Lecture 4

Question 2

Label the structures

Answer 2

1. caudate nucleus
2. thalamus
3. lateral geniculate nucleus
4. medial geniculate nucleus
5. mesencephalon

Question 3

Which tract is associated with the lateral geniculate nucleus?

Answer 3

Optic Tract

Question 4

Which tract is associated with the medial geniculate nucleus?

Answer 4

Auditory tract

Question 5

What is the function of the rostral colliculus?

Answer 5

Visual Reflexes - pupillary dilation, turning the head and blinking the eyes in response to visual stimulation

Question 6

What is the function of the caudal colliculus?

Answer 6

Auditory reflex - startle reflex

Question 7

What is the function of the trochlear nerve? (IV)

Answer 7

Innervates the dorsal oblique m. - intorsion of the eye

Question 8

Where does the trochlear nerve emerge? Which side of the body does it innervate?

Answer 8

Emerges from the dorsal midbrain at the caudal surfcace of the caudal colliculi.

Innervates contralateral dorsal oblique m.

Question 9

Name the structures

Answer 9

1. Rostral colliculus
2. Caudal colliculus
3. Trochlear Neve (IV)
4. origin of CN IV
5. Pretectal nucleus (I don’t think we have to be able to ID that one but I put it on just in case)

Question 10

Which nucleus is responsible for pupillary constriction? On which structure is it found?

Answer 10

1. Pretectal nucleus
2. Rostral colliculus

(number 5 in the image)

Question 11

Label the structures

Answer 11

1. tectum
2. cerebral aqueduct
3. tegmentum

Question 12

Label the structures

Answer 12

1. Corpus callosum
2. Thalamus
3. Midsaggital midbrain

Question 13

Label the structures (sorry to put so many on 1)

Answer 13

1. Cerebrum
2. olfactory bulb
3. corpus callosum
4. thalamus
5. hypothalamus
6. hyophysis
7. optic chaism

Question 14

Label the structures

Answer 14

1. Cerebral aqueduct (aka mesensephalic aqueduct)
2. Tectum
3. Tagmentum

Question 15

Label the structures

Answer 15

1. Optic Nerve
2. Trochlear Nerve
3. Crus Cerebri
4. Pons
5. Pyramid
6. Trapezoid Body

Question 16

1. What kind of tracts make up the crus cerebri?
2. Where do they terminate?

Answer 16

The crus cerebri is made of the descending motor tracts of the cerebral cortex that terminate in the brainstem or spinal cord.

Question 17

Trace a sensory signal through the midbrain and fill in the blank.

Answer 17

Question 18

Label these structures

Answer 18

1. Optic nerve
2. Abducent nerve - emerges from medulla oblongata
3. Pyramid
4. Trochlear Nerve

Question 19

Which muscles are innervated by the oculomotor nerve?

Answer 19

Dorsal rectus, Ventral rectus, ventral oblique, medial rectus

Question 20

Which muscles are innervated by the abducent nerve?

Answer 20

Lateral rectus and retractor bulbi

Question 21

1. What are the smooth muslces of the iris?
2. What are they innervated by?

Answer 21

1. Pupillary spincter muscle and pupillary dilator muscle
2. The pupillary sphincter m. is innervated by the oculomotor nerve. The pupillary dilator m. is innervated by sympathetic fibers.

Question 22

1. What is the role of the ciliary muscle?
2. Which cranial nerve innervates the ciliary muscle?

Answer 22

1. Contraction fo the ciliary muscle allows the lens to change in response to visual stimuli in order to focus
2. It is innervated by the oculomotor nerve.

Question 23

What kinds of fibers make up the Oculomotor nerve?

Answer 23

Somatic and visceral fibers - this means that 2 SEPARATE nuclei give rise to CN III

Question 24

What kind of fibers make up the trochlear nerve?

Answer 24

CN IV is made up of ONLY somatic fibers (inn. skeletal muscle)

Question 25

What clinical signs would you see with damage of the oculomotor nerve?

Answer 25

Ventrolateral strabismus Pupillary Dilation Drooped eyelid The neuro program is really good practice for this stuff, I think he'll probably ask a lot of questions like this.

Question 26

What would you expect to see with a lesion of the trochlear nerve?

Answer 26

Extorsion of the eyeball - very difficult to tell with dogs since they have a round pupil, easier to tell on cats.

Question 27

What clinical signs would you expect to see from a lesion of the abducent nerve?

Answer 27

Medial strabismus, no retraction of the eyeball