Anaesthetics: Anatomy - Larynx, pharynx and oral cavity Flashcards
Which is the largest of the laryngeal cartilages?
Thyroid cartilage
What is the vertebral level of the superior border of the thyroid cartilage?
C4
What are some of the features and connections of the thyroid cartilage?
Laryngeal prominence (fusion of inferior 2/3 of laminae in median plane)
Superior and inferior thyroid notches
Superior horns connected to hyoid superiorly via thyrohyoid membrane
Connected to cricoid cartilage anteriorly via cricothyroid membrane, and inferior horns articulate directly with cricoid cartilage posteriorly (cricothyroid joints)
What structures pierce the thyrohyoid membrane?
Superior laryngeal vessels
Branch of superior laryngeal nerve
What cartilage forms the only complete ring around the larynx?
Cricoid cartilage (“signet ring” shaped, broader posteriorly)
How is the cricoid cartilage connected to other laryngeal structures?
To thyroid cartilage via cricothyroid membrane anteriorly
Articulates directly with inferior horns of thyroid cartilage posteriorly
To first tracheal ring via cricotracheal ligament
What are the nine laryngeal cartilages?
Unpaired: thyroid cartilage, cricoid cartilage, epiglottic cartilage
Paired: arytenoid cartilages x2, corniculate cartilages x2, cuneiform cartilages x2
What are the three processes of the arytenoid cartilages and what does each articulate with? What does the base articulate with?
Apical process: articulates with corniculate cartilage superiorly (attaches to aryepiglottic fold)
Vocal process: provides attachment for vocal ligament
Muscular process: provides attachment for posterior and lateral crico-arytenoid muscles
Base: articulates with superior border of cricoid cartilage (cricoarytenoid joints: for movement of vocal folds)
Describe the attachments of the epiglottic cartilage
Leaf-shaped plate of elastic cartilage with “stalk” attached to posterior surface of anterior thyroid cartilage
What is the function of the epiglottic cartilage?
Flattens and moves posteriorly during swallowing to close off and protect larynx
Where are the corniculate cartilages located?
On apices of arytenoids
Where are the cuneiform cartilages located?
Within aryepiglottic folds (act to strengthen folds)
What do the cuneiform cartilages articulate with?
No direct attachments, located within aryepiglottic folds
What vertebral levels does the larynx span?
C3-6
What are the three sections of the larynx (and their respective interior laryngeal aspects)? What are their boundaries?
- Supraglottis (laryngeal vestible): from inferior epiglottis to vestibular folds
- Glottis (laryngeal ventricle and middle part of laryngeal cavity): vocal cords and 1cm below
- Subglottis (infraglottic cavity): from inferior glottic to inferior border of cricoid
What are the false cords?
Vestibular folds
What kind of epithelium lines the larynx?
All except the vocal cords are lined by respiratory epithelium (ciliated pseudostratified columnar)
Vocal cords are simple squamous
What are the six intrinsic muscles of the larynx?
- Cricothyroid
- Thyro-arytenoid
- Posterior crico-arytenoids
- Lateral crico-arytenoids
- Oblique and transverse arytenoids
- Vocalis
What nerve innervates the intrinsic muscles of the larynx?
All except cricothyroid are innervated by the inferior laryngeal nerve (branch of the recurrent laryngeal nerve from CN X)
Cricothyroid innervated by external laryngeal nerve (branch of superior laryngeal nerve from CN X)
What is the “singer’s muscle”?
Cricothyroid
Describe the origin, insertion and actions of the cricothyroid
Origin: anterolateral cricoid
Insertion: inferior horn of thyroid
Actions: stretches and tenses vocal ligament
Describe the origin, insertion and actions of the thyro-arytenoid
Origin: posterior surface of thyroid laminae, cricothyroid ligament
Insertion: anterolateral arytenoid
Actions: relaxes vocal ligament
Describe the origin, insertion and actions of the posterior crico-arytenoid
Origin: posterior surface of cricoid lamina
Insertion: vocal process of arytenoid
Actions: abducts vocal cords
Describe the origin, insertion and actions of the lateral crico-arytenoid
Origin: arch of cricoid
Insertion: vocal process of arytenoid
Actions: adducts vocal cords
Describe the origin, insertion and actions of the oblique and transverse arytenoids
Origin: one arytenoid
Insertion: contralateral arytenoid
Actions: adducts vocal cords
Describe the origin, insertion and actions of vocalis
Origin: vocal process of arytenoid
Insertion: ipsilateral vocal ligament
Actions: relaxes posterior vocal ligament while maintaining or increasing tension in anterior part
What vocal change does vocal cord adduction produce?
Allows phonation
What vocal change does vocal cord abduction produce?
Allows whispering
What vocal change does vocal cord relaxation produce?
Decreases pitch
What vocal change does vocal cord tension produce?
Increases pitch
What is the primary vocal cord adductor?
Lateral crico-arytenoid
What is the primary vocal cord abductor?
Posterior crico-arytenoid
What is the primary vocal cord tensor?
Cricothyroid
What is the primary vocal cord relaxer?
Thyro-arytenoid
Which three laryngeal muscles help protect the laryngeal inlet during swallowing?
- Lateral crico-arytenoids
- Oblique and transverse arytenoids
- Aryepiglottic muscles
Four extrinsic laryngeal ligaments
- Thyrohyoid: with median and lateral thyrohyoid ligaments (thickenings of membrane)
- Hyo-epiglottic
- Cricotracheal
- Median crico-thyroid (thickening of the cricothyroid ligament)
Two intrinsic laryngeal ligaments
- Cricothyroid
- Quadrangular membrane
What structure forms the vocal ligament?
The free superior margin of the cricothyroid ligament
What structure forms the vestibular ligament?
The free inferior margin of the quadrangular membrane
What structure forms the aryepiglottic ligament?
The free superior margin of the quadrangular membrane
What are the attachments for the quadrangular membrane?
Anterolateral arytenoid to lateral epiglottis
Between what vertebral levels does the pharynx run?
From base of skull to inferior border of cricoid cartilage (C6)
What are the three sections of the pharynx and what are the boundaries of each?
- Nasopharynx: from base of skull to soft palate
- Oropharynx: from soft palate to superior border of epiglottis
- Laryngopharynx: from superior border of epiglottis to inferior border of cricoid cartilage (C6)