Anat class nose on dec7
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The document discusses the anatomy and development of the nose and paranasal sinuses. It describes how the nose develops from embryonic structures and the formation of the nasal cavity, septum, and external nose. It then covers the anatomy of the different areas of the nose in detail, including the vestibule, muscles, bones/cartilages, blood supply, nerves and lymphatic drainage. Finally, it discusses the anatomy of each paranasal sinus, including the sphenoid sinus and its variations in pneumatization.
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Anat class nose on dec7
- 1. Anatomy of the nose and paranasal sinuses
- 2. DEVELOPMENT OF NOSE AND PARANASAL SINUSES • The nasal cavity, is first recognizable in the 5.6 mm (crown-rump distance) embryo in the fourth intrauterine week as the olfactory or nasal placode, a thickening of the ectoderm above the stomatodaeum. • This placode sinks to form the olfactory pit lying between the proliferating mesoderm of the medial and lateral nasal folds of the frontonasal process. This deepens to form the nasal sac by the fifth week.
- 3. • the maxillary process of the first branchial arch grows anteriorly and medially to fuse anteriorly with the medial nasal folds and the frontonasal process which closes the nasal pits off to form widely separated primitive, nasal cavities ). • The primitive nasal cavity and mouth are separated initially by a bucconasal membrane.
- 4. • The lateral nasal folds also form the nasal bones, upper lateral cartilages and lateral crus of the lower lateral cartilages. • The primitive palate begins to form anteriorly with fusion of the maxillary and frontonasal processes by the 13.5 mm embryo stage. • A midline ridge develops from the posterior edge of the frontonasal process in the roof of the oral cavity and extends posteriorly to the opening of Rathke's pouch.
- 6. VESTIBULE AND SKIN • The vestibule is the dilated passageway leading from the external nares into the nasal fossae demarcated by the limen nasi, at the superior margin of the lower lateral cartilage. • It is lined by skin bearing coarse hairs or vibrissae (though without erector muscles), sebaceous glands and sweat glands.
- 7. MUSCLES OF THE EXTERNAL NOSE • The nose has a number of muscles which, in man, have assumed an almost vestigial importance. • As muscles of facial expression, they are all supplied by branches of the facial nerve.
- 9. The supporting framework of the external nose • composed of a bony skeleton provided by the nasal bones, frontal processes of the maxillae and nasal part of the frontal bone and a cartilaginous framework consisting of septum, upper and lower lateral cartilages and a variable number of minor accessory alar cartilages.
- 11. NASAL BONES • The nasal bones unite with each other in the midline, with the frontal bone superiorly at the nasofrontal suture and laterally with the frontal process of the maxilla at the nasolacrimal suture. • They are supported by the nasal spine of the frontal bone and by the perpendicular plate of the ethmoid, both of which groove the bones.
- 12. PYRIFORM APERTURE • The pyriform aperture is bounded below and laterally by the maxilla, and above by the nasal bones. • The anterior nasal spine lies in the middle of inferior border. It can be up to 15 mm in length and is related superiorly to the anteroinferior free end of the septal cartilage.
- 13. CARTILAGES OF THE EXTERNAL NOSE AND COLUMELLA • The nasal cartilages are composed of hyaline cartilage which may be ossified. • The groove between the upper and lower lateral cartilages is known as the limen nasi, which is the site of intercartilaginous incisions.
- 14. • The lower lateral or alar cartilages form the lower third of the nose. They are each composed of a medial and lateral crus which meet at the dome of the tip. • The part of the septum running between the tip of the nose and philtrum is called the columella.
- 15. BLOOD SUPPLY • Branches of the facial artery supply the alar region while the dorsum and lateral walls of the external nose are supplied by the dorsal branch of the ophthalmic artery and the infraorbital branch of the maxillary. • The frontomedian area drains to the facial vein and the orbitopalpebral area to the ophthalmic vein with interconnections to the anterior ethmoidal system and thence cavernous sinus which can be of clinical significance.
- 16. NERVE SUPPLY • The skin of the external nose receives its sensory supply from the two upper divisions of the trigeminal nerve; ophthalmic and maxillary.
- 17. LYMPHATIC DRAINAGE • submandibular and submental nodes, with buccal nodes adjacent to the facial vein sometimes intervening.
