7 – Spinal Cord Anatomy

Question 1

Interverbal disk:

Answer 1

-between bodies of vertebral segments
-acts as a cushion
-has a fibrous capsule (anulus)

Question 2

What does the spinal cord run through?

Answer 2

-vertebral column (spinal column)
>nerves exit at intervertebral foramen

Question 3

Vertebral transitions directions at:

Answer 3

-T11
>anticlinal vertebra
*all spinous process point are cranial after this point

Question 4

What are some special vertebrae?

Answer 4

-C1 (atlas)
-C2 (axis): dens
*neither have prominent dorsal spinous process

Question 5

Atlas:

Answer 5

-shorter
-flatter
-wider

Question 6

SC is supplied by:

Answer 6

-segmental vessels (aorta)
-vertebral arteries
>vertebral
>costocervical
>intercostal
>lumbar

Question 7

Dorsal spinal arteries:

Answer 7

-paired

Question 8

Ventral spinal artery:

Answer 8

-single
-mid-line

Question 9

Blood supply from the brain comes from:

Answer 9

-ventral aspect
>basilary artery
>internal carotid

Question 10

What artery supplies most of the SC? (2/3rds)

Answer 10

-ventral spinal artery

Question 11

Where do spinal nerves exit the vertebral canal?

Answer 11

-via intervertebral foramen

Question 12

Each peripheral nerve is a:

Answer 12

-MIXED nerve
>dorsal root: sensory
>ventral root: motor
*then give rise to dorsal and ventral branch to innervate targets

Question 13

What are the 5 spinal segments?

Answer 13

-cervical
-thoracic
-lumbar
-sacral
-caudal

Question 14

Where does the dura end in the spinal column?

Answer 14

-around the lumbarsacral junction (varies with species)
*after that nerves are part of spinal column but aren’t part of CNS

Question 15

Cauda equina:

Answer 15

-continues as spinal nerves that move caudally to exit at their corresponding vertebral segment

Question 16

What are the implications of the caudal equina?

Answer 16

1. Nerves associated with cauda equina contribute to innervation of pelvis and perineum (ex. S1-S3)
2. A distal lumbar or sacral fracture will damage all of these nerves together (L7-Ca5)=cauda equina syndrome
   >PNS damage, therefore no CNS signs

Question 17

S1-S3 form:

Answer 17

-the pudendal nerve
*convenient location for local anesthesia

Question 18

Cauda equina syndrome:

Answer 18

-caudal spinal nerves that are damaged as a group

Question 19

Dura matter in skull vs. vertebral column:

Answer 19

-fused to periosteum of skull
-NOT fused in the vertebral column

Question 20

Epidural space:

Answer 20

-space between dura and vertebral body
-contains fat, blood vessels and spinal nerves
*can give anesthesia between the vertebral bodies

Question 21

Can give anesthesia between the vertebral bodies:

Answer 21

-anesthetic solution will diffuse locally cranial/caudal through the epidural space to ‘bathe’ the spinal nerves and provide nerve block
*typically done CAUDALLY to anesthetize the structures of the cauda equina (perineum) without causing motor deficits to pelvic limbs

Question 22

Most local anesthetic agents work by:

Answer 22

-inhibiting sodium-channels, therefore AP (nerve conduction) is stopped

Question 23

Subdural space:

Answer 23

-potential space between arachnoid and the dura
-can be site of hemorrhage and subsequent CNS compression

Question 24

Subarachnoid space:

Answer 24

-created by arachnoid trabeculae
-filled with CSF
>CSF collection sites

Question 25

Where are the CSF collection sites?

Answer 25

*collect at the site caudal to the lesion
-lumbar cistern: disease along SC
-cerebellomedullary cistern: if brain disease

Question 26

How much CSF should you collect?

Answer 26

-2 tubes (1 mL/5kg is a safe amount)
>cytology
>protein analysis

Question 27

Spinal cord and vertebral column are susceptible to similar injuries:

Answer 27

-soft tissue trauma (IVDD)
-vascular injury
-fracture
-disease
-toxin/infection
-neoplasia

Question 28

Treatment of SC injuries are more difficult:

Answer 28

-CNS tissues are delicate and damaged more easily
-neural tissue has limited regenerative capacity
-many drugs are ineffective due to protective BBB and B-CSF barriers

Question 29

Compression of spinal cord or peripheral nerves will cause:

Answer 29

-neurological deficits and/or pain

Question 30

IVDD:

Answer 30

-intervertebral disc disease
-common in small breed dogs
-middle-aged to geriatric
-breed dispositions

Question 31

Wobbler’s syndrome:

Answer 31

-cervical spondylomyelopathy
-unknown causes
>growth discrepancy between SC and VC=narrower spinal canal
>boney changes to vertebral column=cause compression
-breed disposition