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Great Vessels, Coronary aa, Paranasal Air Sinuses and the URT Harry Rhodes - 2011 Aims 1. Describe the position and supply of the great vessels of the heart and the coronary aa 2. Follow the upper airway from the nasal cavity to the larynx and name structures along the way 3. Examine the architecture of the nasal cavity and its surroundings 4. Learn the structure and function of the 4 paranasal sinuses • • Maxillary, frontal, ethmoidal, sphenoidal Imaging Recap of Cardiac Blood Flow The Aortic Arch and Its Branches • There are three main components to the thoracic part of aorta: – Ascending aorta – Arch of the aorta – Descending aorta • The arch of the aorta has three main branches – The brachiocephalic trunk – Left common carotid artery – Left subclavian artery • The brachiocephalic trunk splits into – Right subclavian aa right upper limb – Right common carotid right head and neck • Left common carotid aa Left head and neck • Left subclavian left upper limb Superior and Inferior Vena Cava • The SVC and IVC enter the right atrium penetrating the pericardial sac, draining the upper and lower body of venous blood • The IVC has to penetrate the diaphragm (T8) in order to reach the heart • Left and right brachiocephalic veins, which lie anterior to the aortic arch branches, drain into the SVC • Left and right internal jugular veins (draining the head and neck) and subclavian veins (draining the upper limb) feed into their respective brachiocephalic veins Coronary Supply • There are two coronary aa which supply the myocardium – Left and right – Arise from ascending aorta (aortic sinuses) – Circle the heart in the coronary sulcus – Have marginal and interventricular branches which merge near the apex of the heart • Venous blood is returned to the coronary sinus in the right atrium via the cardiac veins Right Coronary Artery • It is the most dominant of the two arteries and supplies – – – – Right atrium and ventricle SAN and AVN Interatrial septum Posteroinferior 1/3 of the interventricular septum – A portion of the posterior part of the left ventricle • Descends anteriorly and to the right from the right aortic sinus within the coronary sulcus, continuing posteriorly • Has three main branches: – Atrial branch SAN branch – Right marginal branch towards apex – Posterior interventricular branch base/ diaphragmatic surface Left Coronary Artery • Arises from the left aortic sinus and supplies: – Most of the left atrium and ventricle – Most of the interventricular septum (AV bundle and branches) • Splits into 2 main branches between the pulmonary trunk and left auricle: – Anterior interventricular branch (LAD) apex • Diagonal branches – Circumflex branch base/ diaphragmatic • Left marginal branch Overview of the URT (Sphenoid sinus) (Frontal sinus) Nasal cavity Uvula Nasopharynx Hard palate Tongue Oropharynx Laryngopharynx Laryngeal cartilages The Nasal Cavities • Uppermost part of the respiratory tract • There are 2 cavities, separated by a midline septum • Air flow travels from anterior nares to posterior choanae • There are 3 key areas of the cavity – Nasal vestibules – Respiratory regions – Olfactory regions • They have 2 main functions: – Respiration – Olfaction • Branches of the olfactory nerve* (CN I) innervate this region • Sense of smell Airflow: Conchae and Meati Respiratory epithelium Clean, warm and humidify air Organised passage of air Conchi Vs. meati Paranasal Sinuses • Outgrowths from nasal cavities and erode into surrounding bones, named after their bone • Lined by respiratory mucosa (ciliated and mucous secreting) • Open into nasal cavities • Innervated by the trigeminal nerve* (CN5) • Function still unsure, several ideas: – – – – Warming/ humidifying air Immune function Lightening the skull Change vocal resonance • Frontal sinus – – – – Superior One on each side Triangular shaped Bridge of the nose to 1/3 way along upper margin of the orbit – Drains into the lateral wall of the middle meatus via the frontonasal duct • Maxillary sinuses • Ethmoidal cells – Clusters of ‘mini sinuses’ in the lateral most parts of the ethmoid bone labyrinths – Between orbit and medial wall of the labyrinths – Divided into anterior middle and posterior clusters • Anterior ethmoidal infundibulum/ frontonasal duct • Middle ethmoidal bulla or lateral wall just above • Posterior lateral wall of the superior nasal meatus – The largest of the sinuses – Pyramidal shaped and occupy most of the maxillary bones – Opens superiorly into the lateral wall of the middle meatus via the hiatus semilunaris Sphenoid Sinus • There are 2 sinuses within the body of the sphenoid • Open into the nasal cavity via apertures on the posterior wall the sphenoethmoidal recess Paranasal Air Sinuses (Imaging) Paranasal Air Sinuses (Imaging) Great Vessels, Coronary aa, Paranasal Air Sinuses and the URT Harry Rhodes - 2011