26-10-22 – Larynx Flashcards
Learning outcomes
- Describe the general structure, and functions of the larynx
- Describe the cartilages and membranes of the larynx
- State the extrinsic muscles of the larynx
- Describe the actions of the intrinsic muscles of the larynx
- Describe (briefly) the neurovascular supply of the larynx
- Discuss the clinical conditions that may affect the larynx, particularly in relation to nerve lesions
What is the larynx?
What does the larynx consist of?
What are 3 functions of the larynx?
- The larynx is the part of the respiratory tract between oropharynx and trachea
- The larynx consists of a membranous (fibro-elastic) tube suspended between cartilages
- 3 functions of the larynx:
1) Transport of air
2) Protective sphincter
3) Phonation - the production or utterance of speech sounds.
What vertebrae is the larynx found between?
If the larynx stationary or mobile?
How does the placement of the larynx differ in new-borns and infants compared to adults?
Why is this?
Where does the hyoid bone sit in relation to the larynx
What does the hyoid bone articulate with? What is it suspended by?
- The larynx is found between the levels of about C3 – C6 (depending on swallowing)
- The larynx is a mobile region
- The larynx is slightly higher in new-borns and infants
- This is because the baby needs to be able to breast feed while respirating
- The hyoid bone sits on top of the larynx
- The hyoid bone does not articulate with any other bone
- It is suspended by muscles
What does the laryngeal skeleton consist of?
What are the 3 single cartilages in the laryngeal skeleton?
What are the 3 paired cartilages in the laryngeal skeleton?
What are the cartilages made of?
What are the 2 exceptions?
Which cartilage is the only complete ring?
- The laryngeal skeleton consists of cartilages connected to each other by ligaments and membranes
- 3 single cartilages in laryngeal skeleton:
1) Epiglottis cartilage
2) Thyroid cartilage
3) Cricoid cartilage - 3 paired cartilages in the laryngeal skeleton:
1) Arytenoid cartilages
2) Corniculate cartilages
3) Cuneiform cartilages (in aryepiglottic fold, so can’t be seen on diagram) - All of the cartilages are hyaline cartilage, except the arytenoid cartilage (composed of both hyaline and elastic cartilage) and the epiglottis cartilage (composed of elastic cartilage)
- The only complete ring is the cricoid cartilage
What is the shape of the epiglottis?
Where can it be found?
What is the function of the epiglottis?
What 2 things does the epiglottis attach to?
How does it attach?
What are the functions of these attachments?
Where do the other sides of the epiglottis attach?
- The epiglottis is leaf shaped
- The epiglottis can be found projecting upwards and backwards into the pharynx, behind the posterior part of the tongue
- The function of the epiglottis is to close over the laryngeal inlet while swallowing
- The epiglottis attaches to:
1) The hyoid bone (superior attachment)
* Attaches to the epiglottis via the hyoepiglottic ligament
* This ligament opens the laryngeal inlet at the end of swallowing (not actively, as ligaments don’t have contractile qualities) and pulls the epiglottis back to its original position
2) The thyroid cartilage (inferior attachment)
* Attaches to the epiglottis via the thyroepiglottic ligament
* This ligament keeps the epiglottis in place
- The other sides of the epiglottis are free, and don’t attach to anything
What is the thyroid cartilage formed by?
What does this fusion form?
Why is this more prominent in men?
What do the superior and inferior horns of the thyroid cartilage attach to?
Where is the superior thyroid notch found?
What 3 muscles attach to the oblique lines of the thyroid cartilage?
- The thyroid cartilage is formed by the fusion of the anterior left and right lamina
- The fusion forms at an angle, known as the laryngeal prominence
- The laryngeal prominence is more prominent in men, and known as the Adam’s apple
- This is because the fusion of lamina in men is at a more acute (smaller) angle than it is in woman, so the laryngeal prominence sticks out more
- Superior horns of the thyroid cartilage attach to the hyoid bone
- Inferior horns of the thyroid cartilage articulate with the cricoid cartilage
- The superior thyroid notch is found superior to the laryngeal prominence
- 3 muscles that attach to the oblique lines of the thyroid cartilage:
1) Sternothyroideus
2) Thyreohyoideus
3) Constrictor pharyngis inferior
What is the shape of the cricoid cartilage?
