Ch 4 Study Guide Part 2

Thyroid cartilage: thyroid notch

at the superior-most point of the thyroid angle

Thyromuscularis

paired muscle masses immediately lateral to each thyrovocalis -with the thyrovocalis, make up the thyroarytenoid muscle -origin: inner surface of thyroid cartilage, near notch and lateral to origin of thyrovocalis insertion: arytenoid process at muscular process and base -contraction adducts and lengthens vocal folds -contraction also relaxes vocal folds -innervation: X vagus, RLN

Thyroid cartilage: palpation of thyroid notch

place finger under chin and on your throat, and bring it downward to the point you might refer to as the Adam's apple when you have found the top of that structure, you have identified the thyroid notch with finger on the notch, you are as close as you can be to touching your vocal folds, because they attach to the thyroid cartilage just behind that point

Thyroid cartilage: cornu/horns

posterior aspect of the thyroid is open and characterized by two prominent sets

Epiglottis: glosso-epiglottic fold

produced by the overlying epithelium of the glossoepiglottic ligaments and root of tongue -this juncture produces the valleculae, important in study of swallowing and swallowing deficit

Arytenoid/Corniculate cartilages: vocal processes

project anteriorly toward the thyroid notch, and it is these processes to which the posterior portion of the vocal folds attach

Thyroid cartilage: inferior cornua

project downward to articulate with the cricoid cartilage

Thyroid cartilage: superior cornua

project superiorly to articulate with the hyoid

Relaxers

relaxes the vocal folds

Thyrohyoid muscle

superior counterpart to the sternothyroid -courses from oblique line of thyroid cartilage to the inferior margin of the greater cornu of the hyoid bone -depresses the hyoid or raises the larynx -innervated by fibers from spinal nerve C1 that course along with the hypoglossal nerves

Epiglottis: pharyngeal recesses

the pyriform sinuses and valleculae

Thyroid cartilage: thyroid angle

where the thyroid laminae are joined at the midline

Referral in Voice Therapy

-Have to determine whether there is a vocal pathology developing on the vocal folds -Could be nodules or early signs of laryngeal cancer -Voice that is progressively weaker/more effort throughout day - referral to neurologist -Myasthenia gravis: myoneural disease that results in a complex of speech disorders, including progressive weakening of phonation, progressive degeneration of articulatory function, and hypernasality, all arising from the use of the speech mechanism over the coarse of the day -Condition is treatable, often SLP is first individual to recognize signs

Interaction of musculature

-Movement of larynx and its cartilages requires both gross and fine adjustments -gross movements associated with laryngeal elevation and depression provide background for fine adjustments of phonatory control -The supra- and infrahyoid muscles raise and lower the larynx, changing the vocal tract length -The intrinsic laryngeal muscles are responsible for the fine adjustments associated with phonation control

Thryoepiglottic muscle (thyroepiglotticus)

-dilates the laryngeal opening -origin: inner surface of thyroid at angle -insertion: lateral epiglottis -innervation: X vagus, RLN

Palpation of the larynx

-first ID thyroid notch -feel lamina -then bring down to angle -at top of notch, hard region is corpus of hyoid bone -palpate lateral and feel superior cornu -lower margin of thyroid and feel cricoid -can feel thyroid and cricoid moving closer together and farther apart as humming -can also feel entire larynx elevate as you reach upper end of range -can feel beginning of trachea at lower margin of cricoid

Infant Larynx

-infant larynx is markedly narrow and higher than adult larynx -laryngomalacia (audible breathing or stridor) is frequently caused by the airway being so pliant and collapsing on itself in infants, as well as the fact that the mucous membrane lining of the larynx is more loosely bound to the larynx than in adults -thyroid cartilage is closer to hyoid bone than in adults -infant larynx is 1/3 size of adult larynx -vocal folds around 4.5 mm long -laryngeal saccule larger in infants than adults -swelling of tissues of airway place infant at risk -by 3 yrs, male larynx begins to get larger than female larynx

