Anatomy of the Autonomic Nervous System

Question 1

What is the role of the autonomic nervous system?

Answer 1

Motor innervation of smooth muscle, cardiac muscle (which make up viscera) and glands.
Revice signals via visceral afferent fibres and respond to stimuli via visceral efferent fibres.

Question 2

What are the division of the nervous system?

Answer 2

Divides into the CNS (brain and spinal cord) and the PNS (cranial nerves and spinal nerves)
The PNS further splits into somatic (motor to skeletal muscle) and autonomic functions.
The autonomic then divides into the sympathetic and parasympathetic division.

Question 3

What does the autonomic system respond to?
What does it control?

Answer 3

Responds to signals from the internal environment to control involuntary processes.

Question 4

What is the function of the sympathetic nervous system?

Answer 4

Stress - fight of flight
Increase HR and BP
Decrease blood for to extremities and GIT through vasoconstriction
Increase blood flow to heart and muscles through vasodilation
Dilates the pupils

Question 5

What is the role of the parasympathetic nervous system?

Answer 5

Rest and digest function
Decrease HR and force of contraction –> decrease BP
Increase blood flow to the extremities and GIT
Constrict the pupils.

Question 6

How is homoestasis between the parsympathetic and sympathetic nervous system regulated?

Answer 6

By the hypothalamus
Controls the balance between sympathetic and parasympathetic tone.

Question 7

Where do sympathetic neurons arise from?

Answer 7

Spinal nerve T1-L2
Thoracolumbar outflow

Question 8

Where do parasympathetic nerves arise from?

Answer 8

Brain stem and spinal segments S2-4
Cranioscaral outflow

Question 9

What is common in all pathways of autonomic nerves?

Answer 9

Consits of a pre-ganglionic and post-ganglionic fibre, that synapse in a ganglia

Question 10

Describe how the adrenal gland medulla is innervated by the autonomic nervous system?

Answer 10

By preganglionic sympathetic neurons only
No post-ganglionic neuron
No parasympathetic innervation
Therefore innervation of the adrenal gland by ANS causes a widespread sympathetic response via hormone release

Question 11

Describe the pathway of a sympathetic efferent.

Answer 11

Pre-ganglionic fibre originates from the lateral horn of grey matter in the T1-L2 spinal segments.
Travels through the ventral root and mixed spinal nerve
Into myelinated white ramus communicants
Synpase with post-ganglionic in the sympathetic ganglion, may travel up or down a few levels
Post-g exist via the grey rammus communicans (unmyelinated) and travels to target tissue via the ventral or dorsal ramus

Question 12

What neurotransmitters are realised by the sympathetic nervous system?

Answer 12

Between pre and post ganglioninc - ACh
By post-g at target tissue NA

Question 13

What are splanchnic nerves?

Answer 13

Autonomic fibres that target viscera
Can be sympathetic or parasympathetic

Question 14

What provides most sympathetic innervation to viscera?

Answer 14

Splanchnic nerves

Question 15

What provides most parasympathetic innervation to viscera?

Answer 15

Vagus nerve

Question 16

What are the expceptions to the rule that splanchnic nerves supply most sympathetic innervation to the viscera?

Answer 16

The pulmonary plexus
The cardiac plexus

Question 17

What is the pattern of travel of the pulmonary plexus?

Answer 17

Pre-g symphattic fibres innervating the lungs synapse in the sympathetic chain at level T1-T4

Question 18

What is the pattern of travel of the cardiac plexus?

Answer 18

Pre-g sympathetic fibres innervating the heart synapse in the sympathetic chain at levels T1-4, as well as some contribution from cervical ganglia

Question 19

What is the pattern of travel of sympathetic splanchnic nerves?

Answer 19

Have thoracolumbar outflow (lateral horn, ventral root, spinal nerve, white communicants, sympathetic ganglion, grey communicants)
Travel through but do not synapse within the sympathetic chain
Prevertebral ganglion lie on surface of blood vessel supplying specific organs
The post-ganglionic fibres are carried along the vessel to the target tissue

Question 20

Describe the sympathetic and parasympathetic innervation of the GIT

Answer 20

Question 21

Describe the pathway of a parasympathetic efferent from the sacral spinal cord?

Answer 21

The efferent neuron will run from the ventral horn of grey matter of the sacral spinal cord S2-S4.
Through the ventral root
Into the spinal nerve
Alonf the dorsal/ventral ramus
To synpases within a ganglion before reaching the target tissue.

Question 22

Where are parasympathetic autonomic ganglia found?

Answer 22

On or near the lining of the target tissue or organ

Question 23

What neurotransmitter is associated with the parasympathetic nervous system?

Answer 23

Aceylcholine is released in th ganglion (between pre and post)
Acetylcholine is released by post-ganglionic parasympathetic fibres.

Question 24

What are the different parasympathetic nerves arising from the brainstem?

Answer 24

Oculomotor nerve (CN3)
Facial nerve (CN7)
Glassopharangeal nerve (CN9)
Vagus nerve (CN10)

Only fancy guests like venison

Question 25

What are the different ganglia for parasympathetic nerves found in the head and neck?

Answer 25

The ciliary ganglion The otic ganglion the Pterygopalating ganglion The submandibular ganglion.

Question 26

Where does the oculomotor nerve originate from?

Answer 26

The parasympathetic fibres originate from the Edinger-Westphal Nucleus in the midbrain All other fibres arise from the oculomotor nucleus

Question 27

Where does the ocoulomotor nerve sysnpase?

