Visual Motor System

Question 1

In order to look to the right, you need to activate which of the following muscles?

• left lateral rectus and right medial rectus
• right lateral recuts and left medial rectus
• right and left medial rectus

Answer 1

right lateral recuts and left medial rectus

Explanation

In order to look to the right, you need to move the eyes to the right. This involves abduction of the right eye (mediated by the right lateral rectus) and adduction of the left eye (mediated by the left medial rectus). The first choice would be mediate looking to the left, and the last choice would produce movement of the eyes toward the nose (this will occur during convergence).

Question 2

Which neural pathway provides innervation of muscles that allow for lens accommodation and pupillary constriction?

• Communication between preganglionic neurons of the intermediolateral cell column and the superior cervical ganglion.
• Communication between preganglionic neurons of the EWN and the ciliary ganglion.
• Communication between the preganglionic neurons of the EWN and the superior cervical ganglion.

Answer 2

Communication between preganglionic neurons of the EWN and the ciliary ganglion.

Explanation

Lens accommodation and pupillary constriction are mediated by two smooth muscles: ciliary muscle and the sphincter pupillae. Both of these muscles are activated by a parasympathetic pathway that begins with viceromotor neurons of the EWN (preganglionic neurons) and post-ganglionic neurons of the ciliary ganglion. Short ciliary nerves originating is this ganglion will innervate the ciliary and sphincter pupillae muscles. Communication betweeen preganglionic neurons of the intermediolateral cell column (lateral horn of the spinal cord) communicate with post-ganglionic neurons of the superior cervical ganglion as part of the sympathetic pathway that mediates contraction of the dilator pupillae and the tarsal muscles.

Question 3

Your patient presents with ptosis of the eye and a constricted pupil. Based on this information you conclude which of the following?

• CN III palsy
• CN VI palsy
• Injury to the superior cervical ganglion

Answer 3

Injury to the superior cervical ganglion

Explanation

Ptosis of the upper eyelid and a constricted pupil is an indicator of damage along the neural pathway that provides innervation to the tarsal muscles and the dilator pupillae (sympathetic pathway). CN III palsy would result in ptosis as well, but with a dilated pupil and the eye would be positioned in a “down and out” position in the orbit. CN VI palsy would result in an esotropia and an inability to abduct the ipsilateral eye.

Question 4

Conjugate eye movements involve movement of the eyes in the same direction.

True or False

Answer 4

True

Explanation

This statement is true: conjugate eye movements involved movement of the eyes in the same direction (look right - both eyes move to the right). NOTE: disconjugate eye movements involve movement of the eyes in the opposite direction (look in at your nose - your right eye moves to the left and your left eye moves to the right).

Question 5

Which of the following is a gaze shifting movement? Select all that apply.

• vestibulo-ocular reflex
• Saccades
• smooth pursuits
• vergence

Answer 5

Saccades, smooth pursuits and vergence

Explanation

There are two types of eye movements: gaze stabilizing and gaze shifting movements: gaze stabilizing movements include the VOR. All of the others are gaze shifting movements.

Question 6

The left horizontal gaze center will produce a horizontal saccade to the right.

True or False

Answer 6

False

Explanation

This statement is false: the right horizontal gaze center will activate LMN that will produce a right horizontal saccade (movement of the eyes to the right).

Question 6

Neurons is the right horizontal gaze center will activate neurons in which of the following nucleus?

• Abducens nucleus on the left
• Abducens nucleus on the right
• Oculomotor nucleus on the left

Answer 6

Abducens nucleus on the right

Explanation

The right horizontal gaze center will activate neurons in the right abducens nucleus (activating LMN to the right lateral rectus and internuclear neurons that contact the left oculomotor nucleus via the medial longitudinal fasciculus).

Question 6

The frontal eye fields are the UMN that will send commands to control voluntary saccades.

True or False

Answer 6

True

Explanation

This statement is true: the frontal eye fields contain UMN that send commands to control the production of voluntary saccades.

Question 7

The tectoreticulospinal system will out put to which of the following areas? Select all that apply.

• horizontal gaze center
• vertical gaze center
• medial located LMN in the cervical segments of the spinal cord

-laterally located LMN in the cervical segments of the spinal cord

Question 7

What would you see if there is a lesion at A, B, C ?

Answer 7

• A- injury to optic nerve therefore no vision nor reflex on both sides
• B- client will see but relfexes will be weaker
• C- both direct and consensual responses will be lost in the eye on the region but will present in other eye