ANATOMY OF LARYNX AND TRACHEA DEPT OF OTORHINOLARYNGOLOGY P I M S
DEVELOPMENT OF LARYNX Larynx develops from the tracheobroncheal groove which is ventral midline respiratory diverticulum of the foregut. Epiglottis and the Thyroid cartilage develop from the fourth branchial arch.
SITUATION OF LARYNX Situated in midline of neck from the level of C-3 to C-6 vertebrae lying in front of laryngopharynx.
CONSTITUTION OF LARYNX Formed by a cartilaginous skeleton held together by ligaments. At puberty male larynx increases in size rapidly, and the thyroid cartilage projects to form the Adam’s apple.
CARTILAGES OF LARYNX- EPIGLOTTIS Epiglottis-leaf shaped fibro elastic cartilage and projects behind the base of the tongue. The narrow lower border is attached by the thyro-epiglottic ligament to the posterior surface of thyroid alae below thyroid notch.
CARTILAGES OF LARYNX- THYROID CARTILAGE Largest cartilage of larynx with two wings or alae joined anteriorly in midline. Two alae form a right angle between them in male while in female the angle is obtuse. the alae project backwards and have superior and inferior cornu.
CARTILAGES OF LARYNX- CRICOID It is signet ring shaped with a broad lamina posteriorly and narrow arch in front. cricoid, thyroid and epiglottis are unpaired cartilages of larynx where as arytenoid,corniculate and cuneiform cartilages are paired.
CARTILAGES OF LARYNX- ARYTENOID Shaped like a pyramid Base participates in crico-arytenoid joint. Anterior vocal process gives attachment to vocal cord. The lateral mescular process provides attachment to the posterior and lateral cricoarytenoid muscles
CARTILAGES OF LARYNX- CORNICULATE & CUNEIFORM Corniculate are situated at the apex of the arytenoids cartilages. Cuneiform lie in the aryepiglottic folds, lateral to the Corniculate cartilages.
JOINTS AND LIGAMENTS Two synovial joints on either side1) Cricothyroid joint2) crico-arytenoid joint Intrinsic ligaments1) Quadrangular membrane2) Conus elasticus3) thyro-epiglottic ligament
INTRINSIC MUSCLES OF LARYNX AND THEIR ACTION Posterior crico-arytenoid- Abductor Lateral crico-arytenoid, inter arytenoid, thyro arytenoid, cricothyroid- Adductors Cricothyroid, vocalis and thyro-arytenoid- tensors and adductors Thyro-epiglottic-Opener of laryngeal inlet Interarytenoid, aryepiglottic- Closers of laryngeal inlet
CAVITY OF LARYNX EXTENT- from laryngeal inlet above to lower border of cricoid cartilage. Inlet of larynx communicates with laryngopharynx.
CAVITY OF LARYNX Divided into three parts by 2 folds of mucus membrane: False cords and True vocal cords Parts are Vestibule, ventricle and subglottic space Length of glottis is about 2.5cm in adult male and about 7-9mm in a child
HISTOLOGY OF LARYNX Mucous membrane lines the entire larynx. Stratified squamous epithelium lines true vocal cords and upper parts of vestibule. Columnar ciliated epithelium lines rest of the cavity. Mucous glands preset in all parts except on free edges of vocal cords
BLOOD SUPPLY OF LARYNX Superior thyroid artery Inferior thyroid artery Cricothyroid artery
NERVE SUPPLY OF LARYNX Superior laryngeal nerve-internal branch is sensory supplies larynx above the level of vocal cords and external branch supplies cricothyroid muscle. Recurrent laryngeal nerve-motor branch supplies all muscles of larynx except the cricothyroid and sensory branch supplies subglottis.
LYMPHATIC DRAINAGE SUPRAGLOTTIS-pre-epiglottic and upper deep cervical nodes. GLOTTIS-Lymphatics are practically absent SUBGLOTTIS-prelaryngeal and pretracheal nodes also lower deep cervical nodes
LARYNGEAL SPACES PRE-EPIGLOTTIC SPACE PARAGLOTTIC SPACE REINKE’S SPACE
ANATOMY OF TRACHEA- DEVELOPMENT Tracheobronchial tree develops from median tracheobronchial groove.
ANATOMY OF TRACHEA Tube made up of cartilage and membrane and measures approx 10-11cm in adult Extends from C-6 to T-5 There are 16-20 incomplete cartilaginous rings. In neck 6-7 rings are present.
BLOOD SUPPLY Mainly by inferior thyroid artery
NERVE SUPPLY Vegus, recurrent laryngeal nerve and sympathetic trunk
LYMPHATICS Pretracheal and paratracheal lymph nodes
FUNCTIONS OF TRACHEOBRONCHIAL TREE Respiration Protection to lungs Warming and moistening of inspired air phonation