Peripheral Nervous System

Question 1

What are the sites of all neuronal cell bodies in the PNS?

Answer 1

Ganglia

Question 2

What neurones have their cell bodies in the spinal cord and brain stem?

Answer 2

Motor and preganglionic autonomic neurons

Question 3

What makes up a nerve?

Answer 3

Bundle of axons, associated glia, myelin sheath and supporting connective tissue

Question 4

What makes up a nerve fibre?

Answer 4

One axon with its myelin sheath and neuroglial (schwann) cells

Question 5

What do the small axons function for?

Answer 5

Pain, olfaction and visceral innervation

Question 6

Where are sensory ganglia present?

Answer 6

Dorsal roots of spinal nerve and on some cranial nerves

Question 7

What is special about sensory ganglia?

Answer 7

Contain unipolar neurons with axons that bifurcate, with one branch entering the CNS and the other into the PNS

Question 8

What does skin have sensory nerve endings for?

Answer 8

Touch, temperature, pain

Question 9

What endings does muscles, tendons and joints contain?

Answer 9

Proprioceptive endings

Question 10

Where does the motor end plate end?

Answer 10

Striated skeletal muscle

Question 11

What is the synaptic transmitter that makes the muscle fibres contract?

Answer 11

Acetylcholine

Question 12

Smooth muscle and glands are innervated by what neurones?

Answer 12

Autonomic ganglia

Question 13

What do the dorsal root fibres divide into?

Answer 13

Ascending and Descending branches

Question 14

What is the third class of sensory endings called?

Answer 14

Interoceptors

Question 15

Where are interoceptors located?

Answer 15

Viscera

Question 16

What are the two categories of sensory endings?

Answer 16

Somatic afferent and Visceral afferent

Question 17

What are somatic afferents for?

Answer 17

Skin, bones, muscles and connective tissue

Question 18

What are visceral afferents for?

Answer 18

Internal organs

Question 19

What are the two categories of efferent neurones?

Answer 19

Somatic efferent and Visceral efferent

Question 20

What is another word for somatic efferent neurones?

Answer 20

Motor neurones

Question 21

Where are somatic efferent neurones located?

Answer 21

In the ventral grey horns of the spinal cord and motor nuclei of cranial nerves

Question 22

Where do the axons of ventral horn cells terminate?

Answer 22

In motor end plates on skeletal muscle fibres

Question 23

What is the special feature of visceral efferent neurones?

Answer 23

They have at least two neurones participate in transmission from CNS to smooth muscle, cardiac muscle or secretory cells.

Question 24

What are the sensory endings supplied by?

Answer 24

Axons that differ in size

Question 25

Where do cutaneous branches of the spinal and cranial nerves pass through?

Answer 25

Subcutaneous connective tissue into the dermis

Question 26

What are the three plexuses formed from the spreading of axons in the dermis?

Answer 26

Subcutaneous plexus, dermal plexus and papillary plexus

Question 27

Where is the subcutaneous plexus?

Answer 27

Loose connective tissue

Question 28

Where is the dermal plexus?

Answer 28

Within the densely collagenous reticular layer of the dermis

Question 29

Where is the papillary plexus?

Answer 29

Papillary layer of the dermis beneath the epidermis

Question 30

Where do free nerve endings occur?

Answer 30

In the subcutaneous tissue and dermis

Question 31

What are free nerve endings?

Answer 31

They are the terminal branches of group C fibres and the unmyelinated terminal branches of group A fibres.

Question 32

What are free nerve endings associated with?

Answer 32

Schwann cells

Question 33

Where are merkel endings found?

Answer 33

Germinal layer of epidermis

Question 34

How does a merkel cell differ from epidermal cells?

Answer 34

Indented nucleus and electron-dense cytoplasmic granules

Question 35

Where are merkel cells found?

Answer 35

In glabrous skin and in the outer root sheaths of hairs

Question 36

What is the Ruffini ending?

Answer 36

An array of terminal branches of a myelinated axon surrounded by capsular cells

Question 37

What is the Pacinian corpuscle?

Answer 37

Consists of a single axons that loses its myelin sheath and is encapsulated by several layers of flattened cells.

Question 38

Where do the Meissners tactile corpuscles occur?

Answer 38

Dermal papillary ridges of the finger tips

Question 39

The types of sensation consciously perceived from the skin are called?

Answer 39

Modalities

Question 40

What innervates muscles spindles?

Answer 40

Sensory and motor neurones

Question 41

How many sensory axons supplies the muscle spindle?

Answer 41

Two

Question 42

What does a motor unit consist of?

Answer 42

One motor neurone and the muscle fibres that innervate it

Question 43

What do the axonal endings within the end plates contain?

Answer 43

Mitochondria and synaptic vesicles

Question 44

What are spinal ganglia?

Answer 44

Swellings on the dorsal roots of spinal nerves

Question 45

Where are spinal ganglia located?

Answer 45

In the intervertebral foramina

Question 46

What does the spinal ganglia contain?

Answer 46

The cell bodies of primary sensory neurones

Question 47

Each cell body within the spinal ganglia is invested by a layer of what type of cell?

Answer 47

Satellite cells

Question 48

What is the entire nerve surrounded by?

Answer 48

Epineurium

Question 49

What surrounds the bundle fibres of a nerve?

Answer 49

Perineurium

Question 50

What surrounds an individual fibre?

Answer 50

Endoneurium

Question 51

What cells do the Epineurium, Perineurium and Endoneurium derive from?

Answer 51

Mesodermal cells

Question 52

Within the endometrium, the axons are intimately ensheathed by what type of cell?

Answer 52

Schwann cells

Question 53

What are Schwann cells derived from?

Answer 53

Neural crest

Question 54

What are the components of Schwann cells?

Answer 54

Neurolemma and myelin sheath

Question 55

What interrupts the myelin sheath at intervals?

Answer 55

Nodes of Ranvier

Question 56

Some axons in nerves do not contain?

Answer 56

Myelin sheaths

Question 57

The thinnest unmyleinated axons are those of?

Answer 57

Olfactory nerves