DLA 28 + lecture 27+28

Question 1

function of lateral rectus eye muscle 
innervation

Answer 1

abduction 
CN VI (abducens)

Question 2

medical rectus function

innervation

Answer 2

adduction 
CN III (oculomotor)

Question 3

superior rectus function

innervation

Answer 3

elevation during abduction
intorsion during adduction

CN III

Question 4

inferior rectus function

innervation

Answer 4

depression during abduction
extorsion during adduction

CN III

Question 5

superior oblique function

innervation

Answer 5

depression during adduction
intorsion during abduction

CN IV (trochlear N)

Question 6

inferior oblique function

innervation

Answer 6

elevation during adduction
extorsion during abduction

CN III

Question 7

medial longitudinal fasciculus

Answer 7

in control of vertical eye movements

found in the midbrain

Question 8

pontine paramedianmreticular formation (PPRF)

Answer 8

participates in saccadic eye movements and lateral gaze

horizontal gaze center

located in pons

Question 9

vestibular nuclei

Answer 9

extend from the pons to the medulla

contribute to the control of eye movements

Question 10

cerebellum and eye movements

Answer 10

Vestibulocerebellum (flocculo-nodular lobe)

participates in the control of optokinetic movements and smooth pursuit

Question 11

area 8

Answer 11

frontal eye field (motor control)

Question 12

visual sensory (motion) input

Answer 12

parieto-occipital eye field

Question 13

Trochlear Nerve Palsy

Answer 13

deficit of the superior oblique muscle
leaves inferior oblique unopposed

eyes are up and to the right during primary gaze

Question 14

Oculomotor Nerve Palsy

Answer 14

the will be deviated down and out during primary gaze

lateral rectus muscle is unopposed

usually see ptosis and mydriasis

Question 15

abducens nerve palsy

Answer 15

eye will be deviated medially

medial rectus muscle is unopposed

Question 16

diplopia (double vision)

Answer 16

eyes are not pointed at the same target

mismatch of the visual field centers of the eyes

will complain of blurry vision

Question 17

medial longitudinal fasciculus lesion

Answer 17

prevents adduction of the side with the lesion during lateral gaze

Question 18

PPRF Lesion

Answer 18

a paralysis of ipsilateral horizontal eye movements

prevents conjugate gaze of both eyes to the side with the lesion

Question 19

One-and-a-half Syndrome

Answer 19

lesion of both the MLF and the PPRF

prevents adduction of the eye with the lesion
prevents conjugate gaze of the both eyes to the side of the lesion

one eye cannot move lateral
and the other can only move outward

Question 20

The 3 divisions of the ear

Answer 20

1. external ear (auricle or pinna) 
collects and amplifies sound 
external meatus (conducts sound to tympanic membrane) 

2. middle ear
   tympanic membrane (separates external meatus from inner ear)
   ossicles (malleus, incus, stapes)
   auditory tube (middle ear to nasopharynx)
3. internal ear
   bony labyrinth
   membranous labyrinth

Question 21

bony labyrinth (inner ear)

Answer 21

made up by semicircular canals (anterior, posterior, lateral)

vestibule
cochlea

perilymph

Question 22

membranous labyrinth (inner ear)

Answer 22

Communicating sacs & ducts suspended within the bony labyrinth

cochlear (cochlear duct)

vestibular (semicircular ducts, utricle, and saccule

endolymph

Question 23

Perilymphatic space

Answer 23

Between wall of bony labyrinth & wall of membranous labyrinth

low K / high Na (similar to extracellular fluid)

Question 24

Endolymphatic spaces

Answer 24

contained within the membranous labyrinth

high K / low Na (similar to intracellular fluid)

Question 25

sensory hairs of the labyrinth

Answer 25

rows of stereocilia

mechanoreceptor transducer channel proteins at the distal ends (communicate with afferent fibers)

Question 26

2 types of hair cells of the vestibular labyrinth

Answer 26

type I: flask shaped and surrounded by afferent fibers; few efferent

type II: cylindrical shaped
afferent and efferent nerves

Question 27

sensory regions of the cochlear labyrinth

Answer 27

spiral organ of corti
sensor of sound vibrations
has inner and outer hair cells; supporting cells
spiral ganglion

Question 28

sensory regions of the vestibular labyrinth

Answer 28

1. the semi-circular ducts
   3 ampullae each contain crista ampullaris
   sensors of angular movement of the head through cupula
   Type I and II cells; supporting cells
2. saccule and utricle
   have maculae (oriented at right angles)
   sensors gravity and linear acceleration (otolithic membrane)
   Type I and II cells; supporting cells

Question 29

cochlea

Answer 29

around a central core called a modiolus

three compartments:

1. scala media (cochlear duct)
   endolymph
   spiral organ of corti
2. scala vestibuli
   perilymph
3. scala tympani
   perilymph space

the vestibuli and tympani connect at the apex of the cochlea via the helicotrema

Question 30

scala media or cochlear duct

Answer 30

contains stria vascularis - production and maintenance of endolymph

Question 31

spiral organ of corti

Answer 31

sensor of sound vibrations

phalangeal and pillar support cells

tectorial membrane (rigid)
gel-like structure
bundles of II, V, and IX collagen; glycoproteins
attached to modiolus

Question 32

stria vascularis

Answer 32

production and maintenance of endolymph
capillary network

3 types of cells:

1. marginal cells - K transport; line endolymphatic space
2. intermediate cells- contain pigment; along capillaries
3. basal cells - separate from spiral ligament

Question 33

hair cells of the spiral organ of corti

Answer 33

inner: 
primary sensory cells for hearing 
cant regenerate 
straight line of stereocilia
single layer 

outer:
variable number of rows
characteristic ‘W’ of stereocilia
play role in amplification

Question 34

conductive hearing loss

Answer 34

Sound waves are mechanically impeded from reaching the auditory sensory receptors of the internal ear

causes: 
ear infection 
lots of ear wax
foreign bodies
otosclerosis

Question 35

Sensorineural hearing loss

Answer 35

injury to the sensory receptors, nerves, or auditory cortex

causes: 
infection of membranous labyrinth 
fracture of temporal bone 
acoustic trauma
aging

Question 36

presbycusis

Answer 36

loss of sensory cells