Spinal Cord

Question 1

Embryological development spinal cord

Answer 1

Neural plate forms on overlying ectoderm and closes = neural tube (NCC above)
Closure sites = ant (—> encephalon) and post (—> spinal cord) neuropore.
The tube closed by 4th week
- Basal lamina→ ant horn
- Alar lamina→ post horn
- Marginal layer→ white matter (axons)
NCC migrates towards spinal cord —> dorsal root ganglia.

Question 2

Rachischisis cause

Answer 2

Neural tube doesn’t close

Question 3

Rachischisis consequences

Answer 3

Whole spinal cord is exposed to amniotic fluid

Question 4

Meningomyelocele cause

Answer 4

Differentiated nervous tissue and body of vertebrae, but no lamina posteriorly = no protection for post part

Question 5

Meningomyelocele consequences

Answer 5

Spinal cord & meningeal sac protrude out of spinal canal

Question 6

Meningocele cause

Answer 6

No lamina but spinal cord remains in the canal

Question 7

Meningocele consequences

Answer 7

Only the meninges + CSF protrude out of spinal canal

Question 8

Spina bifida occulta

Answer 8

Manifests as a tuft of hair. Can be asymptomatic

Question 9

Spinal cord finishes at level

Answer 9

L1-L2

Question 10

Spinal cord contains

Answer 10

The meninges, CSF, nerve roots and vessels

Question 11

Filum terminale externum - definition

Answer 11

Extension of dural sac from where it ends (lumbar cisternae) till coccyx (also called “coccygeal ligament”).

Question 12

Filum terminale externum - function

Answer 12

It keeps the dural sac in place within the vertebrae.

Question 13

Denticulate ligaments - function

Answer 13

They hold spinal cord in place within spinal canal

Question 14

Denticulate ligaments - definition

Answer 14

Alternating extensions of pia mater that anchor the cord to the arachnoid mater.

Question 15

Filum terminale internum - definition

Answer 15

Extension of pia mater beyond conus medullaris that keeps spinal cord in place in rostral-caudal way

Question 16

Neurons in gray matter are classified into

Answer 16

Rexed laminae (I-X)

Question 17

Laminae I - VI

Answer 17

Sensory neurons

Question 18

Laminae VII - IX

Answer 18

Motor neurons

Question 19

Laminae X

Answer 19

Surrounds central medullary canal and
contains ants white commissure & its fibres

Question 20

White matter is divided into

Answer 20

Posterior funiculus
Lateral funiculus
Anterior funiculus
Fascículos proprius

Question 21

Posterolateral sulcus

Answer 21

Small sulcus that separates post funiculus from lat funiculus.
Where the sensory roots enter post horn (DREZ: “dorsal root entry zone”)

Question 22

Anterolateral sulcus

Answer 22

Separates lateral from anterior funiculus

Question 23

Fasciculus proprius

Answer 23

ONLY communicates areas of the spinal cord with other areas of it

Question 24

Enlargements along spinal cord

Answer 24

Cervical enlargement
Lumbar enlargement

Question 25

How do the roots exit the vertebrae?

Answer 25

Cervical roots above vertebrae of = name.
C8 root between C7 and T1
From C8 onwards, below the vertebrae of = name

Question 26

Amount of white matter

Answer 26

Decreases as we descend through spinal cord

Question 27

Amount of grey matter

Answer 27

More in cervical & lumbar enlargements

Question 28

Intermediolateral horn

Answer 28

T1-L2

Question 29

Soma of peripheral motor neurons are in

Answer 29

Ant horn

Question 30

Soma of peripheral sensory neurons are in

Answer 30

Dorsal root ganglion

Question 31

A spinal segment includes

Answer 31

All the parts of spinal cord generating a root

Question 32

Dermatome

Answer 32

Area of skin whose sensation is carried by a specific spinal root / level

Question 33

Myotome

Answer 33

All the muscles that depend on the same spinal root

Question 34

Dermatome of the face

Answer 34

CN V

Question 35

Dermatome of back of the head and neck

Answer 35

Cervical plexus

Question 36

Dermatome of the hand

Answer 36

C6, C7 and C8

Question 37

Dermatome of the foot

Answer 37

Sole of foot, mostly S1
Dorsum of foot, mostly L5
Big toe, L4

Question 38

Dermatome of the leg

Answer 38

Lat part is L5 (to the dorsum)
Post part is S1 (to the sole)

Question 39

Posterior root

Answer 39

Enters spinal cord through DREZ

Question 40

Anterior roots

Answer 40

Somatic efferents
S fibres exit within this ant root too, and then enter sympathetic trunk