11.1 LArynx Flashcards
What are the borders of the larynx
Laryngeal Inlet, through which it communicates with the Laryngopharynx to the level of the inferior border of the cricoid cartilage, where it is continuous with trachea.
Fucntion fo larynx?
Guard the air passages, especially during swallowing when it serves as the sphincter/valve of the lower respiratory tract, thus maintaining the airway.
Phonation
Cough reflex.
Where is the larynx located? Vertebral level?
Anteiror compartment of neck, suspended from hyoid
C3-C6
Describe the structure of the larynx?
The larynx is formed by a cartilaginous skeleton, which is held together by ligaments and membranes.
What are the 3 sections of the larynx?
• Supraglottis
o From the inferior surface of the epiglottis to the vestibular folds (false vocal cords)
• Glottis
o Contains vocal cords and 1cm below them
o The opening between the vocal cords is known as rima glottides, the size of which is altered by the muscles of phonation.
• Subglottis
o From the inferior border of the glottis (+1cm) to the inferior border of the cricoid cartilage.
What is the epithelium lining the larynx?
Ciliated columnar epithelium
What makes up the laryngeal skeleton?
Hyoid and 9 cartilages: 3 unpaired: Epiglottis Thyroid Cricoid 1 set of unpaired: Arytenoid
What is the pie glottis made of?
What is ti attached to?
How does it move in swallowing?
Fibro cartilage – elastic cartilage
Marks the entrance to the larynx
Attached by ligaments to the back of the hyoid bone and thyroid cartilage
During swallowing the epiglottis moves towards the arytenoid cartilages to close off the larynx and prevent aspiration.
What is the upper level of the thyroid cartilage used to make.
Describe its structure.
• Upper surface used to Mark C4 Level
o Bifurcation of common carotid artery
o Level of carotid body
• Composed of 2 laminae, which join together anteriorly to form the laryngeal prominence.
• The posterior border of each sheet project superiorly and inferiorly to form the superior and inferior horns (cornu).
What are the attachments of the thyroid cartilage?
horns
o Superior Thyroid Horns → Ligament → Hyoid Bone
o Inferior Thyroid Horn → Synovial Joint with Cricoid
Describe the cricoid cartilage structure.
Attachements?
Vertebral level
• Most inferior cartilage • Complete ring of hyaline cartilage • Consists of a broad sheet posteriorly and a much narrower arch anteriorly. • Completely encircles airway • 2 Articular facets on each side o Inferior horn of thyroid cartilage o Arytenoid Cartilage • Surface marking for C6 Level, inferior level of the larynx
Describe the shape and location of arytenoid cartilages.
- Pyramid shaped
* Sit on the cricoid cartilage
What are the apex, base and sides of arytenoid cartilage?
Apex – corniculate cartilage
Base – superior border of cricoid cartilage
Vocal process – vocal ligament
Muscular process – posterior and lateral cricoarytenoid muscles
describe the borders of the cricovocal membrane/ligament.
• Lower border attached to cricoid cartilage
• Upper, Free Border = Vocal Ligament
o Attached to the deep surface of the angle of the thyroid cartilage
o Vocal process of arytenoid cartilage
What are the internal divisions of the larynx?
• Supraglottic space
o Laryngeal Inlet →
• Vestibular folds (false vocal cords)
• Glottis
o Vocal Cords and Rima Glottis (space between vocal cords)
• Subglottic Space
o Below vocal cords →
Lower border of Cricoid Cartilage
Give the external laryngeal muscles.
• Infrahyoid muscles o Depress larynx • Suprahyoid muscles o Elevate larynx • Stylopharyngeus (muscle of the pharynx)
What are the functions of the internal laryngeal muscles.
• Vocal folds o Open and close glottis o Control the length and tension of the vocal folds • Aryepiglottic folds o Help to close the laryngeal inlet
What is the innervation of the intrinsic laryngeal msuces?
Inferior laryngeal branch of RLN
Except
Cricothyroid = external laryngeal branch of superior laryngeal nerve.
