Laryngeal System PDF

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notes on laryngeal system...

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Biological Functions of the Larynx ● Larynx is a valve that allows air in and out of the lungs for life-sustaining breathing ● Protecting the airway from infiltration of food or liquid during swallowing ● Protecting the airway from infiltration of foreign videos ● Fixing the thorax during activities demanding highly elevated abdominal pressures ● Biology first, voice second ● Looks at larynx as a biological structure, regardless of what it does to the voice Respiratory Valve ● The larynx devotes more time to respiration than to any other function ● During quiet inhalation the vocal folds abduct, moving away from the midline and widening the glottis ● During exhalation they adduct slightly toward the midline, but always maintaining an open glottal airway ● The larynx also moves vertically as a body during respiration: ○ Downward during inhalation ○ Upward during exhalation ● The downward movement increases the size of the laryngeal inlet, admitting a larger volume of inhaled air; co-occurs downward movement of the diaphragm ● Larynx should not be rigid in movement ● Can move up and down, side to side, tilt forward and backward ○ Tells us that the superior connections are attached ○ The hyoid bone is in between the base of tongue and top of larynx ■ In order for this bone to move, with hyoid bone going up, there are muscles that are attached to the base of the skull. When the muscle contracts, the lighter moves to the heavier, the hyoid bone moves towards the base of the skull, this moves the larynx up ■ To go down, there are muscles attached below, on the sternum, when contracting it pulls larynx down since the hyoid bone is going down. ● If labeling above the hyoid bone ○ Suprahyoid muscles ● Labeling below the hyoid bone ○ Infrahyoid muscles ● Top of the Larynx is attached to the hyoid bone ● Why is the larynx in the position that it is? ○ It is most efficient place to be, you aren't using muscular force it is just relaxed Effortful Closure ● The larynx is sealed to prevent air from escaping from the lungs during effortful physical work, such as lifting and pushing ● It compresses the thoracic and abdominal contents during coughing, throat clearing, vomiting, urination, defecation, and childbirth ● The arytenoid cartilages are brought to the midline ● The false/ventricular vocal folds are brought together by means of thyroarytenoid (TA) muscle contraction

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The thyroid cartilage is  elevated, approximating the hyoid bone as subglottic pressure increases ● Voice is produced by the vocal folds close enough together the air gets trapped below them. Closing the valve and for a brief millisecond they are closed, expiratory air is trapped, the pressure blows them open and the air goes through, it creates the buzzing sound that is the voice ● Have to bring the vocal folds to the midline ● The sounds IS NOT created by the vocal folds hitting each other ● It IS produced by air going across the vocal folds with opening and closing ● Have to trap the ar first ● Voice is produced on exhalation ● Voice is a result of how the muscles and the cartilages moving and being used Larynx During Swallowing ● The larynx rises as the bolus (ball of food) descends onto the back of the tongue; the thyroid cartilage elevates toward the hyoid bone, and the epiglottis is pushed against the posterior pharyngeal wall ○ Moves when you swallow with the goal of protecting the airway from that food or liquid, directing food into the back to the esophagus. (by the movements of the larynx) ● As the bolus passes through the laryngopharynx, a prominent upward movement of the larynx and trachea is begun by the upward and forward movement of the hyoid bone ● As the larynx rises, the epiglottis is forced in the firaction of the bolus, its tip tilting backward ● Esophagus is posterior to the trachea ● The larynx sits on top of the trachea ● The entrance into the trachea and esophagus are at the same level ● Trachea in front, esophagus in back ● Larynx on top of trachea, valve to let air in and out as well as protect from others that aren't supposed to be in there ○ https://aclandanatomy.com/MultimediaPlayer.apx?multimediald=10528451 ● ● The larynx continues to rise, as the bolus is squeezed downward ● As the bolus passes through the mid-pharynx, forward retraction of the larynx stops ● The larynx remains closed while the bolus passes through the cricopharyngeal sphincter into the upper esophagus ● Up down and forward ● Out and down and then back up ● Not straight up and down ● Hourglass shape/ upside down triangle ● Air should stay in the tube until out of the trachea, vice versa ○ So the inside of the tube has to be continuous and the outside of the tube has to be continuous Laryngeal Cavity

