Anatomy of Eye, Ear Flashcards
7 eye muscles
Laterl rectus Inferior and superior rectus Medial rectus Superior and inferior oblique Levator palpabrae
which muscles originate from the orbit
all apart from the SUPERIOR OBLIQUE , INFERIOR OBLIQUE AND LEVATOR PALPABRAE
Where does the superior oblique arise from
sphenoid bone and hooks through the trochlea
where does the inferior oblique and lps arise from
IO- anterior part of orbit
lps- sphenoid
what are the medial and lateral rectus responsible for
medial- intorsion, addiction
lateral- extorsion abduction
role of levator palpabrae
elevates the upper eyelid
primary and secondary action of superior rectus
- elevates the eye
2, adducts and medially rotates
primary and secondary roles of inferior rectus
1-depresses the eye
2- abducts and laterally rotates
Where and what are the semi circular canals
structures inside the inner ear
within the petrous part of temporal bone
3 - anterior, posterior and lateral
why are the SSC at right angles
detects movement of head
what are the 3 senseorgans
crista
macula of uricle
macula of saccule
4 functions of semi circular canala
Detect movement of the head. Send this info centrally.
Rotation of the head in the same plane as one of the canals:
endolymph moves in the opposite direction
cupula and hair cells in the ampulla bend in the opposite direction
muscles in the middle ear ?
tensor tympani and stapedius
Smallest bone in the body ?
Stapes
Role of the middle ear?
Acoustic impedance match between air and fluid filled inner ear
role of the eustachian tube
Helps to drain fluid and equalise air pressure inside your ears
Connects to the pharynx
role of the labyrinth
responsible for balance
3 compartments of the cochlea
Scala Tympani, Scala Media & Scala vestibuli
what is the cochlears role
hearing
Purpose of astrocytic end feet
They regulate the permeability of the blood brain barrier
what are the three layers of the eye
outer layer- sclera and cornea
middle layer- uvea
inner layer- retina
what is the cornea made up from
collagen
5 layers of the cornea
epithelium bowmans layer stroma Descemet's layer endothelium
function of endothelium in cornea
to move water out the cornea so water can pass through
what is the uvea made from
cililary body, iris, and choroid
main function of iris?
contains dilator and sphincter pupillae muscles to change amount of light that can enter
what is the cilialry body made from histology
Ciliary body – glandular epithelium produces aqueous humour ciliary
allow for accommodation
what is between iris and lens
posterior chamber
choroid function?
provides blood supply to outer third of retina
NEURAL PATHWAY IN RETINA
Retinal photorecptors Bipolar cells Amacrine & horizontal cells Mullers glial cells Retinal ganglion cells
FUNCTION OF ANTERIOR SEGMENT
Nutrition to lens and cornea
Aqueous humour
roles of the lens
Transmit light and focus it on the retina
what are opsins
Opsins are transmembrane proteins which contain the light sensitive molecule retinal
Normal papillary light reflex
Ipsilateral pupil contracts - direct response
Contralteral pupil consteicts - consensual response
What is the corneoscelral junction
Where the cornea and sclera meet
What do SO and IO do together
Abduction
Layers of the retina
Outer- pigmented contains melanin
Inner layer - photoreceptors , light transduction vit a storage
Which muscles are innervated by occulomotor
Levator palpebrae
Superior rectus
Inferior rectus
Medial rectus inferior oblique
Which muscle is innervated by trochlear
Superior oblique
Which muscle is innervated by abducens nerve
Lateral rectus
What secretes tears
Lacrimal apparatus
Purpose of macula
Acuity of vision
Contains only cones
What do the ciliary processes make
Aqueous humour
What does damage to optic tract cause
Bitemporal heminopia
Lesion to right optic nerve
Right anopia
Damage right optic tract
Right homonymous hemianopia
How do visual fields work
Nasal tract crosses over
Temporal tract stays on the same side
Three parts of external ear
Auricle
External acoustic meatus
Tympanic membrane
Role of the auricle
Directs sound into external acoustic meatus
Role of external acoustic meatus
Transmits sound to the tympanic membrane
Has cerumen , prevents pathogens and insects from reaching the tympanic membrane
Role of tympanic membrane
Vibrates in response to sound
Transmits vibrations to ossicles
Separates ext and middle ear
Role of oval window
Amplifies sound and transmits it to Scalia vestibuli
What is the cochlear duct filled with
Endolymph
What makes up the organ of corti
Hair cells
Supporting cells
Auditory nerve fibres
3 ossicles in ear
Incus
Malleus
Stapes
Sense organ of hearing and location
Organ of corti
Basilar membrane
Neural pathway of hearing
Eighth cranial nerve Cochlear Olivary nucleus Lateral leminiscus Inferior colliculus Medial geniculate body Auditory cortex
Where do the two components of the vestibulocochlear nerve arise from
Vestibular component - vestibular nuclei in pons and medulla
Cochlear - ventral and dorsal cochlear nuclei in inferior cerebellar peduncles
What is the function of vestibular hair cells
Detect changes in motion and position of the head
Sound pathway
Sound ➡️ ext acoustic meatus ➡️ vibration of tympanic membrane ➡️ ossicle vibration ➡️oval window ➡️fluid filled vibrations in cochlea ➡️organ of corti ➡️ basilar membrane ➡️hair cell depolarisation ➡️cochlear nerve ➡️cn8➡️auditory cortex
Parts of the inner ear
Semi circular Canal
Cochlea
Fluid filled space within a bone
Innervation of stapedius
Facial nerve
Innervation of eustachain tube
Glossopharangyeal
What allows for the transmission of action potentials in thr ear
Different concentration of ions
What is the bony labyrinth formed by
Vestibule
Three semi circular canals
Cochlea
