Autonomic Nervous System

Question 1

Explain the meaning of the terms “craniosacral division” and “thoracolumbar division” in
describing the ANS. Identify the spinal cord segments that give rise to preganglionic fibers in
both divisions of the canine ANS.

Answer 1

“craniosacral division” is the parasympathetic division from brain stem and sacral spinal cord
- contains cranial nn. 3,7,9,10 and sacral 1-3

“thoracolumbar division” is the sympathetic division from thoracic/lumbar spinal cord, specifically T1-L4/5

Question 2

Identify the tissues which are the targets of the ANS.

Answer 2

smooth muscle
cardiac muscle
glands

Question 3

Identify the specific neurotransmitters released at autonomic synapses and review the post-synaptic receptors

Answer 3

sympathetic
ACh on nicotinic R pregang.
NE/E on adrenergic R postgang.

parasympathetic
ACh on nicotinic R pregang.
ACh on muscarinic R postgang.

Question 4

where are sympathetic preganglia found and where do they synapse

Answer 4

preganglia found in thoracic/lumbar spinal cord (T1-L4/5) as the sympathetic chain

synapse at paravertebral ganglion and the ones that don’t, synapse in collateral ganglion in the abdomen

Question 5

what are the paravertebral ganglia

Answer 5

sympathetic chain

Question 6

what are the collateral ganglia

Answer 6

ganglia in the abdominal cavity associated with major branches of abdominal aorta
includes celiacomesenteric ganglion and caudal mesenteric ganglion

Question 7

where are sympathetic postganglia located

Answer 7

abdominal or pelvic viscera

Question 8

what nerve provides sympathetic innervation to pelvic viscera

Answer 8

hypogastric nn.

Question 9

what nerve provides parasympathetic innervation to pelvic viscera

Answer 9

pelvic n.

Question 10

Describe the route by which sympathetic innervation is distributed to the eye and other parts of the head. Identify which spinal cord segments supply this innervation.

Answer 10

T1-2/3 –> smooth m of eye

T1-6/7 –> smooth m of head

Question 11

what is the largest autonomic ganglion

Answer 11

cervicothoracic ganglion

Question 12

what spinal cord segments do splanchnic nn. arise from? where do they synapse to?

Answer 12

arise from T7-L5
pass through sympathetic chain and synapse to collateral ganglia in abdominal viscera at celiacomesenteric ganglion and caudal mescenteric ganglion

Question 13

Identify the adrenal gland. Describe the unique nature of its autonomic innervation.

Answer 13

Preganglionic fibers of some splanchnic nerves innervate chromaffin cells (act as postganglionic neurons) which release epinephrine into the bloodstream

Question 14

what ganglia is cranial nerve III associated with? what is its autonomic function?

Answer 14

ciliary ganglion
pupil constrictor

Question 15

what ganglia is cranial nerve VII associated with? what is its autonomic function?

Answer 15

pterygopalatine ganglion
lacrimal and salivary glands

Question 16

what ganglia is cranial nerve IX associated with? what is its autonomic function?

Answer 16

vagosympathetic trunk
salivary glands

Question 17

what ganglia is cranial nerve X associated with? what is its autonomic function?

Answer 17

vagosympathetic trunk
cervical, thoracic and abdominal viscera

Question 18

Cats are prone to “feline asthma,” an allergic condition that features increased airway secretions and airway constriction. With reference to autonomic innervation and feline airway anatomy, explain why an IV dose of epinephrine might be expected to relieve severe symptoms of feline asthma in an emergency.

Answer 18

Epinephrine binds to 𝛽-2 adrenergic receptors on smooth m in the bronchial region inhibiting muscle contraction, thus it will cause smooth m relaxation relieving severe symptoms