5)The Larynx, Trachea and Lungs.pdf

The trachea and Lungs Paria SHOJAOLSADATI, assistant professor in human anatomy School of Medicine Department of Anatomy LARYNX Larynx Short, somewhat cylindrical airway Location: bounded posteriorly by the laryngopharynx, inferiorly by the trachea. Prevents swallowed materials from entering the low...

The trachea and Lungs Paria SHOJAOLSADATI, assistant professor in human anatomy School of Medicine Department of Anatomy LARYNX Larynx Short, somewhat cylindrical airway Location: bounded posteriorly by the laryngopharynx, inferiorly by the trachea. Prevents swallowed materials from entering the lower respiratory tract. Conducts air into the lower respiratory tract. Produces sounds. 25-3 Larynx Organ of phonation (vocalization) Formed of cartilage, muscles and connective tissue Inner surface is covered by the respiratory mucosa Superiorly opens into the laryngopharynx, inferiorly continuous with the trachea Lies between the level of C3-C6 cervical vertebrae Lower to C6 cervical vertebrae, larynx is continuous with the trachea Larynx Larynx Skeleton of larynx is formed of 3 unpaired and 3 paired cartilages Nine pieces of cartilage three individual pieces Thyroid cartilage Cricoid cartilage Epiglottis three cartilage pairs Arytenoids: on cricoid Corniculates: attach to arytenoids Cuniforms:in aryepiglottic fold held in place by ligaments and muscles. Intrinsic muscles: regulate tension on true vocal cords Extrinsic muscles: stabilize the larynx 25-6 Larynx 7 Larynx Thyroid cartilage Largest cartilage of the larynx Formed of two laminae which fuse anteriorly at the thyroid angle to form laryngeal prominence (Adam’s apple) Thyroid cartilage ♂: 900 ♀: 1200 – 1400 Cricoid cartilage A ring shaped cartilage. Posterior part is called the lamina (B), anterior part is called arch (A). Attaches to the inferior part of the thyroid cartilage by the median cricothyroid ligament. B Inferiorly attaches to the first tracheal ring by the cricotracheal ligament. A Pars lateralis of conus elasticus Median cricothyroid ligament Cricotracheal ligament Cricoid cartilage Arytenoid cartilage Pyramidal in shape. Has three processes. Apex (superior): Articulates with the corniculate cartilage. Vocal process (anterior): Vocal ligament attaches here. Muscular process (lateral): Posterior cricoarytenoid muscle and lateral cricoarytenoid muscle attach here. Epiglottic cartilage A heart shaped cartilage. Inferior end is attached to the thyroid cartilage by the thyroepiglottic ligament, which lies slightly superior to the attachment of the vocal ligaments. Upper part is attached to the hyoid bone by the hyoepiglottic ligament. Most superior end is free. Epiglottic cartilage Corniculate and Cuneiform cartilage These are small cartilages lying in the posterior part of the aryepiglottic fold. Cuneiform (Wrisberg’s) cartilage: Forms cuneiform tubercle. Corniculate (Santorini’s): Forms corniculatum tubercle. Fibroelastic Membrane of the Larynx Lies under the mucosa of the larynx. Forms and maintains shape of the larynx. Has thickenings at certain regions and forms some of the ligaments between the cartilages. Formed of two parts: Quadrangular membrane Conus elasticus Fibroelastic Membrane of the Larynx Keeps the shape of the larynx. Parts: Membrana quadrangularis Laryngeal ventricles Conus elasticus (cricovocal membrane) Fibroelastic Membrane of the Larynx Quadrangular membrane Sacculus Ventricles Conus elasticus Quadrangular membrane A thin submucosal connective tissue extending between the lateral parts of epigliottic and arytenoid cartilages It’s free inferior margin forms the vestibular ligament, which is covered by mucosa to form the vestibular fold (false vocal fold) Conus elasticus (cricovocal membrane) Its free upper margin thickens to form the vocal ligament, which is covered by mucosa to form the vocal fold. The opening between the two vocal folds is called rima glottis Fibroelastic Membrane of the Larynx Fibroelastic Membrane of the Larynx (Membrana quadrangularis) VESTIBULAR LIGAMENT Lig.corniculopharyngeale Ventricle VOCALE LIGAMENT (Conus elasticus) Conus elasticus (cricovocal membrane) Superior view Interior of the Larynx Interior of the larynx is covered by the respiratory mucosa. Extends between the laryngeal inlet to the inferior border of the cricoid cartilage. Divided into three parts Vestibule (lies superior to vestibular folds). Ventricles (lies between the vestibular and vocal folds). Infraglottic cavity (lies inferior to vocal folds). Rima Glottis Opening between the two vocal folds (true vocal folds) is called the