Where is the lamina of the cricoid cartilage located?
What does the cricoid cartilage sit on?
What 2 cartilages does the cricoid cartilage articulate with?
Where do they articulate?
What is the ridge of the cricoid cartilage for?
What are the depressions of the cricoid cartilage for?
- The cricoid cartilage is in the shape of a signet ring
- The lamina of the cricoid cartilage is located posteriorly
- The cricoid cartilage sits on top of the trachea
- 2 cartilages the cricoid cartilage articulates with:
1) Arytenoid cartilage
* Articulates with cricoid cartilage at posterior superior facets
* There is a ‘sloping shoulder’ for arytenoid articulation, which is important in the process of muscles opening the rime glottis (space between vocal cords)
2) Thyroid cartilage
* The inferior horns of the thyroid cartilage articulate with the posterior inferior facets of the cricoid cartilage
* The ridge of the cricoid cartilage is for attachment to the oesophagus
* The depressions of the cricoid cartilage are for the attachment of the posterior crico-arytenoid muscle
Is the arytenoid cartilage single or paired?
What 2 things does the arytenoid cartilage articulate with?
Where do they articulate?
What are the 2 named processes of the arytenoid cartilage?
What muscles/ligaments attach to these processes?
What attach to the 2 depressions of the arytenoid cartilage?
- The arytenoid cartilage is paired
- 2 things the arytenoid cartilage articulates with:
1) Corniculate cartilage (superior articulation)
2) Cricoid cartilage (inferior articulation)
* Articulates with the arytenoid cartilage at the sloping shoulders of the cricoid lamina
- 2 named processes of the arytenoid cartilage:
1) Vocal process
* Located anteriorly
* For the attachment of the vocal ligament
2) Muscular process
* Located posteriorly
* For the attachment of the posterior and lateral crico-arytenoid muscles
- Attachments of the 2 depressions of the arytenoid cartilage:
1) Depression for vestibular ligament
2) Depression for attachment of vocalis muscle
Where does the thyro-hyoid membrane extend between?
How is it thickened anteriorly and posteriorly?
What 2 things is the thyro-hyoid membrane pierced by?
What direction does this neurovascular bundle move in?
- The thyro-hyoid membrane extends between the upper edges of the thyroid lamina and superior horn and the body and greater horns of the hyoid
- The thyro-hyoid membrane is thickened anteriorly and posteriorly as the median and lateral thyro-hyoid ligaments
- The thyro-hyoid membrane is pierced by the superior laryngeal vessels (artery and vein) and superior laryngeal nerve (internal branch)
- This neurovascular bundle moves from outside to inside
What is the inner surface of the larynx covered by?
What is deep to this?
How are fibro-elastic membranes formed?
What are the 2 fibroelastic membranes?
How are the fibro-elastic membranes separated?
- The inner surface of the larynx is covered by mucous membrane
- Deep to the mucous membrane are 2 separate fibro-elastic membranes
- Elastic connective tissue underneath the laryngeal mucous membrane stretches between laryngeal cartilages and form fibro-elastic membranes
- 2 fibroelastic membranes:
1) Quadrangular membrane (superior)
2) Conus elasticus (inferior) - Fibro-elastic membranes are separated from each other by laryngeal ventricle
What 3 things does the quadrangular membrane extend between/attach to?
What are the 2 edges of the quadrangular membrane?
Where are the cuneiform cartilages?
