Part 1 - Dermatomes And Myotomes

Question 1

Anatomically, what is a neural segment known as?

Answer 1

A neural level

Question 2

What day of embryological development does the neural plate form (primitive neural tissue?

Answer 2

18 days

Question 3

What day of embryological development does the neural plate begin to invaginate to form the neural groove?

Answer 3

21 days

Question 4

What week of embryological development does the neural groove close/ fuse together to form the neural tube?

Answer 4

4th week (22days ….)

Question 5

From where does the neural groove start to close and which direction does this closing happen?

Answer 5

Starts centrally
Then the closing happens outwards in the caudal and cephalic direction

Question 6

When do paired somites form in embryological development?

Answer 6

4th week

Question 7

Where are the paired somites located?

Answer 7

Either side of the neural tube

Question 8

In embryological development, which structure contains the precursor cells of the nervous system?

Answer 8

Neural tube

Question 9

What do the somites differentiate into?

Answer 9

Sclerotome
Dermatomyotome

Question 10

Which part of the somite differentiates into the sclerotome?

Answer 10

The ventral side

Question 11

Which part of the somite differentiates into the dermatomyotome?

Answer 11

Dorsal side

Question 12

What does the dermatomyotome differentiate into?

Answer 12

Dermis (Skin) and muscle

Question 13

What does the sclerotome differentiate into?

Answer 13

Vertebrae
Ribs

Question 14

What does each segment of the spinal cord have?

Answer 14

A spinal nerve

Question 15

What do all Dermatomyotome develop in association with?

Answer 15

A specific neural level of the spinal cord

Question 16

As a Dermatomyotome migrates to its area, what does it take with it from the neural tube?

Answer 16

Spinal nerve

Question 17

What is important to know about the nerve supply of the skin and muscle derived from a single dermatomyotome?

Answer 17

They have a common spinal nerve supply

Question 18

What is the connective tissue called that surrounds a single axon?

Answer 18

Endoneurium

Question 19

What are many axons running in parallel called?

Answer 19

Fascicle

Question 20

What is the connective tissue called that surrounds a fascicle?

Answer 20

Perineurium

Question 21

What is a collection of fascicles called?

Answer 21

The nerve

Question 22

What is the connective tissue called that surrounds a nerve?

Answer 22

Epineurium

Question 23

What are the blood vessels called that are found within the Epineurium of the nerve?

Answer 23

Vasa nervorum

Question 24

What are spinal nerve roots?

Answer 24

They connect each spinal nerve to a segment of spinal cord

Question 25

What type of nerve fibres/axons do dorsal/posterior roots contain?

Answer 25

Sensory or afferent fibres

Question 26

What type of nerve fibres do ventral/anterior roots contain?

Answer 26

Motor/efferent and Autonomic fibres

Question 27

What is a dorsal root ganglion?

Answer 27

A group of cell bodies of sensory neurons from the periphery just before the spinal cord is reached

Question 28

What makes up a spinal nerve?

Answer 28

Both Dorsal (sensory) and Ventral (motor) roots together

Question 29

Where do you find spinal nerves?

Answer 29

The intervertebral foramen

Question 30

Where marks the division between the CNS and PNS?

Answer 30

Spinal nerves in the Intervertebral foramina

Question 31

How is a vertebra formed from somites?

Answer 31

The sclerotomes from 2 adjacent somites both contribute to the formation of 1 vertebra

Question 32

What do you call the space created by multiple vertebral foramina?

Answer 32

Spinal Canal

Question 33

What passes through the spinal canal/multiple vertebral foramina?

Answer 33

Spinal cord

Question 34

Through what structure do the spinal nerves leave the spinal canal?

Answer 34

Intervertebral Foramen

Question 35

Where does the spinal cord start?

Answer 35

Inferior margin of medulla oblongata

Question 36

Where does the spinal cord end?

Answer 36

L1 - L2 Called Conus medullaris

Question 37

What happens at the end of the spinal cord (Conus medullaris)?

