Nose and paranasal sinuses
Nose, Paranasal Sinuses and Pterygopalatine Fossa: Anatomy for FCPS
Nose and sinuses for FCPS Part 1: septum and Little's area, lateral wall openings, each paranasal sinus and its relations, nerve and lymph supply, and the pterygopalatine fossa. Covers epistaxis, sinusitis spread, oroantral fistula and pituitary surgery.
Functions of the nose
- Filters, warms and humidifies inspired air so that it is close to body temperature and fully saturated with water vapour by the time it reaches the alveoli; also smell and voice resonance.
- Respiratory mucosa is pseudostratified ciliated columnar with goblet cells and a rich venous (erectile) plexus over the conchae; olfactory epithelium covers the roof, upper septum and superior concha.
Nasal septum and epistaxis
- Bony: perpendicular plate of ethmoid (upper) and vomer (lower); front part is septal cartilage.
- Little's (Kiesselbach's) area: anteroinferior septum where branches of the anterior ethmoidal, sphenopalatine, greater palatine and superior labial arteries meet; source of about 90% of nosebleeds. First aid: firm pressure on the soft part of the nose, leaning forward; then cautery or packing.
- Posterior epistaxis in older hypertensive patients comes from the sphenopalatine artery (from the maxillary artery): posterior packing or endoscopic sphenopalatine ligation.
- Juvenile nasopharyngeal angiofibroma: adolescent boys, recurrent heavy epistaxis, arising near the sphenopalatine foramen, fed mainly by the maxillary artery (its sphenopalatine branch), which is embolised or ligated.
- Other causes: hereditary haemorrhagic telangiectasia, bleeding disorders, anticoagulants, and granulomatosis with polyangiitis (epistaxis, saddle nose, haematuria, c-ANCA).
- Septal haematoma must be drained to prevent cartilage necrosis and a saddle nose.
Lateral wall and openings
| Space | What opens into it |
|---|---|
| Sphenoethmoidal recess | Sphenoid sinus |
| Superior meatus | Posterior ethmoidal cells |
| Middle meatus | Frontal (frontonasal duct), maxillary (hiatus semilunaris), anterior and middle ethmoidal cells (on the ethmoidal bulla) |
| Inferior meatus | Nasolacrimal duct |
- The ostiomeatal complex in the middle meatus drains the frontal, maxillary and anterior ethmoid sinuses; blockage causes chronic sinusitis (functional endoscopic sinus surgery).
Paranasal sinuses
| Sinus | At birth | Key relations and clinical points |
|---|---|---|
| Maxillary | Present; largest | Ostium high on the medial wall, so drainage is poor; orbit above, roots of upper premolars and molars below (the first molar most often) |
| Ethmoidal | Present | Separated from the orbit by the paper-thin lamina papyracea; orbital cellulitis in children |
| Frontal | After about 7 years | Pott's puffy tumour (frontal bone osteomyelitis) |
| Sphenoid | Small, grows in childhood | Pituitary above; cavernous sinus, internal carotid and optic nerve in the lateral wall |
- Oroantral fistula: after extraction of an upper molar (especially the first), the socket opens into the maxillary sinus: drinks leak from the nose and air bubbles through the socket when blowing the nose. Lower molars relate to the inferior alveolar canal, not to a sinus.
- Transsphenoidal pituitary surgery: the internal carotid artery bulges into the lateral wall of the sphenoid sinus, sometimes with no bony cover; drilling there causes torrential arterial bleeding.
- Maxillary sinus cancer presents late (cheek numbness, loose teeth, proptosis, nasal obstruction).
Spread of infection from the nose
- A boil or squeezed pimple beside the nose or in the nasal vestibule spreads by the facial vein to the angular and ophthalmic veins, which are valveless, and so to the cavernous sinus. Fever, proptosis, chemosis and ophthalmoplegia follow.
- In cavernous sinus thrombosis the abducens nerve (VI) is usually affected first because it runs inside the sinus beside the carotid; the patient cannot look laterally.
- Ethmoid infection crosses the lamina papyracea into the orbit; frontal sinusitis can reach the anterior cranial fossa.
Nerves and lymph
| Region | Sensory nerve |
|---|---|
| Anterosuperior septum and lateral wall, tip of nose | Anterior ethmoidal and external nasal nerves (V1): vesicles on the tip (Hutchinson's sign) warn of ophthalmic zoster involving the eye |
| Posterior and inferior septum and lateral wall | Nasopalatine and posterior nasal branches (V2) through the pterygopalatine ganglion |
| Skin of side of nose and lower eyelid | Infraorbital nerve (V2) |
- Lymph: external nose and anterior nasal cavity to the submandibular nodes; posterior nasal cavity and sinuses to retropharyngeal and deep cervical nodes.
