Paranasal sinuses

Paranasal sinuses

Paranasal sinuses

Paranasal Sinuses (PNS) are air containing bony spaces around the nasal cavity. Usually lined by respiratory mucous membrane of ciliated columnar epithelium 4 paired (bilateral) PNS are: Maxillary Frontal, Sphenoidal ,Ethmoidal

Sinus

LATIN word meaning a Fold or Pocket.

TYPES

named according to the bone in which they lie.

1) The Maxillary sinuses: largest of the paranasal sinuses ,are under the eyes in the maxillary bones.

Maxillary Sinuses

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Types of paranasal sinuses

2) The frontal sinuses: superior to eyes in the frontal bone which forms the hard part of the forehead.

FRONTAL SINUSES

Types of paranasal sinuses

3) the ethmoid sinuses: which are formed from several discrete air cells within the ethmoid bone between the nose and eyes.

Ethmoid sinuses

Sphenoid sinus

4) The sphenoid sinuses in the sphenoid bone at the centre of skull base under the pituitary gland.

Lateral Sinus Anatomy

Maxillary sinus

Maxillary sinus is the pneumatic space that is lodged inside the body of the maxilla and that communicates with the environment by way of the middle meatus and the nasal vestibule

ANTRUM

Maxillary sinus is also called “ maxillary antrum” .ANTRUM IS A GREEK WORD MEANING “CAVE”.

ATTRIBUTED TO NATHIENEL HIGHMOORE ENGLISH PHYSICIAN 1600.

Dr NATHANIEL HIGHMOORE

Maxillary sinuses

PARANASAL SINUSES

STRUCTURE OF MAXILLARY SINUS

ANATOMY: FOUR SIDED PYRAMID BASE: medially towards nasal cavity

forming the lateral nasal wall. APEX: Extends laterally into the body of

zygomatic bone. ROOF( upper wall): Floor of the orbit. FLOOR: Alveolar process

PYRAMID

Boundaries

Walls of maxillary sinus

Occipitomental view

Size

Adult maxillary sinus averages 34 mm in anteroposterior direction

Height= 33 mm Width= 23 mm. Volume of max sinus=15 to 20 ml.

Radiological view

Maxillary sinus

Osteum: at the base of sinus.Level: Middle nasal meatusAccessory ostia: 2 or more connect the sinus with middle nasal meatus.

Osteum of max sinus

Pneumatization

Physiologic process that occurs in all paranasal sinus during the growth period causing them to increase in volume.

Pneumatization is the enlargement of the sinus by resorption of alveolar bone that formerly served to support a missing tooth or teeth and then occupies the edentulous space. A thin cortex remains over the alveolar ridge (arrow) to maintain a normal contour

Gradual pneumatization continuous process persisting throughout life.

PNEUMATIZATION

EXPANSION OF MAXILLARY SINUS GREATER BASALLY IMPINGING MORE AND MORE ON ALVEOLAR PROCESS.

pneumatization???

Pneumatization of alveolar process is believed to result from disuse atrophy initiated by tooth removal.

Periapical xray normal sinus

Pneumatization

Pneumatization of the sinus. Extension of the maxillary sinus into the tuberosity as a result of pneumatization

RECESSES RECESSES: The maxillary sinus pneumatization may

extend into nearby bony elements as recesses - infero-medially into hard palate, laterally into zygomatic bone and posteriorly into ethmoids So, the expansions of maxillary sinus beyond the maxillary bone are known as recesses. Found in alveolar process(50 %), zygomatic process(41.5%),frontal process(40.5%),Palatine process (1.75%).

Some processes of maxilla get invaded by air spaces and these are called recesses

Alveolar recess

Recesses

ZYGOMATIC RECESS= Superior alveolar nerves plus vessels in proximity with sinus.

Frontal Recess= invades and surrounds the contents of infraorbital canal.

Alveolopalatine recess; reduce the amount of bone between dental apices and sinus space.most often pneumatizes the floor of sinus adjacent to the roots of the first molar.

Fully developed alveolar recess= 3 depressions separated by 2 incomplete bony septa.

Anterior depression=premolar buds site Middle depression=molar buds, posterior depression= third

molar bud

Microscopic features 3 layers surround the space of the max sinus : 1) Epithelial Layer 2) Basal lamina 3) Subepithelial layer including the periosteum.

Most numerous cells in max sinus are – Columnar ciliated cells.

Additional cells:Basal cells, columnar non ciliated cells, mucus secreting goblet cells

Histology of max sinus

Epithelium

Ciliated Pseudostratified, columnar derived from olfactory epithelium of middle meatus

Most numerous cells in max sinus epithelium Columnar ciliated cells.