- 3 things the quadrangular membrane extend between/attach to:
1) Lateral aspects of epiglottis
2) Arytenoid cartilages
3) Corniculate cartilages - 2 edges of the quadrangular membrane:
1) Aryepiglottic fold – Superior border (also a free border)
2) Vestibular ligament (aka vestibular fold) – Inferior border - The cuneiform cartilages are found in the aryepiglottic fold
What is another name for the conus elasticus?
Where does it extend between?
What does the conus elasticus blend with?
What is the medial cricothyroid ligament used for?
- The conus elasticus is also called the cricovocal membrane
- The conus elasticus extends between the lateral arch of the cricoid ring and the vocal ligament/fold
- The conus elasticus blends anteriorly with the median cricothyroid ligament, which extends from the inferior surface of the thyroid to the superior surface of the cricoid
- The median cricothyroid ligament is the site of emergency access to the airway (tracheotomy)
What is the conus elasticus and quadrangular membrane separated by?
What does the mucous membrane cover?
What does the laryngeal ventricle lead to? What shape is this?
- The conus elasticus and quadrangular membrane are separated by the laryngeal ventricle
- When the mucous membrane is placed on top of the larynx, it covers the quadrangular membrane, goes into the laryngeal ventricle and forms a cleft, comes out and covers the conus elasticus, then covers the tracheal ring
- The laryngeal ventricle leads to the saccules, which are banana shaped
What do the vocal cords consist of?
What 3 things do the vocal cords control?
How does the epithelium lining the vocal cords and the rest of the larynx differ?
Why is this?
What is the Rima glottis?
How is the size of the Rima glottidis altered?
What is the vestibular cord?
- The vocal cords/folds are vocal ligaments + fibres of the vocalis muscle covered with the mucous membrane
- Vocal folds control the laryngeal diameter for:
1) Speech
2) Coughing/sneezing
3) Raising the intra-abdominal pressure - The vocal cords are lined with stratified squamous epithelium
- The rest of the larynx is lined mainly with respiratory epithelium, consisting of ciliated, pseudostratified columnar epithelium with a rich population of goblet cells
- This is because the the vocal cords are vibrating all the time
- The rima glottidis is the space between the vocal ligaments
- Muscles within and adjacent to the vocal folds narrow or widen the opening between them (rima glottis or glottidis), or alter their tension
- The vestibular cord is known as the false vocal cord, as it is not involved in phonation/speech
What 3 things is the laryngeal cavity split into?
- The laryngeal cavity is divided into 3 parts:
1) The vestibule
* Superior to the vestibular fold
* Between the laryngeal inlet and the vestibular folds
2) The laryngeal ventricle
* The recess between the vestibular and vocal folds
* Leads to the saccule, which provides lubricating mucus for the vocal cords
3) The infraglottic cavity
* Inferior to the vocal fold
* Between the vocal folds and trachea
What is the laryngeal inlet?
What is it bound by?
What is the rima glottis/glottidis?
- The laryngeal inlet is the opening of the vestibule
- It is bound by the aryepiglottic fold
- The rima glottis/glottidis the opening between the vocal folds/cords and muscular processes of the arytenoid cartilages
What controls the position of the larynx?
What 3 other things do these muscles do?
- The position of the larynx is controlled by muscles
- 3 other things do these muscles do:
1) Alter laryngeal diameters to allow the passage of air only
2) Control airflow for speech
3) Raise intra-abdominal pressure
Where do intrinsic muscles of the larynx extend between?
What are 4 roles of the intrinsic laryngeal muscles?
- Intrinsic muscles of the larynx extend between laryngeal cartilages
- 4 roles of the intrinsic laryngeal muscles:
1) Adjust the length or tension of the vocal ligaments of the vocal cords - “rocking” at cricothyroid joints
2) Open and close the rima glottis
3) Control the inner dimensions of the vestibule
4) Facilitate closing of the laryngeal inlet
5) Open and close the laryngeal inlet
What 4 extrinsic muscles are involved in the closure of the laryngeal inlet?
What mechanism do they do this through?