- A blow to the medial side of the orbit near the nasal bridge fractures the nasal bones and the thin lacrimal and ethmoid bones (naso-orbito-ethmoid fracture).
Pterygopalatine fossa
A small space behind the maxilla, below the orbit apex, in front of the pterygoid process.
| Communication | Through |
|---|---|
| Middle cranial fossa | Foramen rotundum (V2) |
| Foramen lacerum region | Pterygoid canal (nerve of the pterygoid canal) |
| Orbit | Inferior orbital fissure |
| Nasal cavity | Sphenopalatine foramen |
| Infratemporal fossa | Pterygomaxillary fissure (maxillary artery enters) |
| Oral cavity | Greater and lesser palatine canals |
- Contents: maxillary nerve, pterygopalatine ganglion, third part of the maxillary artery.
- The ganglion receives parasympathetic fibres from the greater petrosal nerve (VII) joined by the deep petrosal (sympathetic) as the nerve of the pterygoid canal. It supplies the lacrimal gland and glands of the nose, palate and pharynx. A lesion causes a dry eye, dry nose and dry palate.
Nasal polyps
- Adults: allergic rhinitis, aspirin-exacerbated respiratory disease (polyps, asthma, aspirin sensitivity).
- Children with polyps: think of cystic fibrosis.
- Nasopharyngeal carcinoma: EBV; an adult with unilateral middle ear effusion needs the nasopharynx examined.
Remember Inferior meatus takes tears; middle meatus takes frontal, maxillary and anterior ethmoid; superior takes posterior ethmoid; sphenoethmoidal recess takes sphenoid.
Exam trap The sphenopalatine artery causes posterior epistaxis and feeds angiofibroma; Little's area causes most anterior bleeds.
Exam trap VI is the first nerve hit in cavernous sinus thrombosis because it lies inside the sinus.
How FCPS asks about this
- Arteries of Little's area: anterior ethmoidal, sphenopalatine, greater palatine, superior labial.
- Opening into the inferior meatus: nasolacrimal duct; maxillary sinus opens into the middle meatus.
- Water from the nose after upper molar extraction: oroantral fistula into the maxillary sinus.
- Torrential bleeding in transsphenoidal surgery: internal carotid artery in the lateral wall.
- Boil beside the nose leading to ophthalmoplegia: facial and ophthalmic veins to the cavernous sinus.
- Dry eye, nose and palate: pterygopalatine ganglion lesion.
- Lymph from the external nose: submandibular nodes.
Test yourself on this topic
5 of the 57 questions in our bank on this topic. Choose an answer to see why every option is right or wrong.
A woman with acute maxillary sinusitis has aching in her healthy upper molar teeth on that side. Which of the following nerves explains the toothache?
Answer: Superior alveolar branches of maxillary nerve
The posterior, middle and anterior superior alveolar nerves, branches of the maxillary nerve and its infraorbital continuation, run in the walls of the maxillary sinus to supply the upper teeth and the sinus lining. Inflammation of the sinus mucosa irritates these nerves, so maxillary sinusitis often presents as pain in the upper molars and premolars. Conversely, an upper dental abscess can cause maxillary sinusitis.
Sinus toothache
- Superior alveolar nerves in sinus walls
- Branches of maxillary nerve (V2)
- Sinusitis felt as upper molar pain
Remember Upper toothache with healthy teeth: think sinusitis.
Exam trap Lower teeth are never involved in maxillary sinus pain.
Why the other options are wrong
- Inferior alveolar branch of mandibular nerve Supplies the lower teeth.
- Greater palatine nerve Supplies the hard palate mucosa, not teeth.
- Nasopalatine nerve Supplies the anterior palate behind the incisors.
- Buccal branch of facial nerve Facial nerve branches are motor to facial muscles.
After a fall onto his face, a man has brisk nosebleeding from high in the nasal cavity, above the middle concha. It continues despite posterior packing and endoscopic ligation of the sphenopalatine artery. Which artery is most likely bleeding?
Answer: Anterior ethmoidal artery
The upper nasal cavity is supplied by the anterior and posterior ethmoidal arteries, branches of the ophthalmic artery from the internal carotid system. Bleeding from this area is not controlled by ligating the sphenopalatine artery, which belongs to the external carotid system. The anterior ethmoidal artery can be ligated through a medial orbital (Lynch) incision or endoscopically. The greater palatine and superior labial arteries supply the lower, anterior septum.
