Nasal Cavity, Paranasal Sinuses, Nasopharynx PDF

Nasal Cavity, paranasal sinuses, nasopharynx MD3001 September 2023 Dr. Alex Gardner [email protected] DR booking update Request resources at “notes dropdown” 2 Learning objectives By the end of this lecture, time spent in the dissecting room, and further private study you should be able...

Nasal Cavity, paranasal sinuses, nasopharynx MD3001 September 2023 Dr. Alex Gardner [email protected] DR booking update Request resources at “notes dropdown” 2 Learning objectives By the end of this lecture, time spent in the dissecting room, and further private study you should be able to 1. List the functions of the respiratory system 2. Define upper and lower divisions of the respiratory tract 3. Identify the main skeletal elements forming the roof, lateral wall and septum of the nasal cavity 4. Describe the neurovascular supply of the nasal cavity and paranasal sinuses 5. Describe the para-nasal air sinuses and their sites of drainage into the nasal cavity 6. Describe the Waldeyer’s ring 7. Describe the relationships of the nasal cavity, nasopharynx and paranasal sinuses to each other and to adjacent structures 8. Describe the functions of the nasal cavity, nasopharynx, pharyngeal and tubal tonsils and paranasal sinuses 9. Discuss clinical conditions that affect the nasal cavity, nasopharynx, pharyngeal and tubal tonsils and paranasal sinuses MD3001 2023 3 Sources N.B. Consult chapters on head and neck (nasopharynx) MD3001 2023 4 Respiration Exchange of oxygen from environment to cells for utilisation (and remove CO2) • Ventilation (breathing) -> move gas to site of exchange • Gas exchange -> capillary beds at lungs and tissues • Cellular Respiration -> cells use oxygen in biochemical processes MD3001 2022 5 Respiratory system Function? • Primarily gas exchange • pH balance • Speech/vocalisation • Other metabolic functions – angiotensin 1 to angiotensin 2 • Prostaglandin synthesis • Protect and maintain itself and rest of body How can the structure enable these functions? MD3001 2023 6 Respiratory system Conducting portion • Nose, nasal cavity, paranasal sinuses • Pharynx (nasopharynx, oropharynx, laryngopharynx) • Larynx • Trachea • Bronchi, bronchial tree • Terminal bronchioles Respiratory portion (gas exchange) • Respiratory bronchioles • Alveoli (ducts and sacs) • 400 million per lung! • Large surface area • Rich vascular supply MD3001 2023 7 Nose • Nose is external structure (cartilage, muscle, soft tissue, nasal bone) • Nares (nostrils) communicate with nasal cavities MD3001 2023 8 Nose • Nose is external structure (cartilage, muscle, soft tissue, nasal bone) • Nares (nostrils) communicate with nasal cavities Fibroaleolar tissue MD3001 2023 9 Nasal muscles • Act to flare or constrict the nostrils i.e. dilator or sphincter • As muscles of facial expression, innervated by facial nerve (CN VII) MD3001 2023 10 Nasal vestibule • Immediately after passing nostrils • Epithelium is squamous (not respiratory) mucosa • Nasal hair, vibrissae, has a filtering effect • Risk of nasal vestibulitis (S. Aureus) From: https://karger.com/iaa/article/156/1/75/166108/Does-Nasal-Hair-Vibrissae-Density-Affect-the-Risk Abscess From: https://www.sciencedirect.com/science/article/pii/S0732889317301840#f0005 MD3001 2023 11 Nasal cavity • Posterior to the nose • Bony structure covered by respiratory mucosa • Floor = hard and soft palate • Lateral wall = Ethmoid (superior and middle conchae), inferior nasal concha, maxilla, sphenoid, palatine bone, lacrimal, nasal bone Hard palate = palatine process maxilla + horizontal plate of palatine bone MD3001 2023 12 Nasal cavity • Posterior to the nose • Bony structure covered by respiratory mucosa • Medial wall = septal cartilage, ethmoid (perpendicular plate), vomer • Roof = frontal bone, ethmoid (cribriform plate), sphenoid • Roof also has specialised olfactory mucosa MD3001 2023 13 Nasal cavity - ethmoid MD3001 2023 14 Nasal cavity - epithelium • Mostly respiratory Also • Olfactory • NALT – nasal associated lymphoid tissue • Squamous mucosa in vestibule MD3001 2023 15 Respiratory mucosa • Ciliated pseudostratified columnar epithelium • Goblet cells • Rich vascular supply and submucosal glands Mucus traps foreign particles and cilia move mucus outside of the airway MD3001 2023 16 Nasal