Nasal cavity and Paranasal Air Sinuses
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The nasal cavity and paranasal air sinuses are described. The nasal cavity has 3 regions and is separated from other structures by bones. Each side has a roof, floor, medial and lateral wall. The lateral wall contains conchae that increase surface area. Paranasal sinuses include the frontal, ethmoidal, sphenoidal and maxillary sinuses. They are described in terms of location, openings, blood supply and innervation.
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Nasal cavity and Paranasal Air Sinuses
- 1. NASAL CAVITY & PARANASAL AIR SINUSES Dr. Prabhakar Yadav Associate Professor (MBBS, MS) Department of Human Anatomy B.P. Koirala Institute of Health Sciences
- 2. NASAL CAVITY • communicates with the exterior through nostril (or naris) and with the nasopharynx through the posterior nasal aperture or the choanae nasal cavities are separated: •from each other - midline nasal septum •from oral cavity - hard palate •from cranial cavity- a parts of the frontal, ethmoid & sphenoid bones. •Lateral to nasal cavities are the orbits •Each nasal cavity has a floor, roof, medial wall, and lateral wall
- 3. Each nasal cavity consists of three regions Nasal vestibule : •small dilated space just internal to the naris • lined by skin and contains hair follicles; Respiratory region: • largest part of the nasal cavity, • has a rich neurovascular supply, • lined by respiratory epithelium; Olfactory region : • small, is at the apex of each nasal cavity, • lined by olfactory epithelium, and contains the olfactory receptors
- 4. 5cm 5-7cm 1.5cm 1-2 mm Roof : • slopes downwards, both in front and behind. • middle horizontal part : formed by the cribriform plate of the ethmoid. • Anterior slope is formed by the nasal part of frontal bone, nasal bone, and nasal cartilages. • posterior slope: formed by inferior surface of body of the sphenoid bone.
- 5. 5cm 5-7cm 1.5cm 1-2 mm Floor: Formed by: • Palatine process of the maxilla •Horizontal plate of the palatine bone.
- 6. Medial wall: • median osseocartilaginous partition between the two nasal cavities. Bony part is formed by: (a) perpendicular plate of ethmoid- (b) Vomer - contributions from: •Nasal spine of the frontal bone, •Rostrum of sphenoid, and •Nasal crests of nasal, palatine & maxillary bones.
- 8. cartilaginous part is formed by : (a) septal cartilage - forms major anterior part (b) septal processes (medial crura) of the two major alar cartilages Cuticular part or lower end: formed by :-fibrofatty tissue covered by skin. The lower margin of septum is called the columella. septum has: (a) four borders: superior, inferior, anterior and posterior; and (b) two surfaces: right and left.
- 9. Arterial Supply of Nasal Septum Anterosuperior part: Anterior & posterior ethmoidal artery (opthalmic art.) Anteroinferiorpart: superior labial branch of facial artery. Posterosuperior part: Sphenopalatine artery (Maxillary Artery) Posteroinferior part: greater palatine artery (Maxillary Artery) Anteroinferior part contains anastomoses between 1. Branches of anterior ethmoidal artery. 2. (septal ramus of) superior labial branch of the facial artery, 3. Branch of sphenopalatine artery, 4. Branches of greater palatine artery This is a common site of bleeding from the nose or epistaxis, and is known a Little's area. capillary network called Kiesselbach's plexus
- 10. Venous Drainage: • veins form a plexus • drains anteriorly into facial vein • posteriorly through shenopalatine vein to pterygoid venous plexus.
- 11. I. General sensory nerves- trigeminal nerve, are distributed to whole of the septum •Anterosuperior part: Internal nasal branch of the anterior ethmoidal nerve. •Anteroinferior part: Anterior superior alveolar nerve •posterosuperior part: Medial posterior superior nasal branches of the pterygopalatine ganglion • posteroinferior part: Nasopalatine Nerve of the pterygopalatine ganglion. II. Special sensory nerves or olfactory nerves :confined to olfactory area.
