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  1. 1. Larynx ANNOUNCEMENTS 1. Faculty laboratory assignments for this week: o Lab 1: Dr. Phelan, Dr. Sims o Lab 2: Dr. Davies o Lab 3: Dr. Tank, Dr. Benes 2. Decalcified temporal bones - Decalcified temporal bones will be provided for today's dissection of the middle ear. You can cut them with a scalpel. Do not dissect the temporal bones on your cadaver! 3. Simulataneous dissections - The larynx and ear dissections can be performed simultaneously. Just be certain that everyone at your table has an opportunity to see the specimens at several dissection stages before soft tissue structures are destroyed. ASSIGNMENTS Moore's Clinically Oriented Anatomy: 1038-1049 Grant's Dissector: 291-295; Start at "Larynx"; Continue through the end of the chapter. HELPFUL HINTS 1. Remove the mucosa to see the underlying muscles - Instructions call for removal of the mucosa on the pharyngeal aspect of the larynx. Simply peel the mucosa off of the entire posterior surface of the larynx. The muscles are directly underneath the mucosa. Extend the cut through the posterior pharyngeal wall inferiorly into the esophagus if necessary if you need more exposure. 2. Laryngeal nerves - Go back to the earlier dissection (anterior cervical triangle) to review the innervation pattern of the larynx. Then, trace the branches into the larynx. WHEN YOU FINISH THIS SECTION, YOU SHOULD BE ABLE TO PERFORM THE FOLLOWING TASKS AND ANSWER THESE QUESTIONS 1. What is the relationship of the thyroid gland to the larynx? 2. How close is the larynx to the esophagus? Study a cross section of the neck to verify your answer. 3. Review the relationship of the larynx to the infrahyoid muscles of the anterior cervical triangle. 4. What is the position of the true vocal folds during phonation? During forced inspiration?
  2. 2. 5. What muscles are responsible for abducting the vocal folds? 6. What nerve supplies the intrinsic muscles of the larynx? 7. Review the arterial supply and venous drainage of the thyroid gland. Do any of these vessels also supply the larynx? 8. When one recurrent laryngeal nerve is cut, describe the effect on the patient's voice. 9. Describe the Valsalva maneuver. List all of the muscles that are involved in this maneuver. BONES, CARTILAGES AND JOINTS (Atlas image 1, Atlas image 2, Atlas image 3, Atlas image 4) Hyoid Bone o Greater horn o Lesser horn o Body Thyroid cartilage (Atlas image 1, Atlas image 2) o Superior horn o Superior tubercle o Lamina o Oblique line o Inferior tubercle o Inferior horn o Laryngeal prominence Epiglottis Arytenoid cartilage (Atlas image) o Muscular process o Vocal process Corniculate cartilage Cricoid cartilage (Atlas image 1, Atlas image 2) o Lamina o Arch o Median ridge (on posterior midline) Joints o Cricothyroid joint o Cricoarytenoid joint  Cricoarytenoid joint capsule
  3. 3. LIGAMENTS AND MEMBRANES Extrinsic o Thyrohyoid membrane (Atlas image 1, Atlas image 2)  Median thyrohyoid ligament  Lateral thyrohoid ligament o Cricotracheal membrane o Hyoepiglottic ligament Intrinsic o Membranes  Conus elasticus  Quadrangular membrane o Ligaments (Atlas image 1, Atlas image 2)  Vocal ligament  Thyroepiglottic ligament EXTRINSIC MUSCLES OF THE LARYNX (These muscles move the larynx relative to the neck) Sternothyroid m. Thyrohyoid m. Stylopharyngeus m. Palatopharyngeus m. INTRINSIC MUSCLES OF THE LARYNX (Atlas image) (These muscles move the laryngeal cartilages within the larynx) Posterior cricoarytenoid m. (Atlas image 1, Atlas image 2) Arytenoideus mm. (2 types) (Atlas image 1, Atlas image 2)) o Transverse arytenoid m. o Oblique arytenoid m. Aryepiglottic m. (Atlas image) Cricothyroid m. (Atlas image) Lateral cricoarytenoid m. (Atlas image) Thyroarytenoid m. (Atlas image) Thyroepiglottic m. ARTERIAL SUPPLY OF THE LARYNX Superior laryngeal a. Inferior laryngeal a. Cricothyroid a. NERVE SUPPLY OF THE LARYNX Superior laryngeal n. o Internal branch o External branch Recurrent laryngeal n.
