Session 7 Head & Neck PDF

The Nasal cavity and paranasal sinuses Dr. Israa Khalil The Nose • The two nasal cavities are the uppermost parts of the respiratory tract , they are elongated wedge-shaped spaces with a large inferior base and a narrow superior apex and are held open by a skeletal framework consisting mainly of b...

The Nasal cavity and paranasal sinuses Dr. Israa Khalil The Nose • The two nasal cavities are the uppermost parts of the respiratory tract , they are elongated wedge-shaped spaces with a large inferior base and a narrow superior apex and are held open by a skeletal framework consisting mainly of bone and cartilage. • The smaller anterior regions of the cavities are enclosed by the external nose, whereas the larger posterior regions are more central within the skull. • The anterior apertures of the nasal cavities are the nares. D • The posterior apertures are the choanae, which open into the __ nasopharynx. __ The nasal cavities are separated: • From each other by a midline nasal septum. • From the oral cavity below by the hard palate, and • From the cranial cavity above by parts of the frontal, ethmoid, and sphenoid bone. Regions of nasal cavity • The nasal vestibule is a small dilated space just internal to the naris that is lined by skin and contains hair . • The respiratory region is the largest part of the nasal cavity, has a rich neurovascular supply, and is lined by respiratory epithelium. • The olfactory region is small, is at the apex of each nasal cavity, is lined by olfactory epithelium, and contains the olfactory receptors. External Nose • The external nose has two elliptical orifices called the nostrils, which are separated from each other by the nasal septum . or Nostrils The framework of the external nose is made up: • Above: by the nasal bones, the frontal Itas aregiff processes of the maxillae, and the nasal part of the frontal bone. • Below: by the plates of hyaline cartilage on each side, support is provided by the e cartilages, and a single septal cartilage in major alar and three or four minor alar the midline that forms the anterior part of the nasal septum. Nerve Supply of the External Nose infratrochlear external nasal infraorbital. 2 of branches ophthalmicnerve branch of maxillarynerve Blood Supply of the External Nose • The skin of the external nose: supplied by branches y ineratiistie of the ophthalmic and the maxillary arteries. • The skin of the ala and the lower part of the septum: supplied by branches from the facial artery. It means that nose is supplied by external internalcarotidartery G The Nasal Cavity • The nasal cavity extends from the nostrils to the posterior nasal apertures or choanae behind, where the nose opens into the nasopharynx. • The nasal cavity is divided into right and left halves by the nasal septum Walls of the Nasal Cavity Each half of the nasal cavity has a floor, a roof, a lateral wall, and medial or septal wall. Floor It is smooth, concave, and much wider than the roof. It consists of: • soft tissues of the external nose, and • the upper surface of the palatine process of the maxilla and the horizontal plate of the palatine bone, which together form the hard palate Roof Formed anteriorly by the nasal and frontal bones, in the middle by the cribriform plate of the ethmoid, and posteriorly by the downward sloping body of the sphenoid. cribriform plated Medial wall The medial wall is formed by the nasal septum. • The upper part of the septum is formed by the vertical plate of the ethmoid and the vomer bones . • The anterior part is formed by the septal cartilage. The nasal septum is typically situated in the midline; however, septal deviation to one side or the other is very common, and in many cases is secondary to direct trauma. Extreme septal deviation can produce nasal occlusion. The deviation can be corrected surgically • On the either sides of the septum there is a small opening lead to an incisive canal, traversed by nasopalatine and descending palatine arteries . O incisive canal Lateral wall The lateral wall of each nasal cavity is complex , it has three projections of bone called the superior, middle, and inferior nasal conchae or turbinate . These conchae increase the surface area of contact between tissues of the lateral wall and the respired air. The space below each concha is called a meatus. Theconcha dividednasalcavityinto a chambers Sphenoethmoidal recess Is a small area above the superior concha. It receives the opening of the sphenoid air sinus Superior meatus • The superior meatus lies below the superior concha It receives the openings of the posterior ethmoid sinuses. Middle meatus The middle meatus lies below the middle concha. It has a rounded swelling called