- 12. Lateral Wall : Bones forming the lateral wall: (a) nasal, (b) frontal process of maxilla, (c) lacrimal, (d) conchae and labyrinth of ethmoid, (e) inferior nasal concha, (f) perpendicular plate of palatine, and (g) medial pterygoid plate of sphenoid. Lateral Wall of Nose : -partly bony, -partly cartilaginous and -partly made up only of soft tissues • conchae: increase surface area for air-conditioning of inspired air.
- 13. Cartilages forming the lateral wall are: (a) lateral cartilage (superior lateral nasal cartilage), (b) major alar cartilage (inferior lateral nasal cartilage), and (c) three to four tiny cartilages of the alae (minor alar cartilages).. Cuticular lower part: formed by fibrofatty tissue covered with skin.
- 14. Lateral wall - subdivided into three parts. (a) Anterior part (vestibule): small depressed area, lined by modified skin containing short, stiff, curved hairs called vibrissae. (b) Middle part: is known as atrium of the middle meatus (c) posterior part :contains conchae. Spaces separating the conchae are called meatuses curved mucocutaneous junction between the atrium and vestibule is known as limen nasi
- 15. Chonchae and Meatuses: • nasal conchae are curved bony projections directed downwards and medially. 1. Inferior concha (largest) is an independent bone. 2. Middle concha & superior concha(Smallest) : projection from the medial surface of the ethmoidal labyrinth. Sphenoethmoidal recess: triangular depression, above & behind the superior concha
- 16. Meatuses: passages beneath overhanging conchae. 1. Inferior meatus: largest and lies underneath the inferior nasal concha. 2. Middle meatus: lies underneath the middle concha. Features: a) Ethmoidal bulla (bulla ethmoidalis): round elevation produced by underlying middle ethmoidal sinuses. (b) Hiatus semilunaris: semicircular sulcus below the Ethmoidal bulla . (c) Infundibulum: short passage at the anterior end of middle meatus. 3. Superior meatus : smallest and lies below the superior concha
- 17. Openings in lateral wall:
- 18. Openings in lateral wall:
- 19. 1. Anterosuperior quadrant: anterior ethmoidal artery, a branch of ophthalmic artery. 2. Anteroinferior quadrant: branches of facial and greater palatine arteries. 3. Posterosuperior quadrant: sphenopalatine artery, a branch of maxillary artery. 4. Posteroinferior quadrant: branches of greater palatine artery, which pierces the perpendicular plate of palatine. Venous Drainage: Veins form plexus Drain into •facial vein, • pterygoid venous plexus, and • pharyngeal venous plexus.
- 21. Lymphatic Drainage: (Of both medial and lateral walls) • Anterior half : drained into submandibular lymph nodes • Posterior half: into retropharyngeal lymph nodes
- 22. I. General sensory nerves derived from the branches of trigeminal nerve are distributed to whole of the lateral wall: 1. Anterosuperior quadrant: Anterior ethmoidal nerve branch of ophthalmic nerve. 2. Anteroinferior quadrant:Anterior superior alveolar nerve, branch of maxillary nerve. 3. posteriorsuperior quadrant: Lateral posterior superior nasal branches of pterygopalatine ganglion suspended by the maxillary nerve 4. posteroinferior quadrant: Nasal branch of greater palatine nerve branch from pterygopalatine ganglion suspended by the maxillarynerve.
- 23. II. Special sensory nerves or olfactory Nerve: distributed to the upper part of the lateral wall ,below the cribriform plate of the ethmoid up to the superior concha
- 25. Paranasal air sinuses: Air-containing cavities in the bones around the nasal cavity Sinuses -- two spurts of growth All sinuses are present in rudimentary form at birth except frontal air sinuses- deveplops at 2/3 years.
