Is the nasal cavity closely relatedto our practice ?? Why did a patient experience bubbling of blood and escape of fluids through his nostril following extraction of his second upper molar ???
Functions A passageway for air to lungs Organ of smell Filters impurities from inspired air Warms and humidifies inspired air Aids in phonation Receives secretions from paranasal sinuses Receives secretions from nasolacrimal duct
Bony framework Nasal bone Frontal process of the maxilla Nasal process of the frontal bone
Bony Framework: Nasal Bone The two nasal bones form the upper part of the bridge of the nose. Each nasal bone is quadrilateral, being longer than it is wide. The superior border articulates with the nasal part of the frontal bone. The inferior border forms the superior boundary of the anterior nasal aperture. The lateral border meets the frontal process of the maxilla and the medial border meets its fellow in the midline.
Bony Framework:Frontal process of the maxilla The frontal process of the maxilla projects postero-superiorly from the body of the maxilla and is situated between the nasal bone in front and the lacrimal bone behind. The process articulates apically with the frontals nasal part, the anterior border with the nasal bone and the posterior border with the lacrimal bone.
Bony Framework:Nasal process of the frontal bone
Bony Framework:Nasal process of the frontal bone The nasal part of the frontal bone is a small, thin plate of bone that projects antero-inferiorly in the midline between the supra-orbital margins and forms a small portion of the roof of the nose.
Cartilaginous framework• Lateral Superior Nasal cartilage• Greater Lower Nasal Cartilages• Minor Alar Cartilages• Septal Nasal Cartilages
Lateral Superior & Greater Nasal cartilages The lateral (upper) nasal cartilages and the greater (lower) nasal cartilages support the lateral surfaces of the external nose. The lateral nasal cartilages are triangular plates. They are united in the midline with each other and with the septal cartilage.
Minor Alar Cartilages The minor alar cartilages are found at the back of the major nasal cartilages, embedded in fibrous tissue that connects them to the maxilla. Function Extend to maintain the patency of the anterior nares.
Septal Nasal Cartilages The cartilaginous elements form the lower part of the external nose and in the midline lies the septal cartilage. It is quadrangular and fits posteriorly into the notch between the perpendicular plate of the ethmoid bone and the vomer. The septal cartilage is also attached to the nasal crest of the maxilla and to the anterior nasal spine. The septal cartilage at the apex of the external nose is termed the columella. The columella can also be defined as the tip of the mobile part of the septum.
The entire nasal cavity extends from the nares (nostrils) anteriorly to the choanae posteriorly Choanae •It is divided into 2 parts by an osseocartilaginous nasal septum
Each half of the nasal cavity has a: Floor Roof Lateral wall Septal wall
The Floor Palatine process maxilla Horizontal plate palatine bone(the superior surface of the hard palate) http://www.netterimages.com/images/vtn/000/000/001/1966-150x150.jpg
The Roof Narrow Formed by a number of bones and cartilagesNasal Cartilages, Nasal, Frontal, Ethmoid,Sphenoid Bones
The Nasal Septum (the medial wall)Divides the nasal cavity into right and left halves It is part osseous and part cartilaginous Perpendicular Plate (ethmoid) Septal Cartilage Vomer
The Lateral WallsMarked by 3 projections: ◦ Superior concha ◦ Middle concha ◦ Inferior concha The area below each concha is referred to as a meatus (passageway).
Paranasal Sinuses are air containing bony spaces around the nasal cavity Usually lined by respiratory mucous membrane of ciliated columnar epithelium
Four pairs of paranasal sinuses surround the nasal cavities and are named from the bones in which they are located: maxillary, frontal, sphenoid, and ethmoid sinuses.
The maxillary sinuses are located lateral to the nasal cavities. Each of the two sinuses is pyramidal in shape with the apex of each located near the zygomatic bone.