the bulla ethmoidalis that is formed by the middle ethmoidal air sinuses, which open on its upper border. A curved opening, the hiatus semilunaris, lies just below the bulla. The anterior end of the hiatus leads into a funnel-shaped channel called the infundibulum, which is continuous with the frontal sinus. o The anterior ethmoidal air sinus open into the infundibulum and the a maxillary sinus opens into the hiatus semilunaris. Inferior Meatus • The inferior meatus lies below the inferior concha and receives the opening of the nasolacrimal duct, which is guarded by a fold of mucous membrane Mucous Membrane of the Nasal Cavity The vestibule is lined with modified skin and has coarse hairs. The area above the superior concha is lined with olfactory mucous membrane. The lower part of the nasal cavity is lined with respiratory mucous membrane. A large plexus of veins in the submucous connective tissue is present in the respiratory region. The nasal cavities adjust the temperature and humidity of respired air by the action of a rich blood supply, and trap and remove particulate from the airway by filtering the air through hair in the vestibule and by capturing foreign material in abundant mucus. The mucus normally is moved posteriorly by cilia on epithelial cells in the nasal cavities and is swallowed. Nerve supply of the nasal cavity Olfactory nerve: in the upper part. Anterior ethmoidal nerve: branch of nasociliarynerve at the front. Nasopalatine nerve: at the back. All glands are innervated by parasympathetic fibers in the facial nerve. Sympathetic fibers are w o ultimately derived from the T1 spinal cord level. 158s Blood Supply to the Nasal Cavity The arterial supply to the nasal cavity is mainly from branches of the maxillary artery . The most important branch is the sphenopalatine artery which E anastomoses with • the septal branch of the superior labial branch of the facial artery • and with anterior and posterior ethmoidal arteries in the region of the vestibule. The venous plexus is drained by veins that accompany the arteries. o Little´s area Is a region in the anteroinferior part of nasal septum where these arteries anastomose to form vascular plexus named kiesselbachs plexus, it is common site for epitaxis (nasal bleeding) , consist of: 1. Sphenopalatine artery(ECA) . III 3. Greater palatine artery(ECA). 2. Septal branch from superior labial artery(ECA). 4. Anterior and posterior ethmoidal arteries(ICA) . 000 arteriovenousshunt t anything CP • Lymph Drainage of the Nasal Cavity The lymph vessels draining the vestibule end in the submandibular nodes. The remainder of the nasal cavity is drained by vessels that pass to the upper deep cervical nodes. The Paranasal Sinuses it The paranasal sinuses are cavities found in the interior of the maxilla, frontal, sphenoid, and ethmoid bones. They are lined by respiratory mucosa and filled with air; they communicate with the nasal cavity through small apertures. All of the paranasal sinuses are • opens into the nasal cavities • All of them are as innervated by branches of the trigeminal nerve. faith nerve The function of the sinuses is to • act as resonators to the voice and • they also reduce the weight of the skull. When the apertures of the sinuses are blocked or they become filled with fluid, the quality of the voice is markedly changed. 0 which one ofparanasalsinuses is thelargest maxillarysin.u Maxillary Sinuses eg isthelargest sinus • The maxillary sinus is pyramidal in shape and located within the body of the maxilla . • The roof is formed by the floor of the orbit, and the floor is related to the roots of the premolars and molar teeth. • The maxillary sinus opens into the middle meatus of the nose through the hiatus semilunaris. Frontal Sinuses • The two frontal sinuses are contained within the frontal bone. • They are separated from each other by a bony septum. Each sinus is triangular. • Each frontal sinus opens into the Ee middle meatus of the nose through the infundibulum Each frontal sinus drains onto the lateral wall of the middle meatus via the frontonasal duct, which is continues as the ethmoidal infundibulum at the front end of the semilunar hiatus. Sphenoidal Sinuses • The two sphenoidal sinuses lie within the body of the sphenoid bone. • Each sinus opens into the sphenoethmoidal recess above the superior concha. and ginger Ethmoid Sinuses • The ethmoidal sinuses are anterior, middle, and posterior and they are contained within the ethmoid bone, between the nose and the orbit . • They are separated from the orbit by a thin plate of bone called lamina papyracea so __ that infection can readily spread from the sinuses into the orbit. antimiadysteror y cen o Q Ethmoidbonecontributetoformationof SEE