Anatomy of Nose & Paranasal sinuses.pptx

Anatomy

1. Anatomy Of Nose And Paranasal Sinuses Capt. Pyae Sone Thu PG 1, ORL-HNS

2. CONTENTS Development of nose and paranasal sinuses Anatomy of Nose Anatomy of Paranasal Sinuses Mucous membrane of Nose Blood supply Nerve Supply Lymphatic Drainage

3. Develpoment of Nose and Paranasal Sinuses The nose develop from the frontonasal process which grows between the primitive forebrain and stomodium. The frontonasal process gets divided into median nasal process and two lateral processes. Primitive nasal cavities are closed at their posterior ends by bucconasal membrane which rupture and forms posterior naries. I f it fails to rupture, it can result in choanal atresia.

4. Olfactory placodes on the frontonasal process become depressed to form the olfactory pits which ultimately form the nasal cavity. Primitive nasal septum divides the nasal cavity in the midline and subsequently definitive septum forms. Paranasal sinuses develop as the outpouching of nasal mucosa. Maxillary sinuses are present at birth but reach full development after the eruption of the permanent dentition of related teeth. Rudimentary anterior ethmoidal sinuses are also present at birth.

5. ANATOMY OF NOSE The antomy of nose is divided into external nose and nasal cavities. External Nose Pyramidal in shape and maintained by skeletal framework which divided into bony part and cartilaginous part. Bony Part support the upper 1/3 of external nose and composed by nasal process of frontal bone, nasal bone and ascending processes of maxillae. Cartilaginous Part support the lower 2/3 of external nose and which is composed of upper lateral cartilage, lower lateral cartilages ( alar cartilages) and quadrilateral cartilage of nasal septum.

6. Cartilages and bones are connected and covered by pericondrium and periosteum. Skin over the upper part of the nose is thin and lower cartilaginous part is thicker where it contains large sebaceous glands. Vestibule lined with skin and contain sebaceous glands and hairs (vibrissae), situated in base of the nose, open downwards and separated by columella. It is limited above and behind by a curved ridge, the limen nasi.

7. Nasal Fossae (Cavities) The right and left nasal fossae are separated by the nasal septum. The nasal fossae communicates with The paranasal sinuses, through their ostia. The nasopharynx, through their posterior choanae. Each nasal fossa if bounded by Floor - palatine process of maxillae anterior ¾ - horizontal parts of palatine bones posterior ¼

8. 2) Roof - very narrow and formed by nasal process of frontal bone (anteriorly), cribriform plate of ethmoid (fibers of olfactory nerve pass through) and body of sphenoid bone (posteriorly). 3) Lateral wall - superior, middle and inferior (largest) turbinates and three meatus lies below and lateral to the coresponding turbinates. Spheno-ethmoidal recess lies above the superior turbinate and recieves the ostium of sphenoid sinus. Superior meatus contians ostia of the post. ethmoidal cells.

9. Middle meatus is most complex and ostia of maxillary, anterior ethmoidal and frontal sinuses open into it. The atrium is a forward continuation of the middle meatus. The aggar nasi is a curved ridge above the atrium. The bulla ethmoidalis is a smooth, rounded mass formed by the bulla or above it. Inferior meatus receive the nasal opening of the nasolacrimal duct.

10. Paranasal Sinuses The nasal accessory sinuses are air spaces which develop in the bones of skull and communicate with the nasal cavity. Anterior group comprises Frontal sinus Maxillary sinus Anterior ethmoidal sinus Posterior group comprises Posterior ethmoidal sinus and Sphenoid sinus

11. Maxillary Sinus The largest sinus with an average capacity of about 15ml in adult. The fully developed maxillary sinus should extent from 1 st premolar to the 3 rd molar tooth. Reaches up to floor of orbit and thus occupies practically the whole body of maxillary bone. Medial boundry is lateral nasal wall with the attachment of inferior turbinate. Ostium lies in the membranous part of middle meatus and sometimes a small accessory ostium below and in front of it.

12. Infraorbital nerve traverses the roof of the maxillary sinus and may partly dehiscent. Floor is formed by alveolar process and hard palate. Covered with only thin plate of bone, in which reason for infection of maxillary air sinus in apical tooth abscess become obvious. Posterior wall is pierced by dental canals and anterior wall extends as far as forwards as the canine ridge. Lined by ciliated columnar epithelium and cilia constantly beat towards this opening.

13. Relations Orbit is separated from antrum by thin roof of sinus which contain infraorbital nerve. Upper part of the antrum is related to the middle meatus of the nose. Internal maxillary artery is related to the posterior wall and maxillary division of V cranial nerve also transverse the pterygopalatine fossa. Nasolacrimal duct passes downwards, medial to the antrum to open into the inferior meatus.

