Summary of "TC 7 : Anatomie du larynx, thyroïde, parathyroïdes [Anatomy of the larynx, thyroid and PTH glands]"
Summary of “TC 7: Anatomie du larynx, thyroïde, parathyroïdes
[Anatomy of the Larynx, Thyroid and Parathyroid Glands]”
Main Ideas and Concepts
1. Overview of the Larynx
- The larynx is a midline, palpable organ in the neck, part of the upper airways.
- Functions:
- Respiratory: allows ventilation.
- Phonation: produces voice via resonance in the vocal folds (Mücke fold).
- Anatomically located in the visceral compartment, connecting superiorly to the pharynx and inferiorly to the trachea.
- The thyroid gland lies anterior to the larynx and trachea.
2. Cartilaginous Framework of the Larynx
- Comprised of several cartilages connected by ligaments and muscles, covered by mucous membrane.
- Cartilages may calcify and become rigid with age.
- Main cartilages:
- Thyroid cartilage: Shield-shaped, forms the Adam’s apple; has right and left plates joined anteriorly.
- Cricoid cartilage (referred to as “Creek aux Ides” or “tricotil”): Ring-shaped, only complete ring, thicker posteriorly, maintains airway patency.
- Epiglottis: Leaf- or tennis racket-shaped cartilage, acts as a flap to close the airway during swallowing.
- Arytenoid cartilages (noted as “thyroid cartilages” in subtitles, likely a transcription error): Small pyramid-shaped paired cartilages on the posterior cricoid cartilage; have vocal and muscular processes for vocal fold attachment and muscle insertion.
- Corniculate cartilages: Tiny cartilages atop arytenoids, visible as small reliefs in clinical exams.
3. Ligaments and Membranes Connecting Cartilages
- Ligaments are generally named after the structures they connect.
- Important ligaments/membranes:
- Thyrohyoid membrane (connects thyroid cartilage to hyoid bone).
- Cricothyroid membrane (connects thyroid and cricoid cartilages).
- Cricotracheal membrane (connects cricoid cartilage to first tracheal ring).
- Vocal ligament and vestibular ligament (key for sound production).
- “Harry and Pig” ligaments (connect lateral epiglottis to thyroid cartilage).
- The larynx is suspended from the hyoid bone.
4. Laryngeal Mucosa and Internal Anatomy
- The mucosa lines the laryngeal cavity and forms folds:
- Vestibular folds (false vocal cords) supported by vestibular ligaments.
- Vocal folds (true vocal cords) supported by vocal ligaments.
- The space between vocal folds is the glottis, the narrowest part of the larynx.
- The laryngeal ventricle lies between vestibular and vocal folds.
- The laryngeal lumen has three levels:
- Vestibule (above vestibular folds).
- Glottis (between vocal folds).
- Infraglottic space (below vocal folds to trachea).
5. Function of the Larynx
- Vocal folds move by intrinsic muscles (innervated by recurrent laryngeal nerves).
- Muscle actions:
- Abduction (opening) of vocal folds for breathing.
- Adduction (closing) for phonation.
- Tilting of thyroid cartilage by cricothyroid muscle to tense vocal cords (important for shouting).
- Epiglottis tilts backward during swallowing to protect airway.
- Mucosal vibration over vocal ligaments produces sound; inflammation (laryngitis) can impair voice by stiffening mucosa.
6. Trachea
- Extends inferiorly from the larynx.
- Composed of incomplete cartilaginous rings open posteriorly, connected by annular ligaments and a trachealis muscle.
- Positioned obliquely downward and backward in the neck.
7. Thyroid Gland
- Endocrine gland located anterior to the larynx and trachea.
- Composed of two lobes connected by an isthmus.
- Regulates basal metabolism and calcium/phosphate metabolism.
- Blood supply:
- Superior thyroid artery (from external carotid artery).
- Inferior thyroid artery (from subclavian artery).
- Venous drainage via superior, middle, and inferior thyroid veins.
