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Larynx

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Larynx function.jpg

The larynx is an organ in the body also known as the voice box. It is located around the neck area of animals, amphibians, reptiles, and humans. It allows the user to breathe, make sounds, and swallow. The larynx protects the trachea from food aspiration. The larynx houses the vocal folds which are essential for phonation. The vocal folds are located below where the tract of the pharynx splits. The larynx controls the volume and pitch of the voice.[1][2]

Anatomy

The larynx is located at the upper end of the air passage. It is found between the trachea and the root of the tongue at the upper and forepart of the neck. The larynx consists of sections that help the organ to function correctly. It consists of a framework of cartilage which surrounds the soft tissue. The most prominent piece of cartilage is a shield shaped structure called the thyroid cartilage. The anterior portion of the thyroid cartilage can easily be observed in thin necks of men and is known as the Adam's apple. On the upper portion of the larynx, there is a U-shaped bone called the hyoid bone. This bone supports the larynx from above and the muscles and the tendons attach themselves to the mandible. On the other hand, the lower portion of the larynx consists of a circular piece of cartilage called the cricoid cartilage. This cartilage resembles a signet ring. The rings of the trachea are located below the cricoid.[2]

Anatomy of the Larynx

The most important part of the larynx are the vocal folds, located in the center of the organ. They are extremely important because they play a key role in the production of the voice, the control of breathing, and the process of swallowing. The vocal folds are made out of thin layer of muscles called mucosa. The folds lie with both sides forming a "V" sign when viewed from above. In the rear portion of each vocal fold, is a small structure called the arytenoids which is made out of cartilage. There are many smaller muscles attached to the arytenoids as well. During breathing, these muscles pull the arytenoids apart from each other which produces an opening in the airway. During speech the vocal folds are brought close together. When the air passes by the vocal folds when in this position, they open and close very rapidly. This quick pulsation of air passing through the vocal folds produces a sound that is then modified by the remainder of the vocal tract to produce speech.[2].

Function

The larynx, sometimes referred to as the voice box, is located in the neck. It is a tube-shaped organ. The larynx can be found in the region that is between the trachea (the breathing tube) and the pharynx (the throat. This organ has three primary functions. These are to produce voice, control breathing (airflow), and swallowing. The larynx is primarily concerned with the production of airflow which in turn generates sound and allows the articulation of the voice. The vocal cords, also known as vocal folds are located in the center of the larynx. A structure that is made of cartilage and is called the arytenoid is located at the back of the vocal cords. Muscles attached to the arytenoid pull apart and open to allow air to flow through it when we breathe. As the air passes near the vocal cords, they open and closes very quickly which results in a change of pressure. This is what produces sound. Intrinsic muscles, deep inside the larynx cause the muscle to change its position and also control the tension of the cords. This is what alters the pitch of the sound. The rest of the organs surrounding the larynx, such as the throat, nose and other structures in the mouth are then involved in the production of the speech sounds and words.[1].[3]

Diseases

There are several factors that can cause the larynx to not function properly. Some of the symptoms of this inability to function are: loss of voice, hoarseness, pain in the throat, and breathing difficulties.

The improper use or overuse of the voice use or may cause nodules. Nodules are calluses on the vocal folds. They occur most commonly in children and females. Nodules prevent the vocal folds from meeting in the midline. This produces an hourglass shaped deformity when the folds close resulting in a raspy and breathy voice. One way to ameliorate this problem is to obtain speech therapy. Occasionally, surgery will be required to remove the nodules.[4]

Occurring mostly in adult males, polyps are benign lesions of the larynx, usually located on the edge of the vocal folds. They prevent the vocal folds from meeting in the midline. This condition can interfere with voice production and may cause a hoarse, breathy voice that causes the speaker to tire easily. Conservative medical therapy and intensive speech therapy may be required in order resolve this problem. Sometimes these lesions are caused b Laryngopharyngeal reflux disease.[4]

Laryngopharyngeal reflux disease, also termed acid reflux, is another common health issue that relates to the larynx. This is a condition that develops over time. Stomach acid travels up into the throat and people experience a sensation of drainage down the back of the throat, excess mucus, a feeling that something is caught in the throat, and a need to clear their throat on a regular basis. The larynx becomes swollen, red, and irritated. Medical treatment, such as taking a daily antacid, will often lesson or even take away the symptoms. Lifestyle changes such as limiting caffeine and spicy foods can also help. [4].

Cancer occasionally occurs in the form of lesions in the vocal folds. If it is detected early, these lesions can be treated with surgery or radiation. There is a high rate of cure for this disease. It is approximately 96%.[4]

Speaking After the Removal of the Larynx

Air that passes through the larynx will cause the vocal cords to vibrate. This produces sound. With assistance of your mouth, teeth, tongue and lips the sound that is made will become your voice. Occasionally, a person develops cancer of the larynx which is serious enough to warrant the removal of the organ. When this occurs the surgeon creates an opening in the neck for a new passage for breathing. This hole, which bypasses the nose and mouth is known as a stoma.[5]

During the surgery, a tube, called a tracheostomy tube is inserted to hold the stoma open. In many cases, after a few weeks, the tube is replaced by a button which is known as a stoma button. It is very difficult, if not impossible, for a person to speak normally when the larynx has been removed. The patient must learn a new way to speak. At first, the person usually communicates by writing either on paper or on the computer. After the surgery has healed it self the individual either uses esophageal speech or an artificial larynx in order to communicate. Esophageal speech occurs when air is taken into your esophagus and then let out. The esophagus vibrates and produces sound. This sound often is difficult to understand in the form of words. Often it is very soft and difficult for others to hear. Therefore, an artificial larynx, although expensive, is used by many people for communication. The majority of people who have had their larynx removed depend upon a mechanical device.[5]

This machine is similar to a microphone. The problem with it is although people can speak so that others can understand the voice quality is cold and robotic in nature and does not allow for emotions to be communicated well. Since technology has improved considerably there are now devices called palatometers which uses pressure sensors to measure the movement of the tongue. Tongue movements correspond almost as well as vocal cord movements to pronunciation.. Since this is the case, a computer is able to calculate the appropriate pronunciation of a word, and the user can actually raise their voice at the end of a sentence to ask a question. This makes it possible to avoid the robotic nature of the mechanical devices.[5].

References

  1. 1.0 1.1 Mangan, Tricia. The Primary Function of the Larynx Live strong.com. Web. accessed on 30 April 2013.
  2. 2.0 2.1 2.2 unknown author. Basic Anatomy Department of Otolasdfy. Web. accessed on 28 April 2013.
  3. Wile, Jay L., and Shannon, Marilyn M. The Human Body: Fearfully and Wonderfully Made!. Cincinnati: Apologia Educational Ministries, Inc., 2001. Pg.417. Print.
  4. 4.0 4.1 4.2 4.3 unknown author. Diseases of the Larynx Texas Voice Center. Web. accessed on 30 April 2013.
  5. 5.0 5.1 5.2 unknown author. Larynx Cancer Speech Association. Web. accessed on 30 April 2013.