Anatomy of Phonation Ch. 4

Spoken Communication Voiceless phonemes or speech sounds- produced without the use of the vocal folds /s/, /f/ Voiced sounds are produced by action of the vocal folds /z/, /v/ Phonation is voicing, the product of vibrating vocal folds Respiration is the energy source that permits phonation to occur https://www.youtube.com/watch?v=bowRggzZ2q4 https://www.youtube.com/watch?v=Z_ZGqn1tZn8

Vocal Folds Made up of five layers of tissue with the deepest layer being muscle Space between the vocal folds is glottis Area below the vocal folds is subglottal region Alternately produce /a/ and /h/- you should feel the vocal folds vibrate and then stop

Functions of the Larynx Phonation Sphincter-vocal folds are capable of a strong and rapid clamping of the airway to keep foreign objects out Hold your breath Lifting heavy objects/Childbirth- “fix” or anchor your larynx which provides muscles of upper body a solid framework

Framework of Larynx A musculocartilaginous structure Comprised of three unpaired and three paired cartilages bound by ligaments and lined with mucous membrane Oddly shaped box that sits atop the last ring of the trachea Adjacent to cervical vertebrae 4-6 in the adult Average length is 44mm- males, 36 mm- females

Cavities of Larynx Aditus- entry to the larynx Vestibule- space between the aditus and the ventricular folds (false vocal folds) Laryngeal ventricle- middle space of the larynx Lies between the margins of the false vocal folds and true vocal folds False vocal folds- not used for phonation except in rare cases Lateral walls are comprised of the aryepiglottic folds Laryngeal ventricle- Contains the laryngeal saccule which has more than 60 mucous glands that secrete lubricating mucous into the laryngeal cavity

Cricoid Cartilage Complete ring resting atop the trachea Most inferior of the laryngeal cartilages Posterior quadrate lamina- provides point of articulation for arytenoid cartilages Lateral surface- point of articulation for inferior horns of thyroid cartilage Cricothyroid joint- diathrodial, pivoting joint permits rotation of the two structures Would fit loosely on your little finger

Thyroid Cartilage Unpaired cartilage Largest of the cartilages Articulates with the cricoid cartilage below Paired processes allow it to rock forward and backward Prominent anterior surface made of two places- thyroid laminae Joined at the midline- thyroid angle Superior most point is the thyroid notch (adam’s apple)

Thyroid Cartilage Vocal folds attach to the thyroid just behind the thyroid notch Posterior aspect is open- two prominent sets of cornu or horns Inferior cornu project downward to articulate with the cricoid cartilage Superior corner project superiorly to articulate with the hyoid

Arytenoid Cartilages Ride on the high-backed upper surface of the cricoid cartilage Form the posterior point of attachment for the vocal folds Paired cartilage Vocal processes project anteriorly toward thyroid notch, posterior portion of the vocal folds attach Muscular process forms the lateral outcropping of the arytenoid pyramid- point of attachment for muscles that adduct/abduct the vocal folds

Corniculate Cartilage Corniculate cartilages Ride on the superior surface of each arytenoid cartilage Prominent landmarks in the aryepiglottic folds

Epiglottis Unpaired cartilage Leaf-like structure arises from the inner surface of the thyroid cartilage just below the notch Attached by the thyroepiglottic ligament Sides are joined with the arytenoid cartilages via the aryepiglottic folds Projects upward beyond the larynx and above the hyoid bone

Epiglottis Attached to the root of the tongue by glosso-epiglottic fold and lateral glosso- epiglottic ligamets This juncture produces the valleculae Pyriform sinuses- lateral recesses Attached to the hyoid bone via the hyoepiglottic ligament Surface is covered with a mucous membrane lining

Cuneiform cartilages Small cartilages embedded within the aryepiglottic folds Situated above and anterior to the corniculate cartilages Provide support for the membranous laryngeal covering

Hyoid Bone Provides the union between the tongue and the laryngeal structure Unpaired small bone Articulates loosely with the superior cornu of the thyroid cartilage U-shaped, being open in the posterior side Corpus or Body- forms the front of the bone, point of attachment for six muscles Greater cornu- lateral surface of the corpus projecting posteriorly Lesser cornu-found at the junction of the corpus and greater cornu

Extrinsic ligaments Thyrohyoid membrane- stretches between the greater cornu of the hyoid and lateral thyroid Lateral Thyrohyoid ligament- superior cornu of the thyroid to posterior tip of the greater cornu hyoid Median Thyrohyoid ligament- from corpus hyoid to upper border of the anterior thyroid Together- these three connect the larynx and the hyoid bone