  4. 4. INTERIOR FEATURES OF THE LARYNX (Atlas image) Vestibular fold (false vocal fold) Vocal fold (true vocal fold) Ventricle Vestibule Rima glottidis Glottis Infraglottic cavity ANATOMY TABLES FOR TODAY'S TOPIC Osteology - Larynx and Hyoid Bone/Cartilage Structure Description Notes hyoid a "U"-shaped bone the hyoid bone ossifies completely in middle life; the consisting of several parts: body articulates with the greater horns via cartilage and body, 2 greater horns, 2 with the lesser horns via fibrous joints prior to lesser horns ossification; an important site for muscle attachments (suprahyoid and infrahyoid muscle groups) body the middle portion of the the body of the hyoid bone articulates with the greater "U"-shaped bone horns posteriorly greater horn posteriorly directed limbs of each greater horn articulates with the body and lesser (cornu) the "U"-shaped bone horns anteriorly; origin of middle pharyngeal constrictor m. and hyoglossus m. lesser horn articulates with the greater the inferior end of the stylohyoid ligament attaches to (cornu) horn at its junction with the the lesser horn body thyroid the large anterior cartilage connected above to the hyoid bone via the thyrohyoid cartilage of the larynx; it has several membrane; connected below to the cricoid cartilage via parts: laminae (2), superior the inferior horn of the thyroid cartilage; connected horns (2), inferior horns (2), posteriorly: to the arytenoid cartilage via the vocal oblique line, superior ligament and thyroarytenoid m., to the epiglottic thyroid notch, cartilage via the thyroepiglottic ligament; it tilts anteriorly to increase the length of the vocal ligament and raise the pitch of the voice lamina a broad flat plate of the laryngeal prominence is the line of fusion of the two cartilage forming one side laminae; each lamina is connected superiorly to the of the thyroid cartilage; two hyoid bone by the thyrohyoid membrane laminae fuse anteriorly in the midline to form the thyroid cartilage superior horn the rounded, superior it is connected superiorly to the greater horn of the projection of the posterior hyoid bone by the lateral thyrohyoid ligament border of the thyroid lamina inferior horn the rounded, inferior it is connected inferiorly to the cricoid cartilage by the projection of the posterior cricothyroid articulation (a synovial joint) border of the thyroid lamina oblique line ridge which descends a line of muscle attachment diagonally from superior to inferior on the lateral
  5. 5. surface of the thyroid lamina laryngeal the line of fusion of the known to the lay person as the "Adam's apple"; the prominence thyroid laminae laryngeal prominence is a secondary sexual characteristic - in postpuberal males the angle of the laryngeal prominence is approximately 90¡ and in females the angle is approximately 120¡ superior the notch at the superior end it is connected to the hyoid bone by the median thyroid notch of the laryngeal prominence thyrohyoid ligament epiglottis the superior part of the epiglottic cartilage is covered by a mucous membrane larynx arytenoid a pyramid shaped cartilage paired; each is connected to the epiglottis above via the cartilage located on the superior aryepiglottic m. and to the thyroid cartilage anteriorly margin of the cricoid lamina via the vocal ligament; paired arytenoid cartilages are pulled together (adducted) by the arytenoid m. corniculate a small cartilage located on corniculate cartilage is found in the base of the cartilage the apex of the arytenoid aryepiglottic fold; it is yellow elastic cartilage cartilage cricoid cartilage the inferior & posterior connected: above to the thyroid cartilage via the inferior cartilage of the larynx; it horn of the thyroid cartilage, to the conus elasticus, to forms a complete the arytenoid cartilages which sit atop the lamina; cartilaginous ring; its arch connected below to the first tracheal ring via the projects anteriorly and its cricotracheal ligament lamina is broad and flat posteriorly cuneiform small cartilaginous nodule cuneiform cartilage is yellow elastic cartilage cartilage located in the aryepiglottic fold Muscles of the Larynx Muscle Origin Insertion Action Innervation Artery Notes sternothyroid posterior oblique line depresses/stabilizes