Additional cells:1)Basal cells 2)columnar non ciliated cells 3)mucus secreting goblet cells

MICROSCPIC FEATURES

MICROSCPIC FEATURES

MICROSCPIC FEATURES

MICROSCOPIC FEATURES

Ciliated cells

Cilia is composed of typical 9+1 pairs of microtubules and provide mobile apparatus to the sinus epithelium

Ciliated cells

Scanning Electron microscopy of nasal/sinus cilia (orange in thisimage). The pink ball is a speck of pollen. The gray blobs are dust

particles

Pathway of sinus drainage inside the maxillary sinus. Ciliated cells continually sweep mucous towards the

ostium.

Ciliated cells

The ciliated cells enclose the nucleus & electron lucent cytoplasm with numerous mitochondria & enzyme containing organelles.

Ciliated cells

The basal bodies serve as attachment of ciliary microtubules.

The cilia provide motile apparatus.

Ciliated cells

By ciliary beating, the mucous blanket lining the epithelial surface moves from the interior of the sinus towards the nasal cavity

Goblet cells

Basal segment contains nucleus Goblet cells contain RER & SER along

with the Golgi apparatus all of which are involved in the synthesis of secretory substances

This means that they contain all the characteristics of secretory cells.

Goblet GLASS

GOBLET CELLS

Subepithelial layer

Contain subepithelial glands and reach the sinus lumen by way of excetory ducts.

The glands contain both serous and mucous acini i.e secrete serous as well as mucous secretion.

Myoepithelial cells surround the acini composed of either both secretory cells

or a pure population of cells of either secretory type.

Subepithelial layer

The subepithelial layer also consists of collagen bundles,fibroblasts,vessels and nerves.

Composition

serous secretion= water, neutral lipids, proteins, carbohydrates.

mucous secretion=compound glycoprotein's and mucopolysaccharides

Subepithelial glands

AUTONOMIC NERVOUS SYSTEM(ANS)Control secretions from these glands.Supplied to max sinus from max nerve

complex.

Functions Of Maxillary Sinus

Warming/Humidification of air. Contribution to immune response i.e bactericidal

lysozyme . Lightening the skull Resonance to voice Assistance in regulation of intracranial pressure Enhance Facio-cranial resistance to shock

Nerve Supply

Nerve Supply: MAXILLARY DIVISION OF V NERVE i.e V2

1) Anterior, middle and posterior superior alveolar nerves,

2) Infra orbital nerves 3) greater palatine

nerve

Maxillary nerve

GREATER PALATINE NERVE

INNERVATION

The innervation of the sinus is important from a diagnostic standpoint. Post wall of the sinus receives its supply from Posterior and Middle Superior Alveolar nerves while anterior wall is by Anterior Superior Alveolar Nerve. These nerves travel enclosed in the wall of the sinus innervating the related teeth (Wallace 1996). Thus it is commonly seen that pain of the sinus is mimicked as toothache and vice versa and is difficult to distinguish

Arterial supply Major blood supply from branches of maxillary

artery 1) infraorbital artery 2) posterior superior dental artery 3) anterior superior dental artery 4) greater palatine 5) sphenopalatineSmaller contribution from facial artery both branches of external carotid artery.

EXTERNAL CAROTID

FACIAL ARTERY

SPHENOPALATINE ARTERY

Venous Drainage

Venous Drainage: Via the Facial vein, Sphenopalatine vein anteriorly and the Pterygoid venous plexus posteriorly Anterior, middle and superior dental veins drain into the infra-orbital vein Pterygoid plexus communicates with the cavernous sinus by emissary veins

Venous Drainage

VENOUS DRAINAGE

CLINICAL IMPORTANCE

The significance of the vascular drainage of the sinus lies in the fact that apart from the joining typical pathways in the maxilla to the jugular veins, it can also drain upward into the ethmoidal and frontal sinuses and eventually reach the cavernous sinus in the floor of the brain. Spread of infections via this route is a serious complication of maxillary sinus infections

Lymph Drainage

PREAURICULAR NODES Submandibular lymph node PAROTID node Facial node

CLINICAL CONSIDERATIONS

CLINICAL CONSIDERATIONS

Developmental anomalies Agenesis( complete absence of max sinus) Aplasia( altered development) Hypoplasia(underdevelopment) Supernumerary sinus(occurrence of 2

completely separated sinuses on the same side)

CLINICAL CONSIDERATIONS

Pituitary gigantism: sinuses larger than normal Some congenital infections: sinuses smaller than

normal e.g congenital syphilis Pathologically generated- functional and

systemic association Transfer of pathologic condition is through

Mechanical blood or lymphatic system.

