L3 - MCQ

Laryngeal Muscles

• Intrinsic laryngeal muscles are further divided into two subgroups: extrinsic and intrinsic muscles.
• Strap muscles, also known as sternothyreoideus and thyreohyoideus, are flat in shape.
• Cricothyreoideus posterior and lateral cricoarytenoideus muscles control the laryngeal inlet.
• Vocalis, cricothyreoideus, and thyroarytenoideus muscles control the movements of the vocal folds.
• A muscle's name is composed of the origin and insertion of the muscle.
• The action of a muscle indicates its function.
• Elevators of the larynx are called laryngeal elevators, while depressors of the larynx are called laryngeal depressors.
• Intrinsic laryngeal muscles are very informative in terms of their nomenclature.
• The sternohyoideus muscle extends from the sternum to the hyoid bone.

Functions of Specific Muscles

• Aryepiglottic and interarytenoideus muscles bring the arytenoids and aryepiglottic folds closer, narrowing the laryngeal inlet.
• Cricothyreoideus muscle increases the length and tension of the vocal folds, leading to a higher pitch.
• Thyroarytenoideus muscle decreases the length and tension of the vocal cords, leading to a lower pitch.

Blood Supply and Innervation

• The superior laryngeal artery supplies blood to the upper half of the larynx.
• The inferior laryngeal artery supplies blood to the lower half of the larynx.
• The internal laryngeal nerve provides sensory innervation to the mucosa from the inlet to the glottis.
• The external laryngeal nerve provides motor innervation to the cricothyroid muscle.
• The recurrent laryngeal nerve provides motor innervation to all intrinsic laryngeal muscles except the cricothyroid muscle.
• The vagus nerve provides sensory and motor innervation to the larynx.
• Lymph vessels drain from the larynx into the deep cervical nodes.

Hyoid Bone and Related Muscles

• The digastric muscle elevates the hyoid bone upwards and backwards.
• The stylohyoid and hyoglossus muscles depress the hyoid bone and thyroid cartilage.
• The sternohyoideus and omohyoideus muscles bring the hyoid bone down in the direction of the sternum.
• The geniohyoid muscle provides stability for tongue movement during swallowing and contributes to hyoid elevation and mandibular depression when the hyoid is fixed.
• The mylohyoideus muscle elevates and performs forward traction on the hyoid bone.
• The stylohyoid and digastric muscles are laryngeal elevators if contracted while the hyoid is fixed.
• The omohyoideus and sternohyoideus muscles depress the hyoid bone.
• The thyrohyoid muscle depresses and retracts the hyoid bone.

Glottis and Related Muscles

• The lateral cricoarytenoideus muscle closes the membranous glottis.
• The interarytenoideus muscle closes the cartilaginous glottis.