L. 8 Nose and Nasal Cavity PDF

THE NOSE AND THE NASAL CAVITY L. 8 Dr. Thana Al-Khishali Objectives Define the nose, Nostrils (external nares), nasal skeleton and piriform aperture Describe the nasal cavity, vestibule, choana, roof, floor, lateral wall and floor Distinguish between skeleton of la...

THE NOSE AND THE NASAL CAVITY L. 8 Dr. Thana Al-Khishali Objectives Define the nose, Nostrils (external nares), nasal skeleton and piriform aperture Describe the nasal cavity, vestibule, choana, roof, floor, lateral wall and floor Distinguish between skeleton of lateral nasal walls and Nasal septum Describe Respiratory epithelium Locate the Olfactory epithelium Learn the neurovasculature of the nasal cavity, Recognize the ostia within the nasal cavity and their significance  The Nose and the Nostrils The nose is the pyramidal shaped, prominent structure located inferior and medial to the eyes Allows entrance into the nasal cavity. It is an olfactory and respiratory organ. Consists of nasal skeleton, which houses the nasal cavity. It is divided into right and left nasal cavities. The inferior portion of the nose contains two apertures called the anterior nares The nostrils (anterior nares), the two round or oval holes below the external nose, are the primary entrance into the human respiratory system Surface Appearance of the Nose The surface anatomical landmarks of the nose: a. The nasal root: Is located superiorly, and is continuous with the forehead. b. The apex of the nose: Ends inferiorly in a rounded ‘tip’ c. The dorsum of the nose: Spanning between the root and apex The nares (Nostrils) are located immediately inferiorly to the apex of the nose A B Surface Anatomy of the nose. A. Anterior view, B. Left lateral view  Nostrils (External nares) The nostrils (external nares), the two round or oval holes below the external nose They are separated by the septal cartilage (Nostrils) is the common name for the two anterior nares (singular: naris) They are the primary entrance into the human respiratory system through the: a. nasal cavity b. posterior or internal nares (choanae) c. the nasopharynx. Nostrils (external )nares  Anatomy of the Nostrils (Nares) Each naris is bounded medially by the nasal septum, and laterally by the ala nasi (the lateral cartilaginous wings of the nose). The two nostrils are of the same shape and size. The septal cartilage or septum forms the wall between the two external nares The separation visible from the outside. “In some individuals the septum may be a little uneven, causing the nostrils to be of different sizes. Such unevenness, in a severe form, is known as deviated septum ” The greater alar cartilage forms the lateral and medial boundaries of the nostrils, also give their overall shape  Skeleton of the nose The skeleton of the nose is composed of an upper bony portion and a lower cartilaginous portion. The proximal portions of the nostrils (alae) are composed of connective tissue with small embedded pieces of cartilage.  Nasal Skeleton The skeleton of the nose is formed by three types of tissue; bone, cartilage and fibro-fatty tissue. It is composed of the external nasal skeleton and internal nasal septum. External Nasal Skeleton. The skeleton of the external nose is made of both bony and cartilaginous components: Bony component – located superiorly, and is comprised of contributions from the: nasal bones maxillae frontal bone.  Nasal Skeleton (continued) Cartilaginous component – located inferiorly, and is comprised of the: Two lateral cartilages Two alar cartilages One septal cartilage. There are also some smaller alar cartilages present. The skin over the bony part of the nose is thin, that overlying the cartilaginous part is thicker with many sebaceous glands. This skin extends into the vestibule of the nose via the nares. Here there are hairs (vibrissae) which function to filter air as it enters the respiratory system  The Nose - Muscles, Blood Vessels Muscles and Nerves A group of small muscles insert into the external nose, contributing to facial expression. All innervated by the facial nerve (CN VII) The procerus the nasalis the depressor septi nasi. Vessels and Lymphatics The blood supply is from branches of the maxillary and ophthalmic arteries. additional supply from the angular artery and lateral nasal artery. branches of the facial artery Venous drainage is into the facial vein, and then in turn into the internal jugular vein. Lymphatic drainage into the deep cervical lymph nodes. Innervation Sensory innervation: is derived from the trigeminal