laryngeal anatomy Flashcards
larynx is a specialized tube or cavity sitting above trachea that contains a sphincter
larynx
supraglottal cavity
region above VF
subglottal cavity
region below VF
laryngeal inlet
aditus
opening to pharynx
-inlet closed by epiglottis
vestibule
space between inlet and false vocal folds
ventricle
space between false vocal folds and true vocal folds
structure of larynx: function 4 primary cartilaginous structures
for sound production
-and airway production
structure of larynx:
1 important cartilage structure
epiglottis
-for protecting airway
structure of larynx:
1 critical bone
hyoid bone
-for anchoring the larynx, protecting airway and moving the larynx up and down
cricoid cartilage
lower most cartilage sitting atop trachea
- specialized tracheal ring fused together
- resembles a signet ring
- supports and articulates with the thyroid cartilage and arytenoid cartilages
narrow anterior aspect of cricoid cartilage
called the arch
-provides clearance for the vocal folds
posterior lamina of cricoid cartilage
provides surface for arytenoid cartilage
on lateral surface of cricoid cartilage
articulator facets which is the site of cricothyroid joint (synovial)
thyroid cartilage
largest cartilage fused at anterior midline and open posteriorly
- plates of arch course forward to form a thyroid angle
- oblique line on side of plates is site of muscle attachments
thyroid is ____ in males and has a greater angle
larger
-sexual dimorphism
lower cornu (horns) of thyroid cartilage
articulate with cricoid cartilage (joint)
superior cornu
or thyroid cartilage
attaches to hyoid bone via thyrohyoid ligament (not joint)
arytenoid cartilage
small paired cartilages with critical function
- rest on top of posterior cricoid
- apex is peak, topped by small corniculate cartilages
- base has concave surface for joint
cricoarytenoid joint allows
rotation
-rocking and gliding of arytenoid cartilages
vocal process
- anterior projection of arytenoid cartilage
- attachment for vocal folds
muscular processes
- lateral projection of arytenoid cartilage
- attachment for muscles that adduct and abduct vocal folds
epiglottis
large fused leaf-like structure
- arises from inner surface of thyroid cartilage below notch
- connective tissue from sides of epiglottis join to arytenoid cartilages via aryepiglottic folds
- has anterior connection to tongue
- glosso-epiglottic folds
- attaches to hyoid bone via hyoepiglottic ligament
epiglottis extends ____ beyond ____ and ___ ____
upward, larynx, hyoid bone
valleculue
formed from juncture of folds and tongue
hyoid bone
only bone in body that is not attached to another bone
- floating bone connected by muscles to other structures
- U-shaped with arch anterior - body of hyoid
- has greater horns (cornu) and lesser horns (cornu)
- greater cornu are posterior
- less cornu arise at junction of body and greater cornu - point upwards
pull hyoid and larynx downward
infra hyoid muscles
pull hyoid and larynx upward and forward
suprahyoids
cricothyroid joint
- junction of inferior cornu of thyroid cartilage and lateral arch of cricoid
- synovial joint allowing thyroid cartilage to rotate and move forwards/backwards
- this joint has primary importance in changing length of vocal folds
cricoarytenoid joint
- synovial joint with less mobility than cricothyroid
- concave inferior surface of arytenoid rests on convex surface of cricoid
- principal motions are gliding, rocking, and rotation
- rocking actions bring vocal processes together (adduct and abduct)
- rocking can abduct vocal processes away from each other
- gliding actions can pull arytenoids close to each other assisting in closure
laryngeal musculature
- each motion described previously allows for closure, opening and length changes of vocal folds
- motions accomplished by muscle contraction
two sets of laryngeal muscles
- intrinsic make connections between laryngeal cartilages
- extrinsic connect laryngeal cartilages to other structures
intrinsic muscles
cricothyroid posterior cricoarytenoid lateral cricoarytenoid thyroarytenoid vocalis interarytenoids: oblique and transverse
extrinsic muscles
sternothyroid
thyrohyoid
inferior pharyngeal constrictor
