Lecture 10 - Pharynx and Larynx PDF

PHARYNX Ü The pharynx is the part of the digestive system located posterior to the nasal and oral cavities. Ü The pharynx extends from the base of the skull to C6 where it continues as the esophagus. Ü It acts as a common channel for respiration and swallowing. PHARYNX The pharynx can be divi...

PHARYNX Ü The pharynx is the part of the digestive system located posterior to the nasal and oral cavities. Ü The pharynx extends from the base of the skull to C6 where it continues as the esophagus. Ü It acts as a common channel for respiration and swallowing. PHARYNX The pharynx can be divided into: 1. Nasopharynx – behind the nasal cavity 2. Oropharynx – behind the oral cavity 3. Laryngopharynx – behind the larynx Nasopharynx ÜIt is related to the nasal cavity. ÜIt communicates with the oropharynx by the pharyngeal isthmus or nasopharyngeal hiatus which is closed during swallowing by the uvula. Nasopharynx Ü In the lateral wall of the nasopharynx, below the roof of the pharynx, above the level of the palate, and behind the inferior nasal concha, there is the opening of the auditory tube, which provides communication between the nasopharynx and the middle ear. This connection allows for stabilization of pressures between the external and middle ear, and it is a route of spread of infection from the pharynx to the middle ear. Nasopharynx Ü The auditory opening is limited superiorly by the tubal elevation or Torus Tubarius. Ü From the torus tubarius two folds containing muscles descend into the palate and the pharynx: Ü Salpingopalatine Fold (palate) Ü Salpingopharyngeal Fold (pharynx) Ü In the posterior wall of the nasopharynx there is an accumulation of lymphatic tissue: pharyngeal tonsils, nasopharyngeal tonsils, or adenoids. Oropharynx Ü Locate at the level of C2-C3, it extends from the soft palate to the superior border of the epiglottis. Ü The palatine tonsils are found in the oropharynx between two folds that contain muscles within them: ÜPalatoglossal Fold ÜPalatopharyngeal Fold Laryngopharynx ÜLocated at the level of C3- C6. ÜIt extends from the upper border of the epiglottis to the lower border of the cricoid cartilage. ÜThe piriform fossa is situated on each side of the larynx. Muscles of the Pharynx Ü EXTERNAL LAYER 1. 2. 3. SUPERIOR CONSTRICTOR: from the side of the tongue and pterygoid hamulus (medial pterygoid plate) to the median raphe MIDDLE CONSTRICTOR: from between the lesser and greater horns of the hyoid to the median raphe INFERIOR CONSTRICTOR: from the cricoid cartilage and inferior horn of the thyroid cartilage to the median raphe Ü LONGITUDINAL LAYER Palatopharyngeus muscle 2. Salpingopharyngeus muscle 3. Stylopharyngeus muscle NOTE: The stylopharyngeus muscle is a landmark structure that separates the superior constrictors from the middle and inferior constrictor muscles. 1. Nerve & Blood Supply of the Pharynx Ü NERVE SUPPLY Ü All the muscles of the pharynx are supplied by CN X (vagus) via its pharyngeal branch through the pharyngeal plexus EXCEPT the stylopharyngeus muscle which is supplied by CN IX. Ü The pharyngeal plexus is formed by: Ü Pharyngeal branch of CN X CN IX (afferent fibers) Ü Sympathetic fibers (SCG) Ü Ü BLOOD SUPPLY Ü Ascending pharyngeal artery (ECA) Ü Inferior thyroid artery (thyrocervical trunk [subclavian]) THE LARYNX Ü It connects the lower part of the pharynx with the trachea. Ü It extends from C3-C6 where it becomes continuous with the trachea. Ü FUNCTIONS: 1. To guard the air passages 2. Maintenance of a patent airway 3. Vocalization Cartilages of the Larynx ÜThyroid (C4-C5) ÜCricoid (C6) ÜArytenoid ÜCorniculate ÜCuneiform ÜEpiglottic Cartilages of the Larynx Ü Thyroid Cartilage: C4-C5. It has