Larynx, Infrahyoid Muscles, Thyroid Flashcards
What are the main functions of the larynx? (3)
- Respiration
- Vocalisation
- Protection of respiratory passages during swallowing
How is food prevented from passing into larynx during swallowing?
Closure of epiglottis
Closure of vocal folds
What is the larynx lined with? What is the exception?
Lined with respiratory epithelium except for vocal folds which have stratified squamous epithelium.
What acts as a semi-rigid support for the larynx?
Cartilages
What are the characteristics of the joints between major cartilages? What are the benefits of this?
Synovial
Allows relative movement of the different cartilages controlled by actions of intrinsic muscles.
What is the appearance of the thyroid, cricoid, arytenoid?
Hyaline and may calcify or even ossify with age
What are the cartilages of the larynx? (7)
- Epiglottis
- Thyroid
- Cricoid
- Arytenoid
- Corniculate
- Cuniform
- Tritiate
What are the characteristics of the thyroid? (4)
- Laryngeal notch and prominence
- Anterior lamina
- Superior and inferior horn (posteriorly)
- Oblique line
What are the characteristics of the cricoid?
- Lamina (posterior)
2. Arch (anterior)
What is the importance of the arytenoid?
Particularly important in laryngeal function as many of the intrinsic muscles attach to this cartilage.
What attaches to the arytenoid?
- Vocal process of arytenoid
- Muscular process of arytenoid
- Base of arytenoid
- Apex of arytenoid
What is the orientation of the vocal process of arytenoid? What does it attach to?
It is directed anteriorly and attaches to vocal ligament/fold/vocalis muscle
What is the orientation of the muscular process of arytenoid? What does it attach to?
It is directed laterally and attaches to many of the intrinsic muscles.
Where is the base of the arytenoid located? What is the functional importance of the base of arytenoid?
Inferior surface of the arytenoid cartilage which hinges on upper surface of cricoid cartilage. Allows arytenoid cartilage to swivel or slide.
How is the apex of arytenoid directed? What is it attached to?
Directed superiorly
It is attached to the aryepiglottic muscle/fold
Where is the corniculate located?
It is a paired and is a separate small cartilage at apex of arytenoids.
Where is the cuniform located?
It is paired and is elongated cartilages in sides of aryepiglottic fold.
Where is the tritiate located?
It is paired and located in thickened posterior part of thyrohyoid membrane (usually defined as thyrohyoid ligament)
What is the characteristics of joints in the larynx?
Synovial
Where is the cricothyroid located?
Medial surface of inferior horn of thyroid cartilage to lateral lamina of cricoid cartilage.
Where is the cricoarytenoid located?
Upper border of cricoid cartilage to base of arytenoid
What are the regions of laryngeal cavity?
- Inlet
- Vetsibule
- Intermediate cavity
- Infraglottic cavity
Where is the inlet of the laryngeal cavity? What is it surrounded by?
Opening from pharynx.
Surrounded by upper border of epiglottis and aryepiglottic folds
Where does the vestibule extend?
From inlet to superior edge of vestibular fold
Where does the intermediate cavity extend?
From vestibular folds down to level of vocal folds
Where are the ventricles of the intermediate cavity located?
Paired cavities in lateral wall between vestibular folds and vocal folds.
What is the rima glottidis?
Gap between vocal folds.
Where does the infraglottic cavity extend?
Inferior edge of vocal folds to top of trachea
What are the vocal folds comprised of?
Consist of elastic vocal ligament and vocalis muscle (medial part of thyroarytenoid muscle)
How is sound and flow in air controlled?
Changes in width and shape of space between folds (rina glottidis)
What are the vestibular folds comprised of? What is their function?
Soft folds of mucous membrane
Play only a minor role in normal phonation but have a protective function and are used in conjunction with the vocal folds to produce specialised sounds
What are the extrinsic membrane/ligaments?
- Thyrohyoid membrane (posterior borders are thickened to form thyrohyoid ligaments)
- Cricotracheal membrane (cricoid cartilage to superior edge of trachea)
Where are the intrinsic ligaments situated? What are the upper and lower part of the intrinsic membrane?
Situated internally between mucosal lining of larynx and cartilage/muscle of larynx
Upper: Quadrangular membrane
Lower: Cricothyroid membrane
What do the free inferior margins form?
Vestibular ligament
What do the free superior margin form?
Vocal ligament
What is lateral to the cricothyroid membrane?
Vocalis muscle
Where are the intrinsic muscles located?
totally within larynx
Where are the extrinsic muscles located?
Connect larynx to adjacent structures.
What are the characteristics of intrinsic muscles? How are they named?
- Small skeletal muscles
- Paired except for transverse arytenoid
Named according to the cartilages to which they attach.
What are the function of the intrinsic muscles?
- Change the relative positions of cartilages of larynx via joints
- This in turn changes:
- Relative positions of vocal cords
- and/or alters tension on the vocal cords
- varies laryngeal inlet
What are the intrinsic muscles visible on the superficial surface of intact larynx?
- Cricothyroid
Where does the cricothyroid extend?
Superficial surface of arch or cricoid to deep surface of thryoid lamina and inferior horn
What are the muscles deep or posterior to thyroid cartilage?
- Aryepiglottic muscles
- Oblique arytenoid muscles
- Transverse arytenoid muscle
- Posterior cricoarytenoid muscle
- Lateral cricoarytenoid muscles
- Thyroarytenoid
Where does the aryepiglottic muscle extend? What do they form?
