Respiratory System (CN) 2024 2 PDF

Respiratory System Department of Anatomy  Learning Objectives After participating in this series of lectures, students should be able to: Enumerate the parts of the respiratory system Describe the anatomy of the nasal cavity and the paranasal sinuses Describe the structure of th...

Respiratory System Department of Anatomy  Learning Objectives After participating in this series of lectures, students should be able to: Enumerate the parts of the respiratory system Describe the anatomy of the nasal cavity and the paranasal sinuses Describe the structure of the larynx & pharynx Describe the anatomy of the trachea and bronchial tree Describe the anatomy of the lungs & pleura List muscles of respiration  The Respiratory System File:Illu conducting passages.svg Parts of the RS: 1. Nose / Mouth 2. Pharynx 3. Larynx 4. Trachea 5. Bronchial tree 6. lungs  Upper Respiratory Junction of Tract larynx & trachea Lower Respiratory Tract URTI Upper respiratory tract infection LRTI Lower respiratory tract infection Nose & paranasal sinuses  The Nose The nose consists of: 1. The external nose 2. The nasal cavity  Framework of the external nose Nasal bones 1. Bone Maxillary bones Frontal bone 2. Cartilage (plates of hyaline cartilage) 3. Fibroareolar tissue  Nasal cavity Divided into 2 cavities by the nasal septum It extends from the nostril in front to the choanae behind choanae Nasal vestibule Nosetril  Walls of the Nasal Cavity 4 walls are described: Medial & Lateral, Roof & Floor. (nostril) The medial wall is formed by the nasal septum The floor is made by the hard palate  Lateral wall of the nasal cavity 3 shelf-like projections (nasal conchae): 1.Superior concha 2.Middle concha 3.Inferior concha The space below each concha is called a meatus Sphenoethmoidal recess: above the superior concha Ostia of the paranasal sinuses open into these areas  Nerve supply of the Nose Sensation of smell: olfactory nerves (CN I) General sensation: From ophthalmic & maxillary nerves (CN V)  Epistaxis (nosebleed) is one of the most common ear, nose, and throat (ENT) emergencies that present to the emergency room or primary care. There are two types of nosebleeds: anterior (more common), and posterior (less common).  Paranasal Sinuses Air-filled cavities within the bones of the skull that surround the nasal cavity These are 4 in number: Only the maxillary and 1. Frontal air sinuses sphenoid sinuses appear at birth, the remaining appear 2. Maxillary air sinuses after birth and grow with age 3. Ethmoidal air sinuses 4. Sphenoidal air sinuses Their function is: 1. to reduce the weight of the skull 2. to act as resonators to the voice  Openings of PNS Sphenoethmoidal Sphenoidal sinuses recess Sup concha Posterior ethmoidal sinuses Superior meatus Maxillary sinuses Mid Frontal sinuses concha middle meatus Anterior & middle ethmoidal sinuses Inf concha Nasolacrimal duct inferior meatus  Clinical note sinusitis File:Maxilar sinusites.jpg Pharynx & Larynx  Larynx Pharynx Part of the Part of the GIT & respiratory tract respiratory tract Anterior Posterior Nasal cavity Pharynx Oral cavity LARYNX esophagus trachea  Definition of Pharynx A musculo-membranous tube that extends from the mouth & nose to the esophagus and larynx Laryngopharynx  Larynx A specialized organ that joins the pharynx to the trachea Location: below the hyoid bone, at the level of the 4th-6th cervical vertebrae Function: 1. a protective sphincter at the inlet of the air passages 2. Voice production  Framework of the Larynx It is made up of cartilages that are held together by membranes & ligaments  Cartilages of the Larynx The larynx is made up of 6 cartilages (3 paired and 3 single), these are: Thyroid Cricoid single Epiglottis Arytenoid Corniculate Paired Cuneiform  Epiglottis A single plate of elastic cartilage It is leaf-shaped and has a fixed stalk and a dilated free upper part lies behind the root of the tongue  Vocal Cords Folds of membranous tissue which project inwards from the sides of the larynx to form a slit across the glottis in the throat, and whose edges vibrate in the airstream to produce the voice. Trachea & Bronchial tree  Trachea “windpipe” It is a midline structure, but it inclines to the right while descending downward. It is formed of U – shaped rings of hyaline cartilages. The posterior free ends of the cartilage are connected by smooth muscle, the trachealis muscle. (to allow for dilatation of the Cross Section of Trachea esophagus during swallowing). It passes through the neck and thorax where it ends by dividing into two bronchi. 26  Trachea & Bronchi Trachea Right Primary Left Primary Bronchus Bronchus 3 Secondary 2 Secondary Bronchi Bronchi Tertiary Tertiary Bronchi Bronchi  The Primary Bronchi The trachea ends at the level of the sternal angle (disc between T4/T5) by dividing into two main (primary) bronchi. This bifurcation of the trachea is called “carina”. The right bronchus is shorter (2.5 cm) and wider than the left bronchus (5 cm). The right bronchus lies in line with the trachea (more vertical), while the left bronchus is more oblique. 28 Bronchial Tree: intrapulmonary part Each main (primary) bronchus divides inside its lung into lobar bronchi, then segmental bronchi, then lobular (terminal) bronchioles, respiratory bronchioles. The bronchioles have no cartilage. 29 30 Lungs & Pleurae  Lungs The lung is a soft and spongy organ It is very elastic; so if the pleural cavity is opened, it shrinks to 1/3 in volume. The right lung is larger, broader & shorter than the left lung. Color: pink (in children) to dark and mottled (in adults) Position: the lungs lie on either side of the mediastinum, surrounded by the pleura 32  Lungs: lobes The right lung is divided by the oblique and transverse fissures into 3 lobes: Upper lobe Middle lobe Lower lobe The left lung is divided by the oblique fissure into 2 lobes: Upper lobe Lower lobe Each lobe has a lobar (secondary) bronchus. 33  Pleura Definition: serous sac that surrounds the lungs & lines the thoracic cavity Layers: 1. Visceral 2. Parietal Pleural cavity  Muscles of Respiration Main muscle: Diaphragm (supplied by the phrenic nerve), assisted by the intercostal muscles (supplied by the intercostal nerves) Accessory muscles of respiration: pectoralis major, pectoralis minor, serratus anterior & serratus posterior, sternocleidomastoid. File:Illu conducting passages.svg