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Anatomy, Head và Neông xã, Larynx Recurrent Laryngeal Nerve
Evan Allen; Katrina Minutello; Benjamin W. Murcek.Author Information
The larynx is a dynamic, flexible structure composed of a cartilaginous core with interconnecting membranes và associated musculature. The larynx is a midline structure positioned at the interface between the digestive sầu & respiratory tracts. In addition to lớn housing the vocal cords và producing phonation, the larynx assists with multiple other functions including but not limited to: airway protection, regulating intrathoracic pressures, & regulating intra-abdominal pressures. The anatomical position, composition, associated musculature & innervation of the larynx all contribute khổng lồ this structure’s capabilities.<1><2><3>
The anatomical position of the larynx is also dynamic in nature & varies from birth to maturity. Initially, at birth & for the first couple years of life, the larynx is further superior in the neông xã than in adults. In infants, this high position results in direct tương tác between the soft palate & epiglottis. This allows inspired air lớn move from the nose lớn the trachea directly. It is because of this anatomical relationship; an infant is able to lớn swallow liquids & breathe almost simultaneously.
By adulthood, the larynx descends inferiorly khổng lồ its final position. The larynx is found within the visceral compartment of the neông chồng và serves as the “floor” of the anterior triangle of the neông chồng. The larynx is the superior portion of the respiratory tract and aligned on its long axis, is vertically adjacent to lớn the trachea, which lies directly inferior khổng lồ the larynx and is connected via the cricotracheal ligament. Anterosuperiorly, the larynx articulates with the hyoid bone via the thyrohyoid membrane. Dorsally, the larynx attaches lớn the muscular walls of the pharynx.
The larynx is composed of nine contributing cartilages: three unpaired cartilages và three paired cartilages, which mô tả connections khổng lồ each other, the hyoid (superiorly), and the trachea (inferiorly). The epiglottic, thyroid, và cricoid cartilages trang điểm the three unpaired cartilages & are arranged superior to lớn inferior respectively. The thyroid cartilage, with the epiglottic cartilage superior, predominates anteriorly and forms the laryngeal prominence (i.e., Adam’s Apple), while the predominate cartilage dorsally is the cricoid cartilage which sits inferior to the thyroid cartilage. The three paired cartilages include the arytenoid, corniculate, & cuneiform cartilages. The paired arytenoid cartilages are found on the dorsal aspect of the larynx, attached superiorly to the cricoid cartilage. Both arytenoid cartilages give sầu off a lateral extension (muscular process) and anterior extension (vocal process) which aid in supporting the vocal ligaments. Additionally, each arytenoid cartilage has an associated corniculate & cuneikhung cartilage. These two small, paired cartilages border the opening inkhổng lồ the laryngeal vestibule both dorsally và laterally. The corniculate cartilage can be found at the apex of both arytenoid cartilages. The cuneisize cartilage can be found sitting anterior và lateral khổng lồ both arytenoids. These cartilages form connections via numerous membranes, ligaments, và synovial joints.
There are two essential synovial joints associated with the larynx. One pair of synovial joints exists between the thyroid và cricoid cartilages. This joint allows the thyroid cartilage khổng lồ rotate about the cricoid cartilage and allows the cricoid cartilage khổng lồ separate from or approximate to lớn the thyroid cartilage anteriorly. The second set of synovial joints exists between the cricoid & arytenoids (cricoarytenoid synovial joint). The cricoarytenoid synovial joint allows the arytenoid cartilages khổng lồ translate on both an anterior-posterior axis and lateral-medial axis, as well as rotate about a cranial-caudal axis.
Laryngeal Folds & Membranes
The aryepiglottic folds extend over the lateral aspects of epiglottic, cuneisize, corniculate and arytenoid cartilages. The aryepiglottic folds demarcate the opening inkhổng lồ the laryngeal lumen. The pirisize sinus can be found just lateral to the aryepiglottic folds, which size the medial border of these sinuses. This is sometimes referred lớn as the lateral food channel. The aryepiglottic folds serve sầu as a protective wall that prevents food from passing inlớn the laryngeal aditus & together, with the associated cartilages forms a protective sầu ring. This ring is not uniform in height, at the dorsal-most aspect, there is a reduction in the height of this fold creating susceptibility to lớn food or liquid incursions. This is called the interarytenoid notch.
The laryngeal ventricle is the fossa or sinus that lies between the vocal & vestibular folds on either side. The vocal folds are commonly referred to as the vocal cords and the vestibular folds as the false vocal cords. The laryngeal ventricle also demarcates the separation between the quadrangular membrane superiorly, và the cricovocal membrane found inferiorly. These two membranes together cover the entire interior portion of the larynx from the epiglottic & arytenoid cartilages superiorly to the cricoid cartilage inferiorly. These membranes are bilateral.
The quadrangle membrane gives tư vấn lớn the aryepiglottic folds superiorly và continues inferiorly as the vestibular folds. The vestibular folds contain the vestibular ligament, which extends from the arytenoid cartilage to lớn the thyroid cartilage. The vestibular folds appear to lớn have sầu no role in phonation & are relatively imthiết bị di động structures.
The laryngeal ventricle begins inferiorly to the không tính phí edge of the vestibular fold & continues laterally. The ventricle exists bilaterally, & secretes mucus over the superior surface of the vocal folds, forming a protective layer.
The lateral cricothyroid ligament is contained within the cricovocal membrane. Like the vestibular ligament, this ligament also extends from the arytenoid cartilage to the thyroid cartilage. However, the lateral cricothyroid ligament also follows the cricoid cartilage as it extends inferiorly. In addition, this ligament gives rise to lớn the vocal ligament as it thickens superiorly. The vocal ligament extends from the thyroid cartilage
The vocal folds, also known as the true vocal cords, are medial projections of the walls of the larynx that can approximate lớn each other in the midline khổng lồ completely obstruct the lumen of the larynx. These vocal folds delineate the plane referred lớn as the glottis. Within these vocal folds is a muscle known as vocalis muscle which runs aside the vocal ligament. The ligament và laông chồng of blood vessels on the surface of the folds result in the characteristic trắng appearance of the pair of vocal folds. This provides visual distinction compared khổng lồ the pink appearing vestibular folds. The space found between the vocal folds is termed the rima glottides.
The laryngeal inlet/aditus is used to refer khổng lồ the entrance of the cavity of the larynx. Superior to lớn the inlet is the laryngopharynx.