ansa cervicalis superior sternothyroid lies surface of of the the hyoid bone thyroid a. deep to the the thyroid sternohyoid m. manubrium cartilage below the origin of the sternohyoid m. thyrohyoid oblique line lower border elevates the larynx; ansa cervicalis superior thyrohyoid lies of the of the hyoid depresses/stabilizes (via fibers thyroid a. deep to the thyroid bone the hyoid bone running with the sternohyoid cartilage hypoglossal nerve that leave XII distal to the superior limb of ansa) stylopharyngeus medial side superior elevates the larynx glossopharyngeal ascending stylopharyngeus, of the border of the nerve (IX) pharyngeal the only muscle styloid thyroid a. innervated by IX,
  6. 6. process cartilage and is the only muscle also into the of the pharyngeal pharyngeal wall NOT wall innervated by the vagus (X) nerve; it is a derivative of the third pharyngeal arch palatopharyngeus posterior posterior elevates the larynx vagus nerve (X) ascending palatopharyngeus margin of wall of the via pharyngeal pharyngeal is part of the inner the bony pharynx and plexus a. longitudinal palate and the posterior muscle layer of the the palatine margin of pharynx aponeurosis the thyroid cartilage posterior posterior muscular draws the muscular inferior laryngeal superior the posterior cricoarytenoid surface of process of process posteriorly, nerve, from the laryngeal a., cricoarytenoid is the lamina the arytenoid which pivots the recurrent cricothyroid the only ABductor of the cartilage arytenoid cartilage laryngeal nerve, a branch of of the vocal folds; cricoid and abducts the branch of the the superior the arteries that cartilage vocal folds vagus nerve (X) thyroid a. supply the larynx anastomose within the larynx to supply the mucous membranes and muscles arytenoid, oblique muscular posterior draws arytenoid inferior laryngeal laryngeal br. the oblique process of surface of cartilages together, nerve, from of the arytenoid m. lies the the adducting the vocal recurrent superior posterior to the arytenoid contralateral folds laryngeal nerve, a thyroid a. transverse cartilage arytenoid branch of the of arytenoid m.; the cartilage, vagus (X) arytenoideus is near its apex often considered to be one muscle with oblique and transverse fibers arytenoid, posterior posterior draws arytenoid inferior laryngeal laryngeal br. the transverse transverse surface of surface of cartilages together, nerve, from of the arytenoid m.lies the the adducting the vocal recurrent superior anterior to the arytenoid contralateral folds laryngeal nerve, a thyroid a. oblique arytenoid cartilage arytenoid branch of the m.; the cartilage vagus nerve (X) arytenoideus is often considered to be one muscle with oblique and transverse parts aryepiglottic apex epiglottis draws the epiglottis inferior laryngeal laryngeal br. the mucosa is (superior posteriorly and nerve, from of the raised by the part) of the downward during recurrent superior underlying arytenoid swallowing laryngeal nerve, a thyroid a. aryepiglottic m. to cartilage branch of the of form the vagus (X) aryepiglottic fold cricothyroid arch of the inferior draws the thyroid external branch of cricothyroid this is the only cricoid border of the cartilage forward, superior laryngeal branch of intrinsic muscle of cartilage thyroid lengthening the nerve, a branch of the superior the larynx that is cartilage vocal ligaments the vagus nerve thyroid a. not supplied by the
  7. 7. (X) recurrent laryngeal n.; ALL other laryngeal muscles are innervated by recurrent laryngeal nerve, via its inferior laryngeal branch lateral arch of the muscular draws the muscular inferior laryngeal superior an antagonist of cricoarytenoid cricoid process of process of the nerve, from the laryngeal a., the posterior cartilage the arytenoid arytenoid cartilage recurrent cricothyroid cricoarytenoid m.; cartilage anteriorly, which laryngeal nerve, a branch of the arteries that pivots the arytenoid branch of the the superior supply the larynx cartilage and vagus nerve (X) thyroid a. anastomose within adducts the vocal the larynx to folds supply the mucous membranes and muscles thyroarytenoid inner lateral draws the arytenoid inferior laryngeal laryngeal its subsidiary parts surface of border of the cartilage