Atlas of Human Anatomy by Netter

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Laryngeal cavity

From laryngeal inlet to tracheal cavity

Can be divided into three parts

Vestibule-above vestibular folds

Ventricle-sinus between vestibular folds above and vocal folds below

Infraglottic cavity-from below vocal folds to inferior border of cricoid cartilage

Vocal folds

Paired, project into laryngeal cavity on either side

Consist of

Vocal ligament-medial free edge of lateral cricothyroid ligament (conus elasticus)

Vocalis muscle-medial fibers of thyroid arytenoids muscle

Overlying mucosa

Source of sound

Produce audible vibrations when free edges of folds closely approximate each other

Are sphincter of larynx when folds are tightly approximated

Rima glottidis

Space between vocal folds

Varies in size with activity

During normal breathing: narrow wedge

During forced respiration: wide apart

During phonation: slit-like

Vestibular folds (false vocal cords)

Folds of mucous membrane over vestibular ligaments superior to vocal folds

Extend between thyroid and arytenoids cartilages

Protective in function

Ventricle of larynx: lateral outpocketings between vocal and vestibular folds on either side

Muscles of the larynx

Extrinsic muscles

Are muscles attached to hyoid bone and thus move thyroid

Infrahyoid muscles: lower larynx and hyoid bone

Sternohyoid

Omohyoid

Sternothyroid

Thyrohyoid

Suprahyoid muscles: Fix hyoid or elevate hyoid bone and larynx

Stylohyoid

Digastric

Mylohyoid

Stylopharyngeus-elevates hyoid bone and larynx

Intrinsic muscles

Alter length and tension of vocal cords

Alter rima glottides

Adductors

Lateral cricoarytenoid muscles

Transverse arytenoids

Abductors: posterior cricoarytenoid muscles

Sphincters

Transverse arytenoids muscles

Oblique arytenoids muscles

Aryepiglottic muscles

Tensors: cricothyroid muscles

Relaxers

Thyroarytenoid muscles

Vocalis muscles

All except cricothyroid supplied by recurrent laryngeal nerve

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Muscle Proximal

Attachment (Origin)

Distal Attachment

(Insertion)

Innervation Blood Supply Action

Cricothyroid Anterior cricoid

cartilage

Inferior border of thyroid

cartilage and its inferior

horn

External branch of

superior laryngeal

nerve

Superior and

inferior thyroid

arteries

Lengthens and tenses vocal

ligaments

Posterior

cricoarytenoid

Posterior surface of

lamina of cricoid

cartilage

Muscular process of

arytenoid cartilage

Recurrent

laryngeal nerve

Superior and

inferior thyroid

arteries

Abducts vocal folds

Lateral

cricoarytenoid

Arch of cricoid

cartilage

Muscular process of

arytenoid cartilage

Recurrent

laryngeal nerve

Superior and

inferior thyroid

arteries

Adducts vocal folds

Thyroarytenoid Posterior aspect of

thyroid cartilage

Muscular process of

arytenoid cartilage

Recurrent

laryngeal nerve

Superior and

inferior thyroid

arteries

Shortens and relaxes vocal

cords