Chapter 10 Flashcards
(16 cards)
The oculomotor nerve (III) innervate which muscles?
Medial rectus (in) Superior rectus (up) Inferior rectus (down) Inferior oblique (up & in)
The trochlear nerve (IV) innervates which muscle?
Superior oblique (down & in)
The abducens nerve (VI) innervates which muscle?
Lateral rectus (out)
Where is the horizontal gaze center located and what is its function?
the paramedian pontine reticular formation.
the horizontal gaze center is responsible for conjugate (eyes move in same direction) movements towards its ipsilateral side.
From the paramedian pontine reticular formation, nerve impulse travel too where in order to coordinate conjugate eye movements?
to the ipsilateral abducens nucleus to control lateral rectus muscle; and interneurons crossing immediately via the medial longitudinal fascicles (MLF) to contralateral oculomotor nucleus to control the medial rectus.
A unilateral lesion in the MLF at/rostral to abducens can cause?
adduction (medial rectus) paralysis in contralateral eye
Where is the vertical gaze center located and what is its function?
in the accessory oculomotor nuclei.
This gaze center acts bilaterally with upward movements represented more dorsally and downward more ventrally.
Where is the vergence gaze center located and what is its function?
near reticular formation near CN III.
vergence controls convergence and divergence eye movements (looking near to far)
Upward gaze paralysis is often the result of what?
pressure being exerted on the rostral midbrain by a pineal gland tumor or from dilation of rostral part of cerebral aqueduct.
What are saccades eye movements?
- voluntary when vision is being moved rapidly from one target to another, like reading a printed page in a book.
- can also be a reflex, as nystagmus and rapid eye movement sleep.
The cortical gaze center includes?
frontal eye field
parietal eye field
temporal eye field
occipital eye field
What is the chief center for voluntary movement in the cortical gaze center and where is it located?
the frontal eye field located in the posterior part of the middle frontal gyrus.
The superior parietal lobule influences what eye movements?
plays a role in visual attention
saccadic movements through reciprocal connections with the frontal eye field and projection to the superior colliculus
The temporal eye field is the chief center for _____ _______ eye movements.
smooth pursuit
Where does the temporal eye field receive input rom and send output to?
receives input from visual cortex
send output to dorsolateral pontine nuclei -> then to vestibular nuclei via vestibulocerebellum
Lesion to temporal eye field is seen by?
loss of ipsilateral smooth pursuit
