nose and pns anatomy

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.

52. The Paranasal Sinuses

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