nerve (CN V). The external nasal nerve, a branch of the ophthalmic nerve (CN V1). The lateral aspects of the nose are supplied by the infraorbital nerve, a branch of the maxillary nerve (CN v2). Motor innervation to the nasal muscles of facial expression is via the facial nerve (CN VII)  Piriform Aperture Piriform aperture is the bony anterior limitation of the nasal skeleton. It is the pear-shaped front door to the nasal cavity. Boundaries: superiorly the inferior edge of both the nasal bones, laterally the nasal (ascending) processes of the maxilla, and inferiorly the horizontal processes of the maxillary bones. The junction between horizontal processes of the maxillary bones forms the anterior nasal spine, a keel-shaped protrusion in which the nasal septum is firmly attached Piriform aperture. Skull: 1, nasal bones; 2, ascending processes of the maxilla; 3, horizontal processes of the maxillary bones; 4, anterior nasal spine.  The Nasal Cavity The nasal cavity is the complex chamber located between the external nares anteriorly and the choanae posteriorly It lies posterior to the vestibule and atrium of the nose Inferior portion is larger than superior portion It is divided into two cavities by the nasal septum.  The Nasal Cavity “continued” Each of the two nasal cavities has: a medial wall formed by the nasal septum a lateral wall is the lateral nasal wall an inferior wall is the nasal floor (palate) a superior wall is the nasal roof (skull base) The two nasal cavities are lined with mucous membrane; pseudostratified columnar ciliated epithelium with goblet cells (Respiratory Epithelium) Respiratory epithelium is highly vascular and easily congested when irritated leading to sneezing  The Nasal Cavity The nasal cavity consists of The Nasal Septum (vid infra) The lateral Walls of the nose: (vid infra) The floor is formed by the hard palate, separating it from the oral cavity. It consists of the palatine bone posteriorly, and the palatine process of the maxilla anteriorly. Roof is formed by the cribriform plate of the ethmoid, frontal, nasal, and sphenoid bones Choanae: aka “the posterior nasal apertures”, connect the nasal cavity to the nasopharynx aka= also known as  Lateral wall of the nasal cavity The roof of the nasal cavity is formed by the frontal bone, nasal bone, cribriform plate of the ethmoid, and the sphenoid bones The floor of the nasal cavity is formed by the palatine process of the maxilla and horizontal plate of palatine bone FLOOR OF THE NASAL CAVITY The floor is horizontal. It’s created by the upper surface of the hard palate, i.e., anterior three-fourth is composed by palatine process of maxilla and posterior 1 fourth is composed by the horizontal plate of the palatine bone. Bony nasal septum. Skull; bony structures of the nasal cavities: 1, nasal bones; 2, anterior nasal spine; 3, inferior turbinate; 4, middle turbinate; 5; horizontal process of the maxilla; 6, horizontal process or the palatine bone; 7, vomer; 8, bony septal ridge in the joint between perpendicular plate of ethmoid and vomer; 9, posterior edge of the vomer articulating in the rostrum of the sphenoid. Nasal Septum The internal nasal septum separates the nasal cavity into two nostrils. The bones that contribute to the nasal septum can be divided into: Paired bones: Nasal, maxillary and palatine bones Unpaired bones: Ethmoid and vomer bones. In addition to the bones of the nose, the septal and greater alar cartilages also constitute part of the nasal septum. MEDIAL WALL OF THE NASAL CAVITY It is composed by nasal septum , created by: Perpendicular plate of ethmoid Vomer Septal cartilage Deviated nasal septum Choanae  CLINICAL SIGNIFICANCE Deviated Nasal Septum (DNS): The deviated nasal septum isn’t unusual and is an essential cause of nasal obstruction. The males are affected more than females. It takes place because of numerous variables like trauma, developmental blunder, etc. If DNS is acute and causing mechanical obstruction, resulting in trouble in breathing, sinusitis, headache, excessive snoring, etc., it’s corrected by submucous resection (SMR) or septoplasty. The septal cartilage not only creates partition between the left and right nasal cavities but also gives support to the dorsum of the anterior two-third of the nose. For that reason, its destruction as a result of disease or excessive removal in submucous resection leads to supratip depression of the external nose.  