The maxillary sinus is the first of the paranasal sinuses to develop, and its growth ends with the eruption of the third molars at approximately 20 years of age
Roof: The roof of the sinus is part of the floor of the orbit and contains the infra-orbital canal, which transmits the infra-orbital nerve and vessels.
Floor The alveolar process and part of the palatine process of the maxilla form the floor of the sinus, which lies below the level of the floor of the nose and is related to the roots of the teeth.
Apex: The apex extends into the zygomatic process of the maxilla.Anterior wall The anterior wall of the maxillary sinus is the facial surface of the maxilla.
Posterior wall The posterior wall is the infratemporal surface of the maxilla. The posterior superior alveolar nerve and vessels pass through canals in the posterior surface of the sinus.
Medial wall: The base or medial wall forms part of the lateral wall of the nose and has the opening (ostium) of the sinus.
√ Size varies from one person to another.√ Asymmetry existed in the same individual.√ Small in children and grows up with aging.√ Average height is about 3.5 cm, depth 3.2 cm and width 2.5 cm.√ Capacity of about 15 cc.
√ Divided into several compartments by bony septa (underwood’s septa).√ Lined with pseduo-stratified columnar ciliary epithelium.
Pneumatization is the enlargement of the sinus by resorption of the alveolar bone that formerly served to support a tooth or teeth
What might be the clinical implications of maxillary sinus pneumatization ??
Each maxillary sinus communicates with the nasal cavity by the ostium which opens into the middle nasal meatus under the overlapping middle nasal turbinate. Although the ostium is located at a higher level than the floor of the maxillary sinus, the normal sinus drains satisfactorily because of the action of the cilia of the pseudostratified columnar epithelium.
Kilic C et al, An Assessment of the Relationship between the Maxillary Sinus Floor and the Maxillary Posterior Teeth Root Tips Using Dental Cone-beam Computerized Tomography, Eur J Dent. 2010 October; 4(4): 462–467.
Mean, standard deviation, minimum and maximum values obtained fromright premolar and molar teeth. N Mean Std. Dev. Minimum Maximum R 1st pm 87 8.42 9.10 −1.32 28.52 R 2nd pm 87 3.75 6.67 −21.00 23.70 R 1st mo bm 87 1.77 6.10 −5.41 27.55 R 1st mo bd 87 0.70 4.69 −4.71 27.17 R 1 st mo pal 87 1.86 6.06 −4.22 29.46 R 2nd mo bm 87 0.42 2.85 −5.06 16.45 R 2nd mo bd 87 0.25 2.17 −5.97 8.76 R 2nd mo pal 87 1.06 2.36 −4.52 9.57 R 3rd mo bm 87 1.63 3.33 −2.67 8.41 R 3rd mo bd 87 0.62 3.40 −3.50 8.48 R 3rd mo pal 87 0.92 3.32 −2.87 8.54
Their results showed that the distance between sinus floor and root tip was longest for the first premolar root tip and shortest for the second molar buccodistal root tip for both right and left sides. No statistically significant differences were found between the right and left side measurements or between female and male patients (P>.05).
Ethmoid Air Sinus The ethmoid sinus is each of the two paranasal sinuses within the ethmoid bone, comprising the ethmoidal air cells and filled with air. They lie between the upper parts of the nasal cavities and the orbits, and are separated from these cavities by thin bony laminae.
Sphenoid Air Sinus The two sphenoidal sinuses are contained within the body of the sphenoid and they vary in size and shape; owing to the lateral displacement of the intervening septum.
Functions of Paranasal Sinuses Humidifying and warming inspired air Regulation of intranasal pressure Increasing surface area for olfaction Lightening the skull Resonance Absorbing shock
Frontal SinusWithin the frontal bone are two funnel-shaped cavities, termed the frontal air sinuses .They lie above and behind the superciliary arches immediately abovethe roof of the nasal cavity and may extend into the medial part of theroof of the orbit. In such cases, a thin layer of bone separates the sinusfrom the floor of the cranial cavity and from the roof of the orbit.