laminae and a median elevation: Adam’s Apple. Ü Cricoid Cartilage: C6. It marks the end of the pharynx and larynx and the beginning of the esophagus and trachea. Ü Arytenoid Cartilage: shaped like a vase for attachment of the arytenoid muscles. Ü Corniculate and Cuneiform Cartilages: located in the ary-epiglottic fold. Ü Epiglottic Cartilage: behind the root of the tongue and the body of the hyoid bone, and in front of the inlet of the larynx. Ligaments of the Larynx Ü Thyrohyoid membrane. Ü Cricothyroid membrane: from the cricoid cartilage to the vocal ligaments: Conus Elasticus (Cricovocal ligament). The free edge becomes the vocal ligament. Ü Vocal Ligament: upper border of the Conus Elasticus. It is covered by the vocal fold of mucous membrane. Ü Ligaments of the Epiglottis: Ü To the hyoid bone: Hyoepiglottic Ligament Ü To the thyroid cartilage: Thyroepiglottic Ligament Muscles of the Larynx-EXTRINSIC Ü These muscles move the larynx. Ü They are: Ü Ü Ü Ü Ü Ü Ü Ü Ü Stylohyoid Thyrohyoid Mylohyoid Digastric Stylopharyngeus Palatopharyngeus Omohyoid Sternohyoid Sternothyroid Muscles of the Larynx-INTRINSIC Ü SPHINCTERS OF THE INLET: Ü TRANSVERSE ARYTENOID MUSCLE: medial arytenoid. Adduction of the vocal cords. Ü OBLIQUE ARYTENOID MUSCLE: adduction of the vocal cords by bringing together the arytenoid cartilages. Ü ARYEPIGLOTTIC MUSCLE: close the inlet of the larynx. Muscles of the Larynx-INTRINSIC OPEN/CLOSE RIMA GLOTTIDIS: LATERAL CRICOARYTENOID MUSCLE: adductor POSTERIOR CRICOARYTENOID MUSCLE: abductor Muscles of the Larynx-INTRINSIC Ü MUSCLES THAT REGULATE THE VOCAL LIGAMENTS: Ü THYROARYTENOID MUSCLE.: Ü Shortens and relaxes the vocal ligament (cord) Ü VOCALIS MUSCLE.: Ü Not attached to the vocal ligament Ü Varies the tension of the vocal cords during singing and phonation Ü CRICOTHYROID MUSCLE.: Ü Tension and adduction of the vocal cords OBLIQUE ARYTENOID MUSCLE (Superior view) ADDUCTOR TRANSVERSE ARYTENOID MUSCLE (Superior view) ADDUCTOR LATERAL CRICOARYTENOID MUSCLE (Superior view) ADDUCTOR POSTERIOR CRICOARYTENOID MUSCLE (Superior view) ABDUCTOR Nerves of the Larynx Ü All the intrinsic muscles of the larynx are supplied by the recurrent laryngeal nerve (vagus) EXCEPT the cricothyroid which is innervated by the external laryngeal nerve from the superior laryngeal branch of the vagus nerve. Ü DAMAGE: injury to the recurrent laryngeal nerve may lead to hoarseness. Damage may occur secondary to a lung tumor (apex), aortic aneurysm, trauma during thyroid surgery. Ü The sensory innervation of the larynx to the area above the vocal cords is provided by the internal laryngeal nerve (superior laryngeal). Below the vocal cords, the recurrent laryngeal nerve supplies the mucosa with sensory innervation. Blood Supply of the Larynx ÜSuperior Laryngeal Artery (superior thyroid artery) ÜInferior Laryngeal Artery (inferior thyroid artery) *The Internal laryngeal branch of the superior laryngeal nerve (vagus) travels with the superior laryngeal artery (superior thyroid) NERVE TO THE MYLOHYOID MS. SUPERIOR LARYNGEAL (INTERNAL BRANCH) MYLOHYOID MS. EXTERNAL LARYNGEAL NERVE THYROID CARTILAGE THYROHYOID MEMBRANE CRICOTHYROID MUSCLE Cavities of the Larynx It's divided into: Vestibule Ventricles Infraglottic cavity Vestibule: from the inlet to the vestibular folds or false vocal cords (laryngopharynx to the larynx). Ventricle: from the vestibular folds (above) to the vocal cords or ligament. The ventricles allow free movement of the vocal cords. The vocal folds or true vocal cords are medial to the vestibular folds (false). Rima Glottidis is the space between the two vocal cords or ligaments. It is a quadrangular membrane connecting the lateral borders of the epiglottic and arytenoid cartilages.