rima glottis Rima glottis widens during inspiration and two vocal folds are approximated during phonation Various changes of the vocal folds determine the color, pitch and the tones of sound Pitch increase with tensing, decreases by relaxation Intensity of expiration determines the loudness of sound Laryngeal Muscles Extrinsic muscles (covered in the neck) These are suprahyoid and infrahyoid muscles They either depress or elavate the larynx and hyoid bone during swallowing Intrinsic muscles (will be covered here) Move the laryngeal parts There are six intrinsic muscles. *Cricothyroid muscle * Cricoarytenoid muscle * Oblique and transverse arytenoid muscles Laryngeal Muscles Laryngeal Muscles Laryngeal Muscles Cricothyroid muscle Tenses the vocal folds by pulling the thyroid cartilage anteroinferiorly (to produce high pitch sound) Laryngeal Muscles Laryngeal Muscles Posterior cricoarytenoid muscle The only muscle widening the rima glottis. Inserts to the muscular process of the arytenoid. Laryngeal Muscles Laryngeal Muscles Lateral crico-arytenoid muscle Approximates the vocal processes thus, narrowing the anterior part of rima glottis (contracts alone during whispering). Inserts to the muscular process of the arytenoid. Laryngeal Muscles Laryngeal Muscles Laryngeal Muscles Arytenoid muscle(transverse-oblique) Has transverse and oblique parts, both parts approximate the arytenoid cartilages. Acting together with the lateral cricoarytenoids, fully narrows the rima glottis (normal phonation occur when air is blown in this position). In case the lateral cricoarytenoids contract without the contraction of the arytenoids, the posterior part of the rima glottis remains open (this is the position of the rima glottis during whispering). Laryngeal Muscles Laryngeal Muscles Thyroarytenoid muscle Relaxes the vocal folds by pulling the arytenoid cartilages anteriorly (to produce low pitch sounds). Laryngeal Muscles Vocalis muscle The most medial fibers of thyroarytenoid muscle form the vocalis muscle. Make minute adjustments to the sound by contracting and relaxing which will increase and decrease the pitch as in singing. Laryngeal Muscles Sound Production Two pairs of ligaments Inferior ligaments, called vocal ligaments covered by a mucous membrane vocal folds: ligament and mucosa. are “true vocal cords” they produce sound when air passes between them Superior ligaments, called vestibular ligaments Covered by mucosa vestibular folds: ligament and mucosa Are “false vocal cords” no function in sound production protect the vocal folds. The vestibular folds attach to the corniculate cartilages. 25-49 Sound Production The tension, length, and position of the vocal folds determine the quality of the sound. Longer vocal folds produce lower sounds More taunt, higher pitch Loudness based on force of air Rima glottidis: opening between the vocal folds Glottis: rima glottidis and the vocal folds 25-50 51 52 53 Arteries of the Larynx R.Brachiocephalic vein L.Brachiocephalic vein. Innervation of the Laryngeal Muscles Nerve supply comes through the superior laryngeal nerve and inferior (recurrent) laryngeal nerve (both are branches of the vagus nerve). Superior laryngeal nerve gives of two branches. Internal laryngeal nerve External laryngeal nerve Innervation of the Laryngeal Muscles Superior laryngeal nerve Internal External Inferior laryngeal nerve Lymphatic Drainage Lymph vessels from the superior part of vocal folds drain into the superior deep cervical lymph nodes. Lymph from the inferior part of the vocal folds drain into inferior deep cervical lymph nodes. Trachea A flexible, slightly rigid tubular organ often referred to as the “windpipe.” Extends through the mediastinum immediately anterior to the esophagus inferior to the larynx superior to the primary bronchi of the lungs. Anterior and lateral walls of the trachea are supported by 15 to 20 C-shaped tracheal cartilages. cartilage rings reinforce and provide some rigidity to the tracheal wall to ensure that the trachea remains open (patent) at all times cartilage rings are connected by elastic sheets called anular ligaments 25-61 62 Trachea At the level of the sternal angle, the trachea bifurcates into two smaller tubes, called the right and left primary bronchi. Each primary bronchus projects laterally toward each lung. The most inferior tracheal cartilage separates the primary bronchi at their origin and forms an internal ridge called the carina. 