forward, nerve, from branch of are the the thyroid arytenoid relaxing and recurrent the superior thyroepiglottic m. cartilage cartilage adducting the vocal laryngeal nerve, a thyroid a. and the vocalis m.; anteriorly folds branch of the the medial most vagus nerve (X) fibers of thyroarytenoid that insert along the vocal ligament are called the vocalis muscle thyroepiglottic inner lateral draws the epiglottic inferior laryngeal laryngeal represents the surface of surface of cartilage downward nerve, from branch of superior fibers of the thyroid the epiglottic recurrent the superior thyroarytenoid cartilage cartilage laryngeal nerve, a thyroid a. muscle which fan near the branch of the out to the laryngeal vagus nerve (X) quadrangular prominence membrane and epiglottis vocalis surface of vocal relaxes segments of inferior laryngeal laryngeal br. represents the the thyroid ligament the vocal ligament, nerve, from the of the innermost fibers of cartilage, thereby adjusting recurrent superior the thyroarytenoid vocal pitch laryngeal nerve, a thyroid a. muscle; the process of branch of the cricothyroid m. the vagus nerve (X) grossly tenses the arytenoid vocal ligaments, cartilage while the vocalis muscle provides the mechanism for fine tuning the vibrations of the vocal folds constrictor, oblique line midline constricts vagus (X), via the ascending the most external inferior of the pharyngeal pharyngeal cavity pharyngeal pharyngeal of the three pharyngeal thyroid raphe plexus, with aid a., superior pharyngeal cartilage, from the superior thyroid a., constructor mm. lateral laryngeal and inferior surface of recurrent thyroid a. cricoid laryngeal nerves
  8. 8. cartilage cricopharyngeus lateral midline constricts the recurrent cricothyroid cricopharyngeus surface of pharyngeal pharyngeal cavity laryngeal nerve, a branch of represents the the cricoid raphe and the entrance to branch of the the superior lowest fibers of the cartilage the esophagus vagus nerve (X) thyroid a., inferior pharyngeal ascending constrictor; it is pharyngeal continuous with a. the esophagus below and marks the beginning of it Nerves of the Larynx Nerve Source Branches Motor Sensory Notes laryngeal, recurrent no named all intrinsic muscles of the mucous inferior laryngeal n. is the inferior laryngeal branches larynx except the cricothyroid; membrane of continuation of the br. of the those muscles are: the larynx recurrent laryngeal n., the vagus n. thyroarytenoid, oblique and below the name change occurs at the (X) transverse arytenoid, posterior vocal fold cricothyroid articulation and lateral cricoarytenoid, aryepiglottic, thyroepiglottic, vocalis; secretomotor to the mucous membrane of the larynx below the vocal fold superior vagus n. internal br., cricothyroid m., inferior mucous external br. supplies the laryngeal (X) external br. pharyngeal constrictor m.; membrane of cricothyroid m.; all other n. secretomotor to mucosal glands the larynx intrinsic muscles of the of the larynx above the vocal above the larynx are supplied by the folds vocal folds recurrent laryngeal n. recurrent vagus n. esophageal upper esophagus, lower upper right recurrent laryngeal n. laryngeal (X) brs., tracheal pharynx, laryngeal mm. (except esophagus, loops posteriorly around n. brs., cardiac cricopharyngeus); smooth lower pharynx, the right subclavian a.; left brs., muscle of the trachea; larynx below recurrent laryngeal n. pharyngeal secretomotor to mucosal glands the vocal loops posteriorly around brs., inferior in the upper esophagus, lower folds, GVA the aortic arch and laryngeal n. pharynx, larynx below the vocal from heart ligamentum arteriosum; fold, trachea; cardiac muscle of the inferior laryngeal br. the heart (slows heart rate, supplies all intrinsic decreases force of contraction) muscles of the larynx EXCEPT the cricothyroid m. Arteries of the Larynx Artery Source Branches Supply to Notes superior laryngeal superior no named branches internal aspect of the superior laryngeal a. penetrates thyroid a. superior larynx the thyrohyoid membrane in company with the internal br. of the superior laryngeal n. inferior laryngeal inferior no named branches internal part of the inferior laryngeal a. accompanies thyroid a. inferior larynx the inferior laryngeal n.