- Close anatomical relationships with:
- Large cervical vessels (carotid artery, jugular vein).
- Parathyroid glands (small endocrine glands regulating calcium/phosphorus).
- Surgical importance: thyroidectomy requires careful preservation of parathyroids and recurrent laryngeal nerves.
8. Parathyroid Glands
- Located posterior to the thyroid gland.
- Essential for calcium and phosphorus metabolism.
- Must be preserved during thyroid surgery to prevent life-threatening complications.
9. Recurrent Laryngeal Nerves
- Motor nerves of the larynx.
- Right nerve has a cervical course; left nerve loops under the aortic arch.
- Injury can cause vocal fold paralysis, leading to voice changes or airway obstruction.
- Bilateral injury may require tracheostomy.
10. Muscles Surrounding the Thyroid and Larynx
- Infrahyoid muscles (referred to as “1. fry to the Indians” due to transcription errors):
- Sternohyoid, omohyoid, sternothyroid, and thyrohyoid muscles.
- These muscles form important surgical landmarks, including the “rhombus of tracheotomy,” an area used for tracheostomy access.
- The thyroid isthmus may complicate tracheostomy, requiring supra-, infra-, or trans-isthmus approaches.
11. Clinical and Surgical Relevance
- The larynx’s cartilages may calcify with age, visible on imaging.
- Endoscopic (laryngoscopic) views of the larynx correspond to the anatomical structures described.
- The laryngeal ventricle can be a site for tumors with poor prognosis.
- Tracheotomy is a critical emergency procedure for airway obstruction.
- Thyroid diseases include goiter, nodules, thyroiditis, and cancer (e.g., post-Chernobyl radiation exposure).
- Preservation of nerves and parathyroids is crucial during thyroid surgery.
Methodology / Instructional Points
Anatomical Construction Approach
- Study the larynx in three views simultaneously: anterior, lateral, posterior.
- Identify and understand the shape and relations of each cartilage.
- Understand ligamentous connections by naming them after the structures they join.
- Use median sagittal and frontal sectional planes to visualize internal anatomy.
- Correlate anatomical structures with endoscopic views for clinical relevance.
Key Anatomical Relationships
- Thyroid cartilage forms anterior shield with Adam’s apple prominence.
- Cricoid cartilage forms a complete ring, thicker posteriorly.
- Epiglottis tilts backward during swallowing to protect airway.
- Arytenoid cartilages control vocal fold tension and position.
- Vocal and vestibular ligaments form the true and false vocal folds.
- The laryngeal lumen is divided into vestibule, glottis, and infraglottic space.
- Recurrent laryngeal nerves run posterior to the thyroid gland, vulnerable during surgery.
- Infrahyoid muscles form surgical landmarks and compartments.
Functional Mechanics
- Vocal fold abduction opens airway for breathing.
- Vocal fold adduction closes airway for phonation.
- Cricothyroid muscle tilts thyroid cartilage to tense vocal folds (pitch control).
- Epiglottis protects airway during swallowing.
- Mucosal vibration over vocal ligaments produces sound.
- Vocal fold mucosa mobility is essential for voice quality; inflammation causes hoarseness.
Surgical Considerations
- Tracheotomy performed via the “rhombus of tracheotomy” between infrahyoid muscles.
- Thyroid isthmus may need to be ligated or bypassed during tracheotomy.
- Careful dissection to preserve recurrent laryngeal nerves and parathyroids during thyroidectomy.
- Awareness of vascular anatomy (superior and inferior thyroid arteries, thyroid veins) is essential.
Speakers / Sources
- The video appears to be a single lecturer (unnamed) presenting a detailed anatomy lecture, likely a professor or medical educator specializing in head and neck anatomy.
- Mention of “Laruns Gautherat Kehal” appears as a reference for anatomical orientation but not as a speaker.
- No other speakers or sources explicitly identified.
End of Summary
Category
Educational