Hypoplasia Maxillary sinus hypoplasia presence of three of following four

criteria: 1. oval-shaped sinus 2. absence of pneumatization of the sinus below the level of the nasal floor 3. presence of medial wall of the sinus laterally to a vertical line drawn tangentially to the medial orbital border 4. lateral extension of the sinus medial to a vertical line drawn through the middle of the orbit at the level of the infundibulum, in the coronal plane

HYPOPLASIA

HYPOPLASIA OF MAXILLARY SINUS

MAXILLARY SINUS HYPOPLASIA

HYPOPLASIA OF MAXILLARY SINUS

Clinical considerations Chronic infections of mucoperiosteal layer cause

neuralgia becoz of superior al n invovolvement. Neuralgia of maxillary nerve “tic doulorex” may mimic sinus pain Non specific bacterial sinusistis Infections caused by

streptococci,staphylococci,pnemococci,virus of common cold.

Clinical considerations/importance/implications

1) Oroantral communication accidental opening in the floor of the

antrum caused during extraction of maxillary first molar which has a thin bone separating the roots from the antrum.

a tract b/w oral cavity and max antrum not lined by epithelium.

Fates of oro antral communication

Either close spontaneouly Become epithelialized and persist as true

fistulae

OROANTRAL COMMUNICATION

Oroantral commmunication/fistula

CAUSES Surgical extraction of first molar Extraction of tooth showing

hypercementosis Radicular cyst Granuloma AbscessTherefore surgical intervention necessary

EXTRACTION OF FIRST MOLAR

PERIAPICAL LESION OR GRANULOMA CAUSING OAF

Pituitary gigantism

Tic doulourox( trigeminal neuralgia)

Malignant lesions

Malignant lesions adenocarcinoma squamous cell carcinoma osteosarcoma fibrosarcoma lymphosarcoma

Malignant lesions

Primary manifestation in max teeth 1) pain 2) loosening 3) Supraeruption 4) bleeding in gingival tissue

MALIGNANT LESION

AXIAL VIEW CT SCAN

CORONAL VIEW CT SCAN

CT SCAN REPORT

CLINICAL CONSIDERATIONS/IMPLICATIONS Infections introduced into the antrum

through periapical infections.

Infections introduced into the antrum through periapical infections.

Maxillary sinusitis

Maxillary sinusitis

Signs symptoms When you begin to experience maxillary sinusitis you will

notice the following symptoms: • Nasal congestion

• Facial pain• Differentiated facial sensations• Night-time coughing• Jawbone pain• Teeth pain• Runny nose• Sinus pressure• Chronic tooth aches

Axial CT showing a displaced tooth root into the right maxillary sinus causing sinusitis

Maxillary Sinusitis of Dental Origin :  Maxillary Sinusitis of Dental Origin Spread of infection from

Periapical or Pdl. Abscess Due to overextension of Sealers, Cements, GP, Silver cones As a result Of Periapical Surgery of posterior maxillary teeth Due to iatrogenic Causes like Perforation of Sinus membrane Or breakage of Instrument

  Maxillary Sinusitis of Dental Origin Spread of infection to the

sinus from a dental abscess: Commonest cause of direct spread of oral infection to the sinus is a “Periapical abscess” Odontogenic sinusitis is seldom associated with acute abscess. It is always secondary to chronic suppuration from a granuloma or a periodontal abscess

Maxillary Sinusitis of Dental Origin : Some common causes of maxillary sinusitis related to dentistry are the

iatrogenic displacement of a maxillary tooth root tip into the sinus during extraction, perforation of the sinus membrane during exodontia, andextrusion of materials used in root canal therapy into the sinus. When teethadjacent to a lone-standing molar have been removed, alveolar bone isresorbed over time mesial and distal to the remaining tooth. This resorptionresults in thinner alveolar bone separating the oral cavity and sinus. If ata later time the lone-standing molar requires extraction, the risk of alveolarbone or maxillary tuberosity fracture with concomitant oroantral commu-nication is high. Other oral and maxillofacial surgery or dental procedures,such as maxillary orthognathic surgery, preprosthetic surgery, sinusmembrane lifts and sinus grafting, and dental implant placement, haveoccasionally been cited as causing sinusitis. The incidence of sinusitis withthese procedures, when properly performed is almost nonexistent, howev

Displacement of root into maxillary sinus during extraction of a tooth.