Embryology

Question 0

Ectoderm

Answer 0

Becomes the skin (epidermis) and NS (CNS)

These cells are on the neural plate

Question 1

Yolk sac

Answer 1

Early nutrition to embryo (tissue)

Question 2

Neural plate

Answer 2

Invaginates into the neural groove (at 20 days)

Piece of thickened ectoderm (thus becomes skin and CNS)

Question 3

Neural groove

Answer 3

Fuses at the dorsal aspect to become the neural tube

Middle step

Question 4

Neural tube

Answer 4

Turns into the brain and SC

The folding over into its formation creates the HOLLOW nature of the brain and SC

Question 5

Neural crest cells (pre neural tube)

Answer 5

Purple ridges on lateral and dorsal aspect of the neural plate
Turn into sensory Ns (most of the sensation for the skin) because they are right next to the ectoderm cells that become skin cells
Sit more dorsally once plate invaginates - why dorsal cord is sensory

Question 6

Neural crest cells (post neural tube)

Answer 6

Grow out to become the dorsal roots
12-15 rootlets at each level that come together as single sensory dorsal root
Turns into spinal N

Question 7

Ventral N roots

Answer 7

From ventral part of neural tube
First as many rootlets into one N root, joins with dorsal N root to make spinal N
80% motor function - to specific myotomes

Question 8

Dorsal roots

Answer 8

Have swelling where cell bodies live
Enter directly into posterior gray matter
Somite + dermal cells = dermatomes

Question 11

Mesoderm

Answer 11

Becomes cardiovascular system, MSK system and dermal layer of the skin

Question 12

Notochord

Answer 12

Ventral to SC and therefore ectoderm cells
Where the vertebral column and annulus pulposus of the discs develop
Remnant of the notochord is the discs

Question 13

Dermatome

Answer 13

Each level of Somites ( specific dorsal root level) that innervate a specific piece of dermis
N testing based on area of skin innervated
Affiliated with mesoderm and ectoderm - a relationship that will always be maintained

Question 14

Myotomes

Answer 14

Piece of mm that develops and is innervated by specific ventral n root

Question 15

Central canal

Answer 15

Of SC in the middle (potential space In adults)
Can have CSF or be closed
Gray matter in inside
White matter on outside

Question 16

White matter

Answer 16

Outer myelinated fibers of SC
High conduction speed
Information travels long distances
Sensory or motor

Question 17

Spins bifida

Answer 17

Failure of neural tube / VC to close. SC exits thru opening - can cause paralysis

Clinical implication

Question 18

Prosencephalon

Answer 18

Forebrain

Divides into telencephalon and diencephalon

Question 19

Mesencephalon

Answer 19

Mid brain

Question 20

Rhombencephalon

Answer 20

Hindbrain; most caudal

Divides into metencephalon and myelencephalon

Question 21

Telencephalon

Answer 21

Anterior portion of primitive forebrain
Includes cerebral hemispheres which develop into:
Cerebral cortex, olfactory bulbs, basal ganglia
2 lateral ventricles

Question 22

Diencephalon

Answer 22

Posterior part of forebrain
Hypothalamus, thalamus, metathalamus, epithalamus
3rd ventricle

Question 23

Mesencephalon

Answer 23

Midbrain
Tectum and cerebral peduncles
1st brainstem segment

Question 24

Metencephalon

Answer 24

Anterior part of hindbrain
Cerebellum (motor coordination) and pons
4th ventricle

Question 25

Myelencephalon

Answer 25

Posterior part of hindbrain

Medulla oblongata

Question 26

Ventricular system

Answer 26

Hollow spaces within the brain; CSF filled
R and L lateral spaces –> 3rd ventricle –> cerebral aqueduct –> 4th –> outside brain
Central canal exits the 4th ventricle

Question 27

Thalamus

Answer 27

Relay center for sensory info to cortex, all 6 sensory pathways will synapses in thalamus

Question 28

Hypothalamus

Answer 28

Major integrating center for endocrine function and ANS

Question 29

Choroid plexus

Answer 29

Blood vessels in the ventricles that filter blood and produce CSF

Question 30

Gray matter

Answer 30

Inner butterfly shape, not myelinated
Processes info, reflexes: inhibiting/facilitating either reflex activity or information

Outer layer of of brain

Question 31

Somites

Answer 31

Small bodies within skin, mm, and bone
Located at each level of the SC and turn into mm, and dermal layer of skin
Show segmentation of NS
Covered c ectoderm
Become myotomes/dermatomes
Located within the dorsal root ganglion