ENT-HNS

1. Dr. Satish kumar ray
ORL-HNS Resident 1st year
PoAHS,pokhara,kaski

2. Embryology of nose & PNS
 The development of the nose and paranasal sinuses
needs to be studied in conjunction with the
development of the face.
 Facial development takes place mainly between the
4th and 8th weeks of intrauterine life.
 The face develops from five facial swellings,frontonasal
process, a pair of maxillary and a pair of mandibular
processes.
 During the 5th week, a pair of ectodermal thickenings
appear on the frontonasal process called nasal
placodes

3. 5TH WEEK 6TH WEEK
7TH WEEK End of 7th week

4.  Nasal placode invaginates to form nasal pit. The raised
rims of these nasal pits form the lateral and medial
nasal processes
 Medial nasal processes move towards each other &
fuse due to medial migration of maxillary processes.
 Nasal pits deepen and coalesce to form a single cavity.
cavity is initially separated from oronasal membrane.
 This membrane ruptures during the 7th week to form
the primitive choana.
 The intermaxillary process grows backward to form
the nasal septum.

5.  The lateral nasal processes enlarge to form lateral
nasal wall which shows multiple anteroposterior
elevations. These are turbinates.
 The floor of the nasal cavity, which is the hard palate,
is formed during the 8th and 9th week. The medial
surfaces of the maxillary processes form thin medial
extensions called palatine shelves.
 The secondary palate also fuses with the lower border
of the developing nasal septum.

6. 6th week 7th week
9th week formation of definitive nasal cavity & oral cavity

7. Processes & structure formed
 Frontonasal: Forehead, bridge of nose, medial and
lateral nasal prominences
 Maxillary: Cheeks, lateral portion of upper lip
 Medial nasal :Philtrum of upper lip, crest and tip of
nose, septum
 Lateral nasal: Alae of nose, lateral nasal wall
 Mandibular :Lower lip and jaw

8. Anatomy of nose
EXTERNAL NOSE: It is pyramidal in shape with its
root up and the base directed downwards.

10.  Upper one-third of the external nose is bony while lower
two-thirds are cartilaginous.
 Bony part consists of two nasal bones which meet in the
midline and rest on the upper part of the nasal process of
the frontal bones.
Cartilaginous part
 Upper lateral cartilage: They fuse with each other and with
the upper border of the septal cartilage in the midline
anteriorly
 The lower free edge of upper lateral cartilage is seen
intranasally as limen vestibule, nasal valve or limen nasi on
each side

11.  Lower lateral cartilages (alar cartilages): It has a lateral
crus which forms the ala and a medial crus which runs
in the columella.
 Lesser alar (or sesamoid) cartilages: Two or more in
number. They lie above and lateral to alar cartilages
connected to adjoining bones by perichondrium and
periosteum.
 Septal cartilage: Its anterosuperior border runs from
under the nasal bones to the nasal tip. It supports the
dorsum of the cartilaginous part of the nose.

12.  NASAL MUSCULATURE: movements of the nasal tip,
ala and the overlying skin.
 procerus, nasalis, levator labii superioris alaequenasi,
anterior and posterior dilator nares and depressor
septi.

13.  VESTIBULE:The nasal vestibule is the anterior most
aspect of the nasal cavity and serves as the entry point
from the external nares into the nasal cavity.
 The vestibule is demarcated by the limen nasi located
at the caudal border of the lower lateral cartilage.
 It is lined by keratinizing stratified squamous
epithelium, and coarse hairs called vibrissae,
sebaceous glands and sweat glands.
 Limen nasi is where marginal incision is given for
external approach rhinoplasty.

14.  Nasal valve area: It is the least crosssectional area of
nose and regulates airflow and resistance on
inspiration.
Midline sagittal CT scan with green line
indicating the relative positions of the
external and internal
nasal valves

15. Endoscopic view of the left external nasal valve(1) septum (2) alar rim (comprised
of lower lateral
crus, sesamoid complex and fibrofatty tissue) (3) nasal sill (4)septum (5) caudal
edge of upper lateral cartilage and (6) head of inferior turbinate.
1
2
3
4
5
6

16.  Nerve supply:
(A) supratrochlear nerve
(B) infratrochlear nerve
(C) anterior ethmoid nerve
(D) infraorbitalnerve.

17.  clinical value when performing a nerve block to this
region during procedures such as rhinoplasty or closed
reduction of nasal fractures.
lymphatic drainage of the external nose is directed
towards the submandibular, submental and facial
nodes.

18. NASAL CAVITY
 Each nasal cavity has a lateral wall, a medial wall, a
roof and a floor.
 The nasal cavity extends from the external nares to the
posterior choanae, where it becomes continuous with
the nasopharynx.
 Three different types of epithelium within the nasal
cavity consist of squamous (nasal vestibule), olfactory
(superior septum,superior turbinate and upper aspect
of the middle turbinate) and respiratory (remainder of
nasal cavity) epithelium.

