Nasal Region Lecture Notes PDF

Lecture three The Nasal Region The Nasal region : a- External Nose , b- Nerve Supply of the External Nose , C- Blood Supply and Venous Drainage of the External Nose , D- Nasal Cavity , E- Nerve Supply of the Nasal Cavity , f- Blood Supply to the Nasal Cavity , g- Venous Drainage of the Nasal C...

Lecture three The Nasal Region The Nasal region : a- External Nose , b- Nerve Supply of the External Nose , C- Blood Supply and Venous Drainage of the External Nose , D- Nasal Cavity , E- Nerve Supply of the Nasal Cavity , f- Blood Supply to the Nasal Cavity , g- Venous Drainage of the Nasal Cavity , h- Lymph Drainage of the Nasal Cavity , i- The Paranasal Sinuses , ( next lecture , lecture 5 ) j- Drainage of Mucus and Functions of Paranasal Sinuses and k- Clinical Notes The internal part of the nose is the nasal cavity The nasal cavity is a large, air-filled space above and behind the nose in the middle of the face. The nasal septum divides the cavity into two cavities, also known as fossae. Each cavity is the continuation of one of the two nostrils. The nasal cavity is the uppermost part of the respiratory system and provides the nasal passage for inhaled air from the nostrils to the nasopharynx and rest of the respiratory tract. The two nasal cavities sit within the external nose and the adjacent skull. The cavities open anteriorly to the face through the two nares. Posteriorly the cavities communicate with the nasopharynx by two apertures called choanae. besides the anterior and posterior apertures, each nasal cavity has a roof, floor, and lateral and medial walls. There are 12 cranial bones in total that contribute to the nasal cavity structure, which include: 1- the paired nasal, 2- maxilla, 3- palatine , 4- lacrimal bones, 5- the unpaired ethmoid 6- sphenoid, 7- frontal and 8- vomer bones. Among all of them, the ethmoid bone is the most important element, for two reasons: 1- it makes the greatest portion of the nasal skeletal framework by forming the roof and walls of the nasal cavities; and 2- it contains ethmoidal cells which, as a group, are one of the four paranasal sinuses. The nasal bones can easily be remembered by using this mnemonic: Nerdy Medical Students are often Very PaLE (Nasal, Maxilla, Sphenod , Vomer, Palatine, Lacrimal, Ethmoid)  Blood supply The arterial supply to the nose may be principally divided into : (1) branches from the internal carotid, namely the branches of the anterior and posterior ethmoid arteries from the ophthalmic artery, and (2) branches from the external carotid, namely the sphenopalatine, greater palatine, superior labial, and angular. There is a rich blood supply to the nasal cavity. In some animals, such as dogs, the capillary beds flowing through the nasal cavity help cool the blood flow to the brain. Blood supply comes from branches of both the internal and external carotid artery, including branches of the facial artery and maxillary artery. The named arteries of the nose are: 1- Sphenopalatine artery and 2- greater palatine artery, branches of the maxillary artery. 3- Anterior ethmoidal artery and posterior ethmoidal artery, branches of the ophthalmic artery 4- Septal branches of the superior labial artery, a branch of the facial artery, which supplies the vestibule of the nasal cavity. Venous Drainage of the Nasal Cavity: The names of the veins that drain the nose and nasal cavity follow that of the arteries with which they pair. A- The maxillary branches drain either into the cavernous sinus or the pterygoid plexus located in the infratemporal fossa. B-The veins of the anterior nasal cavity drain into the facial vein Nerve supply: 1- Innervation of the nasal cavity responsible for the sense of smell is via the olfactory nerve, which sends microscopic fibers from the olfactory bulb through the cribriform plate to reach the top of the nasal cavity. 2- General sensory innervation is by branches of the trigeminal nerve (V1 & V2): Nasociliary nerve (V1) Anterior Ethmoidal nerve from the nasociliary nerve (V1) Posterior nasal branches of Maxillary nerve (V2) 3- The nasal cavity is innervated by autonomic fibers. Sympathetic innervation to the blood vessels of the mucosa causes them to constrict, while the control of secretion by the mucous glands is carried on postganglionic parasympathetic nerve fibers originating from the facial nerve. Lymph Drainage of the Nasal Cavity The external lateral portion of the nose is classed under the lymphatic vessels of the face and drains into the submaxillary nodes. The lymphatic vessels that specifically drain the nasal cavities drain into the nodes based on their placement be it anterior or posterior. The vessels from the anterior third of the nasal cavity follow the vessels of the external nose and end up in the submaxillary nodes. Vessels from the posterior two-thirds of the nasal cavity and the ethmoid sinuses drain partly to the retropharyngeal nodes and partly to the superior deep cervical nodes. Functions: The two nasal cavities condition the air to be received by the other areas of the respiratory tract. 1- Owing to the large surface area provided by the nasal conchae (also known as turbinates), the air passing through the nasal cavity is warmed or cooled to within 1 degree of body temperature. 2- In addition, the air is humidified, and dust and other particulate matter is removed by nasal hair in the nostrils. 3- The entire mucosa of the nasal cavity is covered by a blanket of mucus, which lies superficial to the microscopic cilia and also filters inspired air. The cilia of the respiratory epithelium move the secreted mucus and particulate matter posteriorly towards the pharynx where it passes into the esophagus and is digested in the stomach. 4- The nasal cavity also houses the sense of smell and contributes greatly to taste sensation through its posterior communication with the mouth via the choanae. Diseases of the nasal cavity include : 1- viral, bacterial and fungal infections, 2- nasal cavity tumors, both benign and much more often malignant, as well as inflammations of the nasal mucosa. 3- Many problems can affect the nose, including: A- Deviated septum - a shifting of the wall that divides the nasal cavity into halves B- Nasal polyps - soft growths that develop on the lining of the nose or sinuses B- Nosebleeds C- Rhinitis - inflammation of the nose and sinuses sometimes caused by allergies. The main symptom is a runny nose. 5- Nasal fractures, also known as a broken nose 6- Common cold , 7- Sinonasal tumors 8- Nasal irrigation 9- Danger triangle of the face  You Thank