21._...Respiratorty_System_Part-3,_ANAT_211,_212_and_213,_Term_2,_2023-24.pdf

Respiratory System Part-3 Anatomy Course ANAT 211, 212 and 213 Term 2, 2023-24 Basic Sciences Department, COSHP, KSAU-HS, KSA Respiratory System Part-3 By the end of the lecture, students should be able to: Discuss the anatomy of larynx (location, cartilages, membranes, cavity and nerve supply Descr...

Respiratory System Part-3 Anatomy Course ANAT 211, 212 and 213 Term 2, 2023-24 Basic Sciences Department, COSHP, KSAU-HS, KSA Respiratory System Part-3 By the end of the lecture, students should be able to: Discuss the anatomy of larynx (location, cartilages, membranes, cavity and nerve supply Describe larynx and its functions. The Larynx 1. Location The location of the larynx is at the vertebral level of the C3 to C6 vertebrae. The larynx is an organ for sound production It also provides breathing and acts as sphincter It is about 2-inch-long (present in lower part of pharynx) It is suspended from the hyoid bone above, and below, attached to the trachea. Its cavity is continuous with laryngopharynx superiorly and inferiorly with trachea. The Larynx 2. Cartilages The larynx consists of Four basic components: 1-A cartilaginous skeleton 2-Membranes and ligaments 3-Intrinsic and extrinsic muscles 4-Mucosal lining 1. Cartilages of the larynx Three unpaired cartilages: 1.Thyroid (the largest) 2.Epiglottis (leaf shaped) 3.Cricoid (ring shaped) Three paired cartilages: 1.Cuneiform – (Do not connect with any other cartilage) 2.Corniculate 3.Arytenoid All the cartilages, except the epiglottis (elastic), are of hyaline type The cartilages are connected at joints by membranes & ligaments Cartilages of the larynx A- Thyroid cartilage: Shield shaped, opens posteriorly and is angulated anteriorly Angulation more acute in males (Adam’s apple) It has two laminae which meet at anterior angle and has superior & inferior horns Its function is to shield larynx from injury and provide an attachment to vocal cords Cartilages of the larynx B- Cricoid cartilage:        Signet ring shaped cartilage Its lamina is the posterior broader part than the anterior arched part. It provides base for the larynx Stronger than thyroid cartilage Support to arytenoid cartilage Provides attachment to intrinsic muscles Only part of cartilaginous framework that is a complete ring. C- Epiglottis: Cartilages of the larynx Thin leaf shaped elastic cartilage, situated in midline It extends from the root of the tongue and the hyoid bone to the angle of the thyroid cartilage Its upper free border is broad & rounded that projects up behind base of tongue Prevents food and drinks from entering airway when swallowing Cartilages of the larynx D- Arytenoid cartilages:    Paired cartilages, pyramidal in shape Base articulated with cricoid cartilage Possess three processes- apical (superior), muscular (lateral) and vocal (anterior). ◦ Posterior and lateral crico-arytenoid muscles attach on its muscular or lateral process.  Anterior angle (process) is elongated into vocal processes which receives insertion of vocal ligament 2. MEMBRANES & LIGAMENTS OF LARYNX Laryngeal cartilages are connected by membranes and ligaments, and moved by muscles A- Outer Membranes A- Outer Ligaments 1. Thyrohyoid membrane 1. Lateral and median thyrohyoid ligament 2. Cricothyroid membrane 2. Median cricothyroid ligament 3. Cricotracheal membrane 3. Hyo-epiglottic ligament 4. Thyro-epiglottic ligament B- Inner membranes B- Inner ligament 1. Quadrangular membrane 1. Vestibular ligament 2. Conus Elasticus (Crico-thyroid membrane) 1. Vocal ligament B-Inner Ligaments Functional ligaments: 1.Vestibular ligament is the lower free margin of the quadrangular membrane that extends between the epiglottis and the arytenoid cartilage Lubricate the vocal cords and prevent food entering the lower respiratory organs 2. Vocal ligament is the upper free margin of the cricothyroid membrane (conus elasticus). It is attached anteriorly to the thyroid cartilage and posteriorly to the vocal process of arytenoid cartilage Vibrates to produce sound Laryngeal Inlet Faces backward and upward, and opens into the laryngopharynx of the pharynx The opening is bounded: 1. Anteriorly by the upper border of epiglottis 2. Laterally by aryepiglottic folds 3. Posteriorly & below by arytenoid cartilages E CU CO AEF A Laryngeal Cavity Extends from laryngeal inlet to lower border of the cricoid cartilage. Divided into three separate parts 1.Supraglottic that lies above the vestibular folds and is called the vestibule. 2.Glottic: The part between the vestibular and the vocal folds is called the ventricle. 3.Infraglottic: the part below the vocal folds. Vocal folds 2 folds found within the larynx extending from the wall into the laryngeal cavity. 1. True vocal cords, also known as vocal folds 2. False vocal cords, also known as vestibular folds Vocal folds are made up of vocal ligaments and vocalis muscles Vocal folds control sound production 3. Laryngeal muscles A-Extrinsic muscles (3) 1. Sternothyroid 2. Thyrohyoid 3. Inferior constrictor B-Intrinsic muscles (7) 1. Oblique arytenoid: from arytenoid to epiglottis, narrows laryngeal inlet. 2. Transverse arytenoid: It approximates arytenoid cartilages and adducts the vocal folds. 3. Posterior cricoarytenoid: It pulls the muscular process of arytenoid cartilage backwards that moves its vocal processes laterally and abducts the vocal. Muscles of larynx 4. Lateral cricoarytenoid: It moves vocal process medially and adducts vocal folds 5. Cricothyroid: It tenses the vocal folds by pulling thyroid cartilage forward and tilting the lamina of cricoid cartilage backward Muscles of larynx 6. Vocalis muscle: It runs parallel to the vocal ligament and adjust tension in the vocal folds. 7. Thyroarytenoid: It pulls arytenoid cartilage towards the thyroid cartilage and thus shorten and relaxes the vocal folds. 4. Mucosal lining Blood & Nerve Supply Nerve supply: Motor – Recurrent laryngeal nerve supplies all muscles except cricothyriod which is supplied by external laryngeal nerve Sensory – Sensory supply above the vocal folds is through internal laryngeal nerve and below vocal folds through recurrent laryngeal nerve Arterial supply- from superior and inferior thyroid arteries for supra and infraglottic parts of the larynx. Veinous drainage- into thyroid veins. Lymphatic drainage- into the deep cervical lymph nodes