Clinical Relevance – Saddle Nose Deformity The saddle nose deformity occurs primarily as a result of nasal trauma; whereby septal support to the nose is lost, and subsequently the middle part of the nose appears sunken. This is either a result of direct damage to the septal bone or cartilage, or a consequence of nasal septal haematoma. As cartilage has no blood supply of its own, it relies on oxygen and nutrients diffusing from blood vessels in the surrounding perichondrium. A haematoma between these two structures can result in destruction of the septum, and therefore deformity of the nose.  Nasal Cavity - Boundaries Superior: Nasal, frontal, cribriform plate of the ethmoid, body of the sphenoid Inferior: Palatine process of the maxilla, horizontal plate of the palatine Anterior: External nose Posterior: Choanae (posterior nasal aperture) Medial: Ethmoid (perpendicular plate), vomer, septal cartilage Lateral: Maxilla, ethmoid, palatine, sphenoid (medial pterygoid plate), and inferior nasal concha, lacrimal Boundaries of Nasal Cavity  Nasal Cavity - Relations Superior: Frontal sinus, sphenoid sinus, anterior cranial fossa with frontal lobe of the brain Inferior: Palate, oral cavity Medial: Other half of nasal cavity Lateral: Maxillary sinus, ethmoid sinuses, orbit, and pterygopalatine fossa Relations of the nasal cavity Frontal sinus Sphenoid sinus Air enters the nasal cavity through the anterior nasal aperture and travels through three passages: the superior, middle, and inferior meatuses (arrows). These passages are separated by the superior, middle, and inferior conchae. Air leaves the nose through the choanae, entering the nasopharynx.  Nasal Cavity – Lateral Wall Regions of Lateral Wall Anterior part presents a small depressed area, the vestibule. It’s lined by the skin including vibrissae (short, stiff curved hair). Middle part is called atrium of the middle meatus. Posterior part presents 3 scroll-like projections, the conchae or turbinates. The spaces dividing the conchae are referred to as meatuses. “The conchae and meatuses create the primary features of the lateral wall”  Nasal Cavity – Lateral Wall Conchae Conchae aka turbinates, are the curved bony projections pointed downwards and medially. From above downwards the conchae are superior, middle and inferior nasal conchae. Occasionally a 4th concha, the concha suprema is also present. Superior and middle nasal conchae are the projections from the medial surface of the ethmoidal labyrinth. Inferior concha is a separate bone. The superior concha is smallest and inferior concha is largest in size.  Nasal Cavity – Lateral Wall Meatuses Below and lateral to every concha is a corresponding meatus. Meatuses are the passages (recesses) below the overhanging conchae. They’re visualized once conchae are removed. Inferior meatus is the largest and is located underneath the inferior nasal concha. Middle meatus is located underneath the middle concha. It presents subsequent features: Ethmoidal bulla (bulla ethmoidalis), a round elevation generated by the underlying middle ethmoidal sinuses. Hiatus semilunaris, a deep semicircular sulcus below the bulla ethmoidalis. Infundibulum, a short passage in the anterior end of middle meatus. Superior meatus is the smallest and is located below the superior concha. A triangular depression, above and behind the superior concha is called the sphenoethmoidal recess. Coronal section passing through the nasal cavity showing the lateral wall and the nasal  The Nasal Cavity – Lateral Wall The bones creating the lateral wall are: Nasal Frontal process of maxilla Lacrimal Conchae (ethmoid bone) Inferior nasal concha Perpendicular plate of palatine Medial pterygoid plate of sphenoid The cartilages creating the lateral wall are: Lateral nasal cartilage (upper nasal cartilage) Major alar cartilage (lower nasal cartilage) 3 to 4 miniature cartilages of the alae (small alar cartilages) Function of the Conchae The function of the conchae is to increase the surface area of the nasal cavity – this increases the amount of inspired air that can come into contact with the cavity walls. They also disrupt the fast, laminar flow of the air, making it slow and turbulent. The air spends longer in the nasal cavity, so that it can be humidified.  Roof Superior concha Middle concha Auditory tube Inferior concha Palate Cadaveric image of the nasal cavity Parasagittal section of the skull passing through the cavity of the maxillary sinus and the orbit  The Nasal Cavity - Divisions The nasal cavity is the most superior part of the respiratory tract. It extends from the vestibule of the nose to the nasopharynx, and has three divisions: Vestibule the area surrounding the anterior external opening to the nasal cavity. It’s lined by the skin with sebaceous glands and interlacing rough hair- the vibrissae. As the air goes through the nostrils the large particles of dust in the air are trapped by the vibrissae.  