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The aditus laryngis is the entrance into the larynx ○ The aditus is a triangular opening, wider in front then in back, that slopes obliquely down and back ○ More likely that the epiglottis is going to tilt backwards, also helps protect food not going into the wrong part ■ It is important for the epiglottis to be backwards to guard the entrance into the larynx ○ Is boundaries are the epiglottis in the front, the aryepiglottic folds on each side, and the arytenoid cartilages behind Its shape is variable, depending on the position of the arytenoid cartilages and the epiglottis Slightly tilted entrance, also the entire opening to the larynx sinches shut ○ The aditus sinches ○ This is two levels of protection: ■ Epiglottis: over it ■ Aditus: sinches shut ○ Taking place at the beginning of the larynx ○ The entrance into the esophagus NOT always open, top and bottom when you are not swallowing it is by default, closed, tonic contraction ■ Opens with sensory, and when the larynx elevates that has inter connectivity that actually pull the opening of the esophagus open ● When food enters it opens then it shuts, food at the bottom then opened then closed when it is out Can you swallow without your larynx moving up? ○ ○ THIRD level of protection is midway down: vocal folds coming together The laryngeal vestibule is immediately beneath the inlet and contains two protruding sets of mucosal folds ○ Ventricular folds (more commonly referred to as the false vocal folds) ○ True vocal folds (more commonly referred to simply as the vocal folds) The laryngeal cavity is lines with a wet mucosa that is continuous with the mucosa of the tongue, pharynx, and trachea ○ This is mucosa covers the laryngeal cartilages, membranes, lgaents, and muscles and is rich with sensory receptors and mucus-secreting glands When sitting quietly breathing, the vocal folds are open Ventricular space is the area between the true and false vocal folds ○ Within this space are sacs that secrete mucous to coat the surface of the vocal folds below The area between the vocal folds is the rima glottidis; the glottis refers to the vocal folds and the space in between them False vocal folds up and out of the way True vocal folds vibrating untouched At the source it doesn't sound right it needs to come out of

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The laryngeal cavity can thus be divided into the supraglottic (above glottis) and subglottis (below glottis) space ● The subglottis is narrower than the supraglottis but eventually widens as it joins the tubular trachea ● The laryngeal cavity is lines with a wet mucosa that is continuous with the mucosa of the tongue, pharynx, and trachea ○ This mucosa covers the laryngeal cartilages, membranes, ligaments, and muscles and is rich with sensory receptors and mucus-secreting glands Laryngeal Framework ● The larynx is a constricted tube with a smooth surface ○ If you look down into the larynx, you see the true and false vocal folds protruding ● There is a framework of cartilage, ligaments & membranes, and folds ● Connected to this framework are intrinsic and extrinsic laryngeal muscles ● The larynx is situated between vertebrae C3-C6 (in adults); a bit higher in newborns and children ● Because the larynx is not rigidly fixed in the neck, it is capable of limited up-down and side-to-side movements Hyoid Bone ● Located at the level of C3 with its horns directed backward and slightly upward ● The larynx is suspended from the hyoid bone via the medial and lateral thyrohyoid ligaments ● The base of the tongue inserts superiorly into the hyoid bone ● Divided into three segments: ○ Body ○ Greater cornua/horns ■ Thyroid cartilage suspends from it with lateral ligaments ○ Lesser cornua/horns Laryngeal Cartilages ● Nine cartilages that are joined by various ligaments and membranes: ○ 3 of the cartilages are single (thyroid, cricoid and epiglottis) ○ 3 are paired (arytenoid, corniculate, and cuneiform) ● The laryngeal cartilages are coated with a tough leathery covering (perichondrium) which gives the larynx a waxy look ● Most are not directly connected to each other ● Lining on inside and draping on outside ● They stay fairly rigid due to muscles and ligaments ○ These are in between the various cartilages that help give it its form ● membranes, ligaments ● Spaces in between the cartilages ● Contracts, closer together Listing of the Laryngeal Cartilages ● Epiglottis (elastic) ● Thyroid cartilage (hyaline)

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Cricoid cartilage (hyaline) Arytenoid cartilages, paired, (hyaline) Corniculate cartilages, paired (elastic) Cuneiform cartilages, paired (elastic) When the muscles contract, certain cartilages are going to moe and so is whatever is attached to them Epiglottis ● Flexible leaf-like structure located just behind hyoid bone at the root of the tongue ● Broad, round, and thin at the top and narrows to a stalk-like structure toward the bottom ● Attached by a ligament to the thyroid cartilage just beneath the thyroid notch ● Broadest portion fastens to the hyoid bone by a ligament ● Prevents food from entering the larynx during swallowing by covering entrance to the larynx ● Contributes very little speech ● Inverts and covers the opening of the larynx ● Cricoid doesn't move Thyroid Cartilage ● Largest cartilage of the larynx consisting of two lamina (plates) which joint at the midline ● Can tilt forward and backward ● Where the two plates come together is the adam's apple ● Vocal folds are a little bit below the prominence ● In males the angle comes together differently than in women ○ Males = narrower angle ● Greater horns on top (suspended from the hyoid bone) and lesser horns on bottom (attached, not rigidly, there is a joint to cricoid - cricothyroid joint) ● Anterior angle forms the laryngeal prominence (aka “adams apple”) ● Immediately superior to the laryngeal prominence is a v-shaped thyroid notch ● Anterior angle is attached to the cricoid cartilage via the median cricothyroid ligament ● Superior posterior angle attaches to the hyoid bone via the thyrohyoid ligaments ● Inferior posterior angle attaches to the cricoid cartilage via cricothyroid joints ● Has two horns (aka cornu) projecting from the lamina: ○ Superior horn: attaches to lateral thyroid ligaments ○ Inferior horn: attaches to cricoid cartilage ● Higher in the back than the front ● The cricothyroid joint is where the inferior horns of the thyroid cartilage attached to the cricoid cartilage ● The cricoarytenoid joint is where the base of the two arytenoid cartilages attach to the cricoid lamina Cricoid Cartilage ● The second largest of the cartilages ● Ring-shaped structure connected to the first tracheal ring by ligaments ● The posterior (signet) part of the cricoid is called the lamina and the anterior (band) part is termed the arch

