Anatomy of Nasal Cavity PDF

ANATOMY OF NASAL CAVITY, LARYNX, PHARYNX AND TRACHEA - Divided into right and left halves by the nasal septum. - The nasal septum is deviated to one side making each half asymmetrical - Communicates with the exterior [anteriorly] through the naris or nostril - Behind communicates...

ANATOMY OF NASAL CAVITY, LARYNX, PHARYNX AND TRACHEA - Divided into right and left halves by the nasal septum. - The nasal septum is deviated to one side making each half asymmetrical - Communicates with the exterior [anteriorly] through the naris or nostril - Behind communicates with the nasopharynx through the posterior nasal aperture or the choanae DIVISION OF NASAL CAVITY Each nasal cavity is divided into two portions: - Small antero-inferior part lined by skin – the vestibule - Large postero-superior part line by mucosa – the nasal cavity proper NB: EXAMINATION OF NASAL CAVITY - through the nostril (anterior rhinoscopy) or through the pharynx (posterior rhinoscopy). Anterior rhinoscopy – carried out by inserting a nasal speculum through the nostril The features visualized include: 1. Middle and inferior conchae 2. Superior, middle and inferior meatuses 3. Nasal septum 4. Floor of nasal cavity Posterior rhinoscopy – carried out by inserting a mirror into the pharynx The features visualized include: 1. Choanae 2. Conchae 3. Posterior border of nasal septum Maxillary sinusitis – most commonly infected due to: - infected nose (viral rhinitis) - caries in upper premolar and molar teeth - infected frontal and anterior ethmoidal air sinuses Being most dependent part, it acts as a secondary reservoir for pus from frontal air sinus through frontonasal duct and hiatus semilunaris Infection of maxillary air sinus is detected by - Radiological examinations - Trans illumination test - Proof puncture Surgically maxillary air sinus is drained by - Antral puncture (antrostomy) by using trocar and canula - Fenestrating the antrum through the gingivo-labial sulcus (Caldwell-Luc operation) Carcinoma of maxillary air sinus – arises from the mucous lining of the sinus The sign and symptoms produced by the invasion of the carcinoma leads to: - Upward invasion into the orbit displaces the eyeball causing proptosis (protrusion of eyeball) and diplopia (double vision) - Involvement of infraorbital nerve produces pain over the face below the orbit - The medial invasion encroaches the nasal cavity causing obstruction and epistaxis - Lateral invasion produces swelling on the face and palpable mass in the gingivo-labial fold Backward invasion may involve the palatine nerves leading to severe referred pain to the upper teeth STRUCTURE ASSOCIATED LAB/LECTURE PHOTOS VESTIBULE - The antero-inferior part of nasal cavity - Lined by skin, which contains sweat glands, sebaceous glands and provided with coarse hair – vibrissae - As the air passes through the nostrils the large particles of dust in the air are trapped by the vibrissae - Limen nasi – forms the upper limit of vestibule on the lateral wall of nasal cavity - Columella - forms the medial wall of vestibule NASAL CAVITY PROPER Boundaries: - Roof - Floor - Medial (septal) wall - Lateral wall Roof of the nasal cavity proper - Consists of three parts 1. Anterior or fronto-nasal part - Slopes downwards and forwards - Supported by nasal cartilages, nasal and frontal bones 2. Intermediate or ethmoidal part - Horizontal in course - Supported by cribriform plate of ethmoid – perforated by olfactory nerves and ethmoidal vessels 3. Posterior or sphenoidal part - Continuous posteriorly with the roof of the naso-pharynx - Supported by the anterior and inferior surfaces of the body of the sphenoid Floor of the nasal cavity proper - Almost horizontal - Formed by upper surface of hard palate Hard Palate - Anterior three fourths is formed by palatine processes of maxilla - Posterior one-fourth is formed by horizontal processes of palatine bone Medial wall or Nasal septum Nasal septum – - Develops from frontonasal process - Osseo-cartilaginous partition between the two nasal cavities - Seldom in the median plane - Bulges to one or the other side, more frequently to the right Bony part – mainly formed by - Postero-superior part is formed by perpendicular plate of ethmoid - Postero-inferior part is formed by vomer NB: minor contributions are from: - Nasal spine of frontal bone - Crest formed by the nasal bones - Sphenoidal crest Cartilaginous Part – formed by: - Septal cartilage – forms the major anterior part of nasal septum - Septal processes of lower nasal cartilages NB: Sometimes vomero-nasal cartilage intervenes between the vomer and septal cartilage - contains on each side a mucous pouch – vomero-nasal organ of Jacobson - Pouch is lined by olfactory epithelium and are supplied by olfactory nerves - Vomero-nasal organs are rudimentary in mankind, well developed in macrosmatic animals like rabbit and dog Lateral Wall of the Nasal Cavity Formed by number of bones and