Orbit and nasal cavity Flashcards
What is the function of the nose?
To filter dust entering the respiratory system
Warm the air
Use in breathing
List the bones of the nose
Comprised of paired nasal bones, maxillae, frontal bone and septum
Name the cartilage found in the nose
3 main lateral, major alar and septal
What does the septum do?
Divides the nose into 2 chambers
Describe the inferior surface of the nose
3 projections - superior, middle and inferior conchae
What does the nasal cavity open up into?
Nasopharynx
What arteries supply the nose?
Branches from maxillary and opthalmic
Which nerves supply the nose?
Olfactory, ophthalmic (V1 and maxillary V2)
What type is the olfactory nerve (CN1)?
Sensory - special afferent
Where does the olfactory nerve exit?
Cribriform plate
What is the olfactory nerve responsible for?
Smell
Where are the olfaction receptors located?
In the epithelium lining the roof and walls
What does the epithelium of the nasal cavity do?
Secrete mucus fluid
Describe olfaction
Olfaction is aided by the air flow through the nasal cavity
The epithelium secretes a mucus fluid, odoriferous gases are dissolved into the fluid and then detected by the olfactory nerves
What are paranasal sinuses?
Air filled extensions of the nasal cavity
Where are paired frontal sinuses found?
In the frontal bone
Where does the frontal sinus drain?
Through frontonasal duct
What are ethmoidal cells?
Invaginations in the ethmoid bone and drain into middle meatus or superior meatus
What are sphenoidal sinuses?
In sphenoid bone
Where do sphenoidal sinuses drain?
Sphenoethmoidal recess
Where do paired maxillary sinuses in the maxilla drain?
Middle meatus
List the 7 bones the orbit is made up of
Frontal Maxilla Ethmoidal Lacrimal Sphenoidal Temporal - zygomatic Nasal
What does the eyeball contain?
Optical apparatus for the visual system
Where is the eyeball located?
In the orbit suspended by muscles
How many layers are there to the eye?
3
Name the two outer fibrous structures
Sclera and cornea
Where is the vascular iris located?
On top of muscles
Name the chambers the eye is divided into
Anterior and posterior chambers
What type of nerve is the optic nerve?
Special afferent- Sensory
What is the function of the optic nerve?
Vision
Where does the optic nerve exit the brain?
Optic canal
Describe the embryological development of the optic nerve
Optic stalk grows out and lens vesicle grows in
List the extraocular muscles
Levator Palpebrae, Superior Oblique, Superior Rectus, Medial Rectus, Lateral Rectus, Inferior Rectus, Inferior Oblique
In what directions can the eye move?
Abduct and Adduct
Intort and extort
Elevate an depression
What does the levator palpebrae do?
Lifting up the eyelid
In which direction does the superior rectus cause the eye to move?
Elevation
Adduction
(up and in)
In which direction does the inferior rectus cause the eye to move?
Down and in
In which direction does the medial rectus cause the eye to move?
In
In which direction does the lateral rectus cause the eye to move?
Out
In which direction does the superior oblique muscle cause the eye to move?
Down and out
In which direction does the inferior oblique cause the eye to move?
Up and out
How many positions of gaze are there? `
9
What type of nerve is the oculomotor nerve?
Somatic motor - general somatic efferent to extra-ocular muscles
Which extraocular muscles do the oculomotor nerve not innervate?
Superior oblique
Lateral rectus
Where does the oculomotor nerve exit?
Superior orbital fissure
What type of nerve is the trochlear nerve? (CNIV)
Somatic motor - general somatic efferent
Which muscle does the trochlear nerve innervate?
Superior oblique
Where does the trochlear nerve exit?
Superior orbital fissure
What type of nerve is abducent nerve (CNVI)?
Somatic motor
Which muscle does the abducent nerve innervate?
Lateral rectus
Where does the abducent nerve exit?
Superior orbital fissure
Which cranial nerves are affected in inability of specific eye movements?
CN 3,4,6
Which cranial nerves are affected in a dilated pupil?
CN3
Which cranial nerve is affected in ptsosis?
CN3
Which cranial nerve is affected in abnormal pupil reflex?
CN3
What does the lacrimal apparatus consist of?
Lacrimal gland- orbital and palpebral
Describe the process of crying
secretes lacrimal fluid which passes across the eye and into the lacrimal papilla, lacrimal sac and to the inferior meatus via the nasolacrimal duct.
Name the parasympathetic supply of crying
Secretomotor of CN7
Name the sympathetic supply of crying
Vasoconstrictive (superior cervical ganglion via internal carotid
What is the blood supply to the orbit?
Ophthalmic artery
Infraorbital artery
Central artery