Extrinsic ligaments Hyoepiglottic ligament/Thyroepiglottic ligament- attach the epiglottis to hyoid and inner thyroid cartilage, just below the notch Cricotracheal ligament- attaches the trachea to the larynx

Intrinsic ligaments Quandrangular membranes Connect the cartilages of the larynx and form the support structure for the cavity of the larynx and vocal folds Quandrangular membranes Layer of connective tissue running from the arytenoids to the epiglottis and thyroid cartilage Form false vocal folds Originate at inner thyroid angle and sides of epiglottis and form an upper cone that narrows and terminates at the arytenoid and corniculate cartilages

Intrinsic ligaments Aryepiglottic muscles From the side of the epiglottis to the arytenoid Form the upper margin of the quadrangular membrane Form the aryepiglottic folds Folds are simply the ridges marking the highest elevation of these membranes Pyriform sinus is the space between the aryepiglottic fold and the thyroid cartilage

Vocal Fold Structure Most superficial layer- protective layer of epithelium Glistening white appearance Protective layer Second layer- superficial lamina propria (SLP)- elastin fibers Stretched cushions Third layer- Intermediate lamina propria (ILP)- elastin fibers running in an A-P direction provide elasticity and strength

Vocal Fold Structure Fourth layer- Deep lamina propria (DLP)- Collagen fibers that prohibit extension ILP and DLP combine to make up the vocal ligament Stiffness and support Fifth layer-Thyroarytenoid muscle- active element of the vocal folds Mucosal lining- combination of the epithelial lining and first layer

Movement of the Cartilages Cricothyroid and Cricoarytenoid joints are the only functionally mobile points of the larynx Cricothyroid joint- junction of cricoid cartilage and inferior cornu of the thyroid cartilage Diarthrodial (synovial) joint that permit the cricoid and thyroid to rotate and glide Rotation permits the thyroid cartilage to rock down in front Permits the thyroid cartilage to glide forward and backward slightly Provides the major adjustment for change in vocal pitch

Movement of the Cartilages Cricyarytenoid joint Formed between the cricoid and arytenoid cartilages Synovial joints permit rocking, gliding and minimal rotation Rocking action permits two vocal processes toward each other permitting the vocal folds to approximate Arytenoids glide on the long axis which changes vocal fold length Arytenoids rotate upon a vertical axis which permits abduction

Intrinsic Laryngeal Muscles Have both origin and insertion on laryngeal cartilages Make fine adjustments to the vocal mechanism Assume responsibility for opening, closing, tensing, lengthening and relaxing the vocal folds Movement of the vocal folds into and out of approximation is achieved by the coordinated effort of many of the intrinsic muscles of the larynx Changing pitch is reflected by a change in mass or tension

Intrinsic Laryngeal Muscles Lateral Cricoarytenoid Muscle Attaches to the cricoid and the muscular process of arytenoid Muscular process will be drawn forward Rocks the arytenoid inward and downward Adduction of vocal folds Lengthens the vocal folds Innervated by X vagus nerve

Intrinsic Laryngeal Muscles Transverse Arytenoid Muscle Runs between the two arytenoid cartilages on the posterior surface Pulls the two arytenoids closer together Approximates the vocal folds Increased medial compression which is increased force of adduction Vital element in vocal intensity change Innervation by the Recurrent laryngeal nerve of the X vagus

Intrinsic Laryngeal Muscles Oblique Arytenoid Muscles Paired muscles Originate at the posterior base of the muscular process and course obliquely up to the apex of the opposite arytenoid Form an “X” Pull the apex medially Promotes adduction Enforces medial compression Rocks arytenoid and vocal folds down and in Aids in pulling the epiglottis to cover the opening to the larynx Innervation- Recurrent laryngeal nerve of the X Vagus

Intrinsic Laryngeal Muscles Posterior Cricoarytenoid muscle Sole abductor of the vocal folds Originates from the posterior cricoid lamina Project up to insert into the posterior aspect of the muscular process of the arytenoid cartilage Pulls muscular process posteriorly Rocks the arytenoid cartilage Abducts the vocal folds

Intrinsic Laryngeal Muscles Cricothyroid Muscle- composed of two heads Pars Recta- originates on the anterior surface of cricoid cartilage and courses up to the lower surface of the thyroid lamina Pars oblique- arises from the lateral cricoid cartilage to the point of juncture between the thyroid laminae and inferior horns Both tense the vocal folds Together they are the major contributors for pitch change Innervated by the Superior Laryngeal Nerve of the X Vagus

Intrinsic Laryngeal Muscles Pars Recta Rocks the thyroid cartilage downward Brings thyroid and cricoid closer together in front Makes the posterior cricoid more distant from the thyroid Vocal folds are stretched Pars Oblique Thyroid slides forward Tense the vocal folds