cavity – olfactory anatomy • Cranial nerve 1 (CN I) – olfactory nerve • Olfactory tracts (R+L) are forebrain extensions • Olfactory mucosa -> olfactory nerves (passing through cribriform plate) -> olfactory bulb -> olfactory tract -> medial and lateral striae -> piriform cortices MD3001 2023 17 Nasal cavity – foramina/gateways • Foramen cecum = emissary vein connecting nasal veins with superior sagittal sinus. Potential for infection to track to cranial cavity. • Cribriform plate – olfactory nerves N.B. adjacent foramina for anterior ethmoidal nerve and vessels • Sphenopalatine foramen – sphenopalatine artery, nasopalatine and superior nasal nerves • Incisive canal – nasopalatine artery, greater palatine nerve • Lateral wall foramina – inferior nasal branches of greater palatine nerve, internal nasal branch infra-orbital nerve, alar branches nasal artery Nasopalatine nerve Nasopalatine artery MD3001 2023 18 Nasal cavity – arterial supply Rich vascular supply • Anastomose between external and internal carotid artery branches • Internal carotid • Ophthalmic • Anterior ethmoidal • External nasal • Posterior ethmoidal • Both with septal branches • External carotid • • maxillary artery • Sphenopalatine • Posterior lateral nasal • Posterior septal • descending palatine • greater palatine Facial • superior labial • lateral and septal nasal arteries MD3001 2023 19 Nasal cavity – arterial supply Little’s area or Kiesselbach area = site of epistaxis (nosebleed) due to anastomoses MD3001 2023 20 Nasal cavity – venous drainage • Veins accompany arteries • Cavernous sinus via superior ophthalmic • Pterygoid plexus and facial vein MD3001 2023 21 Nasal cavity – lymphatic drainage • • • • Anterior to submandibular nodes Posterior to retropharyngeal nodes Then to deep cervical nodes Note jugulodigastric node (if inflamed will be palpable) MD3001 2023 22 Nasal cavity - innervation • Mixed innervation • CN 1 – special sensory from olfactory epithelium • CN V1 and V2 (ophthalmic and maxillary divisions of trigeminal nerve) – somatic sensory • V1 (ophthalmic division of trigeminal) -> Nasociliary nerve -> anterior ethmoidal (lateral and septal nasal branches) • V2 (maxillary division of trigeminal nerve) -> nasopalatine and greater palatine MD3001 2023 23 Nasal cavity - innervation • CN VII – facial nerve, parasympathetic secretomotor (greater petrosal branch) • Sympathetic innervation via periarterial fibres, from superior cervical ganglion MD3001 2023 24 Nasal cavity – form to function • Turbinates aid in warming and humidifying air • Large surface area • Well vascularised • Generate turbinate flow, aids in filtering particles before they pass further into the airway “turbulent precipitation” • Mucus and cilia clear trapped particles • Smoking impairs ciliary function MD3001 2023 25 Paranasal sinuses MD3001 2023 26 Paranasal sinuses MD3001 2023 27 Paranasal sinuses Anterior ethmoidal draining here too • Epithelium lined cavities within facial bones around the nasal cavities • Lighten skull, aid in warming and humidifying air • Frontal, sphenoidal, maxillary, ethmoidal (anterior, middle, posterior cells) • Drain into the lateral aspect of the nasal cavity • Maxillary sinus particularly prone to sinusitis MD3001 2023 28 Paranasal sinuses • Small nasal cavity outgrowths at birth, grow by a process termed pneumatization https://www.ajronline.org/doi/pdf/10.2214/ajr.160.5.8470585 MD3001 2023 29 Paranasal sinuses - drainage • Sinuses drain to the nasal cavity • Below each conchae is a space called a meatus • Superior, middle and inferior plus spheno-ethmoidal recess MD3001 2023 30 Paranasal sinuses - Drainage Anterior ethmoidal draining here too Sinus/ air cells Drains to Frontal Ethmoidal infundibulum (middle meatus), via frontonasal duct Anterior Ethmoidal infundibulum (middle ethmoidal cells meatus) Middle Middle meatus (ethmoidal bulla) ethmoidal cells Posterior Superior meatus ethmoidal cells Maxillary Middle meatus via semilunar hiatus Sphenoidal Spheno-ethmoidal recess • Nasolacrimal duct = inferior meatus (not a sinus, but just for completeness) MD3001 2023 31 Paranasal sinuses – adjacent structures Clinical and surgical implications MD3001 2023 32 Paranasal sinuses – nerve and blood supply Sinus Nerve Artery Frontal Supra orbital (CN V1) Anterior ethmoidal (ophthalmic) Sphenoidal Post. Ethmoidal (Nasociliary from CN V1) Orbital branches CN V2 from pterygopalatine ganglion Pharyngeal arteries (maxillary) Ethmoidal Ant. And post. Ethmoidal (Nasociliary from CN V1) Orbital branches CN V2 from pterygopalatine ganglion Anterior and posterior ethmoidal (ophthalmic) Maxillary Infra orbital and superior alveolar branches maxillary nerve (CN V2) Infra orbital and superior alveolar branches maxillary artery MD3001 2023 33 Nasopharynx • First part of pharynx • Communicates with nasal cavity via choanae • Becomes oropharynx below soft palate • Air conduit • Sensory innervation from pharyngeal branch of CN V2 MD3001 2023 34 Nasopharynx - choanae Vomer, horizontal plate of palatine bones, medial pterygoid plate MD3001 2023 35 Nasopharynx – pharyngotympanic tube • Connects lateral wall nasopharynx with middle ear • Cartilaginous tube with muscular attachment covered by mucosa MD3001 2023 36 Nasopharynx – pharyngotympanic tube • AKA auditory tube, Eustachian tube • Closed at rest • Muscle action opens the tube when yawning, swallowing – equalises pressure Muscles arising from tube • Salpingpharyngeus (goes to pharynx) • Tensor veli palatini (goes to soft palate) • Levator palatini (goes to soft palate) MD3001 2023 37 Nasopharynx – tonsil tissue • Tonsils are lymphoid tissue that are important in immune surveillance • 2x Tubal, pharyngeal (adenoid), 2x palatine, lingual • Collectively termed Waldeyer’s ring • A ring of protective tissue around the opening to airway and GI tract MD3001 2023 38 Nasopharynx – Pharyngeal recess • AKA fossa of Rosenmuller • Deep recess posterior to opening of pharyngotympanic tube • Commonest site of nasopharyngeal carcinoma • Rathke’s pouch (embryological evagination) gives rise to the adenohypophysis (anterior pituitary) MD3001 2023 39 Clinical considerations • • • • • • Nosebleed Rhinitis Deviated septum Sinusitis CSF rhinorrhoea – e.g. major trauma Adenoid hypertrophy MD3001 2023 40 Clinical considerations Nosebleed • Remember Little’s area/Kiesselbach area • Common, often managed at home • Severe or repeated cases may require intervention • Chemical cautery (silver nitrate), packing, surgical ligation of sphenopalatine artery MD3001 2023 41 Clinical considerations • Rhinitis • Inflammation – e.g. allergic, infection • Blockage due to increases mucus production and oedema MD3001 2023 42 Clinical considerations • Deviated septum • History of trauma • May predispose to sinus infections • Surgical correction may be necessary https://onlinelibrary.wiley.com/doi/full/10.1111/j.1749-4486.2011.02279.x MD3001 2023 43 Clinical considerations • Sinusitis • Maxillary sinus particularly prone to sinusitis. Why? https://onlinelibrary.wiley.com/doi/pdf/10.1002/alr.21343 MD3001 2023 44 Clinical considerations • CSF rhinorrhoea • Clear, serous fluid leaking from nose • Due to damage at ethmoid/cribriform plate • Often following a serious head injury • May resolve, but likely to require surgery • Potentially fatal if missed MD3001 2023 45 Clinical considerations Maxillary sinus opacity • Polyp • Cyst • Orbital contents (trauma) https://doi.org/10.53347/rID-1000 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4453822/ MD3001 2023 46 Clinical considerations Adenoid hypertrophy • Excessive growth of pharyngeal tonsil • Chronic infection, possibly EBV • Blockage of nasopharynx and thus promotes mouth breathing • Can alter facial growth MD3001 2023 From: https://www.osmosis.org/answers/adenoid-hypertophy 47 Tip from Dr. Cezayirli MD3001 2023 48 EMQ style Q • Waldeyer’s ring is a collection of tonsillar tissue. What tonsil forms the most superior portion of Waldeyer’s ring? • Palatine • Lingual • Tubal • Pharyngeal • Lymphatic tissue on Salpingopharyngeal folds 49 SAQ style Q • The nasal cavity receives multiple sources of innervation. Regarding special and somatic sensory innervation, describe the nerve supply to the nasal cavity. (3 marks) • Special sensory is supplied by CN1, the olfactory nerve, to olfactory epithelium in the superior portion of the nasal cavity • The ophthalmic and maxillary divisions of trigeminal nerve supply somatic sensory innervation. • The ophthalmic division supplies the anterior superior portion and the maxillary division supplies the postero-inferior portion of the nasal cavity 50