larynx Flashcards
what is the larynx commonly known as and why
voice box
- structure that makes the fundamental sounds of speech
how does the larynx play a key role in phonation
- by pressing together the right and left vocal cords as air is forced between them
- resulting vibration of the cords induces vibrations in the air that we ultimately detect as sound
what is important to note about the phonation produced by the larynx
- key role but NOT the only role
- only generates the basic sounds (fundamental vibrations = greatly modified before emerging as spoken words ie by the tongue, palate, lips, teeth, nasal cavity)
what is the other role of the larynx
protects deeper parts of airways (trachea and its branches) from inhaling solid materials
how does the larynx protect the deeper parts
- vocal chords play a role in it (probably why they originally evolved)
- the EPIGLOTTIS = 1st + most important line of protection - flap which covers entrance to the airways when we swallow food
how is the function of the larynx a mammalian response
all mammals use larynx to produce sound other animals (ie bird) use completely different structure
what is the larynx is composed of
series of
cartilages
membranes
ligaments
muscles
- has a cartilaginous skeleton connected by membranes + muscles
- muscles move the various components around
what supplies motor and sensory nerve supplies to the larynx
- branches of cranial nerve X
= vagus nerve
what structure does the larynx lay immediately anterior to
laryngopharynx (most inferior part of pharynx)
what structure is attached to
a) inferior end of the larynx (hangs from its final cartilaginous element )
b) inferior end of the pharynx
what does this result in
a) trachea
b) oesophagus
air in through mouth and nose
directed down into the larynx through the vocal cords
then down through trachea (takes air to lungs) which lies immediately anterior to part of the oesophagus which takes swallowed materials to the stomach, (oesophagus longer as needs to reach into abdomen)
where does the larynx lie
midline of anterior neck
hangs from hyoid bone
which gland wraps partially around the inferior part of larynx and upper part of trachea
thyroid
what are the two major cartilages of the larynx
- thyroid (attached to hyoid bone by thyrohyoid membrane )
- cricoid (most inferior cartilage in larynx )
what are the two important membranes of the larynx
- thyrohyoid
- cricothyroid (runs between the 2 cartilages)
what hangs from the larynx
trachea
which 5 cartilages of the larynx must we consider (not including the smaller cartilages which appear like dots / small pieces)
EPIGLOTTIC (forms core of epiglottis + attaches to inside of thyroid cartilage)
THYROID (large ‘shield’ of cartilage easily felt in neck)
ARYTENOID (2 cartilages - key functions in speech)
CRICOID (most inferior - arytenoid and thyroid cartilages articulate with it)
what is the thyroid cartilage characterised by
- largest cartilage of the larynx
- by two sheets of cartilage that join in the midline anteriorly (its laminae)
how does the thyroid cartilage form the adams apple (laryngeal prominence)
where the 2 laminae fuse there is a region which projects out anteriorly
this most anterior part forms it
why is the laryngeal prominence (adams apple) more prominent in men
bc of effects testosterone has on the larynx at puberty
it causes the throid cartilage to grow in the anterioposterior direction so it sticks out more
(also reason men’s voices tend to be lower pitched than women’s)
what other main feature exists in the thyroid cartilage
HORNS
- superior stick up
- inferior ones stick down (THESE MAKE A JOINT W THE CRICOID CARTILAGE)
what is the shape of the cricoid cartilage (2nd largest) likened to and why
reversed signet ring
its the only complete ring of cartilage in entire respiratory tree
what is the cricoid cartilage characterised by
single lamina placed posteriorly
anterior to the lamina is the arch of the cricoid cartilage
what does the cricoid cartilage articulate with and how
thyroid cartilage and both arytenoid cartilages
contains 2 facets for articulation (1 = for articulation w inferior horn of thyroid cartilage
2= for arytenoid)
what is the significance of the 2 depressions on the posterior surface of the cricoid cartilage
where the right and left posterior cricothyroid muscles originate
why are the posterior cricothyroid muscles most important ones of the larynx
only muscles we have to move vocal cords apart
if they both fail, vocal cords can snap together, making it difficult or impossible to breathe in)
how does the thyroid cartilage articulate with the cricoid cartilage
- inferior horns form right and left cricothyroid joints with facets on the posterolateral aspect of the cricoid
- thyroid cartilage can rotate / pivot around the cricothyroid joints so the cartilage thus laryngeal prominence moves up and down (movement central to determining pitch of the sound larynx produces (determines pitch of the voice)
where do the arytenoid cartilages sit
on top of cricoid (articulate with its facets to form the cricoarytenoid joints - where the arytenoids can rotate / slide closer or further apart)
what are the 3 processes of each arytenoid
1) superior (points upwards + attaches a muscle)
2) muscular (points laterally)
3) vocal (points anteriorly - attaches the posterior end of the vocal cord to arytenoid on each side)
how are the tips of the right and left vocal processes moved
what are these movements called
- when arytenoids rotate around cricothyroid joints
can be - ADDUCTED (moved closer together - towards midline of body)
- ABDUCTED (moved further apart - further away from midline)