The Nasal Cavity – Divisions “continued” Olfactory region – Located at the upper third of the nasal cavity. It is lined by olfactory cells with olfactory epithelium, which includes receptor cells for scent Respiratory region: The remainder of the nasal cavity (lower two- third) is lined by the respiratory epithelium, i.e. pseudostratified ciliated columnar epithelium with goblet cells. The Nasal Cavity – Divisions “continued” The respiratory mucosa is extremely vascular includes cavernous spaces and sinusoids to warm the air. It includes a large number of serous and mucous glands The secretion of the serous glands makes the air damp the secretion of the mucous glands traps the dust and other particles. the cilia on the top layer of the mucous membrane sweep the mucous posteriorly into the pharynx to be removed and swallowed to the GIT.  (C ) (a) (b) Nasal Cavity Every nasal cavity interacts with the outside via nostril (or naris) and together with the nasopharynx via the posterior nasal aperture (or the choana). Every nasal cavity is split into 2 portions: (a) a small anteroinferior part lined by skin- the vestibule, (b) a large posterosuperior part lined by respiratory epithelium-the nasal cavity proper, and ( c) olfactory region for the sense of smell The Nasal Cavity - Functions The nasal cavity has four functions: Warms and humidifies the inspired air. Removes and traps pathogens and particulate matter from the inspired air. Responsible for sense of smell. Drains and clears the paranasal sinuses and lacrimal ducts. During inhalation, the air passes into the nasal cavities through the nostrils, where it is cleaned (of any harmful dust particles or bacteria) and humidified by the cilia and sticky mucus. The purified air then makes its way into the next parts of the respiratory tract.  Why Do We Have Two Nostrils? Nasal Cycle Nasal cycle: is the cyclical changes in the lining of the nasal cavity; where there is a greater airflow in one nostril than in the other. It is an alternation in nasal airflow between left and right nostrils over time It is due to asymmetry in blood flow leading to engorgement of erectile tissue of one nostril over the other This asymmetry blocks the passage of air in one nostril more than in the other. “This is more evident when you have a cold, and your left and right nose takes turns to remain clogged, especially when you lie down” Having two nostrils is believed to enhance the sense of smell (olfaction) Decongested side Congested side  Openings into The Nasal Cavity One of the functions of the nose is to drain a variety of structures. Thus, there are many openings into the nasal cavity, by which drainage occurs. The paranasal sinuses drain into the nasal cavity. The frontal, maxillary and anterior ethmoidal sinuses open into the middle meatus. The location of this opening is marked by the semilunar hiatus The middle ethmoidal sinuses empty out onto the ethmoidal bulla at the level of the superior meatus. Openings into The Nasal Cavity The only structure not to empty out onto the lateral walls of the nasal cavity is the sphenoid sinus. It drains onto the posterior roof. In addition to the paranasal sinuses, other structures open into the nasal cavity: Nasolacrimal duct – acts to drain tears from the eye. It opens into the inferior meatus. Auditory (Eustachian) tube – opens into the nasopharynx at the level of the inferior meatus. It allows the middle ear to equalise with the atmospheric air pressure.  In this diagram, the conchae have been removed, showing the various openings on the lateral wall of the nasal cavity. Clinical Relevance - Spread of Infection As the auditory tube connects the middle ear and upper respiratory tract, it is a path by which infection can spread from the upper respiratory tract to the ear – otitis media which is an infection of the middle ear. Infection of the auditory tube causes swelling of the mucous linings, and the tube becomes blocked. This results in diminished hearing. Openings into The Nasal Cavity  Gateways to the Nasal Cavity Nerves, vasculature and lymphatics need to be able to access the nasal cavity. 