Comparative anatomy of the spinal cord

Question 1

What are the three general functions of the spinal cord?

Answer 1

Conducts info to and from the brain through a system of axonal tracts,
Connects with spinal nerves
The spinal cord also acts as a reflex centre, producing subconscious muscle responses

Question 2

Where does the spinal cord end?

Answer 2

the 6th/7th lumbar vertebrae

Question 3

Where do the axons of each root bind?

Answer 3

they bind laterally to form spinal nerves

Question 4

What do dorsal roots convey?

Answer 4

Dorsal roots convey sensory input to the spinal cord

Question 5

What do ventral roots convey?

Answer 5

Ventral roots carry motor input to muscles and glands

Question 6

Where is the spinal ganglion present?

Answer 6

spiral ganglion are present on each dorsal root

Question 7

Where do paired spinal nerves emerge from?

Answer 7

spaces formed between vertebrae

Question 8

What nerve do the first seven spinal segment rootlets join to form?

Answer 8

spinal roots of the accessory nerve

Question 9

At what point in the spinal cord is the diameter increased?

Answer 9

the two locations where nerves to the limbs arise

Question 10

Which parts does the cervical enlargement innervate?

Answer 10

innervates the thoracic limb

Question 11

What is the conus medullaris?

Answer 11

the terminal end of the spinal cord

Question 12

What is the nerve plexus?

Answer 12

complex, interwoven network of nerves

Question 13

What forms the nerve plexus?

Answer 13

The ventral branches of spinal nerves

Question 14

What tissues do the dorsal roots innervate?

Answer 14

epaxial tissues

Question 15

What tissues do the ventral roots innervate?

Answer 15

hypaxial tissues

Question 16

Where is the majority of growth after birth?

Answer 16

more growth occurs in the vertebral column than in the spinal cord

Question 17

What is the cauda equina?

Answer 17

thick bundle of elongated nerve roots within the lower vertebral canal

Question 18

What is the function of the filum terminale?

Answer 18

glial continuation that persists beyond the functional end of the spinal cord, it stabilises it

Question 19

Where are spinal arteries suspended?

Answer 19

within small strands of tissue called arachnoid trabecula

Question 20

What are denticulate ligaments?

Answer 20

fibrous structures that help anchor the spinal cord in place

Question 21

What is the filum terminale?

Answer 21

fibrous band that extends from the conus medullaris to the periosteum of the coccyx

Question 22

What is grey matter?

Answer 22

consists of neurons and a neuronal blood supply, it is grey due to perikaryal

Question 23

What is white matter?

Answer 23

Myelinated and non-myelinated axons, it is white due to the lipid composition of myelin

Question 24

What is the spinal cord divided into?

Answer 24

symmetric left and right halves by a ventral and dorsal median fissure

Question 25

What are interneurons?

Answer 25

interposed between a particular input and the resulting output from the spinal cord, can either have long or short axons

Question 26

Where in the skull does the spinal cord leave?

Answer 26

It exits through the foramen magnum and then runs through the vertebral column

Question 27

Where does the spinal cord exit?

Answer 27

The level of the 6th/7th lumbar vertebrae

Question 28

What does the centre of the spinal cord contain?

Answer 28

a central canal filled with CSF and lined with ependymal cells

Question 29

What parts of the body does the spinal cord innervate?

Answer 29

neck, trunk, tail, limbs and the caudal/dorsal surfaces of the head

Question 30

What are ependymal cells?

Answer 30

Cells that form the lining of the fluid-filled spaces in the brain and spinal cord

Question 31

What nerves supply the brachial plexus/ front portion of the animal?

Answer 31

Ventral portion of spinal nerves C6-C8 and T1-T2

Question 32

What nerves supply the back-end of the animal?

Answer 32

Ventral portion of spinal nerves L4-L7 and S1-S3

Question 33

Where do remaining spinal nerves exit?

Answer 33

sacral foramina

Question 34

Where does the C8 spinal nerve exit and why?

Answer 34

It exits through the T1 vertebrae because there isn't sufficient cranial vertebrae

Question 35

Where does the first cranial nerve exit?

Answer 35

Through the arch of the atlas in the head

Question 36

Where does the functional spinal cord terminate?

Answer 36

at L6-L7

Question 37

Where are spinal cord arteries suspended?

Answer 37

within small strand of tissue called arachnoid trabecula that connects to the pia mater

Question 38

What is the subarachnoid space in the spinal cord continuous with in the brain?

Answer 38

The foramen magnum

Question 39

Why is white matter white?

Answer 39

Due to the lipid composition of the myelinated neurons

Question 40

What is the dorsolateral sulcus?

Answer 40

Where dorsal roots enter the spinal cord

Question 41

What is the function of the dorsal horn?

Answer 41

contains cell bodies of interneurons where the afferent neurons terminate

Question 42

What is the function of the ventral horn?

Answer 42

contains cell bodies of the efferent motor neurons supplying skeletal muscles

Question 43

What is the function of the lateral horns?

Answer 43

Where autonomic nerve fibres that supply cardiac and smooth muscle originate from

Question 44

What are the ventral branches of spinal nerves that form the brachial plexus?

Answer 44

C6, C7, C8, T1 and T2

Question 45

What spinal nerves form the nerve plexus?

Answer 45

L4, L5, L6, L7, S1, S2 and S3

Question 46

How many segments are usually in the spinal cord of dogs?

Answer 46

36

Question 47

Where is the cervical enlargement of the spinal cord?

Answer 47

C6-C7 intervertebral disc

Question 48

What kind of cells produce CSF?

Answer 48

Ependymal cells

Question 49

What are dorsal/ventral roots made up of?

Answer 49

Thousands of axons

Question 50

What root are spinal ganglion present on?

Answer 50

The dorsal root

Question 51

How many cervical vertebrae and cervical segments/ nerves are there, and what is the significance of this?

Answer 51

There are 7 cervical vertebrae and 8 cervical segments/ nerves, the first cervical nerve exits through the arch of atlas and cervical nerve C8 exits between vertebrae C7 and T1