Digastricus anterior and posterior muscles

-laryngeal elevator -two separate bellies: anterior and posterior, converge at hyoid bone at the intermediate tendon -their paired contraction elevates the hyoid -innervation: anterior belly: V trigeminal, mandibular branch; posterior belly: VII facial nerve, digastric branch

Ain't Misbehavin

-larynx is exquisite structure made up of delicate tissue for use as protective mechanism -can be overused -vocal nodules -addition of toxins -alcohol consumption -cigarette/cigar smoke -excessive dry air -diet

Genioglossus muscle

-muscle of the tongue and hyoid elevator -originates on inner surface of mandible and courses up, back, and down to insert into the tongue and anterior surface of hyoid corpus -elevates hyoid -innervation: XII hypoglossal, motor branch

General function and categorization of extrinsic musculature

-muscles with one attachment to a laryngeal cartilage -a number of muscles attached to the hyoid also move the larynx -infrahyoid muscles - run from the hyoid to a structure below: sternohyoid and omohyoid -suprahyoid muscles - attach to a structure above the hyoid: digastricus, stylohyoid, mylohyoid, geniohyoid, genioglossus, hyoglossus (strap muscles) -elevate or depress larynx -laryngeal elevators: digastricus, stylohyoid, mylohyoid, geniohyoid, genioglossus, hyoglossus, thyropharyngeus -laryngeal depressors: sternohyoid, omohyoid, thryohyoid, sternothyroid

Arytenoid/Corniculate cartilages: function of paired arytenoid cartilages

-reside on superior posterolateral surface of cricoid cartilage -provide the mechanical structure that permits onset and offset of voicing -each cartilage has two processes and four surfaces -apex/base

Sternohyoid muscle

-runs from sternum to hyoid -contraction depresses hyoid or fixes hyoid and larynx -innervation: ansa cervicalis arising from C1 - C3 spinal nerves

Oblique arytenoid muscles

-superficial to transverse arytenoid muscles -paired -origin: posterior base of muscular process -insertion:: apex of opposite arytenoid -X arrangement of muscles -ability of these muscles to pull the apex medially, promoting adduction, enforcing medial compression, and rocking the arytenoid and vocal folds down and in -more adductory force than trasnverse, but less than lateral cricoarytenoid -aids in pulling the epiglottis to cover the opening to the larynx -innervation: X vagus, recurrent laryngeal nerve

Cricothyroid joint

-the junction of the cricoid cartilage and the inferior cornu of the thyroid cartilage -synovial joints that permit the cricoid and thyroid to rotate and glide relative to each other -rotation at the cricothyroid joint permits the thyroid cartilage to glide forward and backward slightly, relative to the cricoid -this joint provides the major adjustment for change in vocal pitch -when the cricoid and thyroid move toward each other in front, the arytenoid cartilage moves farther away from the thyroid cartilage, tensing the vocal folds

Thyropharyngeus muscle

along with cricopharyngeus muscles, constitute the inferior pharyngeal constrictor -involved in propelling food through pharynx -arises from the thyroid lamina and inferior cornu, coursing up medially to insert into the posterior pharyngeal raphe -elevates larynx while constricting pharynx -attachment to thyroid provides opportunity for laryngeal elevation -innervation: X vagus, pharyngeal branch; IX glossopharyngeal, pharyngeal branch

Aryepiglottic muscle (aryepiglotticus)

arises from the superior aspect of the oblique arytenoid muscle and continues as the muscular component of the aryepiglottic fold as it courses to insert into the lateral epiglottis -constricts laryngeal opening -innervation: X vagus, RLN

Auxiliary Musculature

aryepiglotticus, thyroepiglotticus

Transverse arytenoid muscle

band of fibers spanning the posterior surface of both the arytenoid cartilages -runs from the lateral margin of the posterior surface of one arytenoid to the corresponding surface of the other arytenoid -functions to pull the two arytenoids closer together and to approximate the vocal folds -less adductory force than lateral cricoarytenoid -less force than oblique arytenoid -provides additional support for tight occlusion or closing of vocal folds and is a component force in generating medial compression -innervation: X vagus, recurrent laryngeal nerve

