CN VI Abducens

Question 1

CN VI Abducens - Type of Neuron is?

Answer 1

Voluntary motor

-Lateral rectus muscle

Question 2

What muscle does eye Abduction?

Answer 2

Lateral rectus muscle

Question 3

CN VI Abducens - Nucleus located?

Answer 3

Medially in the dorsal tegmentum of caudal pons

-Nerve exits anteromedially

Question 4

CN VI Abducens - Nerve Injury - Medial Strabismus

Answer 4

Adducted position of eye at rest due to unopposed medial rectus

Question 5

CN VI Abducens - Nerve Injury - Lead to inability to?

Answer 5

Abduct the ipsilateral eye beyond midline

Question 6

CN VI Abducens - Nerve Injury - Could also see?

Answer 6

Diplopia

Question 7

CN VI Abducens - Internuclear neurons - have somas in the nucleus of?

Answer 7

CN VI Abducens

Question 8

CN VI Abducens - Internuclear neurons - excite LMNs of?

Answer 8

CN III Oculomotor innervating the medial rectus muscle

-Allows the eyes to move together in the same direction in the horizontal plane (look left or look right)

Question 9

CN VI Abducens - Internuclear neurons - Axons of the internuclear neurons cross midline and enter the?

Answer 9

Contralateral medial longitudinal fasciculus and ascend to the CN III Oculomotor nucleus

Question 10

CN VI Abducens - Nucleus Injury - Damage to the nucleus kills the?

Answer 10

Somas of both the neurons of CN VI Abducens innervating the lateral rectus muscle and the internuclear neurons communicating with CN III Oculomotor neurons innervating the medial rectus muscle

Question 11

CN VI Abducens - Nucleus Injury - Same as injury to the nerve plus?

Answer 11

Conjugate horizontal gaze paralysis

Question 12

What is the Conjugate Horizontal Paralysis?

Answer 12

The inability to abduct the ipsilateral eye beyond midline is accompanied by failure of the contralateral eye to adduct beyond midline during attempted voluntary horizontal movement

Question 13

CN VI Abducens - Nucleus Injury - Adduction of contralateral eye spared during?

Answer 13

Convergence
-Looking at an object up close or when asked to look toward your nose with both eyes

-CN III Oculomotor nerve and the medial rectus muscles are undamaged and healthy

Question 14

CN VI Abducens - Nucleus Injury - A different part of the brain activates CN III Oculomotor for the?

Answer 14

Adduction that occurs with convergence.

Question 15

CN VI Abducens - Nucleus Injury - May be accompanied by?

Answer 15

CN VII Facial palsy

-CN VII Facial LMN wrap around the CN VI Abducens nucleus before proceeding anterolaterally to exit the brainstem