what is the name of the tube that connects the larynx to the right and left bronchi?
Larynx
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The larynx is a complex hollow structure located in the inductive midline region of the neck. It is anterior to the esophagus and at the level of the third to the sixth cervical vertebrae in its normal position. It consists of a cartilaginous skeleton connected past membranes, ligaments and associated muscles that suspend it from surrounding structures. Information technology sits merely to a higher place the trachea and is continuous with the oropharynx (the portion of the pharynx posterior to the oral cavity) in a higher place.
The larynx conducts air into the lower respiratory tract and closes off the airway particularly during swallowing to forestall aspiration of food. It is usually referred to equally the "voice box" or the "organ of phonation" every bit it houses the structure responsible for sound product. It is quite mobile in the neck and can be seen and felt moving upward and forwards during swallowing, endmost off the trachea and opening the esophagus.
| Functions | Air conduction, airway protection, sound production |
| Cartilages | Unpaired (3): Cricoid, thyroid, and epiglottis Paired (iii): Arytenoid, corniculate, and cuneiform |
| Cavity construction | Three parts: Vestibule, middle part, infraglottic cavity Glottis: Vocal folds, rima glottidis |
| Muscles | Extrinsic: Move of the entire larynx Intrinsic: Move of components of the larynx |
| Blood supply | Superior and junior laryngeal arteries, superior and inferior laryngeal veins |
| Lymphatic drainage | Superior and inferior deep cervical lymph nodes |
| Innervation | Vagus nerve: Superior laryngeal nerves (internal and external), inferior laryngeal nerves |
This article will discuss the major anatomical structures and the primary functions of the larynx. It will also outline the blood supply, innervation and lymphatic drainage of the larynx too as a clinical application and an interesting fact.
Contents
- Cartilaginous framework and ligaments
- Cavity of the larynx
- Muscles
- Claret supply and lymphatic drainage
- Innervation
- Clinical application
- Interesting fact
- Sources
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Cartilaginous framework and ligaments
The larynx is composed of 3 large unpaired cartilages (cricoid, thyroid, and epiglottis) and three paired smaller cartilages (arytenoid, corniculate, and cuneiform), making a full of ix individual cartilages. The thyroid cartilage is the largest of the laryngeal cartilages and is composed of hyaline cartilage. It forms the inductive and lateral portions of the larynx and has no posterior component. The broad apartment right and left halves (laminae) of the cartilage fuse anteriorly in the midline to form a 5-shaped anterior projection called the laryngeal prominence (ordinarily chosen the "Adam's apple").
The Adam's apple is typically more prominent in males afterward puberty. This is due to the influence of the hormone testosterone, which stimulates the overall growth of the larynx resulting in a deeper phonation with time. Superior to this prominence is the superior thyroid notch. A less prominent inferior thyroid notch is present along the base of the thyroid cartilage. The posterior margin of each lamina extends upwards into a superior horn and downward into an inferior horn. The longer superior horn, along with the unabridged superior border of the thyroid cartilage, attaches to the hyoid bone by the thyrohyoid membrane. This lath fibroelastic sheet has a thick median region called the median thyrohyoid ligament as well as lateral parts called the lateral thyrohyoid ligaments, which directly attach to the superior horn. The inferior horn bears a facet on its medial surface with which its articulates with the posterolateral surface of the cricoid cartilage to form the cricothyroid articulation.
The cricoid cartilage is a much smaller signet ring-shaped hyaline cartilage located directly below the thyroid cartilage. It forms the inferior aspect of the larynx and is continued to the trachea inferiorly. It is the only complete ring of cartilage that encircles the airway. The cricoid cartilage has a narrow inductive arch (ring portion) and a wider posterior lamina (signet portion) with a midline ridge that serves as a surface of attachment for the esophagus. A dense band of connective tissue, the cricothyroid ligament, attaches the cricoid cartilage to the inferior border of the thyroid cartilage. The cricotracheal ligament attaches the cricoid cartilage to the first tracheal ring.
Located on the superolateral aspects of the wider posterior cricoid cartilage lamina are the paired pyramidal-shaped arytenoid cartilages. Each cartilage has a superior apex, an anterior song process and a big lateral muscular process. Attached to the apices of the arytenoid cartilage are the small, paired and conical- shaped corniculate cartilages.
The last unpaired cartilage, the epiglottis, is a big foliage-shaped elastic cartilage that is covered by mucous membrane. It is attached past its stalk to the inner aspect of the bending formed past the laminae of the thyroid cartilage via the thyroepiglottic ligament in the midline. The epiglottis is also attached to the hyoid os by the hyoepiglottic ligament which extends from the anterosuperior surface of the epiglottis to the body of the hyoid bone. The epiglottis projects superiorly into the pharynx, with its upper margin just behind the root of the tongue. Every bit its name suggests (epi = above, glottis = oral fissure of windpipe), it sits above the laryngeal opening (inlet). During swallowing, as the larynx moves up and forwards, the epiglottis swings downward to close off the laryngeal inlet, and thus prevents materials from entering the airway.
A thin layer of connective tissue, the quadrangular membrane extends between the lateral borders of the epiglottis and the anterolateral margins of the arytenoid cartilage. Its complimentary lower edge is thickened and forms the vestibular ligament. This ligament is enclosed by a fold of mucous membrane to form the vestibular fold (fake song cord) which extends from the thyroid cartilage to the arytenoid cartilage.
