Neuro: development, brain and spinal cord

Question 1

3 embryonic layers present around 3wks gestation

Answer 1

1. endoderm
2. ectoderm
3. mesoderm

Question 2

ectoderm becomes what?

Answer 2

–> neural plate –> neural tube (@ 3-4 wks gestation) –> CNS

Question 3

mesoderm becomes what?

Answer 3

–> notochord –> then adds vertebral column

…and signals the activation of ectoderm development

Question 4

how does closure occur in the neural tube?

what about neural crests?

Answer 4

starts in the middle and goes in either direction
(important clinically)
neural crests migrate away and become the progenitors of neurons and supporting cells of PNS

Question 5

meningocele and spina bifida

Answer 5

meningocele: protrusion of meninges though gap in the spine

spina bifida: incomplete closure of vertebral column

Question 6

what segments of the neural tube become the brain?

Answer 6

10 most rostral

Question 7

what part of the spinal cord is white and what part is grey? butterfly and surrounding?

Answer 7

butterfly: grey
surrounding: white

Question 8

where is the grey matter in the spinal cord located?

5 locations

Answer 8

1. dorsal root ganglion
2. dorsal horn cell columns
3. sympathetic chain ganglia
4. parasympathetic chain ganglia
5. ventral horn cell columns

Question 9

how are the dermatomes organized on the arms and legs?

Answer 9

in longitudinal stripes- “6 shooters, 7, 8” corresponds to CN that innervate that area (same with the legs/feet)

Question 10

what does the sympathetic chain ganglia include?

Answer 10

pre and para vertebral ganglia

Question 11

what does the parasympathetic chain ganglia include?

Answer 11

the head and the enteric plexus

Question 12

how do afferent and efferent go into the spinal cord?

Answer 12

afferent are sensory and enter dorsal horn

efferent are coming out of the ventral horn going to muscle and glands

Question 13

what are the 4 different afferents that enter the dorsal horn?

Answer 13

2 somatic and 2 ANS

1. SSA: special somatic afferent: joint/tendon perception. reflexes for posture and movement (your elbow tells you that its at 90 degrees)
2. GSA: general somatic afferent: innerv. skin and somatic structures (temp, pain, pressure)
3. SVA: special visceral afferent: gut-related receptors, taste buds and olfactory- ( joy of eating)
4. GVA: general visceral afferent: GI, GU, heart and great vessels (vital reflex circuits + sensation, bladder pressure + stomach fullness)

Question 14

what 3 efferents enter the ventral horn?

Answer 14

1. GVE: general visceral efferent - ANS preganglionic (PNS and SNS)
2. SVE/PE: special visceral or pharyngeal (muscles for chewing +facial expression, pharynx, larynx and muscles to move the head
3. GSE: general somatic efferent: motor output of skeletal muscle - LMNs - lower motor neurons. (“final common pathway” of neurons)

Question 15

upper motor neurons (UPNs) go where?

Answer 15

part of CNS: start in motor cortex of brain and go to spine and are about VOLUNTARY control
(spinoreticular and spinothalamic tracts)

Question 16

which layer of longitudinal tract is present at birth and which is not?

Answer 16

1st and 2nd are present at birth

3rd (neo) is not- present at 2 yo..fine motor skills

Question 17

what are the 3 longitudinal tracts?

Answer 17

1. inner: reticular formation and RAS (brainstem). VITAL reflexes (breathing, cardiovascular function, swallowing and vomit)
2. middle layer (paleo): sensation and motor function. primitive functions- present at birth.
   - spinoreticulo and spinothalamic tracts
3. outer layer (neo): fine motor skills, not present till 2 yo

Question 18

collateral communication pathways

Answer 18

inner and middle longitudinal tracts have collateral branches to BYPASS damage
- none in outer layer - can’t get fine motor skills back

Question 19

3 parts of the brain where RAS is

Answer 19

1. medulla: which does vital reflexes (breathing, cardiovascular, reflex)
2. pons: breathing and balance
3. midbrain: eye movement, auditory and vision

Question 20

where does all sensory info flow through in the brain?

Answer 20

thalamus

Question 21

what does the hypothalamus do?

Answer 21

homeostasis control

Question 22

what are the 4 dural venous sinuses

Answer 22

superior, inferior, cavernous, transverse

Question 23

cavernous vs transeverse dural sinus…where would infection to brain come from?

Answer 23

cavernous: eye and face
transverse: ear

Question 24

classify the spaces: subarachnoid, subdural, epidural

Answer 24

subarachnoid: CSF
subdural: venous (low pressure)
epidural: arterial (high pressure)

Question 25

3 artery areas of brain

Answer 25

1. anterior (internal carotid)
2. middle (internal carotid)
3. posterior (vertebral)
   * circle of willis- where all three connect

Question 26

where do veins drain into from brain?

Answer 26

sinuses then into the interjugular vein

Question 27

4 ventricles of brain- to drain CSF

Answer 27

right and left, 3rd and 4th

Question 28

how does the CSF of the brain drain?

Answer 28

secretes from choroid plexus: right and left ventricle –> 3rd –> 4th –> subarachnoids space –> cisterna in spinal canal OR superior sagittal sinus
(reabs by arachnoid villi)