- 18. Nasal cavity • The nasal cavity extends from the external nares or nostrils to the posterior choanae. • Its anterior three-quarters are composed of the palatine process of the maxilla, its posterior one- quarter by the horizontaI process of the palatine bone. • Approximately 12 mm behind the anterior end of the floor is a slight depression in the mucous membrane overlying the incisive canals. This contains the terminal branches of the nasopalatine nerve, the greater palatine artery and a short mucosal canal (Stenson's organ).
- 19. ROOF • The roof is narrow from side to side, except posteriorly, and may be divided into frontonasal, ethmoidal and sphenoidal parts, related to the respective bones. • As both the frontonasal and sphenoidal parts of the roof slope downwards, the highest part of the nasal cavity relates to the cribiform plate of the ethmoid which is horizontal.
- 20. Nasal septum
- 21. HISTOLOGY • The mucous membrane is predominantly respiratory with a small area of olfactory epithelium superiorly adjacent to the cribriform plate. • Respiratory epithelium is composed of ciliated and nonciliated pseudostratified columnar cells, basal pluripotential stem cells and goblet cells.
- 22. • Seromucinous glands are found in the submucosa and are more important in mucus production in the nasal cavity than the goblet cells which are more numerous in the sinuses.
- 23. • Blood supply
- 24. • Cavernous venous system drains via the sphenopalatine vessels into the pterygoid plexus posteriorly and into the facial veins anteriorly. Superiorly, the ethmoidal veins communicate with the superior ophthalmic system and there may be direct intracranial connections through the foramen caecum into the superior sagittal sinus.
- 26. • Nerve fibres arising from the olfactory receptors are slim and nonmyelinated. They join up into approximately 20 bundles which traverse the cribiform plate to reach the olfactory bulbs. • Each bundle carries a tubular sheath of dura and pia-arachnoid, which may be sheared in head injuries, destroying olfaction and potentially producing cerebrospinal fluid leakage.
- 28. The lateral nasal wall INFERIOR MEATUS • The inferior meatus is the largest meatus, extending almost the entire length of the nasal cavity. • The nasolacrimal duct opens into the inferior meatus usually just anterior to its highest point. There is no true valve, the opening being covered by small folds of mucosa.
- 29. INFERIOR TURBINATE • This structure is composed of a separate bone, the inferior concha. • The bone has a maxillary process which articulates with the inferior margin of the maxillary hiatus. It also articulates with the ethmoid, palatine and lacrimal bones, completing the medial wall of the nasolacrimal duct.
- 30. MIDDLE MEATUS • The middle meatus is that portion of the lateral nasal wall lying lateral to the middle turbinate. • It receives drainage from the frontal, maxillary and anterior ethmoidal sinuses.
- 31. ETHMOIDAL INFUNDIBULUM • The ethmoidal infundibulum is a cleft-like, three dimensional space in the lateral wall of the nose that belongs to the anterior ethmoid. • The medial wall of the space is provided by the entire extent of the uncinate process and its mucosal covering. • The major part of the lateral wall of the ethmoidal infundibulum is provided by the lamina papyracea of the orbit, with the frontal process of the maxilla and, in rare cases, the lacrimal bone providing the remainder anterior and superiorly.
- 32. • The posterior border of the ethmoidal infundibulum is composed largely of the anterior surface of the ethmoidal bulla, in front of which the infundibulum opens into the middle meatus through the inferior hiatus semilunaris.
- 33. • If a terminal recess of the ethmoidal infundibulum is present, the ethmoidal infundibulum and frontal recess are separated from each other in this region. The frontal recess then opens into the middle meatus medial to the ethmoidal infundibulum between the uncinate process and the middle turbinate. Ventilation and drainage of the frontal sinus then run medial to the ethmoidal infundibulum. • If the uncinate process reaches the skull base or turns medially, the frontal recess and consequently the frontal sinus open directly into the superior part of the ethmoidal infundibulum.
- 35. • The maxillary sinus ostium is located in the medial wall of the ethmoidal infundibulum, at the transition of its middle to posterior third.
