FUNCTIONAL ANATOMY - Autonomic Nervous System

Question 1

What is the function of the autonomic nervous system?

Answer 1

Regulation of involuntary activity

Question 2

What are the two functional divisions of the autonomic nervous system?

Answer 2

Parasympathetic nervous system
Sympathetic nervous system

Question 3

Where in the central nervous system are the parasympathetic cell bodies located?

Answer 3

Craniosacral (brainstem and sacral region of the spinal cord)

Question 4

Where in the central nervous system are the sympathetic cell bodies located?

Answer 4

Thoracolumbar (thoracic and lumbar regions of the spinal cord)

Question 5

What is the main control centre of the autonomic nervous system?

Answer 5

Hypothalamus

Question 6

Which three cranial nerves provide parasympathetic innervation to the viscera of the head?

Answer 6

Cranial nerve III (oculomotor nerve)
Cranial nerve VII (facial nerve)
Cranial nerve IX (glossopharyngeal nerve)

Question 7

What is the parasympathetic function of cranial nerve III (oculomotor nerve)?

Answer 7

Innervation of the iris for pupil constriction (miosis)

Question 8

Which parasympathetic ganglion does the pre-ganglionic fibre of cranial nerve III (oculomotor nerve) synapse with?

Answer 8

Ciliary ganglion

Question 9

Which four visceral structures of the head receive parasympathetic innervation from cranial nerve VII (facial nerve)?

Answer 9

Nasal glands
Lacrimal glands
Mandibular salivary gland
Sublingual salivary gland

Question 10

Which two visceral structures of the head receive parasympathetic innervation from cranial nerve IX (glossopharyngeal nerve)?

Answer 10

Parotid salivary gland
Zygomatic salivary gland

Question 11

Which cranial nerve provide parasympathetic innervation to the cervical, thoracic and abdominal viscera?

Answer 11

Cranial nerve X (vagus nerve)

Question 12

Where does cranial nerve X (vagus nerve) travel within the body to reach the cervical, thoracic and abdominal viscera?

Answer 12

Cranial nerve X (vagus nerve) leaves the brain stem and travels within the vagosympathetic trunk and branches from the vagosympathetic trunk at the level of the middle cervical ganglion and supplies the thoracic and abdominal viscera via the dorsal and ventral branches of the vagus nerve. Additionally, the vagus nerve gives rise to the recurrent laryngeal nerves which travel cranially to innervate the cervical oesophagus and the larynx

Question 13

Which three spinal nerves provide parasympathetic innervation to the pelvic viscera?

Answer 13

S1 - S3

Question 14

What are the paravertebral ganglia?

Answer 14

Interconnected ganglia located near the spinal cord

Question 15

What is another name for the paravertebral ganglia?

Answer 15

Sympathetic trunk

Question 16

Which five spinal nerves provide sympathetic innervation to the viscera of the head and neck?

Answer 16

T1- T5

Question 17

Which sympathetic ganglion do the T1-T5 pre-ganglionic fibres synapse with?

Answer 17

Cranial cervical ganglion

Question 18

Describe where in the body the pre-ganglionic fibres of the T1-T5 spinal nerves run to reach the cranial cervical ganglion

Answer 18

Pre-ganglionic fibres of the T1-T5 spinal nerves run cranially within the vagosympathetic trunk and synapse with the cranial cervical ganglion

Question 19

Describe the pathway for the sympathetic innervation of the eye

Answer 19

First order neurones from the hypothalamus synapse with the T1, T2 and T3 spinal nerves (pre-ganglionic neurones) which travel cranially up the vagosympathetic trunk and synapse with the cranial cervical ganglion, and from there, the post-ganglionic neurones will continue to innervate the eye

Question 20

Which three visceral structures of the eye are innervated by the sympathetic nervous system?

Answer 20

Iris
Third eyelid
Smooth muscle of the eyelids

Question 21

What are the three effects of sympathetic innervation to the eye?

Answer 21

Pupil dilation (mydriasis)
Retraction of third eyelid
Widening of the palpebral fissure

Question 22

Which disease is caused by the loss of sympathetic innervation of the eye?

Answer 22

Horner’s syndrome

Question 23

What are the four clinical signs of Horner’s syndrome?

Answer 23

Pupil constriction (miosis)
Prolapse of the third eyelid
Narrowing of the palpebral fissure
Enophthalmos

Enophthalmos refers to your eyes sinking deeper in your eye socket

Question 24

What are three possible underlying causes of Horner’s syndrome?

Answer 24

Intervertebral disc herniation
Brachial plexus damage
Otitis media

Question 25

How can intervertebral disc herniation cause horners syndrome?

Answer 25

The interverterbal discs are located ventral to the intervertebral foramina so intervertebral disc herniation can cause compression of the T1 - T3 pre-ganglionic fibres as they leave the spinal cord, resulting in Horner’s syndrome

Question 26

Which nerve is responsible for sympathetic innervation of the bladder?

Answer 26

Hypogastric nerve

Question 27

What is the function of the hypogastric nerve in bladder innervation?

Answer 27

The hypogastric nerve relaxes the detrusor muscle and contracts the internal urethral sphincter to allow for urine storage

Question 28

Which nerve is responsible for parasympathetic innervation of the bladder?

Answer 28

Pudendal nerve

Question 29

What is the function of the pudendal nerve in bladder innervation?

Answer 29

The pudendal nerve contracts the detrusor muscle and relaxes the internal urethral sphincter to allow for bladder emptying

Question 30

What is equine dysautonomia (grass sickness)?

Answer 30

Equine dysautonomia (grass sickness) is impaired gastrointestinal activity due to damage to the autonomic nervous system

Question 31

What are the three clinical presentations of equine dysautonomia (grass sickness)?

Answer 31

Acute
Subacute
Chronic

Question 32

What is the mortality rate for a horse with acute equine dysautonomia (grass sickness)?

Answer 32

100% mortality

Question 33

Between which months is equine dysautonomia (grass sickness) most common?

Answer 33

April to July

Question 34

What are the three risk factors associated with equine dysautonomia?

Answer 34

Grazing
Feed change
Pasture disturbance