Anatomy of the PNS

Question 1

3 main anatomical differences between divisions of autonomic NS (involuntary muscle)

Answer 1

1. Sites of origin of nerves
2. Length of nerve fibres
3. Location of their ganglia

Question 2

Where do fibres in the parasympathetic NS originated?

Answer 2

Brain stem (cranial) or sacral spinal cord

Question 3

Where do fibres in the sympathetic NS originated?

Answer 3

Thoracic and lumbar spinal cord

Question 4

Length of fibres in para vs sympathetic NS?

Answer 4

Preganglionic fibres (ones that originate from CNS and supply the ganglia, first one closest to the spinal cord) in para are long, short in sympathetic
This leads to short postganglionic fibres (cell bodies are ganglia at SP connecting spinal cord to organs) in para and long in sympathetic

CLARIFY THIS W LECTURER DONT REALLY UNDERSTAND THE IMPORTNACE

Question 5

Location of ganglia in para vs sympathetic

Answer 5

Para - within or near the effector organ

Sympa - closer to SP rather than to the effector organ

Question 6

How (based on what) are nerves classified by, give example?

Answer 6

Direction of electrical impulse travel ie.
Motor - away from CNS/PNS to organs
Sensory - from organs to CNS/PNS
Mixed - both motor and sensory signal travels in both directions

Question 7

What protects nerves

Answer 7

3 layers of tissue - endoneurium (surrounds individual nerve axons)
perineurium - (surrounds fascicles - bundles of nerve fibres also known as axons)
epineurium - (surrounds the peripheral/ whole nerve)

Question 8

Location of cell bodies in motor vs sensory nerves

Answer 8

Motor - at least one in the CNS since signal is created at CNS as a response
Sensory - lies outside the CNS convey information towards CNS

Question 9

What regions of the body do spinal nerves supply ?

Answer 9

All regions except the head and some regions of the neck

Question 10

What regions do cranial nerves supply

Answer 10

Head and regions of the neck not supplies by spinal nerves

Question 11

What type of nerves do spinal nerves contain? (motor sensory wise)

Answer 11

All are mixed so contain both motor and sensory

Question 12

How many parts of spinal nerves that attach to spinal cord and what they are

Answer 12

31 - 8 cervical 
12 thoracic 
5 lumbar 
5 sacral
1 coccygeal

Question 13

Where do spinal nerves emerge in relation to their corresponding vertebrae and with what exception?

Answer 13

Just below the corresponding vertebrae with the exception of C1-C7

Question 14

Why are there “pairs” of spinal nerves

Answer 14

At the spinal roots, the nerve fibre separates so that only sensory nerve fibres connect to the dorsal root (posterior) and motor to the ventral (anterior)

Question 15

What is the RAMUS (rami plural)

Answer 15

the region where motor and sensory tracts cross to form mixed spinal nerves

ASK WHY TRACTS

Question 16

Dorsal vs ventral rami difference and similarities

Answer 16

Both have mixed spinal nerves but serve different parts of the body
dorsal provides sensory and motor to skin and back muscle, much smaller than ventral as
ventral provides for trunk and limbs

Question 17

Rami origination and what happens as they move away from CNS, what rami is it only for and why is this important

Answer 17

The tracts that come from within the spinal cord (CNS) cross over at the rami to become ventral and dorsal. Only ventral go on to form plexuses which are fibres of different spinal nerves intersecting together. this is important because a muscle receives input from more than 1 spinal nerve and incase a root gets damaged the muscle may still be able to continue functioning

Question 18

What are the four main nerve plexuses

Answer 18

Cervical
Brachial
Lumbar
Sacral

Question 19

Location and function of cervical plexus

Answer 19

Located under sternocleidomastoid (that muscle when you stretch your neck to the side) and it innervates (supplies with nerves) the skin

Question 20

Location and function of lumbar plexus

Answer 20

within psoas, innervates abdominal wall, anterior and medial thigh

Question 21

Location and function of sacral plexus, anything special about it?

Answer 21

Posterior to lumbar plexus, innervates buttocks, lower limb and pelvis
Contains Sciatic nerve largest branch which serves most of the thigh leg and foot muscles

Question 22

Location and function of brachial plexus

Answer 22

In neck and shoulder, superficial to the clavicle, innervates the arm

Question 23

Ventral rami/SPINAL ROOTS included in brachial plexus

Answer 23

C5-C8 and and T1. In some individuals C4 as well

Question 24

How many trunks formed by the 5/6 roots of the brachial plexus
How many cords do they form? How many peripheral nerves do those form?

Answer 24

3 - upper, middle and lower form 
3 cords - lateral, posterior and medial which form 
5 peripheral nerves - axillary
musculocutaneous 
median
ulnar
radial

Question 25

In what ways can the brachial plexus be injured

Answer 25

Pulling on the arm - can weaken or paralyse the arm
Carpal tunnel syndrome - median nerve is compressed
Ulnar nerve is superficial and hence vulnerable to injury (funny bone)
Brachial plexus birth palsy - injury to plexus during difficult delivery
recovery within 3-6 months usually with physical therapy or surgery

Question 26

How many pairs of cranial nerves and how do they differ from spinal nerves

Answer 26

12

instead of all nerves being mixed they can either be complete sensory, completely motor, or mixed

Question 27

Where are the cranial nerves arranged

Answer 27

Along longitudinal axis

Question 28

Where do CNI, CNII and CNIII - CNXII

Answer 28

1 - cerebrum
2 - diencephalon
3 - 12 - brainstem

Question 29

Q FOE LECTURER

Answer 29

Why is the peripheral divided into efferent and afferent and the efferent divided into para and sympathetic when both para and s have motor and sensory neurons