Intrinsic Laryngeal Muscles Thyrovocalis Muscle (abbreviated as vocalis) Medial muscle of the vocal folds Originates from the inner surface of the thyroid cartilage Inserts into the lateral surface of the arytenoid vocal process Contraction draws the thyroid and cricoid cartilages farther apart in front Glottal tensor- tenses the vocal folds Innervated by the Recurrent Laryngeal Nerve of the X Vagus

Intrinsic Laryngeal Muscles Thyromuscularis Muscle Paired muscle Immediate lateral to each vocalis muscle Originates on the inner surface of the thyroid cartilage near the notch Inserts into the arytenoid cartilage at the base Laryngeal relaxer Relaxes the vocal folds Innervated by the Recurrent Laryngeal Nerve

Extrinsic Laryngeal Muscles Muscles with one attachment to a laryngeal cartilage Laryngeal elevators- muscles that elevate the hyoid and larynx Laryngeal depressors- those that depress the hyoid and larynx

Elevators Digastricus- two separate bellies- elevates the hyoid Anterior- originates on the inner surface of the mandible near the point of fusion Inserts into hyoid hyoid draws up and forward. Innervated by the V Trigeminal Posterior – originates on the mastoid process of the temporal bone and inserts into the hyoid at the juncture of the hyoid corpus and greater cornu hyoid draws up and back. Innervated by the the VII facial

Elevators Stylohyoid Muscle Originates on the styloid process of the temporal bone Courses down and inserts into the corpus of the hyoid Elevates and retracts the hyoid bone Innervated by the VII facial nerve

Elevators Mylohyoid Muscle Originates on the underside of the mandible Courses to the corpus hyoid Fanlike muscle Forms the floor of the oral cavity Innervated by the V trigeminal nerve

Elevators Geniohyoid Superior to the mylohyoid Projects in a course parallel to the anterior belly of the digastricus from the inner mandibular surface down to the hyoid bone at the corpus Elevates the hyoid and draws it forward Innervated by the XII hypoglossal nerve arising from the first cervical spinal nerve

Elevators Hyoglossus Muscle Laterally placed muscle Originates from the superior surface of the greater cornu of the hyoid and inserts into the side of the tongue Innervated by the the XII hypoglossal

Elevators Genioglossus Muscle Hyoid elevator and tongue depressor Originates on the inner surface of the mandible and then down insert into the tongue and anterior surface of the hyoid corpus Innervated by the XII hypoglossal

Elevators Thyropharyngeus Muscle- Originates from the thyroid lamina and courses up Inserts into the posterior pharyngeal raphe Elevates the larynx Constricts the pharynx Innervated by the RLN of the X Vagus

Depressors Sternohyoid muscle Runs from the sternum to the inferior margin of the hyoid Depresses the hyoid Fixes the hyoid and larynx Lowering is clearly evident following the pharyngeal stage in swallowing Innervated by the ansa cervicalis

Depressors Omohyoid Muscle Has two bellies Superior belly terminates on the side of the hyoid corpus Inferior belly has its origin on the upper border of the scapula Passes deep to the sternocleidomastoid Depresses the hyoid bone and larynx Innervated by the ansa cervicalis

Depressors Sternothyroid muscle Depresses the thyroid cartilage Originates from the sternum and first costal cartilage Inserts into the oblique line of the thyroid cartilage Innervated by fibers of the spinal nerves

Depressors Thyrohyoid muscle Originates from the thyroid cartilage to the Inserts into the inferior margin of the greater cornu of the hyoid bone Depress the hyoid or raises the larynx Innervated by the spinal nerve

Laryngeal Stability Stability is the key to control Gained through the development of the infra and suprahyoid musculature Larynx is intimately linked via the hyoid bone, to the tongue Movement of the tongue is translated to the larynx

Vocal Fold Paralysis Most frequent cause- damage to the nerve during thyroid surgery or carotid surgery, blunt trauma, CVA, or aneurysm One side of the Recurrent Laryngeal Nerve is damaged (lower motor neuron)- unilateral vocal fold paralysis Bilateral nerve damage=Bilateral paralysis Adductor paralysis-muscles of adduction are paralyzed and vocal folds remain in the abducted position Abductor paralysis-cannot abduct the folds, respiration is compromised

Vocal Fold Paralysis Damage to Superior Laryngeal nerve results in inability to alter pitch Unilateral paralysis- one vocal fold is still capable of motion and phonation can still occur but it will be breathy Bilateral adductor paralysis results in virtually complete loss of phonation