14. Ethmoidal Sinus Consists of approximately 7 – 15 of thin-walled cavities within the lateral mass of the ethmoid bones and sometimes in aggar nasi and middle turbinate. Contain very small air cells without regular dispositoin, symmetry or fixed number. Divided into two anatomical group - Anterior – usually small and numerous, open into upper part of the hiatus semilunaris and bulla ethmoidalis and drain into middle meatus Posterior – large and few, open into superior meatus

15. The ethmoidal bulla is the most constant and largest cell in the anterior ethmoid. The bulla is a two-dimensional space called the hiathu semilunaris and leads into three-dimensional space of infundibulum. The most anterio-superior insertion of middle turbinate is called the aggar nasi (in which there is usually an aerated cell). The middle section of the attachment of middle turbinate fixes it to the lamina papyracea, it runs in a frontal plane and is called the ground lamella, which d ef ining border between anterior and posterior ethmoid .

16. Relations Anterior cranial fossa lies above and orbit is seprated by the orbital plate of ethmoid bone. Lacrimal sac is related laterally to the anterior cell. Optive nerve is very close to the cell of the posterior group. Anterior and posterior ethmoidal vessels and nerve run from the orbit to nasal fossa between the roof of ethmoidal sinus and under surface of frontal bone.

17. Frontal Sinus Occupies the space in the frontal bones between the inner and outer tables, an upward extension of anterior ethmoidal cells. Not present at birth and developed about age of 5 and average capacity is about 7ml in adult. Right and left sinuses are rarely symmetrical and seprated by thin bony plate. Frontal sinus may extend to outer orbital angle and upward into frontal bone for several centimetres. Anterior cranial fossa lies its posterior wall and orbit lies below the floor of sinus and skin periosteum of forehead cover the anterior.

18. Sphenoidal Sinus Lie s behind the upper part of the nasal fossa and average capacity is about 7ml. Two sphenoidal sinuses occupy the body of sphenoid bone and are rarely symmetrical and separated by septum. Vary widely in size, shape and position , may be almost on top of the other. Mostly, pneumatisation extends inferiorly below the pituitary fossa, which bulges into the sinus, surgically the trans-sphenoidal route to the pituitary take advantage of this.

19. The ostium is situated in the upper part of anterior wall of sinuses and communicates with the superior meatus indirectly through the sphenoethmoidal recess. Relations Roof – pituitary gland, optic chisma, olfactory tract and frontal lobe of brain Floor – Vidian nerve, vessels and nerve from sphenopalatine foramen lies infront of lower part

20. Lateral – Cavernous sinus containing 3 rd , 4 th , 5 th (opthalmic and maxillary division) and 7 th cranial nerves Posterior – Basilar artery and brain-stem Pterygopalatine fossa if situated between the posterior wall of maxillary anteum anteriorly and pterygoid extension of greater wing of the sphenoid posteriorly. It contains 3 rd part of the maxillary artery, maxillary merve and sphenopalatine ganglion.

21. Mucous Membrane of Nose & Paranasal Sinuses Respiratory Lines lower 2/3 of nasal septum and lateral wall of the nose below the superior turbinate and floor of nasal fossa. Pink in colour and covered by ciliated columnar epithelium. 2) Olfactory Lines upper 1/3 of nasal septum, roof of nose and lateral wall, above and including superior turbinate. Yellowish in colour and covered by non-ciliated columnar epithelium and contain serous glands.

22. Blood Supply Of Nose & Paranasal Sinuses Arterial Supply Mainly supply by external and internal carotid arteries. Branches of external carotid artery Sphenopalatine artery; via internal maxillary artery Greater palatine artery; a branch of maxillary artery Superior labial artery; a branch of facial artery Infraorbital and superior dental ; branches of internal maxillary artery Pharyngeal branch of internal maxillary artery

23. 2) Branches of internal carotid artery Anterior and posterior ethmoidal arteries ; branches of the opthalmic artery Venous Drainage The veins from cavernous plexus beneath the mucous membrane open into - Sphenopalatine vein from the plexus Opthalmic veins from the ethmoidal veins Veins on the orbital surface of frontal lobe of brain through the foramina in cribriform plate Superior sagittal sinus through foramen caecum

24. Nerve Supply Of Nose Branches of 5 th Cranial Nerve Anterior ethmoidal nerve, a branch of opthalmic 1 st division, enters the nasal cavity through anterior ethmoidal foramen and divided into Medial branch which supplies the anterior part of the septum Lateral branch which supplies anterior part od lateral wall of the nose and anterior part of middle and inferior turbinates

25. 2) Branches of Sphenopalatine Ganglion Greater palatine nerve which supplies most of the inferior turbinate and middle and inferior meatus Short sphenopalatine nerve which supplies the posterior part of superior and middle turbinates Long sphenopalatine nerve which supplies the remainder of the septum 3) Olfactory Nerve The sense of smell is supplied by 1 st cranial nerve which pass through the foramina in the cribriform plate and enter under surface of olfactory bulb.

26. Lymphatic Drainage The lymphatic vessels arise from a continuous network in the superficial part of the mucous membrane. Best developed at posterior end of superior turbinate. External nose and anterior part of nasal cavity drain into submendibular lymphnodes. The rest of nasal cavity drain into upper deep cervical nodes either directly of through retropharyngeal nodes.

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