- 4 extrinsic muscles involved in the closure of the laryngeal inlet:
1) Salpingopharyngeus
2) Palatopharyngeus
3) Stylopharyngeus
4) Stylohyoid - These extrinsic muscles are pharynx muscles, and close the laryngeal inlet via elevation of the pharynx, which is connected to and also elevates the larynx
What 2 intrinsic muscles close the laryngeal inlet?
How do these 2 intrinsic muscles close the laryngeal inlet alongside extrinsic muscles?
How does opening of the laryngeal inlet occur?
- 2 intrinsic muscles that close the laryngeal inlet:
1) Ary-epiglottic fold muscle
* Acts like a purse string and seals the laryngeal inlet
2) Superior fibres of thyro-arytenoid muscle (a.k.a. thyro-epiglottic muscle)
* Extends from thyroid to the side of the epiglottis
- These 2 intrinsic muscles pull and purse the laryngeal inlet while the extrinsic muscles pull up the larynx, leading to the epiglottis closing over the laryngeal inlet
- Opening of the laryngeal inlet occurs via the descent of the larynx (and pharynx) due to elastic recoil and the hyo-epiglottic ligament, with this ligaments tension pulling the epiglottis to its original breathing position
- This ligament is not an active component since it’s a ligament and doesn’t have contractile properties
What is it the only muscle that opens the rima glottis?
What structure does this muscle act on?
Describe the process of the opening of the rima glottis
- The posterior crico-arytenoid muscle is the only muscle that opens the rime glottis
- The posterior crico-arytenoid muscle acts on the vocal folds/cords, as these are what define the rime glottis
- When this muscle contracts, it internally rotates, causing the arytenoid cartilages that the vocal cords are attached to externally rotate (vocal cords abduct), leading to the widening of the rima glottis
What 3 muscles close the vocal folds/rima glottis?
- 3 muscles that close the vocal folds/rima glottis?
1) Inferior fibres of thyro-arytenoid
2) Lateral crico-arytenoid
3) Transverse arytenoid
What muscles lengthen the vocal folds and alter their tension?
How is this possible?
Describe the process of lengthening and increased tension in the vocal cords
- The crico-arytenoid muscles lengthen, hence increase the tension of the vocal folds
- This possible as the thyroid cartilage articulates with the cricoid cartilage at 2 points (the inferior horns of the thyroid cartilage)
- This means the anterior and inferior part of the thyroid cartilage is not supported, so can rock backwards and forwards
- When the crico-arytenoid muscles contract, they pull down the anterior part of the thyroid cartilage
- The vocal cords are attached to the anterior inferior part of the thyroid cartilage, meaning they will be lengthened, and their tension will be increased
What muscle is responsible for changing the tension, but not the length of vocal cords?
Where does this muscle attach?
How does altering tension change the pitch of voice?
What is the position of the crico-thyroid muscle and vocal folds during this process of increasing tension?
- The Vocalis muscle (part of Thyro-arytenoid muscle) changes the tension of the vocal folds without changing the length
- The Vocalis muscle attaches to the arytenoid cartilage, just above the vocal process
- Increasing the tension but not the length of the vocal cords increases the pitch of voice
- During the process of increasing tension of the vocal folds with the vocalis muscle, the position of the crico-thyroid muscle and vocal folds remains the same
How can both the vestibular folds and vocal folds be seen during a laryngoscopy?
How can vocal folds appear?
- Both the vestibular folds and vocal folds be seen during a laryngoscopy because the vestibular folds are more superior and located more laterally than the vocal folds
- Vocal folds can appear lighter than vestibular folds
What is the shape of the rime glottis during rest/quiet respiration?
- The shape of the rime glottis during rest/quiet respiration is triangular
What is the shape of the rime glottis during forced inspiration?
Why is this?
- The shape of the rime glottis during forced inspiration is a rhomboid
- This is because the rima glottis is widely opened by posterior crico-arytenoid muscles externally rotating the arytenoid cartilages
How do the vocal folds change during phonation?
