Laryngeal inlet and vestibule
The upper expanded section is called the laryngeal vestibule (vestibulum laryngis). It originates from the laryngeal inlet (aditus laryngis) and extends downward to the vestibular folds (plicae vestibulares).
Anatomical boundaries of the laryngeal inlet:
- Anteriorly: posterior surface of the epiglottis.
- Posteriorly: apices of the arytenoid cartilages.
- Laterally: aryepiglottic folds (plicae aryepiglotticae).
The epiglottis plays a crucial role in protecting the respiratory tract. Its position is regulated by the contraction of the aryepiglottic (m. aryepiglotticus) and thyroepiglottic (m. thyroepiglotticus) muscles. During swallowing, it descends and hermetically seals the laryngeal inlet. Between the lateral walls of the vestibule and the inner surface of the thyroid cartilage, a depression is formed — the piriform fossa (recessus piriformis).
Mucous membrane and its structures
The mucous membrane of the larynx (tunica mucosa laryngis) is fixed to the cartilaginous skeleton by means of the fibroelastic membrane of the larynx (membrana fibroelastica laryngis). The tightness of this attachment varies: the loosest connection is observed in the region of the aryepiglottic folds and at the free edges of the vocal cords.
The mucous membrane forms several important structures:
- Vestibular folds (plicae vestibulares) — cover the vestibular ligaments of the same name.
- Vocal folds (plicae vocales) — formed by the mucosa covering the vocalis muscle, vocal ligament, and elastic cone.
- Laryngeal ventricle (ventriculus laryngis) is a small paired depression on the lateral wall between the vestibular folds and vocal folds. Anteriorly, it continues into the blind laryngeal saccule (sacculus laryngis).
Most of the surface is lined with ciliated epithelium. However, areas subjected to the greatest mechanical stress (vocal folds, lingual surface of the epiglottis, and inner surface of the arytenoid cartilages) are covered with stratified squamous epithelium.
Numerous mucous glands (glandulae laryngeales) moisten the surface. They are particularly abundant in the laryngeal ventricles, on the posterior surface of the epiglottis, and near the interarytenoid fold. Glands are absent on the free edges of the vocal folds.
Vocal apparatus and infraglottic cavity
The middle part of the laryngeal cavity is the vocal apparatus (glottis). This is the narrowest section, which visually appears as a sagittal cleft.
Two important slit-like spaces are distinguished here:
- Rima vestibuli (rima vestibuli) — located between the vestibular folds.
- Glottis (rima glottidis / vocalis) — the space between the vocal folds. This is the main structure of phonation.
Topographically, the glottis itself is distinguished into:
- Intermembranous part (pars intermembranacea) — the anterior section between the edges of the vocal folds.
- Intercartilaginous (respiratory) part (pars intercartilaginea) — the posterior section located directly between the arytenoid cartilages.
Posterior to the glottis is the interarytenoid notch (incisura interarytenoidea), which continues upward into the vestibule.
The lower section of the larynx, beginning immediately below the vocal folds, is called the infraglottic cavity (cavitas infraglottica). It has a conical shape, gradually widens downward, and passes into the tracheal cavity without a sharp boundary.
Blood supply, drainage, and innervation
The blood supply and innervation of the larynx are strictly segmented and depend on the level relative to the glottis.
Arterial blood supply:
- Superior laryngeal artery (a. laryngea superior) — a branch of the superior thyroid artery.
- Inferior laryngeal artery (a. laryngea inferior) — a branch of the inferior thyroid artery.
Blood and lymph drainage: Venous drainage occurs via veins of the same name, draining into the superior and inferior thyroid veins. Lymph is directed to the deep anterior cervical (nodi lymphoidei cervicales profundi anteriores) and lateral jugular lymph nodes.
Innervation: Provided by branches of the vagus nerve (n. vagus):
- Above the glottis, the mucosa is innervated by the superior laryngeal nerve (n. laryngeus superior).
- Below the glottis — the inferior laryngeal nerve (n. laryngeus inferior), which is the terminal branch of the recurrent laryngeal nerve.
Briefly: answers to topical questions
Which laryngeal muscles are innervated by the superior laryngeal nerve?
The superior laryngeal nerve provides motor innervation to only one laryngeal muscle.
- Cricothyroid muscle (m. cricothyroideus) — innervated by the external branch (r. externus) of the superior laryngeal nerve.
The internal branch (r. internus) of this nerve is sensory and innervates the mucous membrane of the larynx above the glottis. All other intrinsic muscles of the larynx receive motor innervation from the recurrent laryngeal nerve.
Which cartilages make up the laryngeal skeleton?
The hard skeleton of the larynx is formed by unpaired and paired cartilages.
Unpaired cartilages:
- Thyroid cartilage (cartilago thyroidea) — hyaline cartilage protecting the vocal folds.
- Cricoid cartilage (cartilago cricoidea) — ring-shaped hyaline cartilage.
- Epiglottis (cartilago epiglottica) — elastic cartilage located behind the thyroid cartilage.
Paired cartilages:
- Arytenoid cartilages (cartilagines arytenoideae) — three-sided pyramid-shaped hyaline cartilages.
- Corniculate cartilages (cartilagines corniculatae) — elastic cartilages on the apices of the arytenoids.
- Cuneiform cartilages (cartilagines cuneiformes) — elastic cartilages within the aryepiglottic folds.
Class and exam questions
Where in the larynx is ciliated epithelium absent?
Stratified squamous epithelium is found on the vocal folds, the lingual surface of the epiglottis, and the inner surface of the arytenoid cartilages.
What forms the boundaries of the laryngeal inlet?
The laryngeal inlet is bounded anteriorly by the posterior surface of the epiglottis, posteriorly by the apices of the arytenoid cartilages, and laterally by the aryepiglottic folds.
How is the mucous membrane of the larynx innervated?
Innervation is provided by the vagus nerve: the area above the glottis is innervated by the superior laryngeal nerve, and below by the inferior laryngeal nerve.
What else to study on this topic
- Topography and functions of the arytenoid cartilages
- Structure of the fibroelastic membrane of the larynx
- Mechanism of action of the muscles that narrow and widen the glottis
- Regional lymph nodes of the neck and pathways of lymphatic drainage from the larynx
Study the complete topic in the Anatomy course
This is a summary. The course covers everything tested in classes and exams.
- Complete study guide on "Laryngeal cavity and vocal apparatus" and 1,363 more pages of the subject
- Assignments and quizzes after every topic — just like in a colloquium
- AI tutor answers questions on the topic anytime
- 295 video lessons by subject
Other topics in «Splanchnology / Respiratory System»
Free video lessons: AnatomyShort lessons with study notes — no registration required.
Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.