The final cartilaginous components of the larynx are the 2 pocket-sized club-shaped cuneiform cartilages that prevarication superior and inductive to the corniculate cartilages. They practice not directly attach to any other laryngeal cartilage only are suspended within and strengthen a fibro-elastic membrane called the aryepiglottic membrane. This membrane forms the gratis superior edge of the quadrangular membrane, which as described earlier, connects the arytenoid cartilages to the lateral borders of the epiglottis. It is covered past mucosa to form the aryepiglottic fold. On the posterior aspect of the aryepiglottic folds both the corniculate and cuneiform cartilages are seen as small nodules surrounding the laryngeal inlet.
Cavity of the larynx
At present that we have discussed the external cartilaginous skeleton, let us take a await inside the lumen of the larynx. The mucosa lined cavity of the larynx extends from its superior opening (laryngeal inlet) to the inferior border of the cricoid cartilage which is continuous with the lumen of the trachea. The laryngeal cavity is divided into three regions:
- Vestibule: betwixt the laryngeal inlet and the vestibular folds
- Centre part: between the vestibular folds to a higher place and vocal folds below
- Infraglottic cavity: between the vocal fold and the trachea
The lateral walls of the centre part of the laryngeal crenel bulge outward to class lateral recesses (laryngeal ventricle) between the vestibular fold and the vocal fold. Each ventricle has an elongated blind tubular extension, the laryngeal saccule, that projects anterosuperiorly between the vestibular fold and the thyroid cartilage. Each saccule is lined with fungus glands that produce fungus to lubricate the vocal folds.
The vocal apparatus of the larynx is called the glottis and consists of two song folds (true song cords) and the rima glottidis. Each mucous membrane-covered vocal fold contains a vocal ligament that extends from the inner surface of the thyroid cartilage to the vocal process of the respective arytenoid cartilage. Running parallel to each vocal ligament is the vocalis musculus which is responsible for adjusting the tension of the vocal folds. The song folds are the "true" structures that produce sound as air passes over them, whereas the vestibular folds (faux song cords) take no role in sound production but protect the vocal cords.
The opening betwixt the vocal cords is referred to as the rima glottidis. The shape of this opening depends on the position of the vocal folds. Rotational movements of the arytenoid cartilages at the cricoarytenoid joints can separate (abduct) the song folds, widening the rima glottidis or appose (adduct) the vocal folds and narrow the rima glottidis. Typically, during breathing, the vocal cords are abducted nevertheless, during swallowing, they are adducted to close the rima glottidis. The qualities of the sound produced (east.g. pitch) depends on the length, tension, and position of the vocal folds. Normally, during vox, the song cords are closely apposed resulting in a slit-like rima glottidis. Equally expired air passes over the cords, it causes them to vibrate, producing sound. The sound is and so modified by tongue, jaw and lip movements into spoken language.
Muscles
At that place are two groups of muscles that are associated with the larynx, the extrinsic and intrinsic muscles. The extrinsic laryngeal muscles motility the larynx as a whole. They consist of the suprahyoid muscles that drag the hyoid bone and the larynx during swallowing and vocalisation, and the infrahyoid muscles that depress the hyoid bone and the larynx.
The small intrinsic laryngeal muscles are responsible for moving diverse components of the larynx. They modify the length and tension of the vocal cords equally well as the shape of the rima glottidis during breathing, swallowing and vocalization.
Blood supply and lymphatic drainage
The arterial supply of the larynx is by the superior and inferior laryngeal arteries which are branches of the thyroid arteries. The larynx is tuckered by corresponding veins, namely the superior and inferior laryngeal veins. The lymphatic vessels above the vocal folds drain into the superior deep cervical lymph nodes whereas those beneath the vocal folds drain first to nodes around the trachea (pretracheal and paratracheal nodes) and subsequently into the inferior deep cervical lymph nodes.
Innervation
The right and left superior and inferior laryngeal nerves which are branches of the vagus nerve, the tenth cranial nerve (CN X), provide motor and sensory innervation to the larynx. Each superior laryngeal nerve divides into the internal and external laryngeal nerves. The internal laryngeal nerve accompanies the superior laryngeal artery through the thyrohyoid membrane and provides the sensory and autonomic innervation of the laryngeal cavity to the level of the song cords. The smaller external laryngeal nervus provides motor innervation to the cricothyroid musculus.
The recurrent laryngeal nerves which are ascending branches of the vagus nerves continue toward the larynx as the right and left junior laryngeal nerves. They provide motor innervation to all the intrinsic muscles of the larynx except the cricothyroid muscles and sensory innervation to the laryngeal crenel beneath the vocal cords.
Clinical application
In the setting of an acute life-threatening airway obstacle, physicians may perform a cricothyrotomy past inserting a needle through the cricothyroid ligament to constitute an airway. A bones agreement of the anatomy of the larynx is required to perform this procedure. Under sterile conditions, physicians palpate the laryngeal prominence of the thyroid cartilage (Adam'due south apple) and slide their fingers down till they feel the cricoid cartilage which is the first house bulge felt. The gap felt between the thyroid and cricoid cartilages (the cricothyroid space) is covered by the cricothyroid ligament.
Interesting fact
Older children and adults are unable to consume and exhale through their nose at the same fourth dimension. However, newborns and infants can do this while swallowing milk. This process is called 'obligate nose breathing'. In babies, the larynx sits higher, and with further elevation during swallowing, the epiglottis is able to slide upward behind the soft palate, locking the larynx into the nasopharynx. This anatomical organisation which allows babies to feed and exhale at the same fourth dimension is lost between 2 to 6 years of age, equally the larynx gradually descends into the developed location.
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