A&P Exam 2 Anatomy Flashcards
What is the biological role of the larynx?
Protective role:
- Prevents air from escaping from lungs
- Prevents foreign substances from entering lungs
- Expels foreign substances threatening trachea
What is the non-biological role of the larynx?
Sound generator
Hyoid bone
- Supportive structure for root of tongue.
- Suspends larynx and serves as attachment for extrinsic laryngeal muscles.
- U-shaped
- Level of C3
What is unique about the hyoid bone?
It is not attached to any other bone of the skeleton. It’s held in position by a complex system of muscle and ligaments.
Landmarks of the hyoid bone
Thyroid cartilage & landmarks
Largest laryngeal cartilage. Landmarks:
- Thyroid lamina: quadrilateral plates
- Angle of thyroid: midline fuse of lamina
- Superior thyroid notch
- Superior thyroid cornu: loosely attaches to greater horn of hyoid
- Inferior thyroid cornu: attaches to cricoid cartilage
Cricoid cartilage
Located immediately above upper tracheal ring. Forms lower border of laryngeal framework. Shaped like a backwards signet ring.
Landmarks of the cricoid cartilage
- Arch (anterior)
- Quadrate lamina (posterior): extend superiorly to fill space between inferior horns of thyroid.
- Articular facets:
- Lateral: articulates w/ inferior cornu of thyroid cartilage
- Superior: articulates w/ arytenoid cartilages
Arytenoid cartilages
Paired cartilages on sloping border of quadrate lamina of cricoid cartilage. Roughly resemble a three-sided pyramid.
Landmarks of the arytenoid cartilages
- Muscular process: posterior & lateral
- Vocal process: anterior
- Apex: superior
Corniculate cartilages
Small bead-like cartilages.
Epiglottis
- Flexible leaf-like structure
- Located just behind hyoid bone and root of tongue.
- Attached inferiorly to thyroid angle
- Prevents food from entering larynx during swallow
Cuneiform cartilages
Embedded in aryepiglottic folds. Help support vocal folds & stiffen them to maintain opening to larynx/airway.
Cricoarytenoid joint & its movements
Saddle joint b/w cricoid & arytenoid cartilages. Movements:
- Rocking: move vocal processes of arytenoids up/out or down/in, resulting in approximation or abduction of vocal folds.
- Gliding: move arytenoids on long axis, resulting in changes in vocal fold length
- Rotating: move arytenoids on vertical axis resulting in extreme abduction
Cricothyroid joint & its movements
Synovial joint w/ lateral articular facets on cricoid and inferior horns of thyroid.
Rotation: thyroid rocks down in front
Gliding: thyroid slightly forward/backward relative to cricoid
What happens to the vocal folds when the cricoid and thyroid move together in front?
Arytenoid cartilage moves farther away from thyroid which tenses vocal folds and adjusts pitch.
Extrinsic laryngeal membrane: Thyrohyoid/Hyothyroid
Attaches superior border of thyroid to body and greater horns of hyoid bone. Includes middle and lateral thyrohyoid ligament.
Extrinsic laryngeal membrane: Hyoepiglottic Ligament
Attaches superior aspect of epiglottis to body of the hyoid bone.
Extrinsic laryngeal membrane: Thyroepiglottic Ligament
Attach the inferior stem of the epiglottis to the inside of the thyroid cartilage, just below the notch.
Valleculae
Space between the tongue and the epiglottis.
Extrinsic laryngeal membrane: Cricotracheal Membrane
Connects lower border of cricoid cartilage to upper border of first tracheal ring.
Intrinsic laryngeal membrane: Conus Elasticus (lateral and anterior views)
Continuous sheet that connects inferior border of thyroid, superior border of cricoid, and arytenoid cartilages.
- Includes middle cricothyroid ligament: connects cricoid and thyroid at the middle near the angle.
Intrinsic laryngeal membrane: Conus Elasticus (superior view)
- Courses superiorly and medially.
- Fibers terminate as free thickened margins.
- Go from vocal process of arytenoid to thyroid angle
- Called vocal ligament, or true vocal folds.
Intrinsic laryngeal membrane: Quadrangular Membranes
- Start at lateral margins of epiglottis and thyroid angle
- Terminate superiorly as aryepiglottic folds
- Course posteriorly and inferiorly to medial surfaces of arytenoids
- Terminate inferiorly as free thickened margins called ventricular ligaments (false vocal folds)
Pre-Laryngeal Cavity: Aditus Laryngis
Entry to larynx. Made up of anterior border of epiglottis and aryepiglottic folds.
Laryngeal Cavity: Vestibule
- Supraglottic (above glottis)
- Triangular opening
- Superior border: aditus laryngis
- Inferior border: ventricular folds (false vocal folds)
- Lateral walls: aryepiglottic folds
- Posteriorly: membrane covering arytenoid cartilages
Divisions of the glottis
- Membranous glottis
- Anterior 3/5
- Soft tissue
- AKA “free margin”
- Vibrating element
- Cartilaginous glottis
- Posterior 2/5
- Arytenoids
Glottis
- Space between true vocal folds, inferior to laryngeal ventricle
- Superior to conus elasticus
- Lateral are vocal folds & arytenoids
- 20 mm long in adults
- Posterior opening at rest ~8 mm
Laryngeal Cavity: Laryngeal ventricle
Supraglottic. Space between false and true vocal folds.