19. Nerve supply
The parasympathetic nerve regulates nasal secretions,
sympathetic nerve regulates vascular tone and
turbinate congestion,and the trigeminal nerve controls
nasal cavity sensation.

20. Nasal septum

21.  Nasal septum consists of three parts:
 1. Columellar Septum: formed of columella
containing the medial crura of alar cartilages united
together by fibrous tissue and covered on either side by
skin.
 Membranous Septum. It consists of double layer of
skin with no bony or cartilaginous support.
 Septum Proper. It consists of osteocartilaginous
framework, covered with nasal mucous membrane.

22.  1. the perpendicular plate of ethmoid
 2. the vomer
 3. large septal (quadrilateral) cartilage
 Minor contribution from crest of nasal bones, nasal
spine of frontal bone, rostrum of sphenoid, crest of
palatine bones and the crest maxilla and the anterior
nasal spine of maxilla.
 provides support to the tip and dorsum of
cartilaginous part of nose.

23. The lateral nasal wall
 the underlying bony processes and their articulation,
the lateral nasal wall shows a series of elevations and
depressions.

24.  lateral nasal wall is formed by eight separate bones
 four large bones; the maxilla, the frontal, the
ethmoid and the sphenoid.
 four small bones; the inferior turbinate, the
lacrimal, the palatine and the nasal bones.
 frontal, ethmoid and sphenoid are single unpaired
bone.
 Anteriorly in the area of the nostril, the lateral nasal
wall is lined by skin and has hair; this is the vestibule.
Behind this is a plain structureless area lined by nasal
mucosa called the atrium.

25.  Atrium shows bulge anterior to the middle turbinate
formed by the underlying agger nasi cell.
 Behind the atrium are inferior, middle and superior
turbinates,overlying respective meatii.Occasionally,
there may be a supreme turbinate.
 The inferior turbinate is fairly straight and
structureless.
 The middle turbinate is a convoluted structure
bending in different planes similar to a dried leaf.

27.  The posterior end of the middle turbinate ends at the level
of the roof of the posterior choana.
 Middle turbinate is divided into 3 parts:
 Anterior 1/3rd attatched to cribiform plate & small anterior
attachment to the frontonasal process of the maxilla.
 middle 1/3rd attatched to lamina papyracea. it stabilizes the
middle turbinate, it is called the ground lamella or the
basal lamella.
 The posterior 1/3rd attached to the lamina papyracea and
the perpendicular plate of the palatine bone extending
upto the roof of the posterior choana

28. (1) Anterior attachment of middle turbinate to cribriform plate. (2) Middle
attachment (ground lamella) to lamina papyracea. (3) Posterior attachment to
perpendicular plate of palatine bone. An accessory ostium is seen in the hiatus
semilunaris.

29. Relationship of structures within
the middle meatus

30.  Most anteriorly is a curved ridge called the uncinate
process.
 Behind this is the well pneumatized and most constant
anterior ethmoidal cell, namely the ethmoidal bulla.
 These structures are separated by a semilunar groove called
the hiatus semilunaris.
 The hiatus semilunaris leads to infundibulum.
 The uncinate process, the bulla and the intervening
infundibulum form the key area or the osteomeatal unit
into which the frontal, the maxillary and anterior
ethmoidal sinuses drain.
 The infundibulum leads directly or indirectly into the
frontal recess.

31. The uncinate process is cut to reveal: (1) The infundibulum,
(2) the maxillary ostium, (3) the accessory ostium, and (4) the infundibular cells

32. A close up view of normal and accessory maxillary ostia

33. Axial section of the osteomeatal
unit

34.  The ethmoidal bulla is usually a well pneumatized, most
constant,anterior ethmoidal cell.
 Separated by a recess called the retrobullar recess
 The retrobullar and suprabullar recesses together form a
semilunar space above and behind the bulla called the
sinus lateralis of Grunwald.
 This sinus opens into the middle meatus by a semilunar
cleft which is opposite in orientation to the hiatus
semilunaris and is called the hiatus semilunaris
superioris.
 Thus the hiatus semilunaris inferioris leads into the
infundibulum and the hiatus semilunaris superioris leads
into the sinus lateralis of Grunwald.

35. The suprabullar and retrobullar recesses: (1) The hiatus
semilunaris inferoris, (2) the hiatus semilunaris superioris

36. Blood supply of nasal septum

37. Blood supply of lateral wall

38. Nerve supply
Of lateral &
medial wall
Lateral wall
Medial wall

39. DEVELOPMENT OF PARANASAL SINUSES
 Paranasal sinuses develop as outpouchings from the
mucous membrane of lateral wall of nose.