Answer 27

Pre-ganglionic fibres synpase in the ciliary ganglion

Question 28

What are the target tissues and associated functions of the PANS oculomotor nerve?

Answer 28

Ciliary muscles - lens accomodation Sphincter papillae - constric the pupil

Question 29

Where does the facial nerve originate from?

Answer 29

Parasympathetic fibres from the Salivatory-Lacrimal (superior salivatory) nucleus of the pons The facial nucleus gives rise to all other fibres

Question 30

Where does the facial nerve parasympathetic fibres synapse?

Answer 30

The pterygopalatine ganglion the submandibular ganglion

Question 31

What is the target tissue or the facial PANS fibres and the associated function?

Answer 31

From pterygopalatine fibres to the lacrimal glands to produce eye lubricating fluids From the submandibular gangliong fibres go to the sublingual and submandibular glands to produce saliva

Question 32

Where does the glassopharangeal nerve originate from?

Answer 32

Parasympathetic fibres arise from the Inferior Salivatory Nucleus of the medulla

Question 33

Where does the glassopharangyeal nerve synapse?

Answer 33

The otic ganglion

Question 34

What is the function of the PANS glassopharangeal fibres and their target tissue?

Answer 34

Targets to parotid gland to prodcue saliva.

Question 35

Where does the parasympathetic vagus nerve originate from?

Answer 35

The dorsal motor nucleus of vagus

Question 36

What is the function of the vagus nerve?

Answer 36

Synapses throughout the body Targets - thoracic and abdominal visceral (up to the splenic flexure) Therefore is responsible for the majority of the thoracic and abdominal parasympathetic innervation.

Question 37

What is horners syndrome?

Answer 37

A lesions along the sympathetic nerves supplying the eyes These travel along the internal carotid then the opthalamic arteries The superior tarsal or Mullers muscle (smooth muscle so under autonomic control is unable to function)

Question 38

How does Horners syndrome present?

Answer 38

Miosis - a permenantly small pupil Ptosis - upper eyelid drooping Anhidrosis - an inability to sweat Enophthalmos - a sunken appearance to the eye Central iris

Question 39

What is oculomotor nerve palsy?

Answer 39

Damage to the nervous supply to the levator palpebrae superiors (skeletal muscle) Supplied by CN3 Oculomotr nerve

Question 40

What are the symptoms of oculomotor nerve palsy?

Answer 40

Ptosis Pupillary dilation Able to sweat Inferolateral iris

Question 41

What are the two types of visceral afferents?

Answer 41

Reflexive Nociceptive

Question 42

What are reflexive afferents?

Answer 42

Signals do not reach our consciousness as fibres project only to brainstem or hypothalamus (e.g not awatre of distend bowel and peristalsis)

Question 43

What are nociceptive afferenets?

Answer 43

Reach conscious control but are poorly localised Pain information For example menstraul cramp from upterus is generalised to abdomen

Question 44

What is the pathway of a visceral afferent?

Answer 44

Can follow sympathetic or parasympathetic efferent fibres Ganglia in the Dorsal Root Ganglion

Question 45

What is the pelvic pain line?

Answer 45

Pain from viscera above or in contact with the inferior layer of the peritoneum travel with sympathetic splanchnic nerves T10-L1 Pain from sub-peritoneal organs is carried by pelvic splanchnic nerve (s2-4)

Question 46

Where will pain from above the pelvic pain line be felt?

Answer 46

Dermatimes T10-L1 From umbilicus to inguinal area

Question 47

Where wil pain originating below the pelvic pain line be felt?

Answer 47

Dermatomes supplied by S2-S4 Genitals and bottom

Question 48

What is the peripheral nervous system composed of?

Answer 48

31 pairs of spinal nerves 8 cervical 12 thoracic 5 lumbar 5 sacral 1 coccygeal 12 Paris of cranial nerves

Question 49

What is the difference between the white and grey ramus communicants?

Answer 49

The white communicans is myelinated The grey communicants is unmyelinated.

Question 50

What type of fibres are sympathetic and parasympathetic fibres?

Answer 50

Efferent fibres.

Question 51

Label the relevant cranial nerves containing parasympathetic fibres.

Answer 51

2 - oculomotor 10 - facial 9 - glassopharangeal 8 - vagus

Question 52

Label the four different parasympathetic ganglion in the head and neck.

Answer 52

Yellow is cilliary ganglion Green is pterygoidganglion Pink is Otic ganglion Blue is Submandibular ganglion

Question 53

Identify the Edinger-Westphal Nucleus of the midbrain.

Answer 53

Pink most superior in midbrain

Question 54

Identify the oculomotor nucleus

Answer 54

Orange most superior in midbrain

Question 55

Identify the salivatory lacrimal nucleus.

Answer 55

The superior pink spot (second overall) in the pons

Question 56

Identify the facial nucleus.

Answer 56

Yellow second down in the pons??

Question 57

Identify the inferior salivatory nucleus.

Answer 57

The first down pink in medulla (the third overall)

Question 58

Identify the nucleus ambiggus

Answer 58

The long yellow nucleus in the medulla

Question 59

Identify the dorsal motor nucleus of vagus

Answer 59

Long pink nucleus in medulla

Question 60

Where does innervation from the vagus nerve stop?

Answer 60

The midgut is the last structure to receive parasympathetic innervation from the midgut Therefore terminates at the junction between the midgut and the hindgut (2/3 way along the transverse colon)