  9. 9. cricothyroid superior no named branches cricothyroid m., cricothyroid a. travels with the thyroid a. inferior pharyngeal external br. of the superior constrictor m. laryngeal n. thyroid, inferior thyrocervical ascending cervical a., thyroid gland, lower inferior thyroid a. gives rise to the trunk inferior laryngeal a., larynx, upper trachea, ascending cervical a. as it arches esophageal brs., upper esophagus, deep medially tracheal brs., glandular neck muscles brs. caroticotympanic internal no named branches tympanic cavity caroticotympanic a. courses carotid a. through the petrous portion of the temporal bone Viscera Organ Location/Description Notes vestibular fold fold of mucosa located between the also known as: false vocal fold laryngeal vestibule and the laryngeal ventricle vocal folds fold of mucosa covering the vocal located inferior to the laryngeal ventricle; also known as: true ligament and the thyroepiglottic vocal fold muscle (vocalis part) laryngeal lateral outpouching of the laryngeal laryngeal ventricle may have a small diverticulum called the ventricle mucosa located between the saccule vestibular fold (false vocal fold) and the vocal fold (true vocal fold) laryngeal opening into the larynx; the part of lateral wall of the laryngeal ventricle contains the vestibule the larynx located below the quadrangular membrane (submucosa) epiglottis, between the aryepiglottic folds and above the vestibular (false vocal) folds rima glottidis the opening between the vocal folds the glottis is the vocal fold plus the rima glottidis glottis the vocal folds plus the rima glottidis rima glottidis is the opening between the vocal folds infraglottic cavity the portion of the laryngeal cavity that bounded superiorly by the glottis and opens inferiorly into lies inferior to the vocal folds the trachea aryepiglottic fold a fold of mucous membrane within aryepiglottic fold covers the aryepiglottic muscle the laryngopharynx that extends from the arytenoid cartilage to the epiglottis conus elasticus elastic membrane attaching on the thickened upper margin of the conus elasticus is the vocal upper margin of the arch of the ligament cricoid cart and ending in the vocal ligament vocal ligament an elastic band of connective tissue paired; each vocal ligament is connected to the inner surface located in the vocal fold of the thyroid cartilage anteriorly and to the vocal process of the arytenoid cartilage posteriorly; vocal ligament is the thickened superior margin of the conus elasticus; vibration creates sound; adducted by the actions of the arytenoid mm. and lateral cricoarytenoid m.; abducted by the action of the posterior cricoarytenoid m.
  10. 10. laryngopharynx the portion of the pharynx located connects: superiorly with oropharynx at the superior border posterior to the laryngeal inlet and the of epiglottis, anteriorly with the larynx through laryngeal posterior wall of the larynx inlet, inferiorly with the esophagus at the lower border of the cricoid cartilage; laryngopharynx contains the piriform recesses which are lateral to the aryepiglottic folds larynx located anterior to the laryngopharynx composed of: thyroid, cricoid, epiglottic, arytenoid, at level of C4-6 vertebrae cuneiform & corniculate cartilages; contains the vocal ligaments; controls the airway lateral fold of mucous membrane located lateral glossoepiglottic fold is located lateral to the valleculae glossoepiglottic between the base of the tongue and epiglottica fold the epiglottis median fold of mucosa located between the separates the paired valleculae epiglottica glossoepiglottic base of the tongue and the epiglottis fold piriform recess shallow depression located lateral to the internal branch of the superior laryngeal n. is located the aryepiglottic fold in the immediately deep to the mucosa in this region; also known laryngopharynx as: piriform fossa trachea main airway that lies anterior to the trachea extends from vertebral level C6 to the level of the esophagus T4/5 intervertebral disc; superiorly it is connected to the cricoid cartilage via the cricotracheal ligament; it bifurcates into two primary bronchi valleculae fossa located between the base of the paired; each of the valleculae epiglottica is located between epiglottica tongue and the epiglottis the median glossoepiglottic fold and the lateral glossoepiglottic fold