The functional larynx is a specialized part of the upper respiratory system responsible for sound production, respiration, and protection of the lower respiratory tract. It is equipped with a cartilaginous framework that supports three main components: the vocal folds (also known as true vocal cords), the vestibular folds (false vocal cords), and the epiglottis.
Functions of the Functional Larynx
Speech Production
The primary function of the larynx is to produce speech and allows individuals to vocalize. Speech is created when air from the lungs is expelled from the trachea and passes over the vocal folds, causing them to vibrate. The vibration creates sound waves that are transferred through the pharynx, mouth, and nose to the ears, allowing communication.
Air Passage Protection
During swallowing, the epiglottis prevents food and liquid from entering the trachea while air continues to flow into the lungs. It acts as a valve that covers the larynx opening during swallowing to ensure that food and drink do not enter the airways. This mechanism ensures the airway remains clear and allows for proper breathing while consumption of food or liquid.
Preventing Choking
The functional larynx also plays a crucial role in preventing choking. When food or liquid is in the throat, the epiglottis helps guide it into the esophagus, avoiding the trachea. If the epiglottis does not close properly during swallowing, it can lead to aspiration, where food or liquid enters the lungs, increasing the risk of choking.
Blood供应, Lymphatic drainage and Neuroscience
Blood供应
The larynx is supplied by both superior and inferior laryngeal arteries, which are branches of the thyroid arteries. These arteries provide oxygen and nutrients necessary for the proper functioning of the larynx.
Lymphatic drainage
The lymphatic system is responsible for the drainage of excess fluid from the interstitial space and the removal of waste products. The larynx is drained by superior and inferior deep cervical lymph nodes, which are part of the lymphatic chain that circulates throughout the body.
Neuroscience
The larynx is innervated by the vagus nerve, specifically the ten cranial nerve (CN X). This nerve provides both motor and sensory fibers to the larynx. The vagus nerve carries information from the CNS to the head and neck region, including the larynx. The recurrent laryngeal nerves, which are branches of the vagus nerve, provide motor innervation to the intrinsic larynx muscles, while the external laryngeal nerve provides motor function to the cricothyroid muscle and sensibility to the larynx cavity below the vocal cords.
Clinical Applications and Interesting facts
Acute Life Threatening Airway Obstruction
The functional larynx is crucial in cases of acute life-threatening airway obstructions. In these situations, a healthcare professional may perform a cricothyrotomy, which involves inserting a small needle through the cricothyroid membrane to establish an airway. Understanding the anatomy of the larynx is essential for performing this life-saving procedure.
Changes in Vibration during Inhalation and Exhalation
Individuals with vocal cord dysfunction or paralysis may experience changes in the vibration speed and tension of the vocal folds. This can lead to significant changes in voice quality, making speaking and singing difficult.
Newborn Infants and Oxygen Saturation levels
Newborn infants possess a unique anatomical arrangement that allows them to sleep and breastfeed at the same time without compromising the airway. This ability rapidly disappears as the larynx descends into the adult position, typically around 2 to 6 years of age. A reduction in neonatal oxygen saturation levels can occur following the loss of the newborn's obligate nose breathing ability.
A Rare Condition: Laryngeal Papillomatosis
Laryngeal papillomatosis is a rare condition caused by the human papillomavirus (HPV) that results in non-cancerous growths on the larynx. While most cases are benign, some can develop into cancer. Spasmodic dysphonia, or laryngeal dystonia, can occur when the muscles controlling the vocal cords involuntarily spasm, affecting the way the vocal cords vibrate.
These are just a few examples of the clinical applications and fascinating facts surrounding the functional larynx. Understanding the anatomy and function of the larynx is vital for anyone involved in healthcare, teaching, or research in this field.