Describe the attachment, function and innervation of cricothyroid.
- Cricoid cartilage → inferior horn of thyroid cartilage
- Stretches and tenses the vocal ligaments.
- Important for the creation of forceful speech.
- External laryngeal nerve
Describe the attachment, function and innervation of thyroarytenoid.
- Thyroid cartilage → Arytenoid cartilage
- Relaxes the vocal ligament, allowing for a softer voice
- Inferior laryngeal nerve
Describe the attachment, function and innervation of posterior cricoarytenoid.
- Cricoid cartilage → Arytenoid cartilage muscular process
- Abducts vocal folds – only muscle capable of widening the rima glottidis.
- Inferior laryngeal nerve
Describe the attachment, function and innervation of lateral cricoarytenoid.
- Cricoid cartilage → Arytenoid cartilage (muscular process)
- Adducts the vocal folds, narrowing the tima glottidis, modulating the tone and volume of speech.
- Inferior laryngeal nerve
Describe the attachment, function and innervation of transverse and oblique arytenoids.
- Span across from arytenoid cartilage to arytenoid cartilage
- Adducts the arytenoid cartilages, closing the posterior portion of the rima glottidis.
- Inferior laryngeal nerve
What are the larders of the vocal cords?
- Stratified Squamous Epithelium
- Vocal Ligament
- Vocalis Muscle
Significance of no submucosa in vocal cords?
The mucosa is firmly adherent to the vocal ligament, with no submucosa. This lack of a submucosa means that:
• Vocal cords look pearly white on laryngoscopy
• No oedema during infections
• Delayed spread of carcinoma of vocal cords
What are the movements of the vocal cords?
Abduction and adduction
What muscle abducts vocal cords?
Posterior cricoarytenoid.
What muscles adduct the vocal cords?
Lateral cricoarytenoid
Cricothyroid increase vocal cord tension.
What is the sensory innervation of the larynx above and below the vocal cords?
Above = Superior laryngeal nerve - internal laryngeal nerve Below = RLN
Describe the path of the RLN
Right:
Descends to T2 and curves around the subclavian artery
Left:
Descends to T4 and curves around arch of aorta.
Back up to larynx between trachea and oesophagus.
What causes hoarseness of voice?
Unilateral RLN palsy.
What happens in bilateral palsy of RLN?
Vocal cords paralysed in position between adduction and baduction.
Breathing is impaired and phonation cannot occur.
What happens in partial damage of nerves?
Depending on the cause, nerve damage can be bilateral or unilateral.
In unilateral palsy, one vocal cord is paralysed.
The other vocal cord tends to compensate and speech is not affected to a great degree although the patient may experience hoarseness of voice.
Give some causes of hoarseness of voice.
• Infection
o Laryngitis – Viral, Streptococcal
• Overuse of the voice
• GORD – Gastro Oesophageal Reflux
• Benign nodules on vocal cords (Singers)
• Apical Lung Tumour
o Recurrent Laryngeal Nerve Palsy (Both sides)
• Bronchial Carcinoma
o Left Recurrent Laryngeal Nerve Palsy (right doesn’t go low enough)
Give the blood supply to the larynx.
External Carotid Artery → Superior Thyroid Artery → Superior Laryngeal Artery
Subclavian Artery → Inferior Thyroid Artery → Inferior Laryngeal Artery
(Follows the recurrent laryngeal nerve into the larynx)
Give the venous drainage of the larynx.
superior laryngeal vein + superior thyroid vein –> IJV
Inferior laryngeal vien + inferior thyroid vein –> LEft brachiocephalic vein
What can cause laryngeal obstruction? How is this treated in emergency?
• Laryngeal Oedema
o Infection – Acute epiglottitis, croup, anaphylaxis
• Inhalation of foreign body
• Tumours
In an emergency situation an airway is opening through the Cricothyroid Membrane (Cricothyroidotomy). If less urgent, a Tracheostomy is performed (opening into the trachea).