hyoid muscles
suprahyoid -digastric (anterior and posterior bellies) geniohyoid mylohyoid stylohyoid genioglossus infrahyoid -sternohyoid (sternothyroid & thyrohyoid) omohyoid
posterior cricoarytenoid
PCA
- intrinsic laryngeal muscle
- origin: posterior outer surface of cricoid arch
- insertion: muscular process of arytenoid
- fibers course upward and backward
- contraction pulls muscular process posteriorly
- rocks arytenoids away from each other
action of PCA
abduct vocal folds
-sole muscle that performs this action
importance during respiration and speech
-stabilizes arytenoid position
lateral cricoarytenoid
LCA
origin: superior lateral surface of cricoid
insertion: courses upwards and backwards to muscular process
* antagonist of PCA
interarytenoid muscles
IA
- connect the arytenoid cartilages across the midline
- transverse muscle is a single unpaired muscle spanning cartilages
- oblique interarytenoid muscle overlie transverse in X shape
- contraction of these muscles pulls arytenoids together
action of LCA
action: rocks muscular process inwards leading to vocal fold adduction
- can also adjust amount of compression between folds (medial compression)
action of IA
action: pulls arytenoids together which assists in closing vocal folds
vocal fold muscle
-inner or deep portion of vocal folds is occupied by a muscle
-main mass of folds
general name: thyroarytenoid
fan shaped muscle
inner surface of thyroid cart near arch to arytenoid vocal process
-bottom contributes to vocal fold while top diverges towards epiglottis
*forms thyroepiglottis
thyroarytenoid
- two separate muscles
- pulls arytenoids and thyroid closer
- result: shortens and relaxes vocal folds acting unopposed (almost NEVER happens)
- the muscle divisions appear to have opposing functions
two muscles of thyroarytenoid
-vocalis can tense VF when other intrinsic laryngeal muscles are increasing vocal fold tension and adduction
-thyromuscularis contraction can shorten and relax VFs
together these contribute to pitch control
cricothyroid
origin: arch of cricoid
insertion: inferior horn of thyroid - pars oblique
- contraction pulls thyroid towards cricoid
- increase distance between thyroid and arytenoids
- stretches and tenses vocal folds***
Vagus Nerve
CN X
- arises from nucleus ambigus in brainstem
- regulates cardiac rhythm
- called the wanderer because it wanders throughout body regulating function of many internal organs
emerges from medulla of brainstem
Vagus
- exits skull through jugular foramen
- runs between internal jugular vein and internal carotid giving off branches to pharynx, larynx and constrictors
- continues descending to reach cardiac, pulmonary and esophageal plexuses
superior laryngeal nerve
branches off from vagus
- splits inter external and internal branches
- external brach provides motor innervation to CT
- internal branch provides sensory innervation to entire layers excluding inferior surface of vocal folds
recurrent laryngeal nerve
RLN
- arises more distally
- loops back upwards to larynx
- right side emerges from vagus within neck and loops around subclavian artey
- left side branches off in chest and loops around aorta
- provides motor innervation to ALL the intrinsic laryngeal muscles
- carries sensory info from inferior surface of vocal folds and upper trachea
mucosal membranes and ligaments
external mucosal membrane refers to surface covering oral cavity, nasal cavity, larynx
- intrinsic membranes form the tough connective tissue and ligaments
- includes connective tissue connecting laryngeal cartilages
- not skin, but covers the internal passageways in the same way as skin
- essential to keep mucosa hydrated and healthy
- thickened membranes called ligaments even though they are NOT connecting bones
quadrangular membrane
paired membrane joined anteriorly
connects lateral margins of epiglottis to thyroid, corniculate and arytenoids
-fibers curve and descend around to posterior cartilages
-joins up with conus elasticus
superior lateral margins form thickened aryepiglottic folds
inferior portion forms ventricular ligaments overlying ventricular fold
conus elasticus
inferior portion
- connects thyroid, arytenoid, and cricoid carts