cartilages: - Nasal bone - Frontal process of maxilla - Lacrimal bone - Conchae and labyrinth of ethmoid - Inferior nasal concha - Perpendicular plate of palatine - Medial pterygoid plate of sphenoid Cartilages forming the Lateral Wall - Lateral nasal cartilage - Major alar cartilage - 3 or 4 tiny cartilages of the ala Features in the Lateral Wall Divided into three parts: - Anterior part – vestibule - Middle part – atrium of the middle meatus. I. Limited above by – agger nasi: a faint ridge of mucous membrane  II. Limited below by - limen nasi: is a curved muco-cutaneous junction - Posterior part – presents three scroll- like projections, the conchae I. The spaces between the conchae are called meatuses NB: Conchae and meatuses form the main features of the lateral wall NASAL CONCHAE Three in number: 1. Superior concha – projection from the medial surface of the labyrinth of ethmoid bone 2. Middle concha – projection from the medial surface of the labyrinth of ethmoid bone 3. Inferior concha – independent bone NB: Sometimes above the superior concha is the highest concha or supreme concha. MEATUSES - Passages beneath the overhanging conchae - Recesses or passages beneath the overhanging conchae Inferior Meatus: - Largest and lies beneath the inferior nasal concha - Nasolacrimal duct (6) opens in its anterior part Middle Meatus - Lies beneath the middle concha - Presents bulla ethmoidalis and hiatus semilunaris Bulla ethmoidalis – - Bony bulging containing middle ethmoidal air cells - Middle ethmoidal air cells (4) open into the middle meatus on or above the bulla Hiatus Semilunaris – - Crescentic space below the bulla - Anterior end of hiatus is called infundibulum - maxillary air sinus (5) opens into the hiatus below the bulla - Anterior ethmoidal air sinus (3) opens into the hiatus in front of the bulla - Frontal air sinus opens (2) into the infundibulum through fronto-nasal duct Superior Meatus - Smallest of the meatuses - Lies below the superior concha - Posterior ethmoidal air sinus opens into it Supreme Meatus - Intervenes btw the nasal roof and the superior concha - Sometimes traversed by highest concha or supreme concha NB: Above and behind the superior concha is a depression – spheno- ethmoidal recess, which receives the opening of sphenoidal air sinus (1) LINING OF NASAL CAVITY Vestibule – lined by skin Olfactory region – - Occupies the roof and the adjoining septal and lateral walls of the nasal cavity above the superior concha - Lined by olfactory epithelium (bipolar olfactory cells, tall columnar supporting cells and basal cells) NB: Respiratory region is lined by pseudo stratified ciliated columnar epithelium Due to the presence of cilia and secretions of the serous and mucous glands in the nasal cavity, the air while passing through the nasal cavity is not only filtered but moistened and humidified, a mechanism that protects the lower respiratory tract. ARTERIAL SUPPLY of LATERAL WALL of NC The lateral wall of nasal cavity is supplied by branches of ophthalmic artery, maxillary and facial arteries 1. Antero-superior quadrant – anterior and posterior ethmoidal arteries branches of ophthalmic artery 2. Antero-inferior quadrant – alar branch of facial and terminal branches of greater palatine arteries 3. Postero-superior quadrant – spheno-palatine branch of maxillary artery 4. Postero-inferior quadrant – greater palatine branch of maxillary artery VENOUS DRAINAGE Form a plexus beneath the mucosa from which the blood drains into: I. Infront – Facial Vein II. Behind – retro-pharyngeal veins and pterygoid venous plexus LYMPHATIC DRAINAGE - From the anterior half of lateral wall drain into submandibular nodes - From posterior half drain into retropharyngeal and upper deep cervical lymph nodes NERVE SUPPLY OF THE NC Sense of smell (special sensory) – olfactory zone is supplied by olfactory nerves Nerves of general sense supplied by: 1. Antero-superior quadrant – anterior ethmoidal branch of ophthalmic nerve 2. Antero-inferior quadrant – anterior superior alveolar branch of maxillary nerve and nasal branch of infraorbital nerve 3. Postero-superior quadrant – posterior superior lateral nasal branches of pterygo-palatine ganglion, from maxillary 4. Posterior-inferior quadrant – anterior (greater) palatine branches of pterygo-palatine ganglion, from maxillary ARTERIAL SUPPLY OF THE NASAL SEPTUM 1. Antero-superior part - the anterior and posterior ethmoidal branches of ophthalmic artery 2. Postero-inferior part - the sphenopalatine and greater palatine branches of maxillary artery 3. Mobile part of septum - the septal branches of superior labial of facial artery NB: Little’s Area - An area in the antero-inferior part of the nasal septum just above the vestibule - Highly vascular - septal branches of anterior ethmoidal, sphenopalatine, greater palatine and superior labial arteries anastomose to form a vascular plexus – Kiesselbach’s plexus or Little’s area This area is the common site of