Vocal fold histology
- epithelium: thin stiff capsule that maintains vocal fold shape
- lamina propria:
- superficial layer: loose fibrous components
- Intermediate layer: elastic fibers
- deep layer: cartilaginous fibers
- vocalis muscle: main body of vocal folds
Vocal folds: functional divisions
- Cover: epithelium & superficial layer of lamina propria (mucosal lining)
- Transition: intermediate & deep layers of lamina propria (vocal ligament)
- Body: deep layer (vocalis muscle)
Intrinsic muscles of the larynx
- Includes adductors, abductors, glottal tensors and relaxers
- Make fine adjustments to vocal mechanism
- Both origin and insertion on laryngeal cartilages or hyoid bone
Extrinsic muscles of the larynx
- Includes elevators and depressors
- Have one attachment to structures outside the larynx
- Responsible for major adjustments, support, and fixation of larynx in neck
Adductor: Lateral Cricoarytenoid
- Origin: upper border of anterolateral arch of cricoid
- Course: superior and posterior
- Insert: muscular process of arytenoid
- Action: moves muscular process forward and inward/downward
- Impact on vocal folds: rotate vocal process towards midline (adduct); possibly lengthen
Adductor: Transverse (Inter)arytenoids
- Origin: lateral margin & posterior surface of arytenoid
- Course: horizontal
- Insert: lateral margin & posterior surface of opposite arytenoid
- Action: approximate arytenoids via gliding
- Impact on vocal folds: Adduction, medial compression
Adductor: Oblique (Inter)arytenoids
- Origin: posterior surface of muscluar process of one arytenoid
- Course: diagnoally
- Insert: apex of opposite arytenoid
- Action: pulls apex medially; rocks arytenoid down/in
- Impact on vocal folds: adduction & medial compression
Abductor: Posterior Cricoarytenoid
- Origion: shallow depression of posterior aspect of quadrate lamina of cricoid cartilage
- Course: superior and lateral
- Insert: muscular process of arytenoid
- Action: vertical fibers rotate arytenoid so that vocal processes are abducted and elevated
Glottal tensor: Cricothyroid
Origin: anterolateral arch of cricoid cartilage
- Pars oblique
- Course: superior and posterior
- Insert: inferior cornu of thryoid cartilage
- Action: slides thyroid cartilage forward
- Pars recta
- Course: superior
- Insert: lower margin of thyroid lamina
- Action: tilts thyroid cartilage down
Impact on focal folds: lengthened and tensed
Thyroarytenoid
- Makes up main mass of true vocal folds
- Consists of two muscle masses
- Portion just lateral to vocal ligament (medial-most portion) is (thyro)vocalis
- Lateral to vocalis is thyromuscularis
Glottal tensor: Thyrovocalis
Part of thyroarytenoid
- Origin: inner surface of thyroid cartilage near notch
- Course: posterior
- Insert: vocal process of arytenoids
- Action: draws thyroid and cricoid farther apart in front
- Impact on vocal folds: tenses
Glottal relaxor: Thyromuscularis
Part of thyroarytenoid
- Origin: inner surface of thyroid cartilage near notch (lateral to vocalis)
- Course: posterior (parallel to vocalis)
- Insert: muscular process of arytenoids
- Action: moves muscular process forward
- Impact on vocal folds: adduction and lengthening
Elevators: Digastric
- Anterior belly
- Origin: inner surface of mandible, near midline
- Course: inferior and posterior
- Insert: lesser horn of hyoid
- Posterior belly
- Origin: mastoid process of temporal bone
- Insert: lesser horn of hyoid
- Attach to one another via intermediate tendon
- Action: raise hyoid (and larynx)
Elevators: Stylohyoid
- Origin: styloid process of temporal bone
- Course: parallel to posterior belly of digastric
- Insert: body of hyoid bone
- Action: draws hyoid bone superiorly and posteriorly
Elevators: Mylohyoid
Fanlike fibers that form muscular floor of mouth
- Origin: inner surface of mandible from mental symphysis (midline) to last molar
- Course: inferior and medial
- Insert: with fibers from other side at midline raphe
- posterior fibers onto body of hyoid bone
- Action
- If mandible is fixed, elevate hyoid bone
- If hyoid is fixed, depresses mandible
Elevators: Geniohyoid
Paried muscle superior to mylohyoid
- Origin: lower part of mental symphysis
- Course: posterior and inferior
- Insert: body of hyoid bone
- Action:
- With mandible fixed, raises hyoid bone superiorly and anteriorly
- With hyoid fixed, depresses mandible
Elevators: Genioglossus
- Origin: mental spines of mandible
- Course: lower fibers to hyoid bone; remainder fan out to tongue dorsum
- Insert: lower fibers to hyoid bone; remainder into submucous tissue on undersurface of tongue
- Action: elevates hyoid
Elevators: Hyoglossus
- Origin: body & greater horn of hyoid bone
- Course: upward
- Insert: lateral submucous tissue of posterior half of tongue
- Action:
- If tongue is fixed, elevates hyoid
- If hyoid is fixed, retracts and depresses tongue
Depressors: Sternohyoid
Flat muscle on anterior surface of neck
- Origin: posterior surface of manubrium and medial end of clavicle
- Course: superior
- Insert: inferior body of hyoid bone
- Action: draws hyoid bone inferiorly toward sternum
Depressors: Omohyoid
- Superior belly
- Origin: intermediate tendon (connects superior & inferior bellies)
- Course: up
- Insert: lower border of hyoid
- Action: depresses hyoid
- Inferior belly
- Origin: upper border of scapula
- Course: superiorly and medially
- Insert: intermediate tendon
- Action depress hyoid bone (by pulling on superior belly)
Depressors: Sternothyroid
- Origin: manubrium and first costal cartilage
- Course: superior and lateral
- Insert: thyroid lamina
- Action: may draw thyroid cartilage down
Depressors: Thyrohyoid
- Origin: thyroid lamina
- Course: superior
- Insert: greater horn of hyoid bone
- Action: depresses hyoid or elevates larynx
