Larynx, Trachea, Bronchii Lecture (PDF)

Anatomy – MED 106  Functions of the respiratory system Major function: Gas exchange (oxygen supply, disposal of carbon dioxide) Other functions ❖ Air warming ❖ Phonation ❖ Some immunological function ❖ Some endocrine functions  Lower respiratory system...

Anatomy – MED 106  Functions of the respiratory system Major function: Gas exchange (oxygen supply, disposal of carbon dioxide) Other functions ❖ Air warming ❖ Phonation ❖ Some immunological function ❖ Some endocrine functions  Lower respiratory system Begins with true vocal cords – ends with alveoli Conducting zone Respiratory zone ❖ Larynx ❖ Respiratory bronchioles ❖ Trachea ❖ Main bronchi (x2) ❖ Alveolar ducts ❖Lobar bronchi (Rx3, Lx2) ❖ Alveolar sacs ❖Segmental bronchi ❖Subsegmental bronchi ❖ Alveoli ❖Bronchioles (no cartilage) ❖Terminal bronchioles  Larynx General characteristics ❖ Portion of respiratory tract ❖ Contains vocal cords ❖ ~2inch long, tube ❖ Opens into laryngeal part of pharynx above ❖ Continuous with trachea below  Larynx Functions  Larynx General structure ❖ cartilaginous skeleton ❖ all hyaline cartilage ❖ except epiglottis (elastic) ❖ membranes & ligaments ❖ intrinsic & extrinsic muscles ❖ mucosal lining  Larynx Single Cartilages: ❖ Thyroid ❖ Cricoid ❖ Epiglottis Paired Cartilages: ❖ Arytenoid ❖ Corniculate ❖ Cuneiform  Cricoid cartilage ❖ Most inferior cartilage ❖ Articulation with thyroid cartilage, arytenoid cartilages ❖ Easily palpable The esophagus is attached to the ridge  Thyroid cartilage Articulation with hyoid Adam’s apple Articulation with cricoid  Epiglottis ❖ Leaf shaped cartilage ❖ Connected with thyroid cartilage Laryngeal cartilages articulation  Paired cartilages ❖ Arytenoid cartilages ❖ Corniculate cartilages ❖ Cuneiform cartilages ❖ Important for formation of vocal cords  Joints & ligaments of larynx Thyrohyoid ligament Cricothyroid ligament Cricotracheal ligament  Ligaments of Larynx Fibro-elastic membrane of the larynx links together the laryngeal cartilages Composed of 2 parts: a lower cricothyroid ligament and an upper quadrangular membrane.  Ligaments of Larynx Cricothyroid ligament Αttached to the arch of cricoid cartilage and extends superiorly to end in a free upper margin within the space enclosed by the thyroid cartilage. On each side, this upper free margin attaches : - anteriorly to the thyroid cartilage, and - posteriorly to the vocal processes of the arytenoid cartilages. The vocal ligament (true vocal cord) of the larynx =the thickened free margin of the cricothyroid ligament. Quadrangular membrane The free lower margin is thickened to form the vestibular ligament under the vestibular fold (false vocal cord) of the larynx. Fibro- elastic membrane of the larynx True & false vocal cords  Rima vestibuli and rima glottidis The rima vestibuli: a triangular opening (when viewed from above ) between the two adjacent vestibular folds The rima glottidis: Similar but narrower triangular opening between the two adjacent vocal folds Both the rima glottidis and the rima vestibuli can be opened and closed by movement of the arytenoid cartilages and associated fibro- elastic membranes. Cavity of the larynx Tubular and lined by mucosa. Architectural support provided by the fibro-elastic membrane and laryngeal cartilages to which it is attached.  Cavity of the larynx The vestibule- between the laryngeal inlet and the vestibular folds. The ventricle-The middle part between the vestibular folds above and the vocal folds below. The infraglottic space- between the vocal folds and the inferior opening of the larynx.  Laryngeal cavity Vestibule ❖ Supraglottic part above vestibular fold Ventricle 1 ❖ between vestibular & vocal 2 folds 3 Infraglottic part ❖ below vocal folds  Laryngeal cavity Laryngeal Inlet ❖ Epiglottis Laryngeal cavity (mid portion) ❖ Narrow ❖ Superior border – vestibular folds (false vocal folds) ❖ Inferior border – vocal folds Tracheal Inlet (transition to trachea) ❖ Inferior boarder of cricoid cartilage  Vascularization of the larynx Arterial: Branches of superior thyroid artery (external carotid) and inferior thyroid artery (thyrocervical trunk) Veins: Parallel  Larynx innervation Superior laryngeal nerve ❖ Branch of vagus (X) ❖ Motor for cricothyroid ❖ Sensory above vocal cords  Larynx innervation Recurrent laryngeal nerve ❖ Branch of vagus (X) ❖ Motor for all muscles of larynx (except cricothyroid) ❖ Sensory below vocal cords  Clinical issues Vocal cords palsy In case of recurrent laryngeal nerve trauma (e.g thyroidectomy) Larynx functions (modes) Quiet respiration Larynx functions (modes) Forced respiration Larynx functions (modes) Phonation Larynx functions (modes) Swallowing  Clinical issues Cricothyreoidotomy ❖ Cricothyroid membrane is very thin and superficial ❖ In case of emergent upper airway obstruction, it can easily be incised Clinical issues Aspiration Surface anatomy  Trachea Trachea Flexible tube ❖ 10-12 cm long ❖ 1.5 – 2.5 cm wide Extends from larynx ❖ Cricoid cartilage (C6) ❖ To sternal angle (T4- T5) ❖ 15 – 20 “C” shaped rings Branches ❖ Right main bronchus ❖ Left main bronchus Trachea relationships Esophagus Heart & great vessels  Trachea relationships Trachea ❖ 15 – 20 “C” shaped transverse cartilage rings ❖ open posteriorly ❖ posterior wall composed of smooth muscle (Trachealis m.)  Primary bronchi ❖ 1 per lung ❖ boundaries ❖ Sternal angle ❖ Root of lung ❖ “C” shaped cartilage rings  Right bronchus ❖ Wider ❖ More vertical ❖ 5 cm shorter ❖ C shaped cartilages ❖ 20-30 degree angle  Right bronchus division Right bronchus divisions ❖ Upper lobar bronchus ❖ Middle lobar bronchus ❖ Lower lobar bronchus Right bronchus Important anatomic relations Posterior to – Superior vena cava Anterior to – Esophagus – Azygos vein Left bronchus Left bronchus ❖ Narrower ❖ More angular ❖ Longer ❖ C shaped cartilages ❖ 40-60 degree angle Left bronchus division Left bronchus divisions ❖ Upper lobar bronchus ❖ Lower lobar bronchus Left bronchus Left bronchus Important anatomic relations Inferior to – Aortic arch Anterior to – Esophagus – Descending aorta  Bronchi vascularization Right bronchus: Right bronchial artery (from 3rd intercostal artery) Left bronchus: 2 left bronchial artery (directly from aorta) Veins drain at pulmonary vein or azygos vein  Brochii innervation Sympathetic: From sympathetic trunks Parasympathetic: Vagus nerve Clinical applications Surface anatomy Questions?