Epiglottis: X-Vagus role

beneath the lining of epiglottis, on the posterior concave surface, may be found branches of the internal laryngeal nerve of the X vagus that conducts sensory information from the larynx

Summary of Intrinsic Muscle Activity

throvocalis, thyromuscularis, cricothyroid, lateral and posterior cricoarytenoid, transverse arytenoid, oblique arytenoid, superior thyroarytenoid, thyroepiglotticus, aryepiglotticus -movement of the vocal folds into and out of approximation is achieved by the coordinated effort of many of the intrinsic muscles -physical parameters can be altered to change pitch: mass or tension is likely candidate -increasing tension on the vocal folds stretches them and thereby reduces mass per unit length -both increased tension and reduced mass per unit length increase the frequency of vibration of the vocal folds, while relaxing the vocal folds causes the frequency to drop -if you contract the thyrovocalis, the vocal folds become tenser and pitch increases

Thyroid cartilage: triticeal cartilage

in some individuals, may be found between superior cornu of the thyroid cartilage and the hyoid bone

Superior thyroarytenoid muscle

inconsistently present, arising from inner angle of thyroid cartilage and coursing to muscular process of the arytenoid when it is present it is lateral to the thyromuscularis assumed to serve as a relaxer of the vocal folds

Approximate

make contact

Thyrovocalis muscle

medial muscle of the vocal folds tenses the vocal folds, especially when contracted in concert with the cricothyroid muscle -responsible for adduction of the membranous portion of the vocal folds -origin: inner surface of thyroid cartilage near thyroid notch insertion: lateral surface of the arytenoid vocal process -contraction draws the thyroid and cricoid cartilages farther apaart in front, making this muscle a functional antagonist of the cricothyroid muscle -innervation: X Vagus, RLN

Abductor

moves vocal folds apart

Omohyoid muscle

muscle with two bellies: superior and inferior -superior belly terminates on the side of the hyoid corpus, while the inferior belly has its origin on the upper border of the scapula -joined at the intermediate tendon -passes deep to the sternocleidomastoid -when contracted, depresses the hyoid and larynx -superior belly: innervated by the superior ramus of the ansa cervicalis from C1 spinal nerve -inferior belly: innervated by the main ansa cervicalis, arising from C2 and C3 spinal nerves

Adductors

muscles that adduct the vocal folds

Intrinsic laryngeal muscles

muscles that have both origin and insertion on laryngeal cartilages

Thyroid cartilage: oblique line

on the lateral superficial aspect of the thyroid laminae; this marks the point of attachment for two muscles

Thyroid cartilage: thyroid laminae

two plates that make up the prominent anterior surface of the thyroid

Vocal Hyperfunction

using excessive adductory force, often resulting in laryngitis, which is inflammation of the vocal folds -excessively forceful contraction of the lateral cricoarytenoid and arytenoid muscles is undoubtedly the primary contributor to this problem, although laryngeal tension arising from contraction of other adductors are contributors as well -vocal hyperfunction is the result of general laryngeal tension -can also result in vocal nodules, contact ulcers, vocal polyps, and vocal fatigue -usually behvioral -treatment requires behavioral change

Cricoid cartilage: Cricothyroid joint

on the lateral surfaces of the cricoid - articular facets - marking point of articulation for the inferior horns of the thyroid cartilage -synovial, pivoting joint that permits the rotation of the two articulating structures -joint is encased in a capsular ligament that allows rotation of the thyroid cartilage relative to the cricoid

Stylohyoid muscle

originates on the prominent styloid process of temporal bone, courses medially down and crosses path of posterior digastricus, inserts into the corpus of hyoid -contraction elevates and retracts hyoid bone -innervation: VII facial nerve, motor branch

Mylohyoid muscle

originates on the underside of mandible and courses to the corpus hyoid -fanlike -fibers form the floor of the oral cavity -elevates the hyoid and projects it forward -innervation: V trigeminal, mandibular branch

