinsic muscles, those muscles that attach outside of the larynx and are responsible for controlling the height of the larynx and position of the larynx within the neck. And then we have the intrinsic muscles. These muscles attach inside the larynx and are important for controlling vocal fold opening, abduction and vocal fold closing, or adduction, for coughing and voice production. The intrinsic laryngeal muscles control vocal fold motion. They're divided into two groups, the muscles that close, or adduct the vocal folds, and the muscles that open, or abduct the vocal folds. There are three different muscles that are responsible for closing, or adducting, the vocal folds. The thyroarytenoid muscle, the lateral cricoarytenoid muscle, and the interarytenoidius muscle. The thyroarytenoid on the lateral cricoarytenoid muscle are paired. There's one on the left side and one on the right side. The interarytenoidius muscle, however, attaches between the body of the arytenoid cartilages, and contracts to pull the body of the arytenoid cartilages together during voice production and during swallowing. Vocal fold opening or abduction is controlled by the postier cricoarytenoid muscle. This is a single-paired muscle that is roughly equal in mass to the entire thyroarytenoid muscle and lateral cricoarytenoid muscle together. Here, we see a cartoon of vocal fold opening for respiration. As the posterior cricoarytenoid muscle contracts, it pulls on the back bottom portion of the arytenoid cartilage. As it pulls back here, the vocal process and the vocal folds are pulled open. This is our typical clinical view, and we appreciate the two-dimensional motion of the arytenoid cartilage on the cricoid ring and of the vocal fold. When we look at this lateral cut-away over here, however, we can see that as the posterior cricoarytenoid muscle contracts, it pulls down slightly on the back portion of the arytenoid body, as it pulls down the vocal process not only open in the horizontal plane, but it's pulled upward in the vertical plane. We, as clinicians, need to remember that the vocal folds move in three dimension and must open and close in three dimension, but typically we're limited to this superior view, which only gives us appreciation for the opening and closing motion, and not the horizontal motion that we see here. Similarly, vocal fold closure, or adduction for speaking and coughing is controlled by the lateral cricoarytenoid, thyroarytenoid, and interarytenoid muscles. During speaking, or bringing the vocal folds together, the lateral cricoarytenoid muscle and thyroarytenoid muscles seen here on the left, bring the vocal folds together. They attach to the body of the arytenoid cartilage in the front for the thyroarytenoid muscle and to the posterior or back portion of the arytenoid for the lateral cricoarytenoid muscle. Seen on the left in the superior view, we can appreciate the horizontal or two-dimensional image of these vocal folds moving. However, when we look at the lateral cut away on the right, we can appreciate that is the thyroarytenoid muscle and the lateral cricoarytenoid muscle contract. The vocal process or the back portion of the vocal fold is lowered slightly. The cricoarytenoid muscle attaches on the front of the cricoid ring seen down here, and then on the bottom of the thyroid lamina. As it contracts, it pulls the thyroid lamina forward in relationship to the cricoid ring. When we look at the lateral cutaway, we can see how this action then stretches the vocal folds, and specifically, the vocal ligament, which is attached to the front of the thyroid cartilage. This action is important because it tenses the vocal fold and the vocal ligament and vocal fold mucosa, as the cricothyroid muscle contracts. This helps us elevate pitch, so we can speak in a low pitch and then a higher pitch. All of these intrinsic laryngeal muscles are under control of branches of the tenth cranial nerve. Cranial nerves are nerve that come out of the brainstem and go through the skull base to the muscles of the upper neck. There are 12 of them. The tenth nerve also called the vagus nerve is the nerve that's responsible for innovating the larynx and the pharynx. To innovate the larynx, the tenth cranial nerve has two specific branches. The recurrent laryngeal nerve and the superior laryngeal nerve. The superior laryngeal nerve is further broken down into an internal branch and an external branch. The recurrent laryngeal nerve comes off of the vagus nerve below the level of the voice box, and then recurves up to the voice box. It sends small branches to the trachea, and to the inside of the laryngeal lumen, laryngeal airway, to give sensation. It also sends branches to the vocal fold muscles, the thyroarytenoid, and lateral cricoarytenoid, and the posterior cricoarytenoid, to control vocal fold motion. The superior laryngeal nerve sends an internal branch that gives sensation to all of the skin of the larynx above the level of the vocal folds. It also sends an external branch to the cricothyroid muscle. That controls vocal fold lengthening for alterations and vocal fold pitch. We now know that gallons of anastomosis or nerve branches between the superior laryngeal nerve and the recurrent laryngeal nerve, exist. They exist with different degrees of variability in patients. Some patients have more and some patients have less. Originally, Galen's anastomosis was thought to be only a sensory nerve, but we now know that it contains motor fibers. The extrinsic laryngeal musculature, also known as the strap muscles, are important because they control the height of the larynx with regard to the mandible and the clavicles. We'll see later in module 2 why this height is important. These muscles are more important for swallowing, and they're under control of the 12th cranial nerve, also called the hypoglossal nerve, and branches of the 12th cranial nerve called the ansa cervicalis. These muscles are innervated by the 12th cranial nerve, which starts in a very close area to the 10th cranial nerve within the motor and sensory cortex within the brain. It's therefore no wonder that patients, when they're speaking and swallowing, trying to control the height of the larynx within the neck, and vocal fold opening and closing often have overlap of these functions. 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