epistaxis (nose bleeding) in children and young adults usually due to fingernail trauma following pricking of the nose VENOUS DRAINAGE OF NASAL SEPTUM 1. antero-superior part – into superior ophthalmic vein 2. postero-inferior part – into pterygoid venous plexus - From the mobile part of the septum – into internal jugular vein through the facial vein - An infection from this mobile part may extend into cavernous sinus via deep facial vein and pterygoid venous plexus. LYMPHATIC DRAINAGE OF NS - Anterior part – submandibular lymph nodes - Intermediate and posterior part – into retropharyngeal lymph node AUTONOMIC NERVES - Both sympathetic and parasympathetic fibres supplying the NC derived from Vidian’s Nerve through pterygopalatine ganglion - The parasympathetic fibres supply nasal glands and control nasal secretion - The sympathetic fibres, on stimulation cause vasoconstriction NB: Excessive rhinorrhea (runny nose) due to vasomotor and allergic rhinitis can be controlled by sectioning the Vidian nerve. STRUCTURE ASSOCIATED LAB/LECTURE PHOTO PARANASAL AIR SINUSES - Air-containing cavities in the bones around the nasal cavity - Develop as mucosal diverticulae of the main nasal cavity invading the adjacent bones - Lined by pseudo-stratified ciliated columnar epithelium There are four pairs of paranasal air sinuses: 1. Frontal air sinuses- in the frontal bone 2. Ethmoidal air sinuses- in the ethmoid bone 3. Maxillary air sinuses- in the maxillae 4. Sphenoidal air sinus- in sphenoid bone NB: Ethmoidal Air Sinus arranged in 3 groups: 1. Anterior Ethmoidal Air Sinus 2. Middle Ethmoidal Air Sinus 3. Posterior Ethmoidal Air Sinus Air sinuses are present in rudimentary form at birth except the frontal air sinus, which starts developing 2-3 years after birth The air sinuses exhibit two spurts of growth: - 1st around 7-8 years during eruption of teeth - 2nd at puberty FUNCTIONS - Make the facial bones lighter and establish the adult contour of the face - Add resonance to the voice - Act as air conditioning chamber by adding humidity and temperature to the inspired air. FRONTAL AIR SINUS - Two in number - Lie btw the inner and outer tables of the frontal bone, deep to the medial end of the superciliary arch. - The left and right sinuses are usually unequal in size and rarely symmetrical - Right is larger than left and separated from it by a septum - Each drain into anterior part of hiatus semilunaris (infundibulum) of the middle meatus - It is supplied by supra-orbital nerves and vessels - Lymphatics drain into sub-mandibular group of lymph nodes RELATIONS: I. Anterior Wall – Superciliary Arch II. Posterior Wall - Meninges and Frontal Lobe of brain III. Inferior Wall – roof of nose, roof of orbit and ethmoidal air cells MAXILLARY SINUS (Antrum of Highmore) - Largest of the paranasal air sinus - Present in the body of maxilla - Drains into posterior part of the hiatus semilunaris - First sinus to develop, appears at about 4th month of intrauterine life - Rudimentary at birth, enlarges rapidly during 6-7 years and becomes fully developed at puberty - Pyramidal in shape, with the base directed medially towards the lateral wall of the nose and apex laterally towards the zygomatic bone NB: Base of the sinus presents a large opening – the maxillary hiatus, which is reduced in size by: - Uncinate process of ethmoid – above - Inferior nasal concha – below - Descend process of lacrimal – in front - Perpendicular plate of palatine – behind - Maxillary air sinus opens into the hiatus semilunaris of middle meatus - The opening is located much higher from the floor of the sinus in disadvantageous position for natural drainage - Blood supply – anterior, middle and posterior superior alveolar vessels of maxillary - Lymphatics drain into sub-mandibular group of lymph nodes - Nerve supply – from anterior, middle and posterior superior alveolar nerves of maxillary nerve and infraorbital nerves ETHMOIDAL SINUS - Made up of number of air cells - Present within the labyrinth of ethmoid bone - Ethmoidal air sinus is divided into 3 groups: I. Anterior ethmoidal air sinus – made up of 3 – 7 cells II. Middle ethmoidal air sinus – made up of 1 – 3 cells III. posterior ethmoidal air sinus – made up of 1 -11 cells NB: - The anterior and middle ethmoidal air sinuses drain into the middle meatus - The posterior ethmoidal air sinus drains into the superior meatus - Blood supply – by anterior and posterior ethmoidal vessels - Lymphatics – anterior and middle ethmoidal air sinus drain into submandibular group of lymph nodes and from the posterior ethmoidal air sinus drain into retropharyngeal air sinus SPHENOIDAL AIR SINUS - Sphenoidal air sinuses lie within the body of sphenoid - Separated from each other by a bony septum - The two sinuses are asymmetrical - Each drain into sphenoethmoidal recess - Blood supply – posterior ethmoidal vessels - Nerve supply – posterior ethmoidal nerves - Lymphatics – drain into retro-pharyngeal lymph nodes