Vocal fold paralysis

paralysis: loss of voluntary motor function paresis: weakness -either can arise from damage to the upper motor neurons, arise from the brain and end in the spinal column or brain stem, or lower motor neurons, leave the spinal column or brain stem to innervate muscles involved -unilateral or bilateral -adductor paralysis: muscles of adduction are paralyzed and vocal folds remain in adducted position -abductor paralysis: individual not able to abduct vocal folds, respiration is compromised -SLN involved, individual will lose ability to alter vocal pitch, because cricothyroid is innervated by this branch of the vagus -unilateral: one vocal fold still capable of motion - phonation can occur but will be breathy -bilateral: complete loss of phonation -surgery/trauma/cerebrovascular accidents/hemorrhage/neurodegenerative diseases/aneurysm -phonatory signs - objective evidence of phonatory deficit - not to be taken lightly

Cricothyroid muscle

primary tensor of the vocal folds -rocks the thyroid cartilage forward relative to the cricoid cartilage -composed of two heads: pars recta and pars oblique -pars recta: origin on anterior surface of cricoid cartilage beneath the arch; insertion: lower surface of thyroid lamina -pars oblique: origin: cricoid cartilage lateral to the pars recta; insertion: point of juncture between thyroid laminae and inferior horns -contraction of pars recta rocks thyroid cartilage downward; cricoid rises to meet thyroid; effect is that the vocal folds are stretched -responsible for stiffening the vocal folds -innervation: X vagus, superior laryngeal nerve -together pars recta and pars oblique are responsible for major laryngeal adjustment associated with pitch change

Cricoid cartilage: cricoid arch

provides clearance for the vocal folds that will pass over that point

Cricoid cartilage: posterior quadrate lamina

provides the point of articulation for the arytenoid cartilages

Cuneiform cartilages

small cartilages embedded within the aryepiglottic folds they are situated above and anterior to the corniculate cartilages and cause a small bulge on the surface of the membrane these provide support for the membranous laryngeal covering

Epiglottis: pyriform sinuses

small fossae or indentations between the aryepiglottic folds medially and the mucous lining of the thyroid cartilages

Posterior cricoarytenoid muscle

sole abductors of the vocal folds -origin: posterior cricoid lamina -insertion: posterior aspect of the muscular process of the arytenoid cartilages -direct antagonists to the lateral cricoarytenoids -contraction pulls the muscular process posteriorly, rocking the arytenoid cartilage out on its axis and abducting the vocal folds -active during physical exertion to permit greater air movement into and out of lungs -also active during production of voiceless consonants -innervation: X vagus, recurrent laryngeal nerve

Geniohyoid muscle

superior to the mylohyoid, originating at the mental spines of the inner mandible -insertion: hyoid bone at the corpus -elevates the hyoid and draws it forward -innervation: XII hypoglossal nerve and C1 spinal nerve

Glottal tensors

tenses the vocal folds

Cricoarytenoid joint

the articulation formed between the cricoid and arytenoid cartilages -synovial joints permit rocking, gliding, and minimal rotation -rocking action brings the two vocal processes toward each other, permitting the vocal folds to approximate -arytenoids are also capable of gliding on the long axis of the facet, facilitating changes in vocal fold length

Medial compression

the degree of force that may be applied by the vocal folds at their point of contact -increased medial compression is a function of increased force of adduction -vital element in vocal intensity change

Hyoid and laryngeal depressors

depress and stabilize larynx via attachment to hyoid, but also stabilize the tongue by serving as antagonists to the laryngeal elevators

Laryngeal elevators and depressors

digastricus anterior and posterior stylohyoid mylohyoid geniohyoid genioglossus hyoglossus thyropharyngeus inferior pharyngeal constrictor

Epiglottis: function during swallow

during swallowing, food passes over the epiglottis and, from there, laterally to the pyriform sinuses

Arytenoid/Corniculate cartilages: muscular process

forms the lateral outcropping of the arytenoid pyramid and is the point of attachment for muscles that adduct and abduct the vocal folds

Hyoid bone

forms the union between the tongue and the laryngeal structure -unpaired small bone articulates loosely with the superior cornu of the thyroid cartilage -distinction of being the only bone of the body that is not attached to another bone -U-shaped and open in posterior aspect -three major elements: corpus, greater cornu, lesser cornu

