 | Term | Definition |
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Location of Thyroid gland |
Located deep to sternohyoid and sternothyroid at C5-T1 vertebral levels |
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Blood supply of Thyroid gland |
o Superior thyroid artery (from external carotid artery) o Inferior thyroid artery (from thyrocervical trunk) o ~10% of people also have a thyroid ima artery (branch of brachiocephalic trunk) |
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Venous drainage of Thyroid gland |
o Superior thyroid vein (drains into IJV) o Middle thyroid vein (drains into IJV) o Inferior thyroid vein (drains into brachiocephalic vein) |
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Location of Parathyroid glands |
Located posterior to thyroid gland |
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Pharynx |
o Nasopharynx (posterior to nasal cavity) o Oropharynx (posterior to oral cavity) o Laryngopharynx (posterolateral to larynx; continuous inferiorly with esophagus) |
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Origin of Superior constrictor |
Pterygoid hamulus of sphenoid bone, mandible |
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Origin of Middle constrictor |
Hyoid |
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Origin of Inferior constrictor |
Thyroid and cricoid cartilages |
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Internal muscles of the pharynx |
o Stylopharyngeus m. o Palatopharyngeus m. o Salpingopharyngeus m. |
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Piriform recesses |
• Depressions on either side of the laryngeal inlet • Common site for food to become lodged • Continuous with esophagus (smooth muscle) |
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Innervation of the Pharynx |
Glossopharyngeal nerve (CN IX) and Vagus nerve (CN X) |
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Gag reflex |
sensory: CN IX; motor: CN X |
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Glossopharyngeal nerve (CN IX) |
• Exits skull via jugular foramen • Sensory: mucosa of oropharynx • It supplies only one muscle: stylopharyngeus m. |
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Vagus nerve (CN X) |
• Exits skull via jugular foramen • Motor: constrictor muscles • Sensory: mucosa of laryngopharynx (including piriform recesses) |
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Functions of Larynx |
Functions include phonation (sound production), respiration (continuous superiorly with pharynx and continuous inferiorly with trachea; importantly, the larynx prevents swallowed material from entering the trachea) |
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Location of Larynx |
Located inferior to the hyoid bone at C3-C6 vertebral levels |
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Thyroid Cartilage |
• Laminae (right and left plates, fused anteriorly, do not connect posteriorly) • Laryngeal prominence ("Adam's apple") • Superior horns (or cornua; paired superior projections) • Inferior horns (paired inferior projections; articulate with cricoid cartilage) |
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Cricoid Cartilage |
• Inferior to thyroid cartilage, superior to trachea • Complete ring of cartilage |
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Epiglottic Cartilage |
• Functions to close off the laryngeal inlet (i.e., preventing materials from entering the larynx during swallowing) • Free superior edge • Attached inferiorly to the thyroid cartilage via narrow stalk |
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Arytenoid Cartilage |
•Paired structures• Base articulates with cricoid cartilage • Apex articulates with corniculate cartilages • Muscular process projects posterolaterally from base • Vocal process projects anteriorly from base; the vocal ligament is attached to this process |
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Thyrohyoid membrane |
Connects thyroid cartilage to the hyoid |
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Origin of Cricothyroid ligament |
Arises from the cricoid cartilage |
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Insertion of Cricothyroid ligament |
Attaches anteriorly to the thyroid cartilage as the median cricothyroid ligament and Attaches posteriorly to the vocal processes of the arytenoid cartilages as the lateral cricothyroid ligaments |
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vocal ligament |
free superior margin of Cricothyroid ligament |
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conus elasticus |
The lateral cricothyroid and vocal ligaments. |
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Cricotracheal ligament |
Connects inferior border of cricoid to 1st tracheal ring |
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Tracheotomy |
Establishes an airway by creating an opening between tracheal rings |
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Quadrangular ligament |
• Connects epiglottic and arytenoid cartilages • Its free superior margin, covered with mucosa, forms the aryepiglottic fold • Its free inferior margin, covered with mucosa, forms the vestibular fold |
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Cricothyroid joints |
• Articulations between the inferior horns of the thyroid cartilage and the cricoid cartilage • Permit rotation and gliding of thyroid cartilage, which affects the length of the vocal ligaments |
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Cricoarytenoid joints |
• Articulations between the bases of the arytenoid cartilages and the cricoid cartilage • Permit adduction/abduction, tilting and rotation of the arytenoid cartilages, which adducts/abducts and tenses the vocal ligaments |
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Laryngeal Cavity |
o Vestibule between the laryngeal inlet and the vestibular folds o Ventricle between the vestibular and vocal folds o Infraglottic cavity between the vocal folds and the inferior border of the cricoid cartilage |
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Suprahyoid muscles |
mylohyoid, digastric, stylohyoid, geniohyoid |
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Extrinsic Muscles of the Larynx |
Move the larynx as a whole |
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Action of Cricothyroid |
stretch/tense vocal folds |
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Action of Thyroarytenoid |
relax vocal folds |
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Action of Vocalis |
fine control of vocal folds |
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Action of Lateral cricoarytenoid |
adduct vocal folds (close rima glottides) |
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Action of Posterior cricoarytenoid |
abduct vocal folds (open rima glottidis) |
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Action of Oblique arytenoids |
adducts vocal folds (close rima glottidis) |
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Action of Aryepiglottic |
close laryngeal inlet |
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Innervation of the Larynx |
Accomplished by two branches of the vagus nerve (CN X); the vagus nerve is located deep to and between the internal jugular vein and carotid artery (common or internal) within the carotid sheath |
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Motor innervation of cricothyroid |
Superior laryngeal nerve External branch |
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cough reflex |
Irritation of mucosa of the larynx superior to vocal folds |
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Elevators of the larynx |
• Suprahyoid muscles (mylohyoid, digastric, stylohyoid, geniohyoid) • 1 Infrahyoid muscle (thyrohyoid depresses hyoid, but elevates larynx) |
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Depressors of the larynx |
3 Infrahyoid muscles (sternohyoid, omohyoid, sternothyroid) |
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Motor innervation of Inferior laryngeal nerve |
intrinsic muscles of the larynx (except cricothyroid) |
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Sensory innervation of Inferior laryngeal nerve |
Mucosa of the larynx inferior to vocal folds |
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Vessels of the Larynx |
o Superior laryngeal artery o Inferior laryngeal artery o Superior and inferior laryngeal veins accompany the arteries |
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Superior laryngeal artery |
• Branch of superior thyroid artery • Travels with internal branch of the superior laryngeal nerve through the thyrohyoid membrane |
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Inferior laryngeal artery |
• Branch of inferior thyroid artery • Travels with inferior laryngeal nerve (recurrent laryngeal nerve) |
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