Larynx Flashcards
strutr of teh lrynx
The larynx is formed by a cartilaginous skeleton, which is held together by ligaments and membranes. The laryngeal muscles act to move the components of the larynx for phonation and breathing. More information about each of these structures can be found in their respective sections.
Anatomically, the internal cavity of the larynx can be divided into three sections:
Supraglottis – From the inferior surface of the epiglottis to the vestibular folds (false vocal cords).
Glottis – Contains vocal cords and 1cm below them. The opening between the vocal cords is known as rima glottidis, the size of which is altered by the muscles of phonation.
Subglottis – From inferior border of the glottis to the inferior border of the cricoid cartilage.
The interior surface of the larynx is lined by a mucous membrane which contains ciliated columnar epithelium. An important exception to this is the true vocal cords, which are lined by a stratified squamous epithelium.
what is the larynx and what does it do
The larynx (voice box) is an organ located in the anterior neck. It is a component of the respiratory tract, and has several important functions, including phonation, the cough reflex, and protection of the lower respiratory tract.
what do the laryngeal musles do internally
The structure of the larynx is primarily cartilaginous, and is held together by a series of ligaments and membranes. Internally, the laryngeal muscles move components of the larynx for phonation and breathing.
what are the 3 paired carilges
There are three paired cartilages – the arytenoid, corniculate and cuneiform. They are situated bilaterally in the larynx.
desribe the paired cartilages
Arytenoid Cartilages
The arytenoid cartilages are pyramidal shaped structures that sit on the cricoid cartilage. They consist of an apex, base, three sides and two processes, and provides an attachment point for various key structures in the larynx:
Apex – articulates with the corniculate cartilage.
Base – articulates with the superior border of the cricoid cartilage.
Vocal process – provides attachment for the vocal ligament.
Muscular process – provides attachment for the posterior and lateral cricoarytenoid muscles.
Corniculate Cartilages
The corniculate cartilages are minor cartilaginous structures. They articulate with the apices of the arytenoid cartilages.
Cuneiform Cartilages
The cuneiform cartilages are located within the ary-epiglottic folds. They have no direct attachment, but act to strengthen the folds.
what are the three unpaired cartilages
The three unpaired cartilages are the epiglottis, thyroid and cricoid cartilages.
desribe the unpaired cartilage
Thyroid Cartilage
The thyroid cartilage is a large, prominent structure which is easily visible in adult males. It is composed of two sheets (laminae), which join together anteriorly to form the laryngeal prominence (Adam’s apple).
The posterior border of each sheet project superiorly and inferiorly to form the superior and inferior horns (also known as cornu). The superior horns are connected to the hyoid bone via the lateral thyrohyoid ligament, while the inferior horns articulate with the cricoid cartilage.
Cricoid Cartilage
The cricoid cartilage is a complete ring of hyaline cartilage, consisting of a broad sheet posteriorly and a much narrower arch anteriorly (said to resemble a signet ring in shape).
The cartilage completely encircles the airway, marking the inferior border of the larynx at the level of C6. It articulates with the paired arytenoid cartilages posteriorly, as well as providing an attachment for the inferior horns of the thyroid cartilage.
The cricoid is the only complete circle of cartilage in the larynx or trachea. This is of clinical relevance during emergency intubation – as pressure can be applied to the cricoid to occlude the oesophagus, and thus prevent regurgitation of gastric contents (known as cricoid pressure or Sellick’s manoeuvre).
Epiglottis
The epiglottis is a leaf shaped plate of elastic cartilage which marks the entrance to the larynx. Its ‘stalk’ is attached to the back of the anterior aspect of the thyroid cartilage. During swallowing, the epiglottis flattens and moves posteriorly to close off the larynx and prevent aspiration.
descibe the vestibular folds
The vestibular folds (false vocal cords) lie superiorly to the true vocal cords. They consist of the vestibular ligament (free lower edge of the quadrangular membrane) covered by a mucous membrane, and are pink in colour. They are fixed folds, which act to provide protection to the larynx.
desribe the vocal folds
The vocal folds (true vocal cords) are the more important of the two sets. Under the control of the muscles of phonation, they are abducted, adducted, relaxed and tensed to control the pitch of the sound created.
Histologically, they are structured as follows (superficial to deep):
Non-keratinised stratified squamous epithelium – Stratified layer provides extensive protection against foreign bodies which may accidentally enter the larynx.
Reinke’s space – This watery, amorphous layer is rich in glycosaminoglycans. Due to its fluidity, the epithelium is able to vibrate freely above it to create sound.
Vocal ligament – Lies at the free upper edge of the cricothryoid ligament.
Vocalis muscle – Exceptionally fine muscle fibres that lie lateral to the vocal ligaments.
The vocal folds are relatively avascular, and appear white in colour. The space between the vocal folds is known as the rima glottidis.
what are the two important solf tissue folds within the laynx and what is their role
There are two important soft tissue folds located within the larynx – the vestibular folds and vocal folds. They play an crucial role in protection of the airway, breathing, and phonation.
desribe the extinsic ligaments of the larynx
Median thyrohyoid ligament – Anteromedial thickening of the extrinsic thyrohyoid membrane.
Lateral thyrohyoid ligaments – Posterolateral thickenings of the extrinsic thyrohyoid membrane.
Hyo-epiglottic ligament – Connects the hyoid bone to the anterior aspect of the epiglottis.
Cricotracheal ligament – Connects the cricoid cartilage to the trachea.
Median cricothyroid ligament – Anteromedial thickening of the cricothyroid ligament (see below), connecting the thyroid and cricoid cartilages.
what is the extrinsic membrane of the larynx
Thyrohyoid membrane – Spans between the superior aspect of the thyroid cartilage and the hyoid bone. It is pierced laterally by the superior laryngeal vessels and internal laryngeal nerve (branch of the superior laryngeal nerve).
what is the intrisic mebrane of the larynx
Quadrangular membrane – Spans between the anterolateral arytenoid cartilage and the lateral aspect of the epiglottis. It has a free upper margin and lower margin. The lower margin is thickened to become the vestibular ligament.
what is the intrisic ligament of the larynx
Cricothyroid ligament – Originates from the cricoid cartilage and extends superiorly, where it terminates with an free (unattached) upper margin – which forms the vocal ligament. It is additionally attached anteriorly to the thyroid cartilage, and posteriorly to the arytenoid cartilage.
what are the muscles of the laynx divided into
the external muscles and the internal muscles.