- 26. Functions: 1. Make the skull lighter. 2. Add resonance to the voice. 3. Act as air conditioning chambers for inspired air. 4. Aid in the growth of facial skeleton after birth. Clinically sinuses are divided into: Anterior group: that drain into the middle meatus Posterior group: that do not drain into the middle meatus
- 27. Frontal sinus: • lies in the frontal bone deep to the superciliary arch • opens into the middle meatus at anterior end of the hiatus semilunaris • are usually unequal in size Innervated by: supra-orbital nerve (ophthalmic nerve V1) Arterial supply: supraorbital artery- branches of the anterior ethmoidal arteries Lymphatic drainage: Submandibular Lymph node
- 28. Sphenoidal sinuses: • lie within the body of the sphenoid bone • Opens into the sphenoethmoidal recess • are unequal in size Relations Above: Pituitary gland and optic chiasma. Lateral: Cavernous sinus and internal carotid artery (on each side) Below and in front: Nasal cavities
- 29. Nerve Supply: Posterior ethmoidal nerve (branch of the ophthalmic nerve) Maxillary nerve via orbital branches of pterygopalatine ganglion Arterial supply: Posterior ethmoidal & internal carotid arteries. Venous drainage: Into pterygoid venous plexus and cavernous sinus. Lymphatic drainage: Retropharyngeal nodes.
- 30. Ethmoidal air sinuses: are made up of a number of air cells present within the labyrinth of ethmoidal bone 1.Anterior, consisting of up to 11 cells. --- opens in the hiatus semilunaris 2. Middle, consisting of 1–3, cells. ---- opens on the surface of bull ethmoidalis 3. Posterior, consisting of 1–7 cells. ------- opens in posterior part of superior meatus
- 31. Anterior ethmoidal sinus: Supplied by the anterior ethmoidal nerve and vessels. Middle & posterior ethmoidal sinus: supplied by the posterior ethmoidal nerve and vessels & orbital branches of the pterygopalatine ganglion Anterior & middle ethmoidal sinus- Lymphatic drainage- Submandibular lymphnode posterior ethmoidal sinus- Lymphatic drainage- retropharyngeal lymphnode
- 32. MAXILLARY SINUS: • Largest of paranasal air sinuses, • First to develop --4th month of IU life • Opens in hiatus semilunaris (posterior part) of the middle meatus pyramidal in shape with the base directed medially Roof: Formed by floor of orbit. Infraorbital nerve & artery traverse the roof in a bony canal. Floor: formed by the alveolar process of maxilla, marked by several conical elevations produced by the roots of the upper molar and premolar teeth. Base: formed by lateral wall of the nose; possesses ostium of the sinus in its upper part
- 33. Apex: extends into zygomatic process of maxilla. Anterior wall: Formed by anterior surface of the body of maxilla. Posterior wall: Formed by the infratemporal surface of maxilla, separating the sinus from the infratemporal and pterygopalatine fossae Arterial Supply By anterior, middle &posterior superior alveolar arteries from maxillary & infraorbital arteries. Nerve Supply By anterior, middle & posterior superior alveolar nerves from maxillary & infraorbital nerves.
- 34. Maxillary hiatus: is reduced in size by following bones: 1. Uncinate process of ethmoid, from above. 2. Descending process of lacrimal, from in front. 3. Maxillary process of inferior nasal concha, from below. 4. Perpendicular plate of palatine from behind.
- 35. 1. Rhinitis: Inflammation of mucus membrane lining the nasal cavity. 2.allergic rhinitis. hypertrophy of mucosa over inferior concha Presentation: nasal blockage, sneezing, and water discharge from nose (rhinorrhea). 2.Sinusitis: paranasal air sinuses may get infected from the nose. Maxillary sinusitis is commonest 3.The relations of the nose to the anterior cranial fossa through the cribriform plate, and lacrimal apparatus through the nasolacrimal duct are important in the spread of infection.
- 37. Examination of the nasal cavity (Rhinoscopy): (a) Anterior rhinoscopy: carried out by inserting a nasal speculum through a nostril. features visualized: – Middle and inferior conchae. – Superior ,middle and inferior meatuses. – Nasal septum. – Floor of the nasal cavity. (b) Posterior rhinoscopy: carried out by inserting a mirror into the pharynx
- 38. Deviated nasal septum (DNS): • important cause of nasal obstruction. •If severe, leads to difficulty in breathing, sinusitis, headache, excessive snoring, etc. • corrected by submucous resection (SMR) or septoplasty.
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