40. Paranasal sinuses have been divided into two
group:
 Anterior group: includes maxillary, frontal and
anterior ethmoidal. They all open in the middle
meatus and their ostia lie anterior to basal lamella of
middle turbinate.
 Posterior group. This includes posterior ethmoidal
sinuses which open in the superior meatus and the
sphenoid sinus which opens in sphenoethmoidal
recess.

41. Drainage of: (1) maxillary sinus (black), (2) bulla (blue),
(3) frontal sinus (light brown), (4) sphenoid sinus (green)

42. Maxillary Sinus (Antrum of Highmore)
 It is the largest of paranasal sinuses
 pyramidal in shape
 On an average, maxillary sinus has a capacity of 15 mL
in an adult.
Relations
 • Anterior wall is formed by facial surface of maxilla
and is related to the soft tissues of cheek
 Posterior wall is related to infratemporal and
pterygopalatine fossae.

43.  Medial wall is related to the middle and inferior
meatuses, uncinate process, inferior turbinate.
 Floor is formed by alveolar and palatine processes of
the maxilla and is situated about 1 cm below the level
of floor of nose.
 Roof of the maxillary sinus is formed by the floor of
the orbit. It is traversed by infraorbital nerve and
vessels.

44. 1)Maxillary sinus roof/orbital floor landmark (2)Endoscopic view of right maxillary
sinus antrostomy after removal of anterior ethmoid cells and basal lamella

45. Frontal Sinus
 situated between the inner and outer tables of frontal
bone.
 Often asymmetric and the intervening bony septum is thin
and often obliquely placed or may even be deficient.
Relation
 Anterior wall of the sinus is related to the skin over the
forehead;
 inferior wall, to the orbit and its contents;
 posterior wall to the meninges and frontal lobe of the brain.

46.  The anterior ethmoidal cells may migrate
anterosuperiorly into the frontal recess to produce
different types of frontal cells viz
 Type I A single cell above the agger nasi cell.
 Type II Two or more cells above the agger nasi cell.
 Type III A large cell extending well into the frontal sinus
mimicking the frontal sinus itself (frontal bulla).
 Type IV An isolated “loner cell” separately within
the frontal sinus

47. The frontal recess showing a type I frontal cell

48. Frontal sinus showing frontal recess

49. Ethmoidal Sinuses (Ethmoid Air
Cells)
 thin-walled air cavities in the lateral masses of ethmoid
bone.
 3 to 18 in number.
 They occupy the space between upper third of lateral nasal
wall and the medial wall of orbit.
 Basal lamina divides into anterior & posterior ethmoid
group.
 Roof is formed by medial extension of orbital plate of
frontal bone.
 lateral wall is formed by a thin plate of bone called lamina
papyracea.

50.  Anterior Group:
Some important cells
 1. Agger nasi cells – present in the agger nasi ridge.
 2. Ethmoid bulla – forms the posterior boundary of the
hiatus semilunaris.
 3. Supraorbital cells.
 4. Frontoethmoid cells – situated in the area of the
frontal recess and may encroach the frontal sinus.
 5. Haller cells – situated in the floor of the orbit

51. Posterior Group:
 1–7 in number
 Onodi cell/sphenoethmoid cell:It is the most posterior
cell of this group and extends along the lamina
papyracea, lateral or superior to the sphenoid. Optic
nerve and sometimes the carotid artery are related to it
laterally and are in danger during endoscopic surgery.

54. Sphenoid Sinus
 It occupies the body of sphenoid.
 opens into the sphenoethmoidal recess, medial to the
superior or supreme turbinate.
 situated about 1.5 cm from the upper border of choana
Relations of the Sphenoid Sinus
 Lateral wall of the sphenoid is related to the optic nerve
and carotid artery.
 Roof : Anterior part of the roof is related to the olfactory
tract, optic chiasma and frontal lobe. posterior part is
related to the pituitary gland in the sella turcica.
 laterally to the cavernous sinus.
 Floor of the sinus is related to the Vidian nerve.

55. Relation of sphenoid sinus

56. MUCOUS MEMBRANE OF
PARANASAL SINUSES
 Lined by mucous membrane which is continuous with
that of the nasal cavity through the ostia of sinuses.
 Histologically, it is ciliated columnar epithelium with
goblet cells which secrete mucus.

57. Bibliography
 Scott-Brown's Otorhinolaryngology and Head and
Neck Surgery, Eighth Edition
 Anatomical Principles of Endoscopic Sinus
Surgery: A Step by Step Approach ,renuka bradoo
 Dhingra’s Diseases Of Ear, Nose And Throat &
Head And Neck Surgery