1. The cribriform plate is part of the ethmoid bone. It forms a portion of the roof of the nasal cavity. It contains very small perforations, allowing fibres of the olfactory nerve to enter and exit 2. The sphenopalatine foramen is located at the level of the superior meatus. This hole allows communication between the nasal cavity and the pterygopalatine fossa. The sphenopalatine artery, nasopalatine and superior nasal nerves pass through here. 3. The incisive canal is a pathway between the nasal cavity and the incisive fossa of the oral cavity. It transmits the nasopalatine nerve and greater palatine artery.  Conchae of the Nasal Cavity Concha Regions Drained Location Structures Drained Sphenoethmoidal Superior to the Sphenoidal sinus recess superior meatus Superior Inferior to the Superior meatus Posterior ethmoid sinus superior meatus Anterior ethmoidal sinus Inferior to the Middle ethmoidal sinus Middle Middle meatus middle meatus Maxillary sinus Frontal sinus Inferior to the Inferior Inferior meatus Nasolacrimal duct inferior meatus  Vasculature The nose has a very rich vascular supply – this allows it to effectively change humidity and temperature of inspired air. The blood supply to the nasal cavity arises from 3 major arteries: Ophthalmic Maxillary Facial These 3 vessels are derived from the external and internal carotid arteries and generally follow the paths of the nerves  Vasculature – Internal Carotid Artery Internal carotid branches: Ophthalmic artery within the orbit, gives rise to 2 major branches to supply the nasal cavity 1. Anterior ethmoidal : Travels through the anterior ethmoidal foramen give rise to nasal branches that descend into the nasal cavity: Lateral branch supplies lateral wall of the nose Septal branch supplies the septum of the nose Give rise to the external nasal a., which supplies the external nose Vasculature – Internal Carotid Artery 2. Posterior ethmoidal a.: Travels through the posterior ethmoidal foramen gives rise to nasal branches Lateral branch Septal branch Supplies the superior nasal concha and the nasal septum External carotid branches – Maxillary Artery Sphenopalatine: passes through the sphenopalatine foramen to the nasal cavity, where it gives rise to the posterior and lateral nasal branches to supply the lateral nasal wall and the nasal septum Greater palatine: Travels in the palatine canal, where it gives off greater palatine a., and anastomoses with the terminal branch of the sphenopalatine a. that exits the incisive foramen  External carotid branches – Facial Artery Superior labial artery: Gives rise to the septal branch that travels to the nasal septum Lateral nasal arteries – a branch of the facial artery terminates as the angular artery In addition to the rich blood supply, these arteries form anastomosis with each other. This is particularly prevalent in the anterior portion of the nose.  Little’s Area – Kiesselbach’s Plexus Kiesselbach’s plexus is the anastomosis along the nasal septum formed by: Anterior ethmoid a. Sphenopalatine a. Greater palatine a. Septal branch from the superior labial a.  Q. What are the arteries of the Nasal Septum? The nasal septum is supplied by these arteries: 1. Septal branch of the anterior ethmoidal artery (a branch of ophthalmic artery). 2. Septal branch of the posterior ethmoidal artery (a branch of ophthalmic artery). 3. Septal branch of the sphenopalatine artery (a branch of maxillary artery). 4. Septal branch of the greater palatine artery (a branch of maxillary artery). 5. Septal branch of the superior labial artery (a branch of facial artery).  CLINICAL SIGNIFICANCE LITTLE’S AREA It’s an area in the anteroinferior part of the nasal septum just above the vestibule. It’s highly vascular. Here the septal branches of the anterior ethmoidal sphenopalatine, greater palatine and superior labial arteries anastomose to create a vascular plexus referred to as Kiesselbach’s plexus. This area of nasal septum is the commonest site of epistaxis (nose bleeding) in kids and young adults generally because of finger nail trauma following deciding of the nose ( local), or systemic (such as hypertension).  Vascular Supply of the Nasal Cavity - Veins The veins generally correspond to the arteries The veins of the nose tend to follow the arteries. They drain into the pterygoid plexus, facial vein or cavernous sinus. “In some individuals, a few nasal veins join with the sagittal sinus (a dural venous sinus). This represents a potential pathway by which infection can spread from the nose into the cranial cavity”.  