Why is this?
How are cord length and tension modified?
- During phonation (speech), the vocal folds are adduced (together in the midline)
- This is because air forced through vocal folds causes vibration
- Cord length and tension are altered by cricothyroid, thyro-arytenoid and vocalis muscles
What are 3 examples of when effort closure of the vocal folds might occur?
What are the vocal folds and vestibular folds like during this?
What is the airway closed by?
- Effort closure of the vocal folds might occur during:
1) Child birth
2) Lifting a heavy object
3) Valsalva manoeuvre - During effort closure, the vocal and vestibular folds are adducted (both in midline), with the larynx being sealed from the upper respiratory tract
- The airway is closed by lateral crico-arytenoid and transverse arytenoid
What are 2 laryngeal changes during swallowing?
What anatomy changes after swallowing?
- 2 laryngeal changes during swallowing:
1) Laryngeal elevation
2) Closure of the laryngeal inlet by epiglottis - As the larynx descends after swallowing, the epiglottis springs back by hyo-epiglottic ligament
What are the 2 arteries that supply the larynx?
What arteries are they each branches of?
- 2 arteries that supply the larynx:
1) Superior laryngeal artery
* External carotid - Superior thyroid artery - Superior laryngeal artery
2) Inferior laryngeal artery
* Internal carotid – inferior thyroid artery – inferior laryngeal artery
What are the 2 veins that drain the larynx?
What veins do they drain into?
What veins are at risk during tracheostomy?
- 2 veins that drain the larynx:
1) Superior laryngeal vein
* Superior laryngeal vein – superior thyroid vein – internal jugular vein
2) Inferior laryngeal vein
* Inferior laryngeal vein – inferior thyroid vein – Brachiocephalic vein
- The inferior thyroid veins are at risk during tracheostomy
What are the lymph nodes above the vocal cords?
What 4 types of lymph nodes are below the vocal cords?
Are there lymphatic connections between vocal cords?
- The superior deep cervical lymph nodes are above the vocal cords
- 4 types of lymph nodes below the vocal cords:
1) Prelaryngeal lymph nodes
2) Pretracheal lymph nodes
3) Inferior deep cervical lymph nodes
4) Supraclavicular lymph nodes - There is no lymphatic connection between vocal cords
What 2 nerve branches innervate the larynx?
What side are they each on?
What are they each branches of?
Which artery accompanies which branch?
- 2 nerves supply the larynx:
1) Superior laryngeal nerve
* On the right side
* Arises from the middle of the inferior ganglion of the vagus
2) Inferior laryngeal nerve
* On the left side
* Vagus nerve - recurrent laryngeal nerve - inferior laryngeal nerve
* Accompanied by the inferior laryngeal artery
What are the 2 branches of the superior laryngeal nerve?
Which branch is motor and sensory?
What do they each supply?
Which artery accompanies which branch?
What is the only muscle in the larynx not supplied by the recurrent laryngeal nerve?
- The superior laryngeal nerve divides into:
1) The internal branch (internal laryngeal nerve)
* Internal branch is sensory only
* Pierces thyroid membrane and enters into the laryngeal cavity
* Supplies sensory fibres to the larynx down to the vestibule just above the vocal cords
* Accompanied by the superior laryngeal artery
2) The external branch (external laryngeal nerve)
* Supplies motor fibres to the cricothyroid muscle
* Only muscle in the larynx not supplied by the recurrent laryngeal nerve (raps around aortic arch on left side)
What 3 things does the inferior laryngeal nerve of the recurrent laryngeal nerve supply?
- The inferior laryngeal nerve of the recurrent laryngeal nerve supplies:
1) Motor fibres to all the intrinsic muscles of the larynx except cricothyroid
2) Sensory fibres to the vocal cords and the mucous membrane of infraglottic cavity below the vocal cords of the larynx