High nasal bleeding
- Upper nose: ethmoidal arteries
- From ophthalmic (internal carotid)
- Not stopped by sphenopalatine ligation
Remember High and persisting after SPA ligation: anterior ethmoidal.
Exam trap Embolising the external carotid branches does not stop ethmoidal bleeding.
Why the other options are wrong
- Greater palatine artery Reaches the anterior septum through the incisive canal, low down.
- Superior labial artery Supplies Little's area at the front of the septum.
- Posterior superior alveolar artery Supplies upper molar teeth and the maxillary sinus.
- Ascending pharyngeal artery Supplies the pharynx, not the upper nasal cavity.
An elderly hypertensive man has heavy nosebleeding mainly into the back of his throat that does not stop with anterior pressure. Which artery is most likely bleeding?
Answer: Sphenopalatine artery
Most nosebleeds in the young are anterior, from Little's area (Kiesselbach's plexus). In older people, especially with hypertension or anticoagulants, posterior bleeds from branches of the sphenopalatine artery are more common and heavier, run down the throat and are not controlled by pinching. They need posterior packing or balloon tamponade, and sometimes endoscopic sphenopalatine artery ligation.
Epistaxis
- Young: anterior (Little's area)
- Elderly: posterior, sphenopalatine
- Posterior: blood down the throat
- Treat: posterior pack, balloon, ligation
Remember Old man, blood down the throat: sphenopalatine.
Exam trap Check BP, clotting and anticoagulant use in every serious nosebleed.
Why the other options are wrong
- Anterior ethmoidal artery Bleeds from above; less common.
- Superior labial artery Contributes to Little's area anteriorly.
- Greater palatine artery Contributes anteriorly through the incisive canal.
- Facial artery Not a direct nasal supply.
Two days after being hit on the nose by a cricket ball, a 12-year-old boy has complete blockage of both nostrils. There is a soft, red, fluctuant swelling on both sides of the septum. If it is not drained, what is the most likely result?
Answer: Saddle nose deformity
This is a septal haematoma. Septal cartilage has no blood vessels of its own and is nourished by the overlying mucoperichondrium. Blood collecting between cartilage and perichondrium cuts off this supply, and within a few days the cartilage necroses or becomes infected (septal abscess). Loss of dorsal septal support then produces a saddle-nose deformity, so the haematoma must be incised and drained urgently.
Septal haematoma
- Bilateral fluctuant septal swelling
- Cartilage fed by perichondrium
- Undrained: necrosis, abscess
- Late: saddle nose
Remember Always look inside the nose after nasal trauma.
Exam trap A septal haematoma is easily missed if only the external nose is examined.
Why the other options are wrong
- Cerebrospinal fluid rhinorrhoea Needs a cribriform plate fracture, not a septal haematoma.
- Anosmia from olfactory nerve damage Olfactory filaments are not injured by a haematoma.
- Blockage of the nasolacrimal duct The duct opens into the inferior meatus; not affected.
- Oroantral fistula Follows dental extraction, not nasal trauma.
Nasal endoscopy shows pus draining only from the sphenoethmoidal recess, above and behind the superior concha. Which sinus is the source?
Answer: Sphenoid sinus
The sphenoethmoidal recess lies above and behind the superior concha and receives only the opening of the sphenoid sinus. The frontal, maxillary and anterior ethmoidal sinuses drain into the middle meatus, mainly via the hiatus semilunaris, and the middle ethmoidal cells open on the ethmoidal bulla. Sphenoid sinusitis typically gives deep retro-orbital or vertex headache.
Sinus drainage
- Sphenoethmoidal recess: sphenoid
- Superior meatus: posterior ethmoidal
- Middle meatus: frontal, maxillary, anterior ethmoidal
- Inferior meatus: nasolacrimal duct
Remember Top to bottom: sphenoid, posterior ethmoid, the rest, tears.
Exam trap Do not place the frontal sinus opening in the superior meatus; it drains into the middle meatus.
Why the other options are wrong
- Frontal sinus Drains via the frontonasal duct into the middle meatus.
- Maxillary sinus Drains through the hiatus semilunaris into the middle meatus.
- Anterior ethmoidal air cells Open into the middle meatus.
- Middle ethmoidal air cells Open on the ethmoidal bulla in the middle meatus.
Where this sits in the CPSP syllabus
- Paper 1: Head, neck and back, Nose, paranasal sinuses and pterygopalatine fossa
- Surgery & Allied, Paper 2: Head and neck, Nose, paranasal sinuses and pterygopalatine fossa
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