Extend from apex of arytenoids cartilages to sides of epiglottis
They form aryepiglottic folds
What are the aryepiglottics muscles continuous with?
Oblique arytenoid muscles
Where does the oblique arytenoid muscles extend? What are they superficial to?
Muscular process of one arytenoid cartilage to apex of opposite one
Transverse arytenoid muscle
Where do the transverse arytenoid muscles extend?
Muscular process of one arytenoid cartilage to muscular process of opposite one.
Where do the posterior cricoarytenoid muscles extend?
Posterior cricoid lamina to muscular process of ipsilateral arytenoid.
Where does the lateral cricoarytenoid muscles extend?
Arch of cricoid back and up to muscular process of arytenoid.
Where does the thyroarytenoid extend?
Inner surface of ARCH of thyroid cartilage (anteriorly) to VOCAL PROCESS of arytenoid cartilage (posteriorly)
What does the medial extension of the thyroarytenoid form?
Vocalis muscle in vocal fold
What are the actions of the intrinsic muscles?
- Muscles which vary rima glottidis
2. Muscles which regulated tension on vocal folds
What are the two types of muscles which vary rima glottidis?
- Abductors (move vocal folds apart)
2. Adductors and sphincters (move vocal folds together and close the inlet)
Which muscle is an abductor? What action does it perform?
Posterior cricoarytenoids
rotate vocal processes of arytenoids laterally
What muscles are adductors and sphincters? What specific actions are they responsible for?
- Lateral cricoarytenoids (rotate vocal processes of arytenoids medially)
- Transverse arytenoid - pull arytenoids together
- Oblique arytenoids
What muscles tighten vocal folds?
cricothyroids - lengthen and tense
What muscle relaxes vocal folds?
Thyroarytenoids and vocalis - shorten and relax
What muscles modify inlet?
- Close inlet - sphincter (aryepiglottics, oblique arytenoids)
- Widen inlet (thyroepiglottics)
What are the extrinsic muscles of larynx responsible for?
Move entire larynx up or down
What muscles are responsible for raising larynx and compressing laryngeal orifice?
- Thyrohyoid
- Stylopharangeus
- Palatopharangeus
Where does the thyrohyoid extend?
Thyroid cartilage to hyoid
Where does the stylopharangeus extend?
Styloid to posterior border of thyroid cartilage, some fibres blend with pharyngeal constrictors
Where does the palatopharangeus extend?
Soft palate and salpingopharagneus to posterior border of thyroid cartilage
What muscle is responsible for lowering larynx?
Sternothyroid
Where does the sternothyroid cartilage extend?
Thryoid cartilage to sternum
Where do we locate the vagus nerve?
Leaving the skull via the jugular foramen
What are the best features to locate the vagus?
Its close relationship with carotids and presence of recurrent laryngeal branches
On the left side of the thorax, what does the vagus cross and give off?
Crosses the anterior surface of the arch of aorta and gives off recurrent larygneal nerve which loops under the arch of the aorta
On the right side of the thorax what does the vagus cross and what does it give off?
Vagus crosses the anterior surface of the subclavian artery and gives off recurrent laryngeal nerve which loops under the subclavian artery
What runs on both sides of the thorax? Where does it eventually pass?
The recurrent laryngeal nerves run in the groove between the oesophagus and trachea and then passes deep/posterior to thyroid gland
What does the vagus divide up into in the thorax? What do they eventually form? Where does it enter in the end?
Into plexuses (cardiac, pulmonary and oesophageal) Form anterior and posterior vagi and finally enter abdomen on oesophagus
What are the functions of the vagus?
Motor, parasympathetic, sensory to soft palate, pharynx, larynx and structures in thorax and abdomen
What are the primary branches of the vagus nerve? (2)
- Superior laryngeal nerve
2. Recurrent laryngeal
Where does the superior laryngeal nerve arise?
Arises from upper vagus
What are the 2 branches of the superior laryngeal nerve to larynx?
- Internal branch
2. External branch
Where does the internal branch pass? What does it supply?
- Passes under thyrohyoid muscle and through thyrohyoid membrane.
- It supplies mucosa down to level of and including vocal folds.
What does the superior laryngeal nerve accompany?
Accompanies superior laryngeal branch of superior thyroid artery
What does the external branch of superior laryngeal nerve supply?
Supplies cricothyroid and inferior constrictor of pharynx (in addition to the pharyngeal plexus)
Where does the recurrent laryngeal run?
Ascends in groove between trachea and oesophagus, behind thyroid, passes deep to lower border of inferior constrictor to enter larynx
What does the recurrent laryngeal supply?
Supplies all laryngeal muscles except cricothyroid and also supplies mucus membrane below vocal fold
What is the recurrent laryngeal branch accompanied by? What is that a branch of?
Inferior laryngeal branch of interior thyroidal artery
Branch of thyrocervical trunk
Where do the veins of the larynx drain?
Superior, middle and inferior thyroid veins
Where do the lymph vessels drain?
Drain to deep cervical nodes and from there to jugular trunk
What is the thyroid gland?
Endocrine gland
What is the thyroid gland comprised of?
2 lateral lobes joined medially by an isthmus. May also have an extra pyramidal lobe
Where do the lobes of the thyroid gland extend?
From thyroid cartilage of larynx to 4th and 5th tracheal cartilage
Where is the thyroid located?
Deep to infrahyoid muscles
What does the thyroid gland produce?
- Thyroid hormones (metabolic stimulation)
2. Calcitonin (reduces blood calcium)
Where are the parathyroids?
4, separate organs closely associated with the posterior surface of the thyroid - elevates blood calcium
