Peripheral distribution of Cranial Nerves I and II Flashcards
what is the olfactory nerve involved in
involved in sensory of cell
what are the fibres of the olfactory nerve
- special sensory afferents ( it is purely sensory)
where does the olfactory nerve travel
- first order neurones are in the nasal cavity and they trap the odour molecules, then go through the cribriform plate of the ethmoid bulb and into the olfactory tract
what is the optic nerve involved in
vision
what fibres does the optic nerve have in it
special sensory fibre
- it is purely sensory
describe the pathway of the optic nerve
- extends out of the cerebrum
- made up of the axon of the ganglion retinal cells that receive input from the photoreceptor cells
- they feed into the optic nerve
- the two optic nerves come together at the optic chiasma
- they then cross over and go into the optic tract
- this goes to the lateral deiculum ganglia and to the visual cortex
what are the photoreceptor cells
rods and cones
what do cones do
- colour vision rods
what do rods do
- low light vision
what are the nerves that move the eyeball
- Oculomotor (CNIII), Trochlear (CNIV), & Abducens (CNVI)
how man extraocular muscles are there
- 6 extraocular muscles that move the eye and a 7th muscle that controls the upper eyelid
what are the 6 extraoclular muscles
- superior rectus
- medial rectus
- lateral rectus
- inferior rectus
- superior oblique
- inferior oblique
where do the rectus muscles attach
- they have a common origin of the annulus of Zinn and all attach to the sclera of the eyeball
what innervates the four rectus muscles
- superior rectus - - Oculomotor (CNIII)
- medial rectus - Oculomotor (CNIII),
- lateral rectus - abducens (CNVI)
- inferior rectus - Oculomotor (CNIII),
what does the superior oblique muscle attach to
attaches posterior to the sphenoid bone, it then courses media and goes through the trochlea of the frontal bone this inserts on the eyeball just inferior to the superior rectus muscle on the sclera
what innervates the superior oblique muscle
Trochlear (CNIV)
what does the inferior oblique muscle attaches to
its origin is the maxilla bone, it then attaches to the sclera posterior to the lateral rectus
what is the inferior oblique muscle innervated by
- Oculomotor (CNIII)
what attaches to the annulus of Zinn
- the 4 rectus muscles are attached onto this ring
What is the annulus of Zinn
- tendinous ring
- it divides up the superior orbital fissure into two spaces
what movements does - superior rectus - inferior rectus - medial rectus - lateral rectus - superior oblique - inferior oblique do?
superior rectus – elevation adducts and internally rotates (main movement is elevation )
inferior rectus – depression adduction and externally rotates (main movement is elevation)
medial rectus – adduction
lateral recuts – abduction
superior oblique – depresses, abducts, and internally rotates (main action is depression)
inferior oblique – elevates, abducts and externally rotates (depress the eye main movement)