- 36. HIATUS SEMILUNARIS • Depression seen from a medial view lying between the free posterior margin of the uncinate process and the anterior surface of the ethmoidal bulla. • From the middle meatus, through this 'two- dimensional' cleft, the three-dimensional space of the ethmoidal infundibulum can be approached. • Grunwald described a second hiatus semilunaris, the superior hiatus semilunaris. This cleft lies between the ethmoidal bulla and the frontal portion of the basal lamella of the middle turbinate.
- 37. THE AGGER NASI • It is represented by a small crest or mound on the lateral wall just anterior to the attachment of the middle turbinate.
- 38. FRONTAL RECESS • The term 'frontonasal duct‘ has been generally abandoned as no true duct exists. • frontal recess may be defined as follows: • • medial: middle turbinate; • • lateral: lamina papyracea, lacrimal bone; • • superior: skull base; • • inferior: dependent upon the attachment of the uncinate process; • • pneumatization of agger nasi cells.
- 39. THE ETHMOIDAL BULLA • This is one of the most constant features in the middle meatus containing the largest anterior ethmoidal cell • it may be poorly aerated or completely unpneumatized in 8 percent of patients, hence its alternative nomenclature of torus lateralis (lateral bulge ).
- 40. • Posteriorly the bulla may fuse with the basal lamella of the middle turbinate and superiorly it may reach the roof of the ethmoids forming the posterior wall of the frontal recess. • Sometimes a cleft is encountered between the posterior wall of the bulla and the basal lamella of the middle turbinate, the retrobullar recess. The space between it and the ethmoidal roof is called the suprabullar recess which may connect anteriorly with the frontal recess if the bulla does not reach the skull base. • Suprabullar and retrobullar recess may be continguous or may be separated by complete or incomplete bony septations.
- 41. ROOF OF ETHMOID COMPLEX AND ANTERIOR ETHMOIDAL ARTERY • In a disarticulated dry skull) the ethmoid bone is open superiorly, at Least over its anterior two-thirds. The bony cover for these open clefts and cells of the ethmoid is provided by the frontal bone, which covers these open spaces with its foveolae ethmoidales (ossis frontalis) . • In this area, the frontal bone is both thicker and denser than the adjacent bony ethmoidal structures. This difference is greatest medially, in the transition from the thicker bony lamellae of the frontal bone to the much thinner lateral lamella of the cribriform plate.
- 42. • Anterior ethmoidal artery in its course from the orbit to the olfactory fossa and back into the nasal cavity traverses three compartments of the head: the orbit, the ethmoidal Labyrinth, the anterior cranial fossa and finally down into the nose again.
- 43. SUPERIOR MEATUS • This meatus is again defined by its relationship to the superior turbinate. The posterior ethmoidal cells open into this region. POSTERIOR ETHMOID COMPLEX • The ground lamella of the middle turbinate is the border between anterior and posterior ethmoidal sinuses. • The number of cells that make up the posterior ethmoid varies between one and more than five.
- 44. • SPHENOETHMOIDAL RECESS • The sphenoethmoidal recess lies medial to the superior turbinate and is the location of the ostium of the sphenoid sinus.
- 45. BLOOD SUPPLY OF THE LATERAL WALL • The external and internal carotid arteries supply the lateral wall. • The sphenopalatine artery (from the maxillary artery and thus external carotid artery) contributes the majority of the supply to the turbinates and meatus. It enters through the sphenopalatine foramen which lies just inferior to the horizontal attachment of the middle turbinate and may be damaged in excessive enlargement of a middle meatal antrostomy. Its branches to the respective turbinates and meatus enter posteriorly.
- 46. VENOUS DRAINAGE • Vascular supply to the nose is well-developed and this is enhanced by cavernous plexus found in the lamina propria, in particular on the inferior and middle turbinates, which is controlled autonomically.
- 47. • Venous drainage is to the sphenopalatine veins via facial and ophthalmic vessels, intracranially via the ethmoidal veins to veins on the dura and to the superior sagittal sinus via the foramen caecum.
- 49. NERVE SUPPLY OF THE LATERAL WALL • Apart from the olfactory supply on the superior concha, the lateral wall receives ordinary sensation from the anterior ethmoidal nerve anterosuperiorly and from branches of the pterygopalatine ganglion and anterior palatine nerves posteriorly . • There is a small area innervated by the infraorbital nerve anteriorly and an area of overlap between the ethmoidal and maxillary nerves. • The anterior superior alveolar nerve sends a small branch to the anterior inferior meatus which may be damaged in inferior meatal surgery.