- name refers to cone shaped upper trachea ending at VFs
- forms anterior cricothyroid ligaments and lateral cricothyroid membrane
- free thickened margins from vocal ligaments*
- vocal ligament forms medial margin of VF
- vocal ligament permits highly specific vibration characteristics to VFs
extrinsic membrane
lining surface of larynx and epiglottis is the wet sticky surface called mucosal membrane
- most of if loosely covers underlying structures
- cells forming cover called columner epithelium
squamous epithelium & layers
5 specialized layers including surface membrane, vocal ligament, and muscle
only present for VFs
layer one
protective membranous layer that also retains moisture
- thin layers of cells called squamous epithelium
0. 1 mm
layer two
superficial lamina propria (SLP)
- tough stretchy elastic fibers
- tolerates extensive stretching
layer three
intermediate lamina propina of ILP
1-2mm
-tough stretchy tissue intermixed with SLP
-fibers run in AP direction so are cross-layered
-combination of directions increases strength
layer four
deep lamina propria or DLP
1-2mm
-tough collagen supportive fibers that resist stretching
layer five
muscular layer composed of thyroarytenoid
-forms bulk of VF
extrinsic muscles/hyoid muscles
muscles move larynx up or down or stiffen its position
one attachment to laryngeal cartilages and to another structure
-sternohyoid
-thyrohyoid
-thyropharyngeus
-other muscles attach to hyoid bone but effectively move larynx
**coordinated synergistic function to stabilize or move larynx
- intrinsic muscles act at same time as extrinsic
- extrinsic groups broadly affect laryngeal position and provide stability
- intrinsics are producing fine changes in VF adduction
- muscle groups do NOT work against each other in normal function
thyrohyoid
INFRAHYOID
origin: thyroid cartilage
insertion: hyoid bone
innervation: ansa cervicalis
function: brings hyoid and thyroid closer
- elevates larynx when hyoid fixed
- depressed hyoid when larynx fixed
inferior pharyngeal constrictor
origin: thyroid lamina (external)
insertion: posterior pharyngeal raphe
innervation: Vagus
functon: constricts pharynx and elevates larynx
AKA thyropharyngeus
sternothyroid
INFRAHYOID
origin: manubrium
- insertion: oblique line of thyroid cartilage
innervation: CN XI and C1 & C2
function: depresses or fixates thyroid cartilage and larynx
extrinsic laryngeal muscles
thyrohyoid
inferior pharyngeal constrictor (thyropharyngeus)
sternothyroid
sternohyoid
INFRAHYOID
origin: manubrium
insertion: hyoid
innervation: ansa cervicalis
- together ST and SH can stabilize larynx in medial or depressed position
omohyoid
infrahyoid
origin:
superior: hyoid
inferior: scapula
insertion:
superior: inferior belly by intermediate tendon
inferior: superior belly
innervation: ansa cervicalis
function: contraction of superior belly pulls hyoid down
stylohyoid
suprahyoid
origin: styloid process of temporal bone
insertion: hyoid bone
innervation: CN VII facial nerve
function: elevates and retracts hyoid and larynx
digastric muscle
suprahyoid
origin: temporal bone & mandible
insertion: hyoid bone
innervation: CN VII facial nerve
function: depress mandible but elevate hyoid bone and base of tongue
mylohyoid
suprahyoid
origin: mandible
insertion: hyoid bone
innervation: CN V trigeminal nerve
function: pulls hyoid up and forward when mouth fixed
geniohyoid
suprahyoid
origin: mandible
insertion: hyoid
innervation: CN XII hypoglossal nerve
function: pull hyoid forward and up
hyoglossus
suprahyoid
origin: hyoid bone
insertion: tongue
innervation: CN XII hypoglossal nerve
function: elevates hyoid or pulls tongue back
genioglossus
suprahyoid
origin: hyoid bone
insertion: tongue
innervation: CN XII hypoglossal nerve
function: elevate and protrude tongue which pulls hyoid and larynx up and forward
VF function
protect airway during aspiration
- open during breathing and closed during swallowing
- coughing out foreign particles
- distinct and separate reflex actions
- vibrate to produce sound
cells covering medial portion of vocal folds, ventricular folds and parts of the epiglottis
stratified squamous epithelium
-these cells are tightly bound to underlying tissue