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Higher in the back than the front The cricothyroid joint is where the inferior horns of the thyroid cartilage attach to the cricoid cartilage ● The cricoarytenoid joint is where the base of the two arytenoid cartilages attach to the cricoid lamina Arytenoid Cartilage ● Pyramid shaped ● Sit atop the cricoid cartilage ● Has three surfaces, two processes (muscular process, vocal process), bse, and apex ● Thyroarytenoid (TA) muscle and vocal ligament attach to the vocal process of this cartilage ● Posterior cricoarytenoid (PCA) and lateral cricoarytenoid (LCA) muscles attach to the muscular process of this cartilage ● Pivit, sitting on top of the cricoid on a moveable joint, cricoarytenoid ● Only reason the vocal folds move is because of the movement of the arytenoid, due to the muscles around it ● Muscles acting upon the arytenoid cartilages is what moves the vocal folds together and apart ● NO pulling vocal folds Corniculate Cartilages ● Cone-shaped elastic cartilages on the apex of the arytenoids, extending into the aryepiglottic folds Cuneiform Cartilages ● Cone-shaped, elastic nodules located in the aryepiglottic folds ● Covered by connective tissue, fat, mucous membrane and appear as swellings when viewed from above ● Lend support to aryepiglottic folds and stiffen them to help maintain opening to larynx Laryngeal Joints ● Two pairs of joints ○ Cricothyroid joint ○ Cricoarytenoid joint ● Movements at these joints is determined by the facets of the articulating cartilages (thyroid and/or cricoid) and the surrounding ligaments Cricothyroid Joint ● This joint is formed between the inferior horns of the thyroid cartilage and the cricoid arch: ○ Hs a fibrous capsule, which is lines by a synovial (fluid-filled) membrane ● Rotation at this joint results in the thyroid tilting downward and also gliding forward and back relative to the cricoid ○ This provides the major adjustment for change in pitch via a change in the length of vocal folds Cricoarytenoid Joint

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The cricoarytenoid joint is formed between the superior borders of the cricoid lamina and the arytenoid cartilages: ○ It is also (usually) a synovial joint ● The movement at the joint is described primarily as a rocking-sliding m  otion ○ The rocking motion at this joint primarily results in the vocal processes of the arytenoid cartilages swinging downward and inward (for adduction), or upward and outward (for abduction) ○ The sliding motion primarily results in changed in vocal fold length Laryngeal Muscles ● Extrinsic laryngeal muscles ○ Have one attachment to the larynx and another attachment to some structure external to the larynx ○ They change the position of the larynx in the neck and stabilize/support the larynx ● Major Extrinsic Muscles ○ Three major ■ Sternothyroid ■ Thyrohyoid ■ Inferior pharyngeal constrictor ● Supplementary muscles ○ Attach to the hyoid bone and influence the position and stability of the larynx ○ Originate from either above or below the hyoid bone: ■ Suprahyoid group ■ Infrahyoid group ○ Suprahyoid group ■ Inset into they hyoid bone from the skull ■ Contraction of these muscles raises the larynx ○ Infrahyoid group ■ Inset into the hyoid bone from the sternum ■ Contraction of these muscles lowers the larynx Raising and lowering of the Larynx ○ The raising and lowering of the larynx is observable and noted mainly during the pharyngeal stage of swallowing ○ These Movements severe primarily to help protect the airway from aspiration of food or liquid ○ The extrinsic laryngeal muscles also come into play slightly during production of higher and lower pitches (especially in untrained singers) Intrinsic Muscles of the Larynx ● May be categorized according to their effect on the shape of the glottis and on the vibratory behavior of the vocal folds: ○ Abductor muscles: separate the arytenoids ○ Adductor muscles: bring the arytenoids toward the midline ○ Tensor muscles: elongate and tense the vocal folds

