prof. saeed makarem & dr. zeenat zaidi
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DESCRIPTIONThe Larynx Trachea & Bronchi. Prof. Saeed Makarem & Dr. Zeenat Zaidi. Objectives. At the end of the lecture, the students should be able to: Describe the Extent, structure and functions of the larynx. Describe the Extent, structure and functions of the Trachea. - PowerPoint PPT Presentation
Prof. Saeed Makarem & Dr. Zeenat Zaidi
ObjectivesAt the end of the lecture, the students should be able to:Describe the Extent, structure and functions of the larynx.Describe the Extent, structure and functions of the Trachea.Describe the bronchi and branching of the bronchial tree. Describe the functions of bronchi and their divisions.
The LarynxThe larynx is the portion of the respiratory tract containing the vocal cords.It is 2-inch-long tube.It opens above into the laryngeal part of the pharynx.Below, it is continuous with the tracheaThe larynx functions in:Respiration (breathing).Phonation (voice production).Deglutition (swallowing).
RelationsThe larynx is related to major critical structures in the neck:Arteries: Carotid arteries, Superior & inferior thyroid arteries.Veins:Jugular veins.Nerves:Superior & recurrent laryngeal nerves.vagus nerve.
StructureThe larynx consists of four basic components: 1- A cartilaginous skeleton.2- Membranes and ligaments.3- Intrinsic & extrinsic muscles.4- Mucosal lining.
The CartilagesThe cartilaginous skeleton is comprised of :ThyroidCricoid SingleEpiglottis---------------------------------ArytenoidCorniculate PairedCuneiform
All the cartilages, except the epiglottis, are of hyaline type. Epiglottis is formed of elastic cartilage. The cartilages are:Connected by joints, membranes & ligaments.Moved by muscles.1322314456
Membranes & LigamentsThyrohyoid membrane, median & lateral thyrohyoid ligaments.Median cricothyroid ligament.Cricotracheal membraneHyoepiglottic ligament.Thyroepiglottic ligament
Quadrangular membrane:Extends between the epiglottis and the arytenoid cartilagesIts lower free margin forms the vestibular ligament that lies within the vestibular foldCricothyroid membrane (conus elasticus): Lower margin is attached to upper border of cricoid cartilageUpper free margin forms vocal ligament
Laryngeal InletIt is the upper opening of the larynx.Faces upward and backward and opens into the laryngeal part of the pharynx.Bounded by:Anteriorly: by the upper margin of epiglottis (E)Posteriorly & below by arytenoid cartilages (A)Laterally by the Aryepiglottic folds (AEF)ECUCOAEFA
Laryngeal CavityExtends from laryngeal inlet to lower border of the cricoid cartilageNarrow in the region of the vestibular folds (rima vestibuli) Narrowest in the region of the vocal folds (rima glottidis)Divided into three parts:Supraglottic part or vestibule: it is the part above the vestibular folds.Ventricle: it is the part between the vestibular & the vocal folds.Infraglottic part, the part below the vocal folds. Rima vestibuliRima glottidisBACABC
Mucous MembraneThe cavity is lined with ciliated columnar epitheliumThe surface of vocal folds, is covered with stratified squamous epithelium because of exposure to continuous trauma during phonation.It contains many mucous glands, more numerous in the region of the saccule (for lubrication of vocal folds).MusclesDivided into two groups:Extrinsic muscles: divided into two groups:Elevators of the larynxDepressors of the larynxIntrinsic muscles: divided into two groups:Muscles controlling the laryngeal inlet.Muscles controlling the movements of the vocal cords.
Depressors of the LarynxThe Infrahyoid Muscles:SternohyoidSternothyroidOmohyoid
Elevators of the Larynx The Suprahyoid Muscles: (MSGD)Mylohyoid.Stylohyoid.Geniohyoid.Digastric.The Longitudinal Muscles of the Pharynx:Stylopharyngeus.Salpingopharyngeus.Palatopharyngeus.
Muscles Controlling the Laryngeal InletOblique arytenoid.Aryepiglottic muscle.
Muscle decreasing the Length & Tension of Vocal CordsThyroarytenoid (vocalis)Muscle increasing the Length & Tension of Vocal CordsCricothyroid.NB. It is the only intrinsic muscle which found outside the larynx.
Movements of the Vocal Cords
Adduction Abduction Adductors Lateral cricoarytenoid.Transverse arytenoid.Abductor Posterior cricoarytenoid.
Blood Supply Arteries:Upper half: Superior laryngeal artery, branch of superior thyroid arteryLower half: Inferior laryngeal artery, branch of inferior thyroid arteryVeins:Accompany the corresponding arteriesLymphatics:The lymph vessels drain into the deep cervical lymph nodes
Nerve Supply (very important)Sensory Above the vocal cords: Internal laryngeal nerve, branch of the superior laryngeal branch of the vagus nerve.Below the vocal cords: Recurrent laryngeal nerve, branch of the vagus nerve.MotorAll intrinsic muscles, are supplied by the recurrent laryngeal nerve except the cricothyroid. The cricothyroid muscle is supplied by the external laryngeal nerve of superior laryngeal branch of vagus.
SEMONS LAW OR DAMAGE OF NERVES TO LARYNXSemons Law indicates the different effect between damage and transection of the recurrent laryngeal nerve due to surgery in region of the neck (e.g. thyroidectomy or parathyroidectomy).
Trachea (windpipe)Mobile, fibrocartilginous tube, 5 inches long, 1 inch in diameterBegins: In the neck below the cricoid cartilage of the larynx (C6). Ends: In the thorax at the level of sternal angle (lower border of T4), by dividing into right and left principal (main, primary) bronchi.The ridge at the bifurcation from inside is called carina. It is the most sensitive part of the respiratory tract and is associated with the cough reflex.
Relations in the Superior MediastinumPosteriorEsophagus.Left recurrent laryngeal nerve.AnteriorSternum.Thymus.Left brachiocephalic vein.Origin of brachiocephalic and left common carotid arteries.Arch of aorta.Left sideArch of aorta.Left common carotid and left subclavian arteries.Left vagus & left phrenic nerves.Pleura.
Right sideAzygos veinRight vagus nervePleura
Nerve SupplyBranches of the vagus nerve and recurrent laryngeal nerve (branch of vagus) give supply sensory fibers to the mucous membraneBranches from the sympathetic trunks supply the trachealis muscle and the blood vessels.Blood SupplyArteries: Branches from the inferior thyroid and bronchial arteriesVeins: Drain to inferior thyroid veins.Lymphatic DrainageInto the pretracheal and paratracheal lymph nodes.
Right Principal BronchusAbout one inch long.Wider, shorter and more vertical than the left.Gives superior lobar bronchus before entering the hilum of the right lungOn entering the hilum it divides into middle and inferior lobar bronchi.Left Principal BronchusAbout two inches longNarrower, longer and more horizontal than the rightPasses to the left below the arch of aorta and in front of esophagusOn entering the hilum of the left lung it divides into superior and inferior lobar bronchi
Bronchial DivisionsConduction zone branchesPrimary (main) bronchi.Secondary (lobar) bronchi.Tertiary (segmental) bronchi. (supply the bronchopulmonary segment).Smaller bronchi. Bronchioles.Terminal bronchioles.
Within the lung each bronchus divides into number of branches that can be divided into two groups:
Respiratory zone branchesRespiratory bronchioles.Alveolar ducts.Alveolar sacs.Alveoli.
Thank You& Good Luck