Lecture 15 9/12/23

Question 1

What are the characteristics of pupil innervation?

Answer 1

-hypothalamus sends input to T1 and T2
-preganglionic neuron exits at T1/T2
-pre-ganglionic neuron synapses on ciliary ganglion
-ciliary ganglion (postganglionic neuron) starts by tympanic bulla and innervates pupil

Question 2

What are the signs of Horner’s syndrome?

Answer 2

-small pupil
-droopy upper eyelid
-elevated third eyelid
-enopthalmos/globe sinking into orbit

Question 3

Where is it most common for animals to have a lesion causing Horner’s syndrome, and why?

Answer 3

-at the ciliary ganglion
-ear infections and tumors can occur here and cause Horner’s

Question 4

How can vasodilation from Horner’s syndrome be seen in Siamese cats?

Answer 4

-increased blood vessel dilation will increase temp. on that side of face
-animal will lose dark coloring due to activation of enzyme that breaks down melanin

Question 5

How should the pupils normally react to light?

Answer 5

when a bright light is shown on the pupil, it should constrict

Question 6

How does the pupil react to light?

Answer 6

-light first sensed in retina
-stimuli is carried into brainstem
-brainstem sends signal to constrict pupil in response

Question 7

Which cranial nerve is involved with pupil contraction?

Answer 7

CN 3

Question 8

Where is the preganglionic LMN for pupil constriction?

Answer 8

CN3 oculomotor

Question 9

Where is the postganglionic LMN for pupil constriciton?

Answer 9

short ciliary nerves

Question 10

What is the role of the sphincter pupillae muscle?

Answer 10

to constrict the pupil

Question 11

Why is it important to check the pupillary reflex is blind animals?

Answer 11

-the first part of the vision pathway and pupillary reflex pathway overlap
-vision and pupillary reflex will both be impacted if lesion occurs in the overlap region

Question 12

Where would a lesion be if an animal has blindness and an absent PLR?

Answer 12

-retina
-optic nerve
-optic chiasm
-optic tract

Question 13

Where would a lesion be if an animal has no blindness but an absent PLR?

Answer 13

-brainstem
-CN 3
-pupil

Question 14

Where would a lesion be if an animal has blindness with normal pupils?

Answer 14

forebrain

Question 15

What are the characteristics of the sympathetic nervous system and micturition?

Answer 15

-storage phase
-increased urethral sphincter tone
-decreased detrusor muscle tone

Question 16

What are the characteristics of the parasympathetic nervous system and micturition?

Answer 16

-voiding/peeing phase
-decreased urethral sphincter tone
-increased detrusor muscle tone

Question 17

Which nerves are involved with micturition?

Answer 17

-sympathetic: hypogastric n. (L1-4)
-parasympathetic: pelvic n. (S1-3)
-somatic: pudendal n. (S1-3)

Question 18

What sympathetic receptors are involved with micturition storage?

Answer 18

-alpha receptors controlling internal sphincter contraction
-berta receptors relaxing detrusor muscle

Question 19

How is the somatic nervous system in micturition storage?

Answer 19

contraction of external sphincter

Question 20

How are parasympathetic receptors involved with micturition voiding?

Answer 20

allowing for detrusor muscle contraction

Question 21

Why is inhibition important in micturition voiding?

Answer 21

-inhibit alpha and beta receptors of sympathetic NS
-relax external sphincter