General function of intrinsic laryngeal muscles

Make fine adjustments to the vocal mechanism itself Assume responsibility for opening, closing, tensing, and relaxing the vocal folds

To summarize

-The extrinsic muscles of the larynx include the infrahyoid and suprahyoid muscles -The digastricus anterior and posterior elevate the hyoid, whereas the stylohyoid retracts it -The mylohyoid and hyoglossus elevate the hyoid, and the geniohyoid elevates the hyoid and draws it forward -The thyropharyngeus and cricopharyngeus muscles elevate the larynx, and the sternohyoid, sternothyroid, thyrohyoid, and omohyoid muscles depress the larynx

To summarize

-The laryngeal cartilages have a number of important landmarks to which muscles are attached -The cricoid cartilage is shaped like a signet ring, higher at the back -The arytenoid cartilages ride on the superior surface of the cricod, with the cricoarytenoid joint permitting rotation, rocking, and gliding -The muscular and vocal processes provide attachment for the thyromuscularis and thyrovocalis muscles -The corniculate cartilages attach to the upper margin of the arytenoids -The thyroid cartilage has two prominent laminae, superior and inferior horns, and a prominent thyroid notch -The hyoid bone attaches to the superior cornu of the thyroid, while the cricoid cartilage attaches to the inferior horn via the cricothyroid joint -The epiglottis attaches to the tongue and thyroid cartilage, dropping down to cover the larynx during swallowing -The cuneiform cartilages are embedded within the aryepiglottic folds

Hyoglossus muscle

-arises from entire superior surface of greater cornu and corpus of hyoid and courses up to insert into the side of the tongue -lingual depressor and hyoid elevator -innervation: XII hypoglossal

Epiglottis: placement of epiglottis

-arises from the inner surface of the angle of the thyroid cartilage just below the notch, being attached there by the thyroepiglottic ligament -the sides of the epiglottis are joined with the arytenoid cartilages via the aryepiglottic folds, which are the product of the membranous lining being draped over muscle and connective tissue -projects upward beyond the larynx and above the hyoid bone and is attached to the tongue by means of the median and lateral glossoepiglottic ligaments

Lateral cricoarytenoid muscle

-attach to the cricoid (origin) and the muscular processes of the arytenoids (insertion), causing the muscular processes to move forward and medially -motion rocks the arytenoid inward and downward, adducting the vocal folds and may lengthen the vocal folds -increases medial compression -innervation: X vagus, recurrent laryngeal nerve

Sternothyroid muscle

-contraction depresses thyroid cartilage -originates at manubrium sterni and first costal cartilage -inserts into oblique line of thyroid cartilage -active during swallowing -innervated by fibers from spinal nerves C1 and C2 that pass into the hypoglossal nerve

Laryngeal stability

-the key to laryngeal control -this stability is gained through development of the infra- and suprahyoid musculature -larynx has liberal movement in the vertical dimension and has some horizontal movement as well, but must be a great deal of control in the constriction of musculature for this arrangement to work -larynx is linked via the hyoid bone to the tongue so that movement of the tongue is translated to the larynx -infant begins to gain control of neck musculature at 4 weeks -during this stage, larynx is elevated -as child develops, larynx descends, starting a process of muscular differentiation between the tongue and the larynx -child develops ability to move the tongue and larynx independently, permitting wider set of oral movements -with this differentiation comes the conrol needed for accurate speech production

Muscles associated with laryngeal function

1. Lateral cricoarytenoid 2. Transverse arytenoid 3. Oblique arytenoid 4. Posterior cricoarytenoid 5. Cricothyroid (pars recta, pars oblique) 6. Thyrovocalis (medial thyroarytenoid) 7. Thyromuscularis (lateral thyroarytenoid) 8. Aryepiglotticus 9. Thyroepiglotticus 10. Digastricus anterior and posterior 11. Stylohyoid 12. Mylohyoid 13. Geniohyoid 14. Hyoglossus 15. Genioglossus 16. Thryopharyngeus 17. Inferior pharyngeal constrictor 18. Sternothyroid 19. Omohyoid 20. Sternohyoid 21. Thyrohyoid