The Larynx Flashcards by David Baldwin

2 types of laryngeal musculature

INTRINSIC Musculature - interconnects cartilages of the larynx
EXTRINSIC Musculature - connects larynx to other surrounding structures, e.g. Sternum, hyoid bone, mastoid process, etc. (STRAP MUSCLES)

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Name the 4 main cartilages of the larynx

Cricoid
Thyroid
Epiglottis
Arytenoids

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List Larynx’s 5 Intrinsic Muscles

Thyroarytenoid muscle -
2 parts:
Vocalis - medial tensing (helps with pitch control)
Thyromuscularis - quick shortening

Cricothyroid muscle
2 parts:
Pars recta -
Pars oblique - extends to inferior cornu of thyroid

Lateral cricoarytenoids

Posterior cricoarytenoids

Interarytenoid

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Thyroarytenoid muscle

Attached below thyroid notch

Attachment is called Anterior Commissure

Theoretically divided into 2 parts:
Vocalis - medial tensing (helps with pitch control)
Thyromuscularis - quick shortening

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Cricothyroid muscle

Stretches vocal folds

Originates at anterior arch of cricoid

Main pitch control - elevates cricoid arch, depresses thyroid lamina

2 parts (pars recta & pars oblique)

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Cricoarytenoid muscles

Lateral cricoarytenoids - primary adductor
Closes from vocal processes to anterior commissure

Posterior cricoarytenoids - primary abductor

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Interarytenoid Muscle

connects 2 arytenoids
Aids Lateral cricoarytenoid muscle - closes posterior glottis

2 fiber directions
Transverse (==)
Oblique (X)

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Extrinsic Musculature

2 main groups: elevators and depressors
Act as suspensory mechanism (elastic scaffolding)
Another division: supra-hyoid (above) & infra-hyoid (below)

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5 Depressors

Sternothyroid -primary or direct depressor

Sternohyoid - secondary or indirect depressor (can compress tissue between thyroid and hyoid)

Omohyoid - depresses and retracts hyoid (runs from scapula to hyoid)

Cricopharyngeus - lower sides of cricoid to junction of pharynx and esophagus (May widen lower pharynx)

Trachea - exerts gravitational pull as diaphragm descends (aka Tracheal Pull)

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2 False elevators

Digastric - 2 sections
Anterior - chin to hyoid (retracts mandible)
Posterior - hyoid to mastoid process (elevates hyoid)

Stylohyoid - elevates and retracts hyoid (hence, the larynx)

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6 Elevators

Mylohyoid & Hyoglossus - hyoid bone to tongue

Geniohyoid - mental spine (chin) to hyoid

Genioglossus - mental spine (chin) to lower surface of tongue and hyoid

Both genioglossus and Hyoglossus move hyoid bone and thyroid cartilage forward which stretches the vocal folds (important for higher frequencies)

Stylopharyngeus - styoid process (behind jaw) to palatopharyngeus to superior Cornu of thyroid
dilates and elevates pharynx/ tilts thyroid forward
Helps both with glottal closure and maximum vocal fold elongation
Essential for optimal high voice production

Thyrohyoid - either depressor or elevator (elevates larynx or depresses hyoid)

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Innervation

connection btw brain and body by means of the central nervous system

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Vagus nerve (10th cranial nerve)

Vagus nerve (10th cranial nerve) - longest and most complex of cranial nerves

Leaves brain and skull through same opening as jugular vein - winds through neck into thorax and upper abdomen

Two branches of vagus nerve innervate larynx:

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Two branches of vagus nerve innervate larynx:

Superior laryngeal nerve - leaves vagus just about larynx
2 branches:
Internal - enters through thyrohyoid membrane (supplies laryngeal mucosa (detects foreign objects/tickle sensation))
External - motor nerve - descends behind Sternothyroid muscle (supplies cricothyroid muscle)