25-63 Carina Carina is the cartilaginous projection of the last tracheal ring and lies between the orifices of the main bronchi. Carina is quite sensitive to irritation (cough reflex). Trachea Extends from the inferior end of larynx C6 to T5-T6 Terminates by dividing into right and left main bronchi Division is called ‘tracheal bifurcation’ at the level of T4 is the inner projection Trachea Trachea is formed of tracheal rings which are incomplete posteriorly Posterior parts of the tracheal rings are closed by smooth muscle called the trachealis muscle Trachea is enclosed with a fibroelastic membrane This membrane thickens between the tracheal rings to form anular ligaments (tracheal ligaments) between the adjacent rings Bronchi Tubes that branch off trachea and enter into lungs Ciliated Branches: Primary bronchi—secondary bronchi—tertiary bronchi—bronchioles Bronchioles branch into microscopic alveolar ducts. Terminate into alveolar sacs Gas exchange with blood occurs in sacs. Bronchi Tree A highly branched system air-conducting passages originate from the left and right primary bronchi. Progressively branch into narrower tubes as they diverge throughout the lungs before terminating in terminal bronchioles. Primary bronchi Incomplete rings of hyaline cartilage ensure that they remain open. Right primary bronchus shorter, wider, and more vertically oriented than the left primary bronchus. Foreign particles are more likely to lodge in the right primary bronchus. 25-68 Bronchi Tree Primary bronchi enter the hilum of each lung Also entering hilum: pulmonary vessels lymphatic vessels nerves. Secondary bronchi (or lobar bronchi) Branch of primary bronchus left lung: two lobes two secondary bronchi right lung three lobes three secondary bronchi. Tertiary bronchi (or segmental bronchi) Branch of secondary bronchi left lung is supplied by 8 to 10 tertiary bronchi. right lung is supplied by 10 tertiary bronchi supply a part of the lung called a bronchopulmonary segment. 25-69 Bronchi Tree Branching of the bronchial tree Trachea Principal bronchus Lobar bronchi (secondary bronchi) Segmental bronchi (tertiary bronchi) Terminal bronchiol Respiratory bronchiol Alveolar duct Alveolar sac Alveolus 72 Respiratory Bronchioles, Alveolar Ducts, and Alveoli Contain small saccular out pocketings called alveoli. An alveolus is about 0.25 to 0.5 millimeter in diameter. Its thin wall is specialized to promote diffusion of gases between the alveolus and the blood in the pulmonary capillaries. Gas exchange can take place in the respiratory bronchioles and alveolar ducts as well as in the lungs, which contain approximately 300–400 million alveoli. The spongy nature of the lung is due to the packing of millions of alveoli together. 25-74 75 77 78 Clinical note Aspiration of foreign bodies Foreign bodies are more likely to enter the right bronchus as it is wider and runs more vertically. Bronchoscopy It is possible to observe the carina by bronchoscopy. Carina is the cartilaginous projection of the last tracheal ring and lies between the orifices of the main bronchi Carina is quite sensitive to irritation (cough reflex) Morphological changes in carina may be an indication of a cancer metasthasis to the tracheabronchial lymph nodes Clinical Anatomy Gross Anatomy of the Lungs Each lung has a conical shape. Its wide, concave base rests upon the muscular diaphragm. Its relatively blunt superior region, called the apex or (cupola), projects superiorly to a point that is slightly superior and posterior to the clavicle. Both lungs are bordered by the thoracic wall anteriorly, laterally, and posteriorly, and supported by the rib cage. Toward the midline, the lungs are separated from each other by the mediastinum. The relatively broad, rounded surface in contact with the thoracic wall is called the costal surface of the lung. 25-83 84 85 86 Lungs Lungs are organs of respiration Their main function is to oxygenate the blood by bringing the inspired air into close relation with the venous blood in the pulmonary capillaries The hilum of the lung is the area where the structures entering or leaving the lungs pass through Lungs Left lung has two lobes seperated by oblique fissure Right lung has three lobes seperated by horizontal and oblique fissures Bronchial arteries are the arteries supplying blood to the tissue of the lungs Pulmonary arteries bring blood from the right ventricle of the heart for oxygenation Lymphatic Drainage Lymph nodes and vessels are located within the connective tissue of the lung as well as around the bronchi and pleura. The lymph nodes collect carbon, dust particles, and pollutants that were not filtered out by the pseudostratified ciliated columnar epithelium. 