- 51. LYMPHATIC DRAINAGE OF THE LATERAL WALL • The lateral wall drains with the external nose to the submandibular nodes anteriorly and to the lateral pharyngeal, retropharyngeal and upper deep cervical nodes posteriorly.
- 53. The sphenoid bone and sinuses • OSTEOLOGY • The sphenoid bone is the largest in the skull base and divides the anterior and middle cranial fossa. It is composed of a body (pneumatized to a variable degree), two wings (greater and lesser) and two inferior plates (lateral and medial pterygoid plates).
- 55. • Four general forms of pneumatization are described: • 1. Conchal pneumatization, with only a rudimentary sinus (2-3 percent) . • 2. Presellar, in which the sinus is pneumatized as far as the anterior bony wall of the pituitary fossa ( 1 1 percent) . • 3. Sellar, in which pneumatization extends back beneath the pituitary fossa ( 59 percent) . • 4. Mixed (27 percent) .
- 57. • The greater wings contribute to the middle cranial fossa and lateral wall of the orbit. The superior orbital fissure separates it from the lesser wing on each side; the inferior border contributes to the inferior orbital fissure.
- 59. • In addition, the bone is traversed by a number of foramina. • The foramen rotundum transmits the maxillary nerve, the foramen ovale the mandibular nerve, accessory meningeal artery and sometimes the lesser petrosal nerve, and the middle meningeal artery passes through the foramen spinosum with a meningeal branch of the mandibul ar nerve.
- 61. • The optic nerve and internal carotid artery produce variable prominences in the lateral and posterior walls of the sinus, with an intervening deft which can be deep. BLOOD, NERVES AND LYMPHATIC DRAINAGE • The sphenoid sinuses are supplied by the posterior ethmoidal vessels and nerves, with additional supply from the orbital branches of the pterygopalatine ganglion. • Lymphatics drain to the retropharyngeal nodes
- 62. The frontal bone and sinuses • OSTEOLOGY • The frontal bone forms the forehead and orbital roof • It forms the roof of the ethmoidal sinuses, which produce individual impressions upon the frontal bone, the fovea ethmoidales ossis frontalis. • The sinus is usually L shaped, composed of a horizontal and a vertical and incomplete septa are frequently encountered. • Intersinus septum is usually present
- 63. • BLOOD, NERVES AND LYMPHATIC DRAINAG E • The supraorbital and anterior ethmoidal arteries supply the frontal sinuses. • Venous drainage superior ophthalmic vessels. • The nerve supply is derived from the supraorbital nerve • Lymphatics drain to the submandibular gland.
- 64. • OSTEOLOGY • The maxilla is the second largest facial bone, forming the majority of the roof of the mouth, the lateral wall and floor of the nasal cavity and the floor of the orbit. The body is usually described as a quadrilateral pyramid, and contains the maxillary sinus. • The bone has four processes: zygomatic, frontal, palatine and alveolar.
- 65. • The roof of the maxillary sinus forms most of the orbital floor. It is traversed by the infraorbital canal, which may be dehiscent. • The posterior, infratemporal surface of the bone is convex and grooved by the posterior superior alveolar nerves. Inferiorly, it bears the maxillary tuberosity from which the medial pterygoid muscle takes a small attachment. • The medial nasal surface forms the floor of the pyramid and contains a large defect, the maxillary hiatus. This is completed in life by a number of bones and mucous membrane leaving the natural maxillary ostium at the base of the ethmoidal infundibulum.
- 66. • HISTOLOGY • The maxillary sinus is lined by ciliated columnar epithelium which contains the highest density of goblet cells compared to the other paranasal sinuses
- 67. • BLOOOD, NERVES AND LYMPHATIC DRAINAG E • Small branches of the facial, maxillary, infraorbital and greater palatine arteries and veins supply the maxilla. • Venous drainage is to the anterior facial vein and pterygoid plexus. • The maxillary division of the trigeminal nerve supplies sensation via the infraorbital, superior alveolar (anterior, middle and posterior) and greater palatine nerves.
- 68. References • Scott brown 7th edition