The Larynx Flashcards
What is the larynx, where is it located and its functions?
Part of respiratory tract between oropharynx and trachea. Located between C3 and C6, below hyoid bone but will move when swallowing and is slight higher in newborns. It transports air, acts as a protective sphincter and is involved in phonation
Name the laryngeal cartilages
- Epiglottis
- Thyroid
- Cricoid (only complete ring)
- Arytenoid
- Corniculate and cuneiform
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where does the epiglottis project and where is it attached too?
- Projects upwards and backwards into the pharynx behind the posterior part of tongue.
- Attaches to thyroid cartilage via thyroepiglottic ligament.
- Attaches to hyoid bone by the hypoepiglottic ligament
Describe the structure of the thyroid cartilage
- Left and right laminae,
- Superior and Inferior horns (superior attach to hyoid, inferior to cricoid)
- Superior thyroid notch
- Thyroid angle = laryngeal prominence (adams apple)
- Oblique line for muscle attachment.
Describe the structure of the cricoid cartilage
- Articulates with arytenoid and thyroid
- Shape of a signet ring
Describe structure of the arytenoid cartilages
- Articulates with sloping shoulders of cricoid lamina and superiorly with corniculate cartilage.
- Vocal process anteriorly for attachment of vocal ligament
- Muscular process posteriorly for attachment of the posterior and lateral crico-arytenoid muscles
- Depressions for vestibular ligament and attachment of vocalis muscle.
Describe structure of thyro-htoid membrane
- Extends from thyroid laminae and superior horns to greater horns of hyoid.
- Thickened anteriorly and posteriorly as the median and lateral thyro-hyoid ligaments.
- Pierced by superior laryngeal vessels and nerve.
What is the fibro-elastic membrane?
It is elastic connective tissue underneath the laryngeal muscous membrane and strtches between laryngeal cartilages and forms the fibro-elastic membranes.
What is the fibro-elastic membrane separated by?
The laryngeal ventricle to form superiorly quadrangular membrane and inferiorly conus elasticus.
Describe the positioning of the quadrangular membrane
It extends between lateral aspect of epiglottis, arytenoid and corniculate cartilages. The edges form the aryepiglottic fold and the vestibular ligament which when covered by mucous membrane forms vestibule fold.
What is the clinical significance of the conus elasticus?
(cricovocal membrane)
- Blends anteriorly with the median cricothyroid ligament which is the site of emergency access to airway (Tracheotomy)
Describe the functions of the vocal cord
It controls laryngeal diameter for:
- Speech
- Coughing/sneezing,
- Raising intra-abdominal pressure
What widens or alters the tension of rima glottis?
the muscles within and adjacent to the vocal folds.
What is the vestibule?
Between the laryngeal inlet and vestibular folds
What is the laryngeal ventricle
Recess between vestibular and vocal folds which leads to the saccule which lubricates the vocal folds
What is the infraglottic cavity?
It is the area between the vocal folds and trachea.
What is the laryngeal inlet bound by?
Aryepiglottic folds
What is the rima glottis?
Opening between vocal cords and muscular processes of arytenoid.
Name the extrinsic muscles laryngeal muscles and their function
- Suprahyoid and infrahyoid muscle groups. They arrange position of larynx and facilitate closing of laryngeal inlet.
What are the functions of the intrinsic laryngeal muscles
Adjust length or tension of vocal ligaments,
- Open or close rima glottis,
- control inner dimensions of vestibule,
- facilitate closing of laryngeal inlet.
Name the elevators of the pharynx (extrinsic muscles) SPS
- Salpingopharyngeus
- Palatopharyngeus
- Stylopharyngeus
Name the elevators of the larynx (extrinsic muscles)
- Stylohyoid
- Mylohyoid
- Geniohyoid
- Thyrohyoid
- Digastric
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Name the depressors of the larynx
- Sternothyroid,
- Thyrohoid,
- Sternohyoid
What are the muscles that close the laryngeal inlet?
- Salpingopharyngeus,
- Palatopharyngeus,
- Stylopharyngeus,
- Stylohyoid
- Ary-epiglottic muscle (Intrinsic muscle that acts as a purse string)
- Superior fibres of thyro-arytenoid muscle)
- (and elevation of larynx and pharynx by extrinsic muscles)
What opens the laryngeal inlet?
Decent of laryngeal by elastic recoil and the hypoepiglottic ligament.
What opens the rima glottis?
Posterior crico-arytenoid muscle
What closes the rima glottis?
- Inferior fibres of thyro-arytenoid,
- Lateral crico-arytenoid,
- Transverse arytenoid muscle
What causes lengthening of the vocal folds which in turn alters tension in vocal folds?
Thyroid cartilage may be rocked forwards and backwards at the cricothyroid joint
- The crico-thyroid muscles changes in length
- Vocalis muscle (changes in tension alter pitch of voice)
Describe what occurs to the vocal folds in phonation
The vocal folds are adducted and air being forced through them makes a vibration.
What occurs in effort closure?
Both vocal and vestibular folds are adducted so the airway is closed.
Describe the process of swallowing
During swallowing the larynx elevated and there is the closure of the laryngeal inlet by the epiglottis. After, as the larynx descends the epiglottis springs back by hypoepiglottic ligament
What is the arterial supply of larynx?
Superior laryngeal artery and the inferior laryngeal artery
What is the venous drainage of the larynx and its clinical significance?
Superior laryngeal vein (drains to internal jugular vein) and the inferior laryngeal vein (drains to brachiocephalic). The inferior thyroid is at risk during tracheostomy
Describe the lymphatic drainage of the larynx
Above the vocal cord - Superior deep cervical lymphnodes.
Below vocal cord - Prelaryngeal, pretracheal, inferior deep cervical and supraclavicular lymph nodes.
Describe the neural supply of the laryngeal cavity
Branches of the superior laryngeal nerve (SLN) (branch of vagus), the Internal branch of SLN (sensation of larynx down to just above vocal folds) and the external branch of SLN (supplies cricothyroid muscle). Then inferior laryngeal nerve (branch of vagus) and the reccurent laryngeal nerve (supplies intrinsic muscles of larynx except cricothyroid and sensation to vocal cords and below)