25-93 Pleura and Pleural Cavities The outer surface of each lung and the adjacent internal thoracic wall are lined by a serous membrane called pleura, which is formed from simple squamous epithelium. The outer surface of each lung is tightly covered by the visceral pleura, while the internal thoracic walls, the lateral surfaces of the mediastinum, and the superior surface of the diaphragm are lined by the parietal pleura. The parietal and visceral pleural layers are continuous at the hilum of each lung. 25-94 Pleura and Pleural Cavities The outer surface of each lung is tightly covered by the visceral pleura, while the internal thoracic walls, the lateral surfaces of the mediastinum, and the superior surface of the diaphragm are lined by the parietal pleura. The potential space between these serous membrane layers is a pleural cavity. The pleural membranes produce a thin, serous fluid that circulates in the pleural cavity and acts as a lubricant, ensuring minimal friction during breathing. 25-95 96 Pleura Visceral pleura – Invests the lungs Parietal pleura – Lines the pulmoary cavities and inner surface of the thorax Pleural cavity – Lies between the two layers of the pleura Contains a capillary layer of serous fluid Lubrication of the pleural surfaces allow the two layers slide on each other smoothly during lung movements Parietal Pleura During expiration, the lungs do not completely fill the pulmonary cavities. Parietal pleura forms two recesses: Costodiaphragmatic recess Costomediastinal recess Parietal Pleura Clinical note Injury to the cervical pleura and the apex of the lung Lungs and pleural sac may be injured in the wounds of the neck as the cupula of pleura lies here (deep to the inferior attachments of the SCM muscle). This may lead to pneumothorax – presence of air in the pleural cavity. Pneumothorax May occur due to a penetrating wound, tear by fractured ribs etc. Results with collapse of the lungs. Pulmonary collapse If sufficient air enters the pleural cavity, lungs will collapse. The amount of air inside the pleural cavity determines the degree of collapse. Clinical note Hydrothorax May occur due to pleural effusion (escape of fluid into pleural cavities) Hemothorax Accumulation of blood in the pleural cavity (may occur due to a penetrating wound) Clinical note Thoracentesis Performed by inserting a needle through an intercostal space, into the pleural cavity. Performed in order to obtain a fluid sample or remove blood or pus. When the patient is in upright position, fluid in the pleural cavity accumulates in the costodiaphragmatic recess. Clinical note Thoracentesis Inserting the needle through the 9th intercostal space in the midaxillary line and during expiration will avoid the inferior border of the lung. The needle should be angled upward to avoid penetrating the deep aspect of the recess. Thoracosentesis Auscultation of the lungs Listening to the sound of air as it passes the tracheobronchial tree is called the auscultation and carried by a stethescope. Auscultation of the lungs Thoracic Wall Dimensional Changes During Respiration Lateral dimensional changes occur with rib movements. Elevation of the ribs increases the lateral dimensions of the thoracic cavity, while depression of the ribs decreases the lateral dimensions of the thoracic cavity. 25-108 Thoracic cage movment during breathing Muscles that Move the Ribs The scalenes help increase thoracic cavity dimensions by elevating the first and second ribs during forced inhalation. The ribs elevate upon contraction of the external intercostals, thereby increasing the transverse dimensions of the thoracic cavity during inhalation. Contraction of the internal intercostals depresses the ribs, but this only occurs during forced exhalation. Normal exhalation requires no active muscular effort. A small transversus thoracis extends across the inner surface of the thoracic cage and attaches to ribs 2–6. It helps depress the ribs. 25-111 Muscles that Move the Ribs Two posterior thorax muscles also assist with respiration. These muscles are located deep to the trapezius and latissimus dorsi, but superficial to the erector spinae muscles. The serratus posterior superior elevates ribs 2–5 during inhalation, and the serratus posterior inferior depresses ribs 8–12 during exhalation. In addition, some accessory muscles assist with respiratory activities. The pectoralis minor, serratus anterior, and sternocleidomastoid help with forced inhalation, while the abdominal muscles (external and internal obliques, transversus abdominis, and rectus abdominis) assist in active exhalation. 25-112 113 114 115 116 117 Thank you…