Paranasal Sinuses

Question 1

1. What do the paranasal sinuses develop as
2. What are they lined by
3. Where do they open into
4. What are they innervated by

Answer 1

1. Outgrowths from the nasal cavities and erode into surrounding bones
2. Lined by respiratory mucosa which is ciliated and mucus secreting
3. Open into nasal cavities
4. Innervated by branches of trigeminal nerve (V)

Question 2

Where does the frontal sinus drain

Answer 2

Onto lateral wall of middle meatus via the frontonasal duct (which continues as the ethmoidal infundibulum) at the front end of the semilunar hiatus

Question 3

Innervation of the frontal sinus

Answer 3

Innervated by branches of the SUPRAORBITAL nerve from the ophthalmic nerve (V1)

Question 4

Blood supply of frontal sinus

Answer 4

Branches of the anterior ethmoidal arteries

Question 5

Where do the anterior ethmoidal cells open into

Answer 5

Ethmoidal infundibulum/frontonasal duct

Question 6

Where do the middle ethmoidal cells open onto

Answer 6

Ethmoidal bulla (or lateral wall just above this structure)

Question 7

Where do the posterior ethmoidal cells open onto

Answer 7

The lateral wall of the superior nasal meatus

NOTE - ethmoidal cells often erode into bones beyond the boundaries of the ethmoidal labyrinth, so their walls may be completed by the frontal, maxillary, lacrimal, sphenoid and palatine bones

Question 8

What are the ethmoidal cells innervated by

Answer 8

• Anterior and posterior ethmoidal branches of the nasociliary nerve from the ophthalmic nerve (V1)
• Maxillary nerve (V2) via orbital branches from the pterygopalatine ganglion

Question 9

Blood supply of the ethmoidal cells

Answer 9

Through branches of the anterior and posterior ethmoidal arteries

Question 10

Where does the maxillary sinus open into

Answer 10

Semilunar hiatus (grooves the lateral wall of the middle meatus)

Question 11

Innervation of maxillary sinuses

Answer 11

Infra-orbital and alveolar branches of the maxillary nerve (V2)

Question 12

Blood supply of maxillary sinuses

Answer 12

Infra-orbital and superior alveolar branches of the maxillary arteries

Question 13

Relationships of the maxillary sinus

Answer 13

Orbit

Roots of upper molar and premolar teeth

Face

Infratemporal fossa

Question 14

Where do the sphenoidal sinuses open into

Answer 14

Roof of nasal cavity via apertures on the posterior wall of the spheno-ethmoidal recess

Question 15

Relations of the sphenoidal sinuses

Answer 15

• Above to the cranial cavity, particularly to the pituitary gland and optic chiasm
• Cranial cavity (cavernous sinuses)
• Nasal cavities

Question 16

Why is it that the pituitary gland can be surgically approached through the sphenoidal sinuses

Answer 16

Only thin shelves of bone separate the sphenoidal sinuses from the nasal cavities below and hypophyseal fossa above

Question 17

Innervation of the sphenoidal sinuses

Answer 17

• Posterior ethmoidal branch of the ophthalmic nerve (V1)
• Maxillary nerve (V2) via orbital branches from the pterygopalatine ganglion

Question 18

Blood supply of the sphenoidal sinuses

Answer 18

Branches of the pharyngeal arteries from the maxillary arteries