Recurrent Laryngeal Nerve - motor nerve
Leaves vagus well below larynx in upper thorax
Supplies remaining laryngeal muscles
2 branches: left & right
Left Side–significantly longer
Nervous signals arrive first to right side (only slight delay)
May be linked w/ vibrato

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2 layer scheme of vocal fold soft tissue

Cover: epithelium, superficial layer, intermediate later

2. Body: deep layer, muscle

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5 layer scheme of vocal fold soft tissue

From outside in:

Epithelium
Superficial layer
Intermediate layer
Deep layer
Muscle

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3 layer scheme of vocal fold soft tissue

Mucosa (epithelium & superficial layer)
Ligament (intermediate layer & deep layer)
Muscle (muscle)

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Bundles of muscle tissue

Muscle fascicles

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Hyaluronic acid

Acid present in vocal folds helping protect from impact

More present in male than female

Epithelium

.05-.1mm 
Stratified squamous (layered, scale-like)

3 layers of the lamina propria, their thickness and composition

Superficial (.5mm), elastin
Intermediate, primarily elastin, also some collagen
Deep, collagen

Intermediate + Deep = 1-2mm

Thickness of thyroarytenoid muscle (vocalis)

7-8mm

Quadrangular membrane

Secretes lube for the vocal folds

2 parts of thyroarytenoid muscle

Vocalis - medial tensing (helps with pitch control)

Thyromuscularis - quick shortening

Attachment of the thyroarytenoid muscle is called?

Anterior commisure

Nerve branch that serves the cricothyroid muscle

External branch of the superior laryngeal nerve

2 parts of cricothyroid muscle

Pars recta - extends to lower border of thyroid lamina | Pars oblique - extends to inferior cornu of thyroid

Scalene muscles

cervical spine to 1st two ribs | Postural and serves respiratory function by helping to elevate upper thorax.

What are false elevators?

muscles whose use produces excess tongue and pharyngeal tension

2 chest voice conditions

Very small longitudinal tension Very little elongation of the vocal folds

2 chest voice characteristics

Slack vocal ligaments Thick vocal folds

3 chest voice characteristics

Large amplitudes (glottis opens widely between vibrations) Firm glottal closure Vertical phase differences (opens and closes at bottom first, followed by top)

2 falsetto voice conditions

Great longitudinal tension and medial compression Great elongation of the vocal folds

2 falsetto voice consequences

Tense vocal ligaments Thin vocal folds

3 falsetto voice characteristics

Small amplitudes Imperfect glottal closure Negligible vertical phase differences

2 sections of the digastric muscle

Anterior - chin to hyoid (retracts mandible) | Posterior - hyoid to mastoid process (elevates hyoid)

Primary or direct depressor

Sternothyroid

Secondary or indirect depressor (can compress tissue between thyroid and hyoid)

Sternohyoid

Elevator muscle that helps both with glottal closure and maximum vocal fold elongation Essential for optimal high voice production

Stylopharyngeus

Describe thyroid cartilage

2 plates fused together/shaped like a shield Inferior Cornu - joined flexibly to cricoid Superior Cornu - loosely jointed with hyoid bone Adam's apple or thyroid notch - apex

Describe arytenoid cartilages

2 triangular pyramids resting on upper edge on back of cricoid Glide medially and laterally, rotate, glide anteriorly and posteriorly Vocal process and muscular process Corniculate cartilage at top of structure

Describe the epiglottis

Very elastic, cartilaginous material Shaped like leaf or tongue of a shoe Attaches just above the vocal folds (anterior of the thyroid cartilage) Pulled down during swallowing by Aryepiglottic folds and back of tongue

Describe the cricoid cartilage

shaped like a signet ring/sits on top of the trachea

False Vocal Folds

Ventricular Folds Primary purpose is to assist vocal folds in closing the airway Difficult to control, not much muscle fiber Upper border of Ventricles of morgagni and below them is glands secreting lube onto vocal folds

Describe the hyoid bone

Horseshoe shaped bone located above the thyroid Connected to thyroid by the thyroid membrane Only free floating bone in the body Suspended by the strap muscles