○ Relaxer muscles: shorten the vocal folds Intrinsic laryngeal muscles include: ○ Thyroarytenoid muscle (TA) ○ Posterior cricoarytenoid muscle (PCA ○ Lateral cricoarytenoid muscle (LCA) ○ Interarytenoid muscles (IA) ○ Cricothyroid muscle (CT Thyroarytenoid muscle ● These paired muscles form the bulk of the muscular portion of the vocal folds ● Consists of two separate muscle bundles ○ Thyrovocalis ■ Fibers originate on the inner surface of the thyroid cartilage near the thyroid notch ■ Fibers insert on the lateral surface of the vocal process of the arytenoid ■ Contraction draws the cricoid and thyroid cartilages apart, tensing the vocal folds ○ Thyromuscularis ■ Fibers of the muscularis originate on the thyroid cartilage just lateral to those of the vocalis ■ Fibers insert on the muscular process of the arytenoid ■ Contraction of the muscularis draws the arytenoid cartilages forward, relaxing and adducting the vocal folds ●

**cartilage, muscle, membrane, etc what they do and what they connect to

Intercostal muscles are always used

Laryngeal Membranes and Ligaments ● Two categories of membranes and ligaments connect laryngeal cartilages with adjacent structures

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Extrinsic ■ Connect the laryngeal apparatus with structures outside of the larynx for support ○ Intrinsic ■ Connect laryngeal cartilages with each other to regulate movement Extrinsic Laryngeal membranes and ligaments ● Some of these ligaments and membranes connect: ○ Hyoid bone to the temporal bone ○ Epiglottis to the hyoid bone or tongue ○ Epiglottis to the laryngeal cartilages ○ Laryngeal cartilages to the hyoid bone ○ Laryngeal cartilages to the trachea ○ Stylohyoid ligaments ○ Thyrohyoid membrane and ligaments ○ Hyoepiglottic and thyroepiglottic ligaments ○ Cricotracheal membrane ligament Stylohyoid Ligaments ● Originates at the styloid process of the temporal bone ● Inserts into the lesser horn of the hyoid bone Thyroid Membrane ● Connects the inferior surface of the hyoid bone with the superior border of the thyroid cartilage ● The internal branch of the superior laryngeal nerve (SLN) and the superior laryngeal artery penetrate this membrane on each side Thyrohyoid Ligament ● These ligaments suspend the larynx from the hyoid bone ○ Medial ligament is unpaired ○ Lateral ligaments are paired Hyoepiglottic Ligament ● Unpaired, midline, elastic ligament extending from the anterior surface of the epiglottis to the upper border of the body of the hyoid bone ○ Connects the epiglottis to the hyoid bone Cricotracheal Membrane ● Connects the most superior tracheal cartilage with the inferior border of the cricoid cartilage Intrinsic Laryngeal Membranes ● Arise from a common sheet of connective tissue called the elastic membrane: ○ Quadrangular membrane (lines supraglottis) ○ Conus elasticus (lines subglottis) ● The dividing line between these upper and lower membranes is the ventricular space Quadrangular membranes ● Paired membranes that connect the epiglottis with the arytenoid and thyroid cartilages

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Originate in the lateral margins of the epiglottis and adjacent thyroid cartilage Attach to the corniculate cartilage and the lateral surface of the arytenoid The free superior margins of the quadrangular membranes from the ventricular ligaments, also known as the false vocal folds Conus Elasticus ● Connects the cricoid cartilage with the thyroid and arytenoid cartilages via the medial and lateral cricothyroid ligaments ● The free superior borders of the conus elasticus from the vocal ligaments Mucosal Lining ● The mucous membrane that lines the mouth and pharynx continues through the larynx and down to the trachea ● Rich in mucous glands between the vocal and ventricular ligaments ● Adheres closely to the epiglottis, aryepiglottic folds, an the vocal folds Vascular Supply to the Larynx ● Blood supply comes from the thyroid artery: ○ Superior laryngeal artery (epiglottis down to vocal folds, including PCA/LCA/IA muscles) ○ Inferior laryngeal artery (subglottis, including CT muscle) ● There are blood vessels along the medial edge and the body of the TA muscle ● Blood volume decreases during vocal fold vibration, which prevents hemorrhaging Venous Drainage From the Larynx ● The venous drainage is supplied by the superior and inferior laryngeal veins ● Blood drains into the cervical lymph nodes ● The inferior arteries and veins serve the upper larynx ● The superior arteries and veins serve the lower larynx

Laryngeal Innervation ● ●

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The central nervous system (CNS) and the peripheral nervous system (PNS) coordinate all laryngeal o...