Peripheral nervous system

Question 1

What are ganglions?

Answer 1

knots of cell bodies in the PNS

Question 2

Where are the ganglia located in autonomic neurones?

Answer 2

outside of the spinal cord. this is where their axons synapse.

Question 3

How many neurones does the autonomic system need to reach its target?

Answer 3

2 neurones. Pre-ganglionic and post ganglionic. Somatic system only requires one neurone.

Question 4

Where do the autonomic neurones arise from?

Answer 4

The brain and spinal cord.

Question 5

Where exactly are sympathetic cell bodies found?

Answer 5

Thoracic and lumbar spinal cord segments.

Question 6

where do parasympathetic neurones arise from? and are they located close or far from target organ?

Answer 6

Arise from cranial nerves or lumbo-sacral spinal cord. The parasympathetic ganglion are not grouped together in a chain (unlike sympathetic which are grouped together into paravertebral ganglion chain) as they are located CLOSE to target organ

Question 7

What is the origin of nerve signals initating movement?

Answer 7

the pre-central gyrus in the brain.

Question 8

how many neurones are involved in the somatic nervous system?

Answer 8

Only 1 neurone. CNS neurones synapse with somatic neurones in the spinal cord. Somatic neurones contact directly with target without any further synapses.

Question 9

What is the difference between autonomic and somatic nervous system?

Answer 9

• Autonomic is subconscious control- it innervates smooth muscle of tissue or glands. Autonomic involves sympathetic and parasympathetic.
• somatic is conscious control.

Question 10

The spinal nerves arise from the spinal cord. At each vertebral level, both a dorsal (posterior/back) and ventral (anterior/front) root emerges from the spinal cord and then they mix to form the spinal nerve. What are the dorsal and ventral roots carrying?

Answer 10

Dorsal carry afferent/sensory information - from periphery to CNS

Ventral carry efferent/motor information - from CNS to periphery.

Question 11

what is a plexus?

Answer 11

A plexus forms when many spinal nerves leaving the spinal cord at different spinal levels merge together.

Question 12

What is a dermatome and myotome?
And what is the relationship to spinal nerves?

Answer 12

Dermatome- distinct area of skin
Myotome - distinct area of muscle

Each spinal nerve supplies or is supplied by a dermatome or myotome.

Question 13

Two types of spinal nerves are sciatic and femoral. What do these nerves do?

Answer 13

sciatic- motor to muscles of posterior thigh (BACK OF LEG)
femoral- motor to muscles of anterior thigh. (FRONT OF LEG)

Question 14

How many cranial nerves are there?

Answer 14

12

Question 15

What is Bells Palsy? What is a probable causative agent of this?

Answer 15

loss of cranial nerve 7 facial nerve. causes unilateral face paralysis. Herpes Simplex Virus is a causative agent.

Question 16

What is Guillian Barre Syndrome?

Answer 16

a condition when the own immune system (after fighting off an infection) attacks myelin sheath of peripheral nerves. It affects the longest nerves first, and therefore your feet and hands are affected first.

Question 17

A plexus is when many nerves blend together. Which vertebrae are involved in the lumbar plexus?

Answer 17

T12-L5

Question 18

What is a causative agent of Bells palsy ?

Answer 18

Herpes simplex virus

Question 19

What is a dermatome?

Answer 19

An area of skin supplied by sensory afferents from one spinal nerve

Question 20

What is a myotome?

Answer 20

A group of muscles supplied by motor efferents and sensory afferents from one spinal nerve