Larynx Flashcards
(14 cards)
What is the Larynx?
The larynx is the organ that connects the lower part of the pharynx with the trachea. It serves (1) as a valve to guard the air passages, especially during swallowing, (2) for the maintenance of a patent airway, and (3) for vocalization.
What is the larynx made up of?
The larynx possesses three single cartilages (thyroid, cricoid, and epiglottic) and three paired cartilages (arytenoid, corniculate, and cuneiform). The thyroid, cricoid, and arytenoid cartilages are composed of hyaline cartilage and may undergo calcification, endochondral ossification, or both, thereby becoming visible radiographically. The other cartilages are elastic in type.
Thyroid cartilage
The thyroid cartilage (fig. 53-9) comprises two spring-like plates termed laminae, which are fused anteriorly but divergent posteriorly. The laminae produce a median elevation termed the laryngeal prominence (“Adam’s apple”), which is palpable and frequently visible. The posterior border of each lamina is prolonged superiorly and inferiorly as cornua, or horns. The superior horn is anchored to the tip of the greater horn of the hyoid bone. The inferior horn articulates medially with the cricoid cartilage. The lateral surface of each lamina is crossed by an oblique line for the attachment of muscles.
Cricoid cartilage
The cricoid cartilage (fig. 53-9) is shaped like a signet ring. It comprises a posterior plate, called the lamina, and a narrow, anterior part, the arch. The lamina articulates superolaterally with the arytenoid cartilages. The cricoid cartilage is at the level of the C6 vertebra, and its arch is palpable. The inferior border of the cricoid cartilage marks the end of the pharynx and larynx and hence the commencement of the esophagus and trachea.
Arytenoid cartilage
The arytenoid cartilages (fig. 53-9B) articulate with the superior border of the lamina of the cricoid cartilage. Each has a superiorly-positioned apex (which supports the corniculate cartilage) and a base that comprises its inferior part. The base sends a vocal process anteriorward (for attachment to the vocal ligament) and a lateral, muscular process (for muscular attachments). The corniculate and (inconstant) cuneiform cartilages are nodules in the aryepiglottic folds (figs. 53-10B and 53-12).
Epiglottic cartilage
The epiglottic cartilage (see fig. 53-9) is covered by mucous membrane to form the epiglottis. The epiglottis is situated posterior to the root of the tongue and the body of the hyoid bone and anterior to the inlet of the larynx. The inferior end, or stalk, of the leaf-shaped cartilage is anchored to the posterior aspect of the thyroid cartilage. Taste buds are present in the posterior surface of the epiglottis.
Joints of the larynx
Two synovial joints are present on each side. The cricothyroid joint, between the lateral aspect of the cricoid cartilage and the inferior horn of the thyroid cartilage, allows mainly rotation of the thyroid cartilage around a horizontal axis through the joints of the two sides. This produces a tipping motion where the anterior part of the thyroid cartilage moves anterior and inferior. The cricoarytenoid joint, between the superior border of the lamina of the cricoid cartilage and the base of the arytenoid cartilages, allows gliding and rotation of the arytenoid cartilages.
Muscles of the larynx
The larynx as a whole can be elevated and depressed by extrinsic muscles (e.g., the stylopharyngeus and palatopharyngeus and the infrahyoid muscles).
The intrinsic laryngeal muscles are complicated, but they may be classified as follows:
- The sphincters of the inlet: transverse arytenoid; oblique arytenoid and aryepiglottic.
- The muscles that close and open the rima glottidis: lateral cricoarytenoid (adductor) and posterior cricoarytenoid (abductor).
- The muscles that regulate the vocal ligaments: thyroartenoid and vocalis; cricothyroid.
The muscles of the larynx are illustrated in figures 53-13 and 53-14D and summarized in table 53-2.
Three muscles arise from the cricoid cartilage: the cricothyroid, arising from the lateral aspect of the cricoid cartilage and passing posteriorward to insert on the lamina and inferior horn of the thyroid cartilage; the lateral cricoarytenoid, extending posteriorward to the muscular process of the arytenoid cartilage; and the posterior cricoarytenoid, extending laterally to the muscular process of the arytenoid cartiage (fig. 53-13). Two muscles, closely related to each other, connect the thyroid and arytenoid cartilages: the thyroarytenoid and the vocalis (fig. 53-14D). Two muscles unite the arytenoid cartilages: the transverse and oblique arytenoids (fig. 53-13D).
Abduction of the vocal cords is carried out solely by the posterior crico-arytenoid muscles, which, extending laterally from the posterior aspect of the cricoid cartilage to the muscular processes, rotate the arytenoid cartilages laterally (fig. 53-14B and C). Abduction widens the gap of the glottis (batween the vocal cords), which is necessary for respiration. Adduction of the vocal cords is carried out by the lateral cricoarytenoid muscles, which, extending posteriorward from the arch of the cricoid cartilage to the muscular processes, rotate the arytenoid cartilages medially (fig. 53-14D). This closes the glottis, as in phonation (fig. 53-14A, B and C). The oblique and transverse arytenoid muscles are needed in order to maintain approximation of the posterior portions of the vocal cords. After closure of the glottis, the vocal folds can be tightened and lengthened by the cricothyroid muscles to change the pitch and tone of the voice. The cricothyroid muscle, by tipping the thyroid cartilage anterior on the cricoid cartilage will increase the anteroposterior dimension of the larynx and tighten the vocal cord
False vocal folds
vestibular folds
How many cartilages are in the larynx?
9 total (3 single and 3 paired)
Hyaline Cartilages
- Thyroid Cartilage (2 lamina fused together)- laryngeal notch “Adams Apple”. Thyrohyoid Membrane connects Thyroid Cartilage to Hyoid Bone
- Cricoid Cartilage (shaped like cygnate ring)
- Arytenoid Cartilage (paired!)
Elastic Cartilages
Epiglottic Cartilage Corniculate Cartilage (paired) Cuneiform Cartilage (paired)
How many muscles are in the larynx?
7 Cricothyroid Thyroarytenoid (muscle of the vocal fold) Posterior cricoarytenoid Lateral cricoarytenoid Transverse arytenoid Oblique arytenoid Vocalis
Vocal Folds Anatomy
Epiglottis Arytenoid cartilages False vocal fold (ventricular) True vocal fold Aryepiglottic folds Glottis Inner lining of trachea Corniculate cartilage Anterior Commissure