Venous Drainage A well-developed cavernous plexus lies deep to the mucous membrane The plexus is more marked in the region of little’s area It drains into the following series of veins: Emissary: Vein from the cavernous plexus in the nasal cavity passes through the foramen cecum to drain into the superior sagittal sinus Sphenopalatine v. Anterior ethmoid v. Posterior ethmoid v. Septal branch of the superior labial v. VENOUS DRAINAGE OF to superior sagittal sinus NASAL CAVITY The veins of nasal cavity drain into: Superior sagittal sinus Facial vein Pterygoid venous plexus Cavernous sinus  Clinical Relevance – Danger Triangle of the Face The venous drainage of the nose and surrounding area is unique as a result of communication between the facial vein and cavernous sinus, via the ophthalmic vein. As the cavernous sinus lies within the cranial cavity, this enables infections from the nasal area to spread to the brain. This retrograde spread of infection can therefore cause cavernous sinus thrombosis, meningitis or brain abscess.  Nerve Supply of the Nasal Cavity The nasal cavity is supplied by 2 major types of sensory innervation : Olfactory nerve: Carry sense of smell (special visceral afferent) from olfactory region of nasal cavity. General sensation: (General somatic afferent) via ophthalmic and maxillary divisions of the trigeminal nerve  Nerve Supply of the Nasal Cavity The olfactory nerve for the sense of smell The olfactory bulb, part of the brain, lies on the superior surface of the cribriform plate, above the nasal cavity. Branches of the olfactory nerve run through the cribriform plate to provide special sensory innervation to the nose.  Nerve Supply of the Nasal Cavity Ophthalmic division (sensory) – Gives off anterior ethmoidal n. from the Nasociliary n. Maxillary division (sensory) Infraorbital Nasopalatine from Pterygopalatine ganglion Posterior inferior lateral nasal arises from greater palatine n. Posterior superior nasal gives off lateral and medial branches – arises from pterygopalatine ganglion They carry sensations of touch, temperature and pain from respiratory region and vestibule of nasal cavity. Posterior superior lateral nasal nerve Enters the nasal cavity by way of the sphenopalatine foramen. Named for the region of the lateral nasal wall that they innervate. Sensory nerve of the nasal septum Nerve Supply of the Nasal Septum  Clinical Relevance: Cribriform Plate Fracture A fracture of the cribriform plate can occur as a result of nose trauma. It is either fractured directly by the trauma, or by fragments of the ethmoid bone. A fractured cribriform plate can penetrate the meningeal linings of the brain, causing leakage of cerebro-spinal fluid. Exposing the brain to the outside environment like this increases the risks of meningitis, encephalitis and cerebral abscesses. The olfactory bulb lies on the cribriform plate and can be damaged irreversibly by the fracture. In this case, the patient may present with anosmia (loss of smell).  Thin bone at the junction of the fovea ethmoidalis of the ethmoid sinus and the middle turbinate is an area of injury Rhinorrhoea CSF leak causing CSF leak. Nasal cavity: Lymphatic Drainage of Nasal Cavity Lymph from Anterior half of nasal cavity (both medial and lateral walls) is emptied into submandibular lymph nodes Posterior half into retropharyngeal lymph nodes.  Nerve Supply of the Nasal Cavity – Autonomic Nerves Autonomic nerves: Both parasympathetic and sympathetic fibres furnishing nasal cavity They are distributed through the sensory branches of the maxillary division of the trigeminal nerve via the pterygopalatine ganglion (parasympathetics) and the superior cervical ganglion (sympathetics)  Nerve Supply of the Nasal Cavity – Autonomic Nerves “continued” Autonomics travel to the glands and blood vessels of the nasal cavity Derived from Vidian’s nerve (nerve of pterygoid canal) via pterygopalatine ganglion. The parasympathetic fibres supply nasal glands and restrain nasal secretion. The sympathetic fibres, on stimulation, cause vasoconstriction.  CLINICAL SIGNIFICANCE - RHINITIS It’s the inflammation of mucus membrane lining the nasal cavity. The hypertrophy of mucosa over inferior concha is a familiar characteristic of allergic rhinitis. Medically it presents as: nasal blockage, sneezing and water discharge from nose (rhinorrhea). The excessive rhinorrhea on account of vasomotor and allergic rhinitis can be restrained by sectioning the Vidian nerve.  Anterior rhinoscopy Posterior rhinoscopy CLINICAL SIGNIFICANCE EVALUATION OF THE NASAL CAVITY (RHINOSCOPY) The nasal cavity can be analyzed in the living individual either via the nostril (anterior rhinoscopy) or via the pharynx (posterior rhinoscopy). THANK YOU