Answer 37

Long spinal roots come out from the conus medullaris and descend down until they exit at their respective foramina

Question 38

What is the group of long descending roots from the conus medullaris called?

Answer 38

Cauda equina

Question 39

Do the C1 - C7 spinal nerves exit their intervertebral foramina above or below their corresponding vertebrae?

Answer 39

ABOVE THEIR VERTEBRAE

Question 40

How many cervical vertebrae are their?

Answer 40

7

Question 41

How many cervical nerves are their?

Answer 41

8

Question 42

Where does the spinal nerve C8 exit the spinal canal?

Answer 42

Between C7 and T1 Under C7 but above T1

Question 43

Do the spinal nerves T1 - L5 exit ABOVE or BELOW their corresponding vertebrae?

Answer 43

BELOW THIER VERTEBRAE

Question 44

What is special about the structure of the sacral vertebrae (S1 - S4)?

Answer 44

They are fused together forming the Sacral bone

Question 45

What are the foramina called by which the S1 - S4 spinal nerves exit through?

Answer 45

Sacral foramina

Question 46

What structure does the S5 and Co1 spinal nerves exit via?

Answer 46

Sacral hiatus

Question 47

What happens once a spinal nerve exits the an intervertebral foramen?

Answer 47

Branches into 2 ram II

Question 48

What are the 2 rami that form when the spinal nerve exits the intervertebral Foramen?

Answer 48

Dorsal/posterior ramus Ventral/anterior ramus

Question 49

What do the dorsal/posterior rami supply?

Answer 49

Deep muscles and skin of the dorsal (posterior trunk, so the back)

Question 50

What do the ventral/anterior rami supply?

Answer 50

Muscles and skin of UPPER and LOWER LIMBS and LATERAL and VENTRAL TRUNK

Question 51

What is a meningeal branch?

Answer 51

A brach off of the spinal nerve which renters the spinal canal via the intervertebral Foramen

Question 52

What do the meningeal branches supply?

Answer 52

Vertebrae Ligaments Blood vessels Meninges

Question 53

What are the 2 types of Rami communicantes?

Answer 53

White Rami communicantes Grey Rami communicantes

Question 54

What does the white rami communicantes contain?

Answer 54

Sympathetic pre ganglioninc MYELINATED fibres They come off between T1 and L2 FIbres enter sympathetic chain and synapse

Question 55

What do the Gray rami communicantes contain?

Answer 55

Post ganglionic fibres supplying the periphery Come off at all levels

Question 56

What do the Dorsal Rami of spinal nerves supply?

Answer 56

Muscle and skin of posterior trunk

Question 57

What do the ventral rami of the spinal nerves supply?

Answer 57

Anterior trunk Lateral trunk Upper limbs Lower limbs

Question 58

How do the dorsal/posterior rami further divide?

Answer 58

Medial branch Lateral branch

Question 59

Compare the supply of the dorsal/posterior rami to the skin to the ventral/anterior rami?

Answer 59

Dorsal = Supply skin to oback in tidy segmental manner Ventral = Trunk is segmental, complicated for limbs due to plexuses

Question 60

What is a Dermatome?

Answer 60

An area of skin supplied by a single spinal nerve

Question 61

What is a plexus?

Answer 61

Network of intersecting nerves arising from the anterior/ventral rami

Question 62

What nerves make up the brachial plexus?

Answer 62

C5 - T1

Question 63

What does the brachial plexus supply?

Answer 63

Upper limbs

Question 64

What spinal nerves make up the Lumbo-sacral plexus?

Answer 64

L1 - S5

Question 65

What does the lumbo-sacral plexus supply?

Answer 65

Lower limbs

Question 66

On the Dermatome map, what is the next Dermatome in the trunk following C4?

Answer 66

T2

Question 67

What landmark can be used to find T10 Dermatome?

Answer 67

Umbilicus (belly button)

Question 68

What landmark is roughly used for the T4, T5 Dermatome?

Answer 68

